Peiwen Li

Interests

Research

Fuel cell and electrolysisHydrogen productionRenewable energy technologiesThermal energy storageThermal-driven water technology

Teaching

Thermodynamics; Heat transfer; Fluid mechanics; Numerical heat transferFuel cell analyses and designsRenewable energy systemsEnergy conversion systems; Energy storage Heating, ventilation, air-conditioning, and refrigerationLab instrumentation

Courses

Scholarly Contributions

Journals/Publications

• Haddad, F., & Li, P. (2023).

  Optimization of Dimensions of Smooth and Twisted-Tape-Inserted Tubes for Heat Transfer with NaCl/KCl/MgCl2 Molten Salts by Principle of Entropy Generation Minimization

  . Journal of Solar Energy Engineering, 146(1). doi:10.1115/1.4062719
• Hu, Q., & Li, P. (2023).

  Modeling and Optimal Design of a Desalination System Integrated Between a Glass-Covered Solar Collection Water Chamber and a Heat Dissipating Chimney

  . Journal of Thermal Science and Engineering Applications, 15(5). doi:10.1115/1.4056879
• Li, P. (2023).
  1. Qichao Hu,  Xiaoxin Wang, Ahmed Gamil, Peiwen Li,  Experimental study of a Desalination System Integrated between a Glass-covered Solar Collection Water Chamber and a Heat Dissipating Chimney, Energy Nexus, Vol. 9, p. 100171, 2023.
  . Energy Nexus, 9. doi:https://doi.org/10.1016/j.nexus.2023.100171
• Li, P. (2023). A review to the advancement of long-term energy storage through green hydrogen production via electrolysis of water. Annual Review of Heat Transfer, 26. doi:DOI: 10.1615/AnnualRevHeatTransfer.2023049436
• Li, P. (2023). Facile fabrication of efficient Cu(I)–Y zeolite adsorbent towards the adsorption desulfurization. Microporous and Mesoporous Materials, 350. doi:https://doi.org/10.1016/j.micromeso.2023.112450
• Li, P. (2023). Helical Fins for Concentrated Solar Receivers: Design Optimization and Entropy Analysis. ASME J. of Energy Resources Technology, 145(12). doi:https://doi.org/10.1115/1.4063207
• Li, P. (2023). In-situ Thermophysical Measurement of Flowing Molten Chloride Salt Using Modulated Photothermal Radiometry. Solar Energy, 265. doi:https://doi.org/10.1016/j.solener.2023.112124
• Li, P. (2023). Modeling and Analysis of a Relocatable Solar Tower for Pressurized Water Heating and Storage Providing Low to Medium-Temperature Industrial Process Heat. Energy Conversion and Management, 296. doi:https://doi.org/10.1016/j.enconman.2023.117698
• Li, P. (2023). Modeling and Optimization of a Desalination System Integrated between a Glass-covered Solar Collection Water Chamber and a Heat Dissipating Chimney. Thermal Science and Engineering Application. doi:https://doi.org/10.1115/1.4056879
• Li, P. (2023). Recyclable Co₃O₄/NaF for hydrogen generation from ethyl acetate: The promoting effect between Co₃O₄ and NaF. Fuel, 343.
• Li, P. (2023). Thermal Conductivity Measurement Using Modulated Photothermal Radiometry for Nitrate and Chloride Molten Salts. Int. J. Heat Mass Transfer, 217(124652). doi:https://doi.org/10.1016/j.ijheatmasstransfer.2023.124652
• Pidaparthi, B., Missoum, S., Xu, B., & Li, P. (2023).

  Helical Fins for Concentrated Solar Receivers: Design Optimization and Entropy Analysis

  . Journal of Energy Resources Technology, 145(12). doi:10.1115/1.4063207
• Ding, Y., Cai, Y., Li, P., Gu, S., Song, S., Guan, J., Shen, Y., Han, Y., & He, W. (2022). Recyclable regeneration of NiO/NaF catalyst: hydrogen evolution via steam reforming of oxygen-containing volatile organic compounds. Energy Conversion and Management, 258.
• Ding, Y., Zhang, T., Li, P., Ge, Z., & Shen, Y. (2022). High-efficiency steam reforming of methanol on the surface of a recyclable NiO/NaF catalyst for hydrogen production. Composites Part B, Engineering, 243.
• Li, P., Gamil, A., Ali, B., & Hamid, M. A. (2022). Concentrating solar thermal power generation in Sudan: Potential and challenges. Renewable and Sustainable Energy Reviews.
• Li, P., Missoum, S., & Pidaparthi, B. (2022). Entropy-based Optimization for Heat Enhancement in Tubes with Helical Fins Transfer Enhancement in Tubes with Helical Fins. ASME Journal Heat Transfer, 144.
• Xu, B., Li, P., Hu, Q., Wang, X., Zhang, Y., & Liu, Q. (2022). Experimental Study of Eutectic Molten Salts NaCl/KCl/ZnCl2 Heat Transfer Inside a Smooth Tube for High-Temperature Application. Journal of Solar Energy Engineering, 144(4). doi:10.1115/1.4053974
• Li, P., Gwesha, A. O., & Alfulayyih, Y. M. (2021). Optimization of Fixed Photovoltaic Panel “Tilt” Angles for Maximal Energy Harvest Considering Year-Around Sky Coverage Conditions. ASME Journal of Solar Energy Engineering, 143.
• Missoum, S., Li, P., & Pidaparthi, B. (2021). Entropy-Based Optimization for Heat Transfer Enhancement in Tubes With Helical Fins. Journal of Heat Transfer, 144(1). doi:10.1115/1.4052582
• Wang, K., Li, M., Zhang, Z., Min, C., & Li, P. (2021). Evaluation of alternative eutectic salt as heat transfer fluid for solar power tower coupling a supercritical CO2 Brayton cycle from the viewpoint of system-level analysis. Journal of Cleaner Production, 279.
• Wang, X., Rincon, J. D., Li, P., Zhao, Y., & Vidal, J. (2021). Thermophysical properties experimentally tested for NaCl-KCl-MgCl2 eutectic molten salt as a next-generation high-temperature heat transfer fluids in concentrated solar power systems. Journal of Solar Energy Engineering, 143.
• Zeng, J., Chung, K. M., Wang, Q., Wang, X., Pei, Y., Li, P., & Chen, R. (2021). Measurement of high-temperature thermophysical properties of bulk and coatings using modulated photothermal radiometry. International Journal of Heat and Mass Transfer, 170.
• Alfulayyih, Y., Li, P., & Gwesha, A. O. (2020). A Generic Algorithm for Planning the Year-Round Solar Energy Harvest/Storage to Supply Solar-Based Stable Power. ASME Journal of Solar Energy Engineering, 142(4).
• Chao, W., Diaz, G. V., Wang, K., & Li, P. (2020). 3D-printed tubes with complex internal fins for heat transfer enhancement—CFD analysis and performance evaluation. American Institute of Mathematical Science (AIMS) Energy, 8(1), 27-47. doi:10.3934/energy.2020.1.27
• Chu, L., Gu, S., Jin, Q., Zhu, P., Shen, Y., & Li, P. (2020). Hydrogen production from formaldehyde steam reforming using recyclable NiO/NaF catalyst. International Journal of Hydrogen Energy, 45(53).
• Guo, P., Li, T., Li, P., Zhai, Y., & Li, J. (2020). Study on a novel spray-evaporation multi-effect distillation desalination system. Desalination, 473.
• Li, P., Gwesha, A. O., & Alfulayyih, Y. M. (2020). Optimization of Fixed Photovoltaic Panel “Tilt” Angles for Maximal Energy Harvest Considering Year-Around Sky Coverage Conditions. Journal of Solar Energy Engineering, 143(2). doi:10.1115/1.4048016
• Wang, Y., Li, P., Wang, Z., Yang, B., & Yuan, G. (2020). The Benefit of Using Multiple Thin Tanks Versus a Short Big Tank for Thermal Storage in Ceramic-Sphere Packed Bed With Airflow. Journal of Solar Energy Engineering, 142(2).
• Xu, X., Xu, B., & Li, P. (2020). An O(n) Framework for Internal Coordinate Molecular Dynamics Applicable to Molecules with Arbitrary Constraints and Geometries. MOLECULAR SIMULATION, 46(5), 362-374. doi:10.1080/08927022.2019.1706738
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  Xiankun Xu, Ben Xu & Peiwen Li (2020) An (n) framework for internal coordinate molecular dynamics applicable to molecules with arbitrary constraints and geometries, Molecular Simulation, 46:5, 362-374, DOI: 10.1080/08927022.2019.1706738
• Li, P., Wang, Y., Wang, Z., Yang, B., & Yuan, G. (2019). The Benefit of Using Multiple Thin Tanks Versus a Short Big Tank for Thermal Storage in Ceramic-Sphere Packed Bed With Airflow. Journal of Solar Energy Engineering, 142(2). doi:10.1115/1.4044768
• Li, P., Xue, Z., Shen, Y., Chu, L., Wang, Y., Zhang, Y., Sun, Z., Wang, J., Zeng, Y., & Zhu, S. (2019). NaCl-induced nickel-cobalt inverse spinel structure for boosting hydrogen evolution from ethyl acetate and water. Journal of Materials Chemistry, A(7), 1700-1710. doi:DOI: 10.1039/c8ta10414j
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  The proper design of an NaCl-induced nickel–cobalt inverse spinel structure is reported as a promisingcatalyst for boosting H2 evolution from the energy benign sources of ethyl acetate and water. Thedesigned NiCo0.5Oy/NaCl catalyst exhibits the optimal performance with 100% EA conversion, 88.1%H2 selectivity and high stability during autothermal reforming at 650 C and achieves a very high H2selectivity of 96.3% at 600 C by accelerating the water–gas shifting reaction (the rate-determiningstep). The multiple (NixCo1x)(NiyCo2y)O4 inverse spinel structures play significant roles in the enhancedcatalytic performance. Benefiting from the unique advantages of (i) stable inverse spinel structures, (ii)abundant domains and defects, (iii) abnormal Ni2+/Ni3+ (0.36) and Co2+/Co3+ (3.03) ratios, and (iv) richredox ability, the catalyst possesses high adsorption capacity towards EA and H2O, abundant active sitesand fast electron exchange ability between the reactants and the catalyst. Consequently, the catalystexhibits a highly efficient and robust hydrocarbon fuel reforming performance. These findings will lead tothe development of novel catalysts based on inverse spinels for hydrogen production applications.
• Wei, C., Diaz, G. A., Wang, K., & Li, P. (2019). 3D-printed tubes with complex internal fins for heat transfer enhancement—CFD analysis and performance evaluation. AMER INST MATHEMATICAL SCIENCES-AIMS Energy, 8(1).
• Xue, Z., Shen, Y., Chu, L., Wang, Y., Zhang, Y., Sun, Z., Wang, J., Zeng, Y., Li, P., & Zhu, S. (2019). NaCl-induced nickel–cobalt inverse spinel structure for boosting hydrogen evolution from ethyl acetate and water. Journal of Materials Chemistry A, 7(4).
• Zhang, W., Feng, Y., Chen, Y., Li, P., Zhu, S., & Shen, S. (2019). High-efficiency treatment of PTA wastewater using a biogas jet assisted anaerobic fluidized bed reactor. Environmental technology, 40(12).
• Chen, Y., Feng, Y., Li, P., Shen, S., Zhang, W., & Zhu, S. (2018).

  High-efficiency treatment of PTA wastewater using a biogas jet assisted anaerobic fluidized bed reactor

  . Environmental Technology, 40(12), 1534-1542. doi:10.1080/09593330.2018.1426636
• Li, P. (2018). A systematic comparison of different S-CO2 Brayton cycle layouts based on multi-objective optimization for applications in solar power tower plants.. Applied Energy, 109-121..
• Li, P. (2018). Basic Properties of Eutectic Chloride Salts NaCl-KCl-ZnCl2 and NaCl-KCl-MgCl2 as HTFs and Thermal Storage Media Measured using Simultaneous DSC-TGA. Solar Energy, 162, 431-441.
• Li, P. (2018). Controllable synthesis of carbon nanotubes via autothermal reforming of ethyl acetate. Materials and Design, 141, 150-158..
• Li, P. (2018). Experimental Test of Properties of KCl-MgCl2 Eutectic Molten Salt for Heat Transfer and Thermal Storage Fluid in Concentrated Solar Power Systems. ASME J. Solar Energy Engineering, Vol. 140.
• Li, P. (2018). Mesoporous TiO2-SiO2 adsorbent for ultra-deep desulfurization of organic-S at room temperature and atmospheric pressure. RSC Advances, 8(14), 7579-7587..
• Li, P. (2018). Promoting effects of lanthanum oxide on the NiO/CeO2 catalyst for hydrogen production by autothermal reforming of ethanol. Catalysis Communications, 108, 12-16.
• Li, P., Xue, Z., Shen, Y., Zhang, Y., Li, J., Qin, B., Zhang, J., Zeng, Y., & Zhu, S. (2018). Key Role of Lanthanum Oxychloride: Promotional Effects of Lanthanum in NiLaO _y /NaCl for Hydrogen Production from Ethyl Acetate and Water. Small, 14(34), 1800927. doi:10.1002/smll.201800927
• Li, P. (2017). Hydrogen production via catalytic autothermal reforming of desulfurized Jet-A fuel.. Int. J. Hydrogen Energy, 1932-1941..
• Qiu, Y. u., He, Y., Li, P., & Du, B. (2017). A comprehensive model for analysis of real-time optical performance of a solar power tower with a multi-tube cavity receiver. APPLIED ENERGY, 185, 589-603.
• Hao, Q., Xu, X., Li, P., Molina, E., Wang, K., Dehghani, G., Kohli, A., Kassaee, M. H., Jeter, S. M., & Teja, A. S. (2016). Thermal and Transport Properties of NaCl–KCl–ZnCl2 Eutectic Salts for New Generation High-Temperature Heat-Transfer Fluids. Journal of Solar Energy Engineering, 138(5). doi:10.1115/1.4033793
• Li, P. (2016). Radiation heat transfer enhanced absorber for high temperature solar thermal applications. Ceramic International, 42(8), 10531-10536.
• Li, P., Chen, Y., Chen, L., Xu, Y., Fan, M., Zhu, S., & Shen, S. (2016). Enhanced performance of microbial fuel cells by using MnO2/Halloysite nanotubes to modify carbon cloth anodes. Energy, 109, 620–628. doi:https://doi.org/10.1016/j.energy.2016.05.041
• Li, P., Fang, Z., Lu, C., Ma, D., Wei, L., Ni, Y., Tao, S., & Xu, Z. (2016). Optical properties and thermal stability of La1-xSrxCoO3- (0.2 ≤x≤0.8) ceramics. Solar Energy, 137, 73-79. doi:https://doi.org/10.1016/j.solener.2016.07.057
• Li, P., Hao, Q., Jeter, S. M., & Teja, A. S. (2016). Thermal and Transport Properties of NaCl-KCl-ZnCl2 Eutectic Salts for New Generation High Temperature Heat Transfer Fluids. Journal of Solar Energy Engineering, 138(5), 054501. doi:10.1115/1.4033793
• Li, P., Lu, Y., Zhang, R., Wei, L., Lu, C., Ni, Y., Xu, Z., & Tao, S. (2016). Novel spectral properties for La0.7Ca0.3CrO3 ceramics by Mo6+doping. Material Science: Mater Electron, 27, 2412-2418.
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  Cite this article as: Lu, Y., Zhang, R., Wei, L. et al. J Mater Sci: Mater Electron (2016) 27: 2412. doi:10.1007/s10854-015-4039-3
• Li, P., Xu, B., & Lik Chan, C. (2015). Energy Storage Start-up Strategies for Concentrated Solar Power Plants With a Dual-Media Thermal Storage System. Journal of Solar Energy Engineering, 137(5). doi:10.1115/1.4030851
• Xu, B., Li, P., Waller, P. M., & Huesemann, M. (2015). Evaluation of flow mixing in an ARID-HV algal raceway using statistics of temporal and spatial distribution of fluid particles. Algal Research, 9, 27-39. doi:doi:10.1016/j.algal.2015.02.027
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  This paper analyzes and evaluates the flow mixing in an open channel algal raceway for biofuel production. The flow mixing governs the frequency of how algae cells are exposed to sunlight, due to the fluid movement between the surface and the bottom of the algal raceway, thereby affecting algal growth rate. In this work, we investigated the flow mixing performance in a table-sized model of the High Velocity Algae Raceway Integrated Design (ARID-HV). Various geometries of the raceway channels and dams were considered in both the CFD analysis and experimental flow visualization. In the CFD simulation, the pathlines of fluid particles were analyzed to obtain the distribution of the number of times that particles passed across a critical water depth, Dc, defined as a cycle count. In addition, the distribution of the time period fraction that the fluid particles stayed in the zones above and below Dc was recorded. Such information was used to evaluate the flow mixing in the raceway. The CFD evaluation of the flow mixing was validated using experimental flow visualization, which showed a good qualitative agreement with the numerical results. In conclusion, this CFD-based evaluation methodology is recommended for flow field optimization for open channel algal raceways, as well as for other engineering applications in which flow mixing is an important concern.
• Ben, X., Peiwen, L. i., & Waller, P. (2014). Study of the flow mixing in a novel ARID raceway for algae production. Renewable Energy, 62, 249-257.
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  Abstract: A novel flow field for algae raceways has been proposed, which is fundamentally different from traditional paddlewheel-driven raceways. To reduce freezing and heat loss in the raceway during cold time, the water is drained to a deep storage canal. The ground bed of the new raceway has a low slope so that water, lifted by propeller pump, can flow down in laterally-laid serpentine channels, relying on gravitational force. The flow rate of water is controlled so that it can overflow the lateral channel walls and mix with the main flow in the next lower channel, which thus creates a better mixing. In order to optimize the design parameters of the new flow field, methods including flow visualization, local point velocity measurement, and CFD analysis were employed to investigate the flow mixing features. Different combinations of channel geometries and water velocities were evaluated. An optimized flow field design and details of flow mixing are presented. The study offers an innovative design for large scale algae growth raceways which is of significance to the algae and biofuel industry. © 2013 Elsevier Ltd.
• Li, C., Li, P., Wang, K., & mOLINA, E. e. (2014). Survey of Properties of Key Single and Mixture Halide Salts for Potential Application as High Temperature Heat Transfer Fluids for Concentrated Solar Thermal Power Systems. AIMS (American Institute of Mathematical Science) Journal, 2(2), 133-157.
• Li, P., Xu, B., Han, J., & Yang, Y. (2014). Verification of a Model of Thermal Storate Incorporated with an Extended Lumped Capacitance Method for Various Solid-fluid Structural Combinations. Solar Energy, 105, 71-81.
• Liu, H., Akhtar, Z., Peiwen, L. i., & Wang, K. (2014). Mathematical modeling analysis and optimization of key design parameters of proton-conductive solid oxide fuel cells. Energies, 7(1), 173-190.
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  Abstract: A proton-conductive solid oxide fuel cell (H-SOFC) has the advantage of operating at higher temperatures than a PEM fuel cell, but at lower temperatures than a SOFC. This study proposes a mathematical model for an H-SOFC in order to simulate the performance and optimize the flow channel designs. The model analyzes the average mass transfer and species' concentrations in flow channels, which allows the determination of an average concentration polarization in anode and cathode gas channels, the proton conductivity of electrolyte membranes, as well as the activation polarization. An electrical circuit for the current and proton conduction is applied to analyze the ohmic losses from an anode current collector to a cathode current collector. The model uses relatively less amount of computational time to find the V-I curve of the fuel cell, and thus it can be applied to compute a large amount of cases with different flow channel dimensions and operating parameters for optimization. The modeling simulation results agreed satisfactorily with the experimental results from literature. Simulation results showed that a relatively small total width of flow channel and rib, together with a small ratio of the rib's width versus the total width, are preferable for obtaining high power densities and thus high efficiency. © 2014 by the authors.
• Liu, H., Li, P., Juarez-Robles, D., Wang, K., & Hernandez-Guerrero, A. (2014). Experimental Study and Comparison of Various Designs of Gas Flow Fields to PEM Fuel Cells and Cell Stack Performance. Frontiers in Energy Research, Article 2.
• Tumilowicz, E., Chan, C. L., Li, P., & Xu, B. (2014). An Enthalpy Formulation for Thermocline with Encapsulated PCM Thermal Storage and Benchmark Solution Using the Method of Characteristics. International Journal of Heat and Mass Transfer, 79, 362-377.
• Xinhai, X. X., Zhang, S., Peiwen, L. i., & Shen, Y. (2014). Desulfurization of Jet-A fuel in a fixed-bed reactor at room temperature and ambient pressure using a novel selective adsorbent. Fuel, 117(PART A), 499-508.
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  Abstract: The adsorptive desulfurization of Jet-A fuel (with sulfur concentrations above 1000 ppmw) using a novel, low-cost adsorbent, 10NiO-CeO 2/7.5Al2O3-SiO2 was investigated in fixed-bed tests. The desulfurization was designated to operate at room temperature and ambient pressure. The flow rate of fuel, size of adsorbent particles, and dimensions of an adsorbent-packed fixed-bed were optimized to obtain a high sulfur adsorption capacity per unit mass of adsorbent. At a breakthrough sulfur concentration of 10 ppmw a very high sulfur adsorption capacity of 0.633 mg S/g adsorbent was achieved. At a mean sulfur concentration of 30 ppmw in the treated accumulated fuel, the best capacity achieved is 1.98 mg S/g adsorbent. The scaling-up strategies for the fixed-bed reactor and the method for adsorbent regeneration are also investigated. Finally, preliminary tests of adsorbent regeneration showed that the first-time regenerated adsorbent could recover 83% of the sulfur removal capacity compared to a fresh adsorbent, and a second time regeneration could recover 50.4% of that of fresh adsorbent. © 2013 Elsevier Ltd. All rights reserved.
• Xu, X., Zhang, S., & Li, P. (2014). Autothermal Reforming of n-Dodecane and Desulfurized Jet-A Fuel for Producing Hydrogen-rich Syngas. International Journal of Hydrogen Energy, 39(34), 19593-19602.
• Xu, X., Zhang, S., Li, P., & Shen, Y. (2014). Adsorptive Desulfurization of Liquid Jet-A Fuel at Ambient Conditions with an Improved Adsorbent for On-board Fuel Treatment for SOFC Applications. Journal of Fuel Processing Technology, 124, 140-146.
• Yang, Y., Han, J., Li, P., Hou, H., & Xu, B. (2014). Thermal Energy Storage Characteristics of Sand as Filler Material for Solar Thermocline Tank. CIESC Journal, 65(11), 4285-4292.
• Ben, X. u., Peiwen, L. i., & Waller, P. (2013). Optimization of the flow field of a novel ARID raceway (ARID-HV) for algal production. ASME 2013 7th Int. Conf. on Energy Sustainability Collocated with the ASME 2013 Heat Transfer Summer Conf. and the ASME 2013 11th Int. Conf. on Fuel Cell Science, Engineering and Technology, ES 2013.
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  Abstract: This paper addresses issues of flow field optimization for a water raceway which is used to grow algae for biofuels. An open channel raceway is the typical facility to grow algae in medium to large scales. The algae growth rate in a raceway is affected by conditions of temperature, nutrients, and sunlight intensity etc. These conditions are essentially associated with the fluid mixing in the flow field. Good flow mixing at low consumption of pumping power for the water flow is desirable for an economic algal growth facility. A novel design of an open channel raceway for medium- and large-scale algae growth field has been proposed by the authors previously, which is called High Velocity Algae Raceway Integrated Design (ARID-HV). Optimization analysis using CFD and experimental visualization has been applied to a table-sized ARID-HV test model with various geometries of dams and their spacing in the system. CFD results and flow visualization allow us to understand the flow mixing in the entire raceway. Data is also processed to show the statistics of the locations of 'fluid particles' at different height and time period during one flow path. Different flow field designs were thus compared quantitatively based on this statistics according to the understanding that the "tumbling times" of fluid particles at bottom/top of the water is tightly related to the growth rate of algae. Copyright © 2013 by ASME.
• Li, P., Kane, P., & Mokler, M. (2013). Modeling of solar tracking for giant Fresnel lens solar stoves. Solar Energy, 96, 263-273.
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  Abstract: A fundamental modeling for the optical features and control algorithm has been developed for a solar stove heat collection system which uses a giant Fresnel lens. The modeling work helps to implement autonomous solar tracking in the system by controlling the Fresnel lens to maintain a stationary focal point on the heat-collecting surface of the solar stove. Two-axis solar tracking for the particular work was chosen. The update time interval during tracking causes misalignment of the lens' optical axis versus the sunrays. From modeling, the defocus (due to the misalignment) and the change of the shape and location of the focal point on the static heat-collecting surface could be calculated. The results of the analysis have been incorporated into the control algorithm which has been implemented in the control system of a prototype solar stove which successfully demonstrated the predicted efficient solar tracking. © 2013 Elsevier Ltd.
• Liu, H., & Peiwen, L. i. (2013). Even distribution/dividing of single-phase fluids by symmetric bifurcation of flow channels. International Journal of Heat and Fluid Flow, 40, 165-179.
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  Abstract: This study addresses a fundamental issue of distributing a single-phase fluid flow into a number of flow channels uniformly. A basic mechanism of flow distribution is accomplished through bifurcation of channels that symmetrically split one flow channel into two downstream channels. Applying the basic mechanism, cascades flow distributions are designed to split one flow into a large number of downstream flows uniformly. Some key parameters decisive to the flow distribution uniformity in such a system have been identified, and the flow distribution uniformity of air was studied for several versions of flow distributor designs using CFD analysis. The effect of the key parameters of the flow channel designs to the flow distribution uniformity was investigated. As an example of industrial application, a novel fluid packaging device of high efficiency was proposed and some CFD analysis results for the device were provided. The optimized flow distributor makes a very good uniform flow distribution which will significantly improve the efficiency of fluid packaging. The technology is expected to be of great significance to many industrial devices that require high uniformity of flow distribution. © 2013 Elsevier Inc.
• Liu, H., & Peiwen, L. i. (2013). Maintaining equal operating conditions for all cells in a fuel cell stack using an external flow distributor. International Journal of Hydrogen Energy, 38(9), 3757-3766.
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  Abstract: This paper presents a novel fuel cell stack architecture that allows each fuel cell to work at the same condition, maintaining the same performance from each individual cell and creating a maximum power output from the cell stack. A fuel cell stack having four PEM fuel cells was fabricated to experimentally compare its performance when fuel and air supplying/distribution schemes are different. The performance of the fuel cell stack and individual cells in the stack is measured to achieve a detailed evaluation of the effect of the different fuel and air supplying schemes. Experimental data shows that non-uniform flow distribution to individual cells has a considerable influence on individual cell performance, which affects the power output of the fuel cell stack. The fuel cell stack with the novel approach of fuel and air feeding shows a better power output performance compared to a different fuel and air feeding approach to the fuel cell stack.© 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd.
• Liu, H., & Peiwen, L. i. (2013). Optimization of PEM fuel cell flow channels-modeling analysis and experimental tests. ASME 2013 11th Int. Conf. on Fuel Cell Science, Eng. and Technology Collocated with the ASME 2013 Heat Transfer Summer Conf. and the ASME 2013 7th Int. Conf. on Energy Sustainability, FUELCELL 2013.
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  Abstract: The dimensions of gas flow channels and walls/ribs of PEM fuel cells are optimized using a convenient mathematical model. Experimental work for several PEM fuel cells with modeling-optimized gas flow channels was conducted, and the tested results validate the modeling work and the optimization. The model considered average mass transfer and species' concentrations in flow channels, which allows the determination of an average concentration polarization, the humidity in anode and cathode gas channels, and thus the proton conductivity of membranes, as well as the activation polarization. An electrical circuit for the current and ion conduction is applied to analyze the ohmic losses from anode current collector to cathode current collector. The modeling computation required relatively less computational time and thus can be applied to compute a large number of cases with various flow channel designs and operating parameters for optimization analysis. Optimum ratio of the width of flow channels against the walls/ribs was found from the modeling analysis. In the experimental work, PEM fuel cells were fabricated based on the flow channel dimensions optimized from the modeling analysis. Experimental results agreed with the modeling analysis satisfactorily in respect to the comparison of V-I performance between fuel cells with several optimized designs. The model is recommended as a tool for optimization design of gas flow channels for PEM fuel cells. The optimization results are of significance to the improvement of PEM fuel cell designs and performance. Copyright © 2013 by ASME.
• Liu, H., Peiwen, L. i., & Wang, K. (2013). Optimization of PEM fuel cell flow channel dimensions - Mathematic modeling analysis and experimental verification. International Journal of Hydrogen Energy, 38(23), 9835-9846.
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  Abstract: The objective of this work is to optimize the dimensions of gas flow channels and walls/ribs in a proton-exchange membrane (PEM) fuel cell. To achieve this goal conveniently, a relatively easy-to-approach mathematical model for PEM fuel cells has been developed. The model was used for the design optimization of fuel cells, which were fabricated and experimentally tested to compare the performance and examine these optimization effects. The model analyzes the average mass transfer and species' concentrations in flow channels, which allows the determination of an average concentration polarization, the humidity in anode and cathode gas channels, the proton conductivity of membranes, as well as the activation polarization. An electrical circuit for the current and ion conduction is applied to analyze the ohmic losses from anode current collector to cathode current collector. This model needs relatively less amount of computational time to find the V-I curve of the fuel cell, and thus it can be applied to compute a large amount of cases with different flow channel dimensions and operating parameters for optimization. Experimental tests of several PEM fuel cells agreed with the modeling results satisfactorily. Both simulation and experimental results showed that relatively small widths of flow channels and ribs, together with a small ratio of the rib's width versus channel's width, are preferred for obtaining high power densities. To further demonstrate the advantage of optimized fuel cell designs, two four-cell stacks, one with optimized channel/rib designs and the other without, were compared experimentally and a much better performance of the one with the optimized design was confirmed. Copyright © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
• Tumilowicz, E., Chan, C. L., Ben, X. u., & Peiwen, L. i. (2013). An enthalpy formulation for thermocline with encapsulated PCM thermal storage and benchmark solution using the method of characteristics. ASME 2013 Heat Transfer Summer Conf. Collocated with the ASME 2013 7th Int. Conf. on Energy Sustainability and the ASME 2013 11th Int. Conf. on Fuel Cell Science, Engineering and Technology, HT 2013, 1.
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  Abstract: An enthalpy-based model of thermocline operation general to both single phase and encapsulated phase change filler materials was created in MATLAB. The method of characteristics is applied in space and time, mapping fluid temperature and filler enthalpy to a numerical grid, and in the case of a melting filler, allowing accurate tracking of phase state interfaces to fractional positions of the grid. Careful consideration of various possible heat transfer conditions along with placement of phase state interfaces in the numerical grid allows for extreme versatility and accuracy in model application. Input of specific fluid and filler properties, tank size, time of operation, and initial and boundary conditions returns a full representation to any desired amount of charge/discharge processes or cycles. The paper covers mathematical formulation, certain intricacies of numerical implementation, model verification, and the beginnings of application to prove proper operation and generality. Copyright © 2013 by ASME.
• Wang, K., Li, P., & Arabyan, A. (2013). Achieving quasi-isothermal air compression with multistage compressors for large-scale energy storage. ASME 2013 7th Int. Conf. on Energy Sustainability Collocated with the ASME 2013 Heat Transfer Summer Conf. and the ASME 2013 11th Int. Conf. on Fuel Cell Science, Engineering and Technology, ES 2013.
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  Abstract:The round trip efficiency of compressed air for energy storage is greatly limited by the significant increase in the temperature of the compressed air (and the resulting heat loss) in high-ratio adiabatic compression. This paper introduces a multi-stage compression scheme with low-compression-ratio compressors and inter-compressor natural convection cooling resulting in a quasi-isothermal compression process that can be useful for large-scale energy storage. When many low pressure ratio compressors work inline, a high overall compression ratio can be achieved with high efficiency. The quasi-isothermally compressed air can then be expanded adiabatically in turbines to generate power with the addition of thermal energy, from either fuel or a solar thermal source. This paper presents mathematical models of such an energy storage system and discusses its round-trip performance with different operating schemes. Copyright © 2013 by ASME.
• Xinhai, X. u., Peiwen, L. i., & Shen, Y. (2013). Small-scale reforming of diesel and jet fuels to make hydrogen and syngas for fuel cells: A review. Applied Energy, 108, 202-217.
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  Abstract: This paper reviews the technological features and challenges of autothermal reforming (ATR) of heavy hydrocarbon fuels for producing hydrogen and syngas onboard to supply fuels to fuel cells for auxiliary power units. A brief introduction at the beginning enumerates the advantages of using heavy hydrocarbon fuels onboard to provide hydrogen or syngas for fuel cells such as solid oxide fuel cells (SOFCs). A detailed review of the reforming and processing technologies of diesel and jet fuels is then presented. The advantages of ATR over steam reforming (SR) and partial oxidation reforming (POX) are summarized, and the ATR reaction is analyzed from a thermodynamic point of view. The causes and possible solutions to the major problems existing in ATR reactors, including hot spots, formation of coke, and inhomogeneous mixing of fuel, steam, and air, are reviewed and studied. Designs of ATR reactors are discussed, and three different reactors, one with a fixed bed, one with monoliths, and one with microchannels are investigated. Novel ideas for design and startup strategies for ATR reactors are proposed at the end of the review. © 2013 Elsevier Ltd.
• Xinhai, X. u., Zhang, S., & Peiwen, L. i. (2013). Desulfurization of liquid phase jet-A fuel by selective adsorption at room temperature. ASME 2013 11th Int. Conf. on Fuel Cell Science, Eng. and Technology Collocated with the ASME 2013 Heat Transfer Summer Conf. and the ASME 2013 7th Int. Conf. on Energy Sustainability, FUELCELL 2013.
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  Abstract: To produce syngas from reforming of jet fuels for fuel-cell-based auxiliary power units, it is necessary to keep the fuel ultraclean of sulfur. Several Ni-Ce based adsorbents for sulfur cleaning from jet-A fuel under room temperature were developed and tested in fixed bed reactors in this work. The adsorbent preparation procedure and calcination atmosphere were optimized for the highest adsorbent desulfurization capacity. Desulfurization performance due to the ratio of fixed bed column diameter (Dc) and adsorbent particle size (Dp) and liquid hourly space velocity (LHSV) were also investigated in a factorial experiment. The adsorbents can effectively remove sulfur in Jet- A fuel from over 1000 ppmw level to below 30 ppmw. The highest sulfur adsorption capacity achieved is 2.44 mg S/g adsorbent at the breakthrough point of 30 ppmw. To effectively scale up the fixed bed reactor, the LHSV should be kept lower than 0.65 and the Dc/Dp needs to be larger than 124. Copyright © 2013 by ASME.
• Xinhai, X. u., Zhang, S., Peiwen, L. i., & Shen, Y. (2013). Equilibrium and kinetics of Jet-A fuel desulfurization by selective adsorption at room temperatures. Fuel, 111, 172-179.
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  Abstract: The performance of desulfurization of Jet-A fuel at room temperature and atmospheric pressure by using an innovative Nickel-Cerium (Ni-Ce)-based adsorbent is investigated in this work. The adsorbent preparation conditions, including the calcination temperature and length of time, and the compositions of support materials and catalysts were optimized to obtain the best efficiency of sulfur removal. The effects of the adsorbent-fuel mass ratio and the interaction time of adsorbent to fuel on the desulfurization performance were also investigated through batch-test experiment. The sulfur adsorption equilibrium and kinetics were examined. The results showed that the BET model can best represent the equilibrium isotherm, and a pseudo-second order model can best fit the kinetics data. For Jet-A fuel in a total sulfur concentration of 1037 ppmw, the lowest achieved sulfur concentration at room temperature in the treated fuel was 22.13 ppmw. The corresponding equilibrium adsorptive capacity at this maximum desulfurization efficiency was found to be 1.32 mg S/g adsorbent. This is a significant achievement regarding the desulfurization efficiency, especially at room temperature and using commercial Jet-A fuel with no pretreatment. © 2013 Elsevier Ltd. All rights reserved.
• Ben, X. u., Li, P., & Chan, C. L. (2012). Extending the validity of lumped capacitance method for large Biot number in thermal storage application. Solar Energy, 86(6), 1709-1724.
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  Abstract: In a typical thermal energy storage system, a heat transfer fluid is usually used to deposit/extract heat when it flows through a packed bed of solid thermal storage material. A one-dimensional model of the heat transfer and energy storage/extraction for a packed-bed thermal storage system has been developed previously by the authors. The model treats the transient heat conduction in the thermal storage material by using the lumped capacitance method, which is not valid when the Biot number is large. The current work presents an effective heat transfer coefficient between the solid and fluid for large Biot numbers. With the corrected heat transfer coefficient, the lumped capacitance method can be applied to model the thermal storage in a wide range of Biot numbers. Four typical structures for the solid thermal storage material are considered. Formulas for the effective heat transfer coefficient (and effective Biot number) are presented. To verify the prediction by the lumped capacitance method using the effective heat transfer coefficient, we compare the results to the corresponding analytical solutions. The results are in very good agreement. The effective heat transfer coefficient extended the validity of the lumped capacitance method to large Biot numbers, which is of significance to the analysis of thermal energy storage systems. © 2012 Elsevier Ltd.
• Liu, H., Peiwen, L. i., & Hartz, A. (2012). A fuel cell stack architecture to make all cells have equal operational conditions and performance. ASME 2012 10th International Conference on Fuel Cell Science, Engineering and Technology Collocated with the ASME 2012 6th International Conference on Energy Sustainability, FUELCELL 2012, 153-159.
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  Abstract: This paper presents a novel architecture for a proton-exchange membrane (PEM) fuel cell stack, which is based on the concept that every cell in the stack works at the same condition and thus each cell has the same contribution to the overall output voltage and power. To meet this proposed requirement, special flow distributors were used to evenly distribute fuel and airflow to every fuel cell in the stack. Details of the flow distributor and experimental tests of a four-cell fuel cell stack are presented in the paper. The experimental results demonstrated the desired high performance of the fuel cell stack. It is proved that the novel architecture for fuel cell stack is successful and of significance to the development of high performance fuel cell stacks. Copyright © 2012 by ASME.
• Liu, H., Peiwen, L. i., Lew, J. V., & Juarez-Robles, D. (2012). Experimental study of the flow distribution uniformity in flow distributors having novel flow channel bifurcation structures. Experimental Thermal and Fluid Science, 37, 142-153.
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  Abstract: Symmetric flow channel bifurcations were proposed in this article for the purpose of creating better flow uniformity in flow distribution. Two categories of flow channel bifurcation structures were considered. Characteristic parameters that can identify and standardize the structural design of the flow channel bifurcations were designated. Six flow distributors, divided into two groups, were fabricated for experimental testing. Each group of distributors is distinguished by one basic channel bifurcation structure category, but distributors within a group differ in the characteristic parameters exhibited in their designs. The axial velocities of the airflow at the exit of the distributor flow channels were measured experimentally, and the uniformity of the flow distribution was investigated for each distributor. Comparison and evaluation of the figure-of-merit of flow distribution uniformity is made for the six studied flow distributors. The novel concept of symmetrically bifurcated flow distributor designs and the experimental results and conclusions obtained in this study are of great significance to the development of high performance industrial devices, such as heat exchangers, reactors, fuel cells, heat sinks, and fluid product packaging machines. © 2011 Elsevier Inc.
• Park, J., Peiwen, L. i., & Bae, J. (2012). Analysis of chemical, electrochemical reactions and thermo-fluid flow in methane-feed internal reforming SOFCs: Part II-temperature effect. International Journal of Hydrogen Energy, 37(10), 8532-8555.
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  Abstract: In order to study the heat and mass transfer characteristics of direct internal reforming solid oxide fuel cells (DIR SOFCs), this research conducted a 3D numerical simulation to a large single cell having an active area of 25 cm 2 with parallel fuel and air flow channels. Reaction rate distributions by the chemical kinetics models are presented as numerical results. The electrochemical oxidations of carbon monoxide and hydrogen were both considered to contribute to the fuel cell local current densities. The average current density contributed by carbon monoxide was found being as high as 568.7 A/m 2 under an operation temperature of 850°C, which was 10 times greater than that under a temperature of 650°C. When considering the current density contributed by electrochemical reaction of hydrogen, an average current density of 7949.2 A/m 2 was seen at the temperature of 850°C. The total average current density under operating temperature of 650°C was as high as 3802.9 A/m 2, and it increased to 8517.9 A/m 2 under an operating temperature of 850°C. The effect of the inlet fuel and air temperature to the maximum and average current densities due to electrochemical reactions of carbon monoxide and hydrogen were also investigated. © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
• Park, J., Peiwen, L. i., & Bae, J. (2012). Analysis of chemical, electrochemical reactions and thermo-fluid flow in methane-feed internal reforming SOFCs: Part i - Modeling and effect of gas concentrations. International Journal of Hydrogen Energy, 37(10), 8512-8531.
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  Abstract: Direct internal reforming solid oxide fuel cells (DIR SOFCs) have complicated distributions of temperature and species concentrations due to various chemical and electrochemical reactions. The details of these properties are studied by a 3-D numerical simulation in this work. The simulation modeling used governing equations (mass, momentum, energy and species balance equations) generally suitable to porous medium with porosity variable of zero (solid), 0.3 (porous medium) and 1.0 (fluid). Chemical kinetics equations for the internal reforming and shift reactions based on the Langmuir-Hinshelwood model were incorporated. Hydrogen and carbon monoxide oxidations were considered both participating in electrochemical reactions. The experimentally measured current density-potential curves were compared with the simulation data to validate the code, which revealed that the simulation model was able to predict the dilution effect of nitrogen and the mass transfer under high current densities. It is found that the temperature dramatically declined near the fuel inlet with strong endothermic reactions, but it increased along the fluid flow with electrochemically exothermic reactions. A low steam-to-carbon ratio (SCR) led to high steam reforming and water gas shift reaction rates, which generated a greater amount of hydrogen. Therefore, current density increased with low SCR. The average current density due to carbon monoxide electrochemical oxidation varies from 205.3 A/m 2 under an SCR of 2.0 to 47.6 A/m 2 under an SCR of 4.0. The average current density due to hydrogen electrochemical oxidation was 5535.4 A/m 2 under an SCR of 2.0, which was 27 times higher than that of carbon monoxide. The total current density ranged from 5740.8 A/m 2 under an SCR of 2.0 to 2268.9 A/m 2 under an SCR of 4.0. © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
• Peiwen, L. i., Ki, J., & Liu, H. (2012). Analysis and optimization of current collecting systems in PEM fuel cells. International Journal of Energy and Environmental Engineering, 3(1), 1-10.
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  Abstract: This paper presents analytical and experimental studies on optimization of the gas delivery and current collection system in a proton exchange membrane (PEM) fuel cell for the objective of reducing ohmic loss, thereby achieving higher power density. Specifically, the dimensions of current collection ribs as well as the rib distribution were optimized to get a maximized power density in a fuel cell. In the modeling process, the power output from a fixed area of membrane is calculated through analysis of an electrical circuit simulating the current from electrochemical reaction flowing to the current collectors. Current collectors of two-dimensional ribs and three-dimensional pillars were considered. Analyses found that three-dimensional pillars allow higher power density in a PEM fuel cell. Considering the mass transfer enhancement effect, three-dimensional pillars as current collectors in gas flow field may be a good choice if the fuel cell operates at low current density and there is no liquid water blocking the flow channels. The analyses did not consider the existence of liquid water, meaning the current density is not very high. The study concluded that decreasing the size of both the current collector and its control area yields a significant benefit to a higher power density. A preliminary experimental test in a PEM fuel cell has verified the conclusion of the analytical work. © 2012 Li et al; licensee Springer.
• Peiwen, L. i., Lew, J. V., Chan, C., Karaki, W., Stephens, J., & O'Brien, J. (2012). Similarity and generalized analysis of efficiencies of thermal energy storage systems. Renewable Energy, 39(1), 388-402.
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  Abstract: This paper examined the features of three typical thermal storage systems including: 1) direct storage of heat transfer fluid in containers, 2) storage of thermal energy in a packed bed of solid filler material, with energy being carried in/out by a flowing heat transfer fluid which directly contacts the packed bed, and 3) a system in which heat transfer fluid flows through tubes that are imbedded into a thermal storage material which may be solid, liquid, or a mixture of the two. The similarity of the three types of thermal storage systems was discussed, and generalized energy storage governing equations were introduced in both dimensional and dimensionless forms. The temperatures of the heat transfer fluid during energy charge and discharge processes and the overall energy storage efficiencies were studied through solution of the energy storage governing equations. Finally, provided in the paper are a series of generalized charts bearing curves for energy storage effectiveness against four dimensionless parameters grouped up from many of the thermal storage system properties including dimensions, fluid and thermal storage material properties, as well as the operational conditions including mass flow rate of the fluid, and the ratio of energy charge and discharge time periods. Engineers can conveniently look up the charts to design and calibrate the size of thermal storage tanks and operational conditions without doing complicated individual modeling and computations. It is expected that the charts will serve as standard tools for thermal storage system design and calibration. © 2011 Elsevier Ltd.
• Ramos-Alvarado, B., Hernandez-Guerrero, A., Juarez-Robles, D., & Peiwen, L. i. (2012). Numerical investigation of the performance of symmetric flow distributors as flow channels for PEM fuel cells. International Journal of Hydrogen Energy, 37(1), 436-448.
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  Abstract: This work reports on the performance of a single PEM fuel cell using symmetric flow patterns as gas delivery channels. Three flow patterns, two symmetric and one serpentine, are taken from the literature on cooling of electronics and they are implemented in a computational model as gas flow channels in the anode and cathode side of a PEMFC. A commercial CFD code was used to solve the physics involved in a fuel cell namely: the flow field, the mass conservation, the energy conservation, the species transport, and the electric/ionic fields under the assumptions of steady state and single phase. An important feature of the current modeling efforts is the analysis of the main irreversibilities at different current densities showing the main energy dissipation phenomena in each cell design. Also, the hydraulic performance of the flow patterns was studied by evaluating the pressure drop and pumping power. The first part of this work reveals the advantages of using a serpentine pattern over the base symmetric distributors. The second part is an optimization of the symmetric patterns using the entropy minimization criteria. Such an optimization led to the creation of a flow structure that promotes an improved performance from the point of view of power generation, uniformity of current density, and low pumping power. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
• Shen, Y., Peiwen, L. i., Xinhai, X. u., & Liu, H. (2012). Selective adsorption for removing sulfur: A potential ultra-deep desulfurization approach of jet fuels. RSC Advances, 2(5), 1700-1711.
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  Abstract: Jet fuels are strategic fuels widely used in airplanes. Through appropriate reforming and shifting processing, jet fuels can be converted into syngas, which is a suitable fuel to solid oxide fuel cells for many auxiliary and backup power units. Integrated micro fuel processors in combination with solid oxide fuel cell (SOFC) stacks using jet fuels have been viewed as attractive portable power sources. Because the sulfur in jet fuels easily causes catalyst poisoning for fuel processing reactions and the electrochemical reactions in fuel cells, ultra-deep sulfur removal in jet fuels and many other hydrocarbon fuels has become a very important and active research subject worldwide in the last 15 years. Amongst the state-of-the-art technologies, selective adsorption for removing sulfur (SARS) is emerged to be very attractive. SARS has been regarded as the most promising approach because it obtains ultra-deep desulfurization efficiency at ambient temperature and atmospheric pressure without hydrogen consumption. In this paper, we survey the current status and prospect of the SARS technology for jet fuels, and will discuss some important issues remaining for the SARS technology in the future. The final goal of this survey is to find/innovate a promising method for jet fuel desulfurization, which is most suitable for supplying fuels to solid oxide fuel cell auxiliary and backup power units. © 2012 The Royal Society of Chemistry.
• Shen, Y., Xinhai, X. u., & Peiwen, L. i. (2012). A novel potential adsorbent for ultra deep desulfurization of jet fuels at room temperature. RSC Advances, 2(15), 6155-6160.
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  Abstract: Using jet fuels in an integrated system by micro fuel processors and SOFC stacks for portable power sources is very attractive. This technology needs ultra-deep desulfurization of jet fuels to maintain high performance of fuel processors and SOFCs. So far, investigations on the adsorbents for direct ultra-deep desulfurization of jet fuels with high sulfur content at room temperature and atmospheric pressure are insufficient, and the achieved desulfurization performance is not satisfactorily high. This article presents the design and analysis of a new adsorbent, Ni-Ce/Al 2O 3-SiO 2, for direct desulfurization of jet-A fuel with total sulfur content of 949.03 mg kg -1 at room temperature and atmospheric pressure without any other assisted reaction conditions. Experimental tests were conducted and high desulfurization efficiency (96.43%) was obtained, which verifies the expected effect. The analysis and experimental data demonstrates broad application prospects of the Ni-Ce/Al 2O 3-SiO 2 adsorbent for room temperature and atmospheric pressure ultra-deep desulfurization of high-sulfur-content jet fuels. This journal is © 2012 The Royal Society of Chemistry.
• Valmiki, M. M., Karaki, W., Peiwen, L. i., Lew, J. V., Chan, C., & Stephens, J. (2012). Experimental investigation of thermal storage processes in a thermocline tank. Journal of Solar Energy Engineering, Transactions of the ASME, 134(4).
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  Abstract: This paper presents an experimental study of the energy charge and discharge processes in a packed bed thermocline thermal storage tank for application in concentrated solar power plants. A mathematical analysis was provided for better understanding and planning of the experimental tests. The mathematical analysis indicated that the energy storage effectiveness is related to fluid and solid material properties, tank dimensions, packing schemes of the solid filler material, and the durations of the charge and discharge times. Dimensional analysis of the governing equations was applied to consolidate many parameters into a few dimensionless parameters, allowing scaling from a laboratory system to an actual industrial application. Experiences on the system design, packing of solid filler material, system operation, and data analysis in a laboratory-scale system have been obtained in this work. These data are used to validate a recently published numerical solution method. The study will benefit the application of thermocline thermal storage systems in the large scale concentrated solar thermal power plants in industry. © 2012 American Society of Mechanical Engineers.
• Waller, P., Ryan, R., Kacira, M., & Peiwen, L. i. (2012). The algae raceway integrated design for optimal temperature management. Biomass and Bioenergy, 46, 702-709.
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  Abstract: The Algae Raceway Integrated Design (ARID) minimizes diurnal and seasonal temperature fluctuations and maintains temperature within the optimal range, between 15 and 30 °C, during day and night and during all seasons in Tucson, Arizona. The system regulates temperature by adjusting the water surface area and thus regulates the energy transfer to and from the atmosphere and raceway. A temperature model of the raceway was developed and was based on a standardized energy balance model for agricultural crops. The model includes the Penman-Monteith evapotranspiration equation, long wave radiation, short wave radiation, sensible heat transfer (convection) and soil heat flux. The temperature model predicted minimum daily raceway water temperature within 1-2 °C over a range of atmospheric conditions during a 21 day algae growth experiment. Because the model is based on standard agricultural weather station data, it can be used in any location that is in proximity to an agricultural weather station. The model automatically downloads data from any weather station in Arizona, allows specification of various cover and liner conditions, specifies the timing of circulation, and has a dynamic simulation mode. © 2012 Elsevier Ltd.
• Karaki, W., Peiwen, L. i., Lew, J. V., Valmiki, M. M., Chan, C., & Stephens, J. (2011). Experimental investigation of thermal storage processes in a thermocline storage tank. ASME 2011 5th International Conference on Energy Sustainability, ES 2011, 1389-1396.
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  Abstract: This paper presents an experimental study and analysis of the heat transfer of energy charge and discharge in a packed-bed thermocline thermal storage tank for application in concentrated solar thermal power plants. Because the energy storage efficiency is a function of many parameters including fluid and solid properties, tank dimensions, packing dimensions, and time lengths of charge and discharge, this paper aims to provide experimental data and a proper approach of data reduction and presentation. To accomplish this goal, dimensionless governing equations of energy conservation in the heat transfer fluid and solid packed-bed material are derived. The obtained experimental data will provide a basis for validation of mathematical models in the future. Copyright © 2011 by ASME.
• Liu, H., & Peiwen, L. i. (2011). CFD assisted design optimization of a flow distributor for uniform fluid distribution. ASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011, 6(PARTS A AND B), 97-106.
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  Abstract: This study addresses a fundamental issue of distributing a fluid flow into a number of flow channels uniformly. A basic mechanism of flow distribution is accomplished through a channel bifurcation that symmetrically split one flow channel into two downstream channels. Applying the basic mechanism, cascades flow distributions are designed to split one flow into a large number of downstream flows uniformly. Some key parameters decisive to the flow distribution uniformity in such a system have been recognized, and the flow distribution uniformity was studied for several versions of flow distributor designs using CFD analysis. The effect of the key parameters of the flow channel designs to the flow distribution uniformity was investigated. As an example of industrial application, a novel fluid packaging device was proposed and some CFD analysis results for the device were provided. The optimized flow distributor makes a very good uniform flow distribution which will significantly improve the efficiency of fluid packaging. The technology is expected to be of great significance to many industrial devices that require high uniformity of flow distribution. Copyright © 2011 by ASME.
• Peiwen, L. i., Lew, J. V., Karaki, W., Chan, C., Stephens, J., & Wang, Q. (2011). Generalized charts of energy storage effectiveness for thermocline heat storage tank design and calibration. Solar Energy, 85(9), 2130-2143.
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  Abstract: Solar thermal energy storage is important to the daily extended operation and cost reduction of a concentrated solar thermal power plant. To provide industrial engineers with an effective tool for sizing a thermocline heat storage tank, this paper used dimensionless heat transfer governing equations for fluid and solid filler material and studied all scenarios of energy charge and discharge processes. It has been found that what can be provided through the analysis is a series of well-configured general charts bearing curves of energy storage effectiveness against four dimensionless parameters grouped up from the storage tank dimensions, properties of the fluid and filler material, and operational conditions (such as mass flow rate of fluid and energy charge and discharge periods). As the curves in the charts are generalized, they are applicable to general thermocline heat storage systems. Engineers can conveniently look up the charts to design and calibrate the dimensions of thermocline solar thermal storage tanks and operational conditions, without doing complicated modeling and computations. It is of great significance that the generalized charts will serve as tools for thermal energy storage system design and calibration in energy industry. © 2011 Elsevier Ltd.
• Peiwen, L. i., Tao, G., & Liu, H. (2011). Effect of the geometries of current collectors on the power density in a solid oxide fuel cell. International Journal of Energy and Environmental Engineering, 2(3), 1-11.
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  Abstract: An analytical model is proposed and an analysis is conducted for solid oxide fuel cells with goals of higher power densities. The analytical model is designed to help optimize the size, spacing, and geometrical shapes of current collectors. The model fully considers the ohmic, species concentration, and activation polarizations. From the analysis of several cases, it is recommended that 3D pillars be used for the current collectors in SOFCs while incorporating appropriate measures to ensure a uniform flow distribution. It is also clear that unless limited by the fabrication technologies for the bipolar plates, smaller control areas and current collectors are preferable for SOFCs to have higher power densities.
• Ramos-Alvarado, B., Peiwen, L. i., Liu, H., & Hernandez-Guerrero, A. (2011). CFD study of liquid-cooled heat sinks with microchannel flow field configurations for electronics, fuel cells, and concentrated solar cells. Applied Thermal Engineering, 31(14-15), 2494-2507.
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  Abstract: A study of the heat transfer performance of liquid-cooled heat sinks with conventional and novel micro-channel flow field configurations for application in electronic devices, fuel cells, and concentrated solar cells is presented in this paper. The analyses were based on computations using the CFD software ANSYS FLUENT®. The flow regime in heat sinks is constrained to laminar flow in the study. Details of the heat transfer performance, particularly, the uniformity of temperature distribution on the heating surface, as well as the pressure losses and pumping power in the operation of the studied heat sinks were obtained. Comparisons of the flow distribution uniformity in multiple flow channels, temperature uniformity on heating surfaces, and pumping power consumption of heat sinks with novel flow field configurations and conventional flow field configurations were conducted. It was concluded that the novel flow field configurations studied in this work exhibit appreciable benefits for application in heat sinks. © 2011 Elsevier Ltd. All rights reserved.
• T., J., Peiwen, L. i., Chan, C. L., Karaki, W., & Stephens, J. (2011). Analysis of heat storage and delivery of a thermocline tank having solid filler material. Journal of Solar Energy Engineering, Transactions of the ASME, 133(2).
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  Abstract: Thermal storage has been considered as an important measure to extend the operation of a concentrated solar power plant by providing more electricity and meeting the peak demand of power in the time period from dusk to late night everyday, or even providing power on cloudy days. Discussed in this paper is thermal energy storage in a thermocline tank having a solid filler material. To provide more knowledge for designing and operating of such a thermocline storage system, this paper firstly presents the application of method of characteristics for numerically predicting the heat charging and discharging process in a packed bed thermocline storage tank. Nondimensional analysis of governing equations and numerical solution schemes using the method of characteristics were presented. The numerical method proved to be very efficient, accurate; required minimal computations; and proved versatile in simulating various operational conditions for which analytical methods cannot always provide solutions. Available analytical solutions under simple boundary and initial conditions were used to validate the numerical modeling and computation. A validation of the modeling by comparing the simulation results to experimental test data from literature also confirmed the effectiveness of the model and the related numerical solution method. Finally, design procedures using the numerical modeling tool were discussed and other issues related to operation of a thermocline storage system were also studied. © 2011 American Society of Mechanical Engineers.
• Valmiki, M. M., Peiwen, L. i., Heyer, J., Morgan, M., Albinali, A., Alhamidi, K., & Wagoner, J. (2011). A novel application of a Fresnel lens for a solar stove and solar heating. Renewable Energy, 36(5), 1614-1620.
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  Abstract: This paper presents a novel design and the prototyped solar cooking stove which uses a large Fresnel lens for the concentration of sunlight. The technology demonstrates high safety and efficiency of solar cooking and heating using Fresnel lenses which are low cost and available from off-the-shelf. The stove has a fixed heat-receiving area located at the focal point of the lens. The sunlight tracking system rotates the Fresnel lens about its focal point in both zenith and azimuth angles. The tracking is accomplished through a revolving motion of two rotation arms that hold the lens and a horizontal rotation of a platform that the lens system stands on. The rotation of the arms tracks the sunlight in zenith plane, while the rotation of the platform tracks in the azimuth plane. Since the solar tracking allows the Fresnel lens to concentrate sunlight to a fixed small heat-receiving area, relatively low heat loss and high energy efficiency is made possible. The heat is used to maintain a stovetop surface at temperatures around as high as 300 °C, which is practical for cooking applications in a very safe, user-friendly, and convenient manner. The system also demonstrates the possibility of transferring heat using a working fluid for indoor heating and cooking. Wider applications using the system for solar thermal collection and utilization are also undergoing development. © 2010 Elsevier Ltd.
• Karaki, W., T., J., Peiwen, L. i., Chan, C. L., & Stephens, J. (2010). Heat transfer in thermocline storage system with filler materials: Analytical model. ASME 2010 4th International Conference on Energy Sustainability, ES 2010, 2, 725-734.
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  Abstract: Parabolic trough power systems utilizing concentrated solar energy have proven their worth as a means for generating electricity. However, one major aspect preventing the technologies widespread acceptance is the deliverability of energy beyond a narrow window during peak hours of the sun. Thermal storage is a viable option to enhance the dispatchability of the solar energy and an economically feasible option is a thermocline storage system with a low-cost filler material. Utilization of thermocline storage facilities have been studied in the past and this paper hopes to expand upon that knowledge. The heat transfer between the heat transfer fluid and filler materials are governed by two conservation of energy equations, often referred as Schumann [1] equations. We solve these two coupled partial differential equations using Laplace transformation. The initial temperature distribution can be constant, linear or exponential. This flexibility allows us to apply the model to simulate unlimited charging and discharging cycles, similar to a day-today operation. The analytical model is used to investigate charging and discharging processes, and energy storage capacity. In an earlier paper [2], the authors presented numerical solution of the Schumann equations using method of characteristics. Comparison between analytical and numerical results shows that they are in very good agreement. © 2010 by ASME.
• Liu, H., Peiwen, L. i., & Lew, J. V. (2010). CFD study on flow distribution uniformity in fuel distributors having multiple structural bifurcations of flow channels. International Journal of Hydrogen Energy, 35(17), 9186-9198.
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  Abstract: This work studied the issues of uniform flow distribution for general application in fuel cells, fuel processing chemical reactors, and other industrial devices. A novel method for uniform flow distribution was proposed, in which multiple levels of flow channel bifurcations were considered to uniformly distribute a flow into 2n flow channels at the final stage, after n levels of bifurcation. To study the effect of the flow channel bifurcation structure and dimensions on the flow distribution uniformity, numerical analysis was conducted. Parameters such as the flow channel length and width at each level of bifurcation as well as the curvature of the turning area of flow channels were particularly investigated. Important results concerning the geometrical design of flow distributors for better flow distribution and uniformity are presented. The best structure of a flow distributor was selected based on the criterion of flow distribution uniformity and low pressure loss. Since the studied novel flow distributor distributes a flow into a number of parallel channels in a remarkable uniformity, the flow distribution structure is expected to be widely used in fuel cells, fuel cell systems, and variety of industrial reactors and heat exchangers to significantly improve the performance of these devices. The studied flow regime is limited to laminar flow. A CFD tool FLUENTat the was used for the simulation. The numerical treatment of convection terms in governing equations was based on the QUICK scheme, and the coupled computation solving for pressure and velocity fields was based on the SIMPLE algorithm. © 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.
• Milobar, D. G., Peiwen, L. i., & O'Brien, J. E. (2010). Analytical study, 1-D optimization modeling, and testing of electrode supported solid oxide electrolysis cells. Proceedings of the ASME Micro/Nanoscale Heat and Mass Transfer International Conference 2009, MNHMT2009, 2, 271-281.
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  Abstract: The need for an infrastructure to provide hydrogen as a next generation energy carrier is ever increasing. High temperature solid oxide electrolysis cells (SOECs) have been proven to be a viable technology in the production of hydrogen [1], With the increasing use of SOECs in various operating environments it is important to be able to specify the best SOEC for any given situation. We have developed a straightforward model to estimate cell performance in a timely and inexpensive manner. Composite electrode planer type SOEC models have been developed previously. It is a common assumption that all electrochemical reactions in these cells occur at the interface of the electrolyte and the electrode [2], It has been shown by S. Gewies et al. [3] that the reactions occurring throughout a Ni/YSZ cermet electrode occur in a nonlinear fashion . Our one dimensional model has been developed to optimize SOECs with composite electrodes. This model takes into account ohmic, activation, and concentration polarizations. The electrochemical reaction that occurs within the electrode functional layers has been accounted for in the calculation of the concentration polarization. This is believed to give a more realistic view of the mass transfer that occurs in SOECs with composite electrodes via a simple and straightforward 1 -D model. Copyright © 2009 by ASME.
• Ramos-Alvarado, B., Hernandez-Guerrero, A., Juarez-Robles, D., Peiwen, L. i., & Rubio-Arana, J. (2010). Parametric study of a symmetric flow distributor. ASME International Mechanical Engineering Congress and Exposition, Proceedings, 9(PART B), 883-889.
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  Abstract: A parametric study was conducted in order to reduce the pressure drop and to improve the uniformity of flow distribution in a symmetric flow distributor. A CFD model was employed to simulate the flow behavior by solving the Navier-Stokes equations in a complete 3D model. The present work is a complete parametric study of a base model, reported in previous studies, but keeping the same flow pattern. To improve the performance of the base design, three known successive parametric ratios, as functions of the hydraulic diameters of the channels, were tested in order to study the advantages and disadvantages of each one in terms of two dimensionless parameters that measure the uniformity of flow distribution. A remarkable improvement in the performance of the base model was achieved by modifying the width ratio of the channels. The present work is a contribution to the study of flow distributors to be used as heat exchangers, PEMFC flow channels and other flow devices. Copyright © 2010 by ASME.
• Ramos-Alvarado, B., Peiwen, L. i., Liu, H., & Hernandez-Guerrero, A. (2010). CFD analysis of flow and heat transfer in a novel heat sink for electronic devices. ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 7(PARTS A AND B), 1589-1596.
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  Abstract: Novel flow channel configurations in heat sinks for electronics cooling were proposed in this paper. Computational analyses were carried out to better understand the heat transfer performance, the uniformity of temperature fields of the heat sinking surface, as well as the pressure losses and pumping power in the operation of heat sinks. Comparison of the overall performance regarding to temperature uniformity on the heat sink surface and pumping power consumption was made for heat sinks having novel flow channel configurations and having traditional flow channel configurations. It has been found that the novel flow channel configuration dramatically reduces the pressure loss in the flow field. Giving the same pumping power consumption of an electronics cooling process, the temperature difference on surface of the heat sink which has novel flow channel configuration can be much lower than that of the heat sinks which have traditional flow channel configurations. Copyright © 2010 by ASME.
• T., J., Peiwen, L. i., Chan, C. L., Karaki, W., & Stephens, J. (2010). Transient heat delivery and storage process in a thermocline heat storage system. ASME International Mechanical Engineering Congress and Exposition, Proceedings, 6, 139-148.
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  Abstract: Parabolic trough power systems utilizing concentrated solar energy have proven their worth as a means for generating electricity. However, one major aspect preventing the technologies widespread acceptance is the deliverability of energy beyond a narrow window during peak hours of the sun. Thermal storage is a viable option to enhance the dispatchability of the solar energy and an economically feasible option is a thermocline storage system with a low-cost filler material. Utilization of thermocline storage facilities have been studied in the past and this paper hopes to expand upon that knowledge. The current study aimed to effectively model the heat transfer of a working fluid interacting with filler material. An effective numerical method and efficient computation schemes were developed and verified. A thermocline storage system was modeled under specific conditions and results of great significance to heat storage design and operation were obtained. Copyright © 2010 by ASME.
• Xinhai, X. u., Valmiki, M. M., Pradhan, S., Liu, H., & Peiwen, L. i. (2010). Solar thermal closed-helium brayton cycle with high temperature phase-change thermal storage. ASME 2010 4th International Conference on Energy Sustainability, ES 2010, 2, 627-635.
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  Abstract: A 1 MW closed helium Brayton cycle is proposed in this study to eliminate the use of water in solar thermal power plants in arid areas. The power system uses highly concentrated sunlight to generate heat at temperatures around 850 to 900 °C. The heat is used in a closed, helium Brayton cycle and is partly stored in a high temperature phase-change material to provide heat for nighttime use. The energy efficiency of the system is analyzed. Other technical issues are discussed. © 2010 by ASME.
• Farber, A. M., & Li, P. (2009). Analysis and optimization design of proton-exchange-membrane electrolysis cell. Proceedings of the 7th International Conference on Fuel Cell Science, Engineering, and Technology 2009, 799-804.
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  Abstract: Although much work has been done to optimize individual components of electrolyzers and fuel cells, very little has been done to simulate and optimize the entire system. A thorough paper review has been conducted to increase the accuracy of the PEM electrolyzer model and simulation discussed in this study. Data on optimal thicknesses and electrical properties of various electrolyzer elements was collected from various sources and collated. The simulation was then implemented to optimize the current collector rib dimensions for maximum performance and efficiency over a variety of temperatures. This paper shows higher temperatures significantly improve the efficiency of the cell while also increasing the optimal rib width dimensions. The increased efficiency is most likely due to the excess heat contributing towards the threshold energy required for the electrolysis while the varying resistances of the proton exchange membrane, with respect to temperature, can explain the increased rib width. Copyright © 2009 by ASME.
• Li, P. -., Sahrawat, S., Sepulveda, J. L., Loutfy, R. O., & Chang, S. (2009). An easy-to-approach mathematical model and optimization of planar type proton-conductive SOFC. Proceedings of the 7th International Conference on Fuel Cell Science, Engineering, and Technology 2009, 573-582.
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  Abstract: A mathematical model for proton-conductive solid oxide fuel cell (H-SOFC) is presented in this work. The analysis and optimization of fuel cell components is to help the design and fabrication of H-SOFCs which are experimentally studied by the current authors. The mathematical model considers mass transfer and concentration polarization using an average mass transfer model analogous to the convective heat transfer in a duct flow and across a wall. The average concentrations of species at interfaces of electrodes/electrolyte at any operating current densities are calculated, and therefore the species concentrations are included in the calculation for activation polarizations. The ohmic loss is considered through analysis of a circuit simulating the electron and proton conduction. Empirical coefficients for the exchange current density in activation polarization analysis were determined and validated by referring to experimental results from multiple publications. Parametric analysis has also been done to show how the performance of H-SOFC is dependent on properties of fuel cell components. Copyright © 2009 by ASME.
• Li, P. W., Kotwal, A., Sepulveda, J. L., Loutfy, R. O., & Chang, S. (2009). An easy-to-approach and comprehensive model for planar type SOFCs. International Journal of Hydrogen Energy, 34(15), 6393-6406.
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  Abstract: An easy-to-approach and comprehensive mathematical model for planar type solid oxide fuel cells is presented in the current work. It provides a tool for researchers to conduct parametric studies with less-intensive computation in order to grasp the fundamentals of coupled mass transfer, electrochemical reaction, and current conduction in a fuel cell. In the model, the analysis for the mass transfer polarization at a known average fuel cell operating temperature is based on an average mass transfer model analogous to an average heat transfer process in a duct flow. The effect of the species' partial pressure at electrode/electrolyte interfaces is therefore included in the exchange current density for activation polarizations. An electrical circuit for the current and ion conduction is used to analyze the ohmic losses from anode current collector to cathode current collector. The three types of over-potentials caused by different polarizations in a planar type solid oxide fuel cell can be identified and compared. The effects of species concentrations, properties of fuel cell components to the voltage-current performance of a fuel cell at different operating conditions are studied. Optimization of the dimensions of flow channels and current-collecting ribs is also presented. The model is of significance to the design and optimization of solid oxide fuel cells for industrial application. © 2009 International Association for Hydrogen Energy.
• Li, P., Kotwal, A., Sepulveda, J. L., Loutfy, R. O., & Chang, S. (2009). An easy-to-approach comprehensive model and computation for SOFC performance and design optimization. UECTC'09 - Proceedings of 2009 US-EU-China Thermophysics Conference - Renewable Energy.
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  Abstract: This paper presents an easy-to-approach mathematical model for planar type solid oxide fuel cells. It is developed to be used as a tool for students in fuel cell class to conduct parametric studies in order to grasp fundamentals and to understand the effects of mass transfer, electrochemical reaction, and current conduction on the voltage-current relationship in a fuel cell at different operating conditions. Using the model, the three over-potentials caused by different polarizations in a planar type solid oxide fuel cell can be identified and compared. The analysis for the mass transfer polarization is based on average mass transfer model analogous to an average heat transfer process in a duct flow. The effect of species' partial pressures on the exchange current density in activation polarization is counted in the activation polarization model. A discretized current conduction circuit is applied to analyze the ohmic losses from anode current collector to cathode current collector. The model is of significance to the design and optimization of solid oxide fuel cells in industrial application. Copyright @2009 by ASME.
• Peiwen, L. i., Coopamah, D., & Dhar, N. (2009). Analysis and optimization of flow distribution channels for uniform flow in fuel cells. 2008 Proceedings of the ASME Fluids Engineering Division Summer Conference, FEDSM 2008, 1(PART B), 915-920.
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  Abstract: The paper presents the results of investigation about flow distribution and uniformity of flow fields in three types of flow distributors with novel design. The flow distributors have a number of bifurcations to split one flow into a number of sub-streams of equal flow rates on a bipolar plate which may accommodate the electrochemical reaction in a fuel cell. There are three types of bifurcation structures studied, which are the 90° tee-type, rounded-type, and slanted-type. Numerical analysis and experimental test was conducted to investigate the flow uniformity in a multiple channels that come from several stages of bifurcations. Pressure drops of the whole flow field from inlet to outlet of the bipolar plates were also studied in the numerical simulation. Overall evaluation of flow uniformity and pressure drops in the three designs was also conducted. Copyright © 2008 by ASME.
• Peiwen, L. i., Dhar, N., & Dumay, A. (2009). Development and fabrication of passive DMFCs. Proceedings of the 7th International Conference on Fuel Cell Science, Engineering, and Technology 2009, 39-44.
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  Abstract: The present work developed direct methanol fuel cells (DMFC) which have passive methanol feeding designs integrated. The design eliminated any mechanical parts in the DMFC and both methanol feeding and carbon dioxide exclusion on the anode side are accomplished through the special designs of the fluidic channels on current collecting plate on anode side. The anode of this DMFC is not submerged into liquid methanol. Therefore, the crossover of methanol and water from anode side to cathode side is significantly reduced, which relieves cathode water flooding dramatically. The cathode is designed to have air-breathing function that draws air by natural convection mass transfer method. A stable and lasting power output of 1.5 (mW/cm2) at 0.35 (V) was obtained for a single cell which operates at room temperature and completely eliminated with parasitic parts. It is expected that the methanol delivery and control in a passive mode through the presently developed special design of flow channels will greatly promote the development of cost-effective DMFCs with easy maintenance and high reliability. Copyright © 2009 by ASME.
• Sepulveda, J. L., Loutfy, R. O., Chang, S., Peiwen, L. i., & Kotwal, A. (2009). Functionally graded composite electrodes for advanced anode-supported, intermediate-temperature SOFC. Ceramic Engineering and Science Proceedings, 29(5), 203-214.
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  Abstract: This paper describes the development and modeling of anode-supported intermediate-temperature solid oxide fuel cells (ACN-AS-IT-SOFC) that exhibit high electrochemical efficiency, high degree of fuel utilization, and low operating temperature characteristics. The proposed cell design is fuelled by hydrogen or in-situ reformed fuel and operates at a lower temperature of 600-800°C producing a maximum power density of 2-2.2 W/cm 2. The innovative design for the ACN-AS-IT-SOFC fuel cell makes use of a porous anode consisting of a combination of a highly conductive anode capillary network (ACN) running through the supporting anode manufactured using MER poly capillary material technology. The highly porous anode allows for free fuel gas access to the functional anode. Operating at low temperature of 600-800°C it allows the use of less expensive interconnect materials such as ferritic steels. A method to identify over-potentials caused by different polarizations in an SOFC with multi-layer hybrid electrodes is also presented. The contributions of each polarization to the total loss in a fuel cell can be identified. The polarization causing the maximum over-potential is then considered as the primary source of internal losses, and optimization is focused to improve the power density. The analysis for the mass transfer polarization considers bulk convection and diffusion in porous layers from bulk flow to the interface of the electrode and electrolyte. Values of the exchange current densities are determined empirically by matching analytical and experimental results. Effects of porosities and thicknesses of anode, cathode, and functional graded layers are modeled and optimized to attain maximum power density.
• Peiwen, L. i. (2008). Energy storage is the core of renewable technologies: Substitute and clean energy resources are driving the development of renewable energy. IEEE Nanotechnology Magazine, 2(4), 13-18.
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  Abstract: Fossil fuel has been the major energy resource for two centuries, driving the industrialization and the modernization of human society. In the short term, the world economy will continue to rely largely on fossil fuel, especially oil. However, it also has been widely recognized that the worldwide oil production has peaked in recent years [1], [2], while the new discoveries of oil reserves experiences a significant time lag. With the production peaking and demand increasing, the world has to find new energy resources, or improve current energy technologies dramatically. The world also has recognized that heavy use of fossil fuels causes our environment to suffer [3]. The needs for substitute and clean energy resources and environment protection drive the development of renewable energy to be one of the urgent issues in the world. There is no doubt that renewable energy must take a significant proportion in our energy package in order for the world economy and environment to have a sustainable development. © 2008 IEEE.
• Peiwen, L. i., & Tao, G. (2008). Effect of the geometries of current collectors on the power density in a solid oxide fuel cell. ASME International Mechanical Engineering Congress and Exposition, Proceedings, 6, 579-586.
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  Abstract: An analytical model is proposed, and the analysis is conducted for solid oxide fuel cells in order to achieve higher power densities. The analytical model is designated to help designers to optimize the current collector sizes and spacing, and also the geometrical shapes of the current collectors as well. The analytical model basically has a whole consideration about the ohmic polarization, the species concentration polarization, and the activation polarization; while the load of optimization computations and analysis is greatly alleviated for engineering designers. From the analysis of several cases, it is recommended that 3D pillars be used for the current collectors in SOFCs incorporating with appropriate measures of a uniform flow distribution. It is also clear that unless limited by the fabrication technologies for the bipolar plates, a smaller control area and current collectors are preferable to SOFCs to have higher power densities. Copyright © 2007 by ASME.
• Peiwen, L. i., Coopamah, D., & Ki, J. (2008). Uniform distribution of species in fuel cells using a multiple flow bifurcation design. Proceedings of the 6th International Conference on Fuel Cell Science, Engineering, and Technology, 897-902.
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  Abstract: This paper presents the results obtained from the study about flow distribution in maintaining uniformity of flow fields in fuel cells. Three novel flow distribution designs on bipolar plates are proposed for a proton exchange membrane fuel cell (PEMFC). The flow distributors have multiple levels of bifurcations to split a flow into sub-streams of equal flow rates. There are three types of bifurcation structure proposed and studied, which are the 90° tee-type, rounded-type and slanted-type. Experiments were carried out to test the velocities of flows from the multiple channels after bifurcations, and the flow uniformity on the bipolar plate is estimated and studied. Overall evaluation of flow uniformity in the three designs was conducted. The rounded-type bifurcation structure showed the best flow uniformity. After experimental verification of the uniform flow distribution in the novel design, three PEM fuel cell was fabricated which adopted the novel flow fields. From the experimental test and comparison under dry fuel and air condition, it is found that the PEMFC with new flow field can have a better performance. Thorough experimental investigation is planned for the future study. Copyright © 2008 by ASME.
• Peiwen, L. i., Chan, C. L., & Chen, C. F. (2007). Buoyancy-driven circulation flow of an electrically conductive liquid in a rectangular annulus. 2007 Proceedings of the ASME/JSME Thermal Engineering Summer Heat Transfer Conference - HT 2007, 1, 865-871.
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  Abstract: A study on the characteristics of a buoyancy-driven flow in a rectangular circulation channel in a solar-energy-harvesting device is presented in this paper. The solar-energy-harvesting device is projected to convert solar radiation into electrical energy. As a first step of the energy conversion in the device, a flow is generated by an imbalance of buoyancy forces in the heating and cooling sections for a liquid in the circulation channel. Whereas solar energy is collected to provide the heat, free convection of ambient air provides the cooling in the device. The fluid used in the circulation channel is electrically conductive and has high thermal expansion coefficient. The present investigation focuses on the effects of channel dimensions on the buoyancy-driven flow field and uniformities of velocities. Both analytical and numerical approaches are applied in the study. Analytical closed-form solution is obtained by assuming uni-direction flow. Steady-state two-dimensional laminar solutions are obtained by numerical computation using QUICK scheme and SIMPLE algorithm. Copyright © 2007 by ASME.
• Chen, S. P., Li, P. W., & Chyu, M. K. (2006). Optimization of gas delivery and current collecting system in fuel cells. Proceedings of 4th International ASME Conference on Fuel Cell Science, Engineering and Technology, FUELCELL2006, 2006.
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  Abstract: The over-potentials in a fuel cell due to ohmic losses and concentration polarization can be reduced if the gas delivery field and the current collection system are well designed. To obtain such a substantial understanding for designing the gas delivery and current collection system, this study proposed a model to theoretically analyze the current collection process, and finally a method and tool of optimization for scales of gas channels and current collection ribs is presented. The analysis found that small current collectors and collection area is advantageous for getting high power density in both PEMFCs and SOFCs. Copyright @ 2006 by ASME.
• Chen, S. P., Li, P. W., Chyu, M. K., Cunha, F. J., & Abdel-Messeh, W. (2006). Heat transfer in an airfoil trailing edge configuration with shaped pedestals mounted internal cooling channel and pressure side cutback. Proceedings of the ASME Turbo Expo, 3 PART A, 819-828.
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  Abstract: Described in this paper is an experimental study of heat transfer over a trailing edge configuration preceded with an internal cooling channel of pedestal array. The pedestal array consists of both circular pedestals and oblong shaped blocks. Downstream to the pedestal array, the trailing edge features pressure side cutback partitioned by the oblong shaped blocks. The local heat transfer coefficient over the entire wetted surface in the internal cooling chamber has been determined by using a "hybrid" measurement technique based on transient liquid crystal imaging. The hybrid technique employs the transient conduction model in a semi-infinite solid for resolving the heat transfer coefficient on the endwall surface uncovered by the pedestals. The heat transfer coefficient over a pedestal can be resolved by the lumped capacitance method with an assumption of low Biot number. The overall heat transfer for both the pedestals and endwalls combined shows a significant enhancement compared to the case with thermally developed smooth channel. Near the downstream most section of the suction side, the land, due to pressure side cutback, is exposed to the stream mixed with hot gas and discharged coolant. Both the adiabatic effectiveness and heat transfer coefficient on the land section are characterized by using the transient liquid crystal technique. Copyright © 2006 by ASME.
• Li, P. W., Chen, S. P., & Chyu, M. K. (2006). To achieve the best performance through optimization of gas delivery and current collection in solid oxide fuel cells. Journal of Fuel Cell Science and Technology, 3(2), 188-194.
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  Abstract: Aimed at improving the maximum available power density in a planar-type solid oxide fuel cell, an analytical model is proposed in this work to find the optimum size of a current collector that collects the current from a specific active area of the electrode-electrolyte layer. Distributed three-dimensional current collectors in gas delivery field are designated to allow a larger area of the electrode-electrolyte layer to be active for electrochemical reaction compared to conventional designs that gas channels are separated by current collectors. It has been found that the optimal operating temperature of a planar-type solid oxide fuel cell might be around 850°C, if the sizes of the distributed current collectors and their control areas are optimized. Decreasing the size of both the current collector and its control area is advantageous in achieving a higher power density. Studies also show that the optimal sizes of the current collector and the current collection area investigated at 850°C and zero concentration polarization are applicable to situations of different operating temperatures, and different concentration polarizations. The optimization results of the sizes of current collectors and their control areas are relatively sensitive to the contact resistance between the current collectors and the electrodes of the fuel cell. Results of great significance are provided in the analysis, which will help designers to account for the variation of contact resistance in optimization designing of a bipolar plate of fuel cells. Copyright © 2006 by ASME.
• Uysal, U., Li, P. -., Chyu, M. K., & Cunha, F. J. (2006). Heat transfer on internal surfaces of a duct subjected to impingement of a jet array with varying jet hole-size and spacing. Journal of Turbomachinery, 128(1), 158-165.
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  Abstract: One significant issue concerning the impingement heat transfer with a jet array is related to the so-called "crossflow," where a local jet performance is influenced by the convection of the confluence from the impingement of the jet/jets placed upstream. As a result, the heat transfer coefficient may vary along the streamwise direction and creates more or less nonuniform cooling over the component, which is undesirable from both the performance and durability standpoints. Described in this paper is an experimental investigation of the heat transfer coefficient on surfaces impinged by an array of six inline circular jets with their diameters increased monotically along the streamwise direction. The local heat transfer distributions on both the target surface and jet-issuing plate are measured using a transient liquid crystal technique. By varying the jet hole-size in a systematic manner, the actual distribution of jet flow rate and momentum within a jet array may be optimally metered and controlled against crossflow. The effects on the heat transfer coefficient distribution due to variations of jet-to-target distance and interjet spacing are investigated. The varying-diameter results are compared with those from a corresponding array of uniform jet diameter. Copyright © 2005 by ASME.
• Li, P. W., & Chyu, M. K. (2005). Electrochemical and transport phenomena in solid oxide fuel cells. Journal of Heat Transfer, 127(12), 1344-1362.
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  Abstract: This paper begins with a brief review of the thermodynamic and electrochemical fundamentals of a solid oxide fuel cell (SOFC). Issues concerning energy budget and ideal energy conversion efficiency of the electrochemical processes in an SOFC are addressed. Chemical equilibrium is then discussed for the situations with internal reforming and shift reactions as an SOFC is fed with hydrocarbon fuel. Formulations accounting for electrical potential drops incurred by activation polarization, ohmic polarization, and concentration polarization are reviewed. This leads to a discussion on numerical modeling and simulation for predicting the terminal voltage and power output of SOFCs. Key features associated with numerical simulation include strong coupling of ion transfer rates, electricity conduction, flow fields of fuel and oxidizer, concentrations of gas species, and temperature distributions. Simulation results based primarily on authors' research are presented as demonstration. The article concludes with a discussion of technical challenges in SOFCs and potential issues for future research. Copyright © 2005 by ASME.
• Li, P. W., & Chyu, M. K. (2005). Numerical simulation and performance optimization of solid oxide fuel cells. Journal of the Chinese Society of Mechanical Engineers, Transactions of the Chinese Institute of Engineers, Series C/Chung-Kuo Chi Hsueh Kung Ch'eng Hsuebo Pao, 26(3), 221-231.
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  Abstract: This paper describes a numerical analysis for comparing the performance of two geometrically different solid oxide fuel cells (SOFC), i.e. tubular-type and planar-type SOFCs. The analysis uses a custom-developed computer code which is capable of simulating the complete energy conversion process in SOFC, including fuel reforming and water shift. The detailed numerical procedures are based on strong coupling of electrochemistry, electricity, material properties and transport phenomena. This simulation effort is followed by an optimization study to further enhance the power density of anode-supported planar SOFC. The optimization procedure is to identify optimal combination of the size of current collector and its domain of influence.
• Li, P. W., Chen, S. P., & Chyu, M. K. (2005). Novel gas distributors and optimization for high power density in fuel cells. Journal of Power Sources, 140(2), 311-318.
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  Abstract: A novel gas distributor for fuel cells is proposed. It has three-dimensional current-collecting elements distributed in gas-delivery fields for effective current collection and heat/mass transfer enhancement. An analysis model has been developed in order to understand the performance of the output power density when the dimensions and distributive arrangement of the current collectors are different. Optimization analysis for a planar-type SOFC was conducted in order to outline the approach in optimizing a gas-delivery field when adopting three-dimensional current-collecting elements in a fuel cell. Experimental test of a proton exchange membrane (PEM) fuel cell adopting the novel gas distributor was conducted for verification of the new approach. Significant improvement of power output was obtained for the proposed new PEM fuel cells compared to the conventional ones under the same conditions except for the different gas distributors. Both the experimental results and modeling analysis are of great significance to the design of fuel cells of high power density. © 2004 Elsevier B.V. All rights reserved.
• Uysal, U., Li, P. -., Chyu, M. K., & Cunha, F. J. (2005). Heat transfer on internal surfaces of a duct subjected to impingement of a jet array with varying jet hole-size and spacing. Proceedings of the ASME Turbo Expo, 3 PART A, 141-150.
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  Abstract: One significant issue concerning the impingement heat transfer with a jet array is related to the so-called "crossflow", where a local jet performance is influenced by the convection of the confluence from the impingement of the jet/jets placed upstream. As a result, the heat transfer coefficient may vary along the streamwise direction and creates more or less non-uniform cooling over the component, which is undesirable from both the performance and durability standpoints. Described in this paper is an experimental investigation of the heat transfer coefficient on surfaces impinged by an array of six inline circular jets with their diameters increased monotically along the streamwise direction. The local heat transfer distributions on both the target surface and jet-issuing plate are measured using a transient liquid crystal technique. By varying the jet hole-size in a systematic manner, the actual distribution of jet flow rate and momentum within a jet array may be optimally metered and controlled against crossflow. The effects on the heat transfer coefficient distribution due to variations of jet-to-target distance and inter-jet spacing are investigated. The varying-diameter results are compared with those from a corresponding array of uniform jet diameter. Copyright © 2005 by ASME.
• Yixin, L. u., Schaefer, L., & Peiwen, L. i. (2005). Numerical simulation of heat transfer and fluid flow of a flat-tube high power density solid oxide fuel cell. Journal of Fuel Cell Science and Technology, 2(1), 65-69.
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  Abstract: To both increase the power density of a tubular solid oxide fuel cell (SOFC) and maintain its beneficial feature of secure sealing, a flat-tube high power density (HPD) solid oxide fuel cell is under development by Siemens Westinghouse, based on their formerly developed tubular model. In this paper, a three dimensional numerical model to simulate the steady state heat transfer and fluid flow of a flat-tube HPD-SOFC is developed. A computer code is programmed using the FORTRAN language to solve the governing equations for continuity, momentum, and energy conservation. The highly coupled temperature and flow fields of the air stream and the fuel stream inside and outside a typical channel of a one-rib flat-tube HPD-SOFC are investigated. This heat transfer and fluid flow results will be used to simulate the overall performance of a flat-tube HPD-SOFC in the near future, and to help optimize the design and operation of a SOFC stack in practical applications. Copyright © 2004 by ASME.
• Yixin, L. u., Schaefer, L., & Peiwen, L. i. (2005). Numerical study of a flat-tube high power density solid oxide fuel cell: Part I. Heat/mass transfer and fluid flow. Journal of Power Sources, 140(2), 331-339.
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  Abstract: The flat-tube high power density (HPD) solid oxide fuel cell (SOFC) is a new design developed by Siemens Westinghouse, based on their formerly developed tubular type SOFC. It has increased power density, but still maintains the beneficial feature of secure sealing of a tubular SOFC. In this paper, a three-dimensional numerical model to simulate the steady state heat/mass transfer and fluid flow of a flat-tube HPD-SOFC is developed. In the numerical computation, governing equations for continuity, momentum, mass, and energy conservation are solved simultaneously. The highly coupled temperature, concentration and flow fields of the air stream and the fuel stream inside and outside the different chambers of a flat-tube HPD-SOFC are investigated. The variation of the temperature, concentration and flow fields with the current output is studied. The heat/mass transfer and fluid flow modeling and results will be used to simulate the overall performance of a flat-tube HPD-SOFC, and to help optimize the design and operation of a SOFC stack in practical applications. © 2004 Elsevier B.V. All rights reserved.
• Li, P. W., Chen, S. P., & Chyu, M. K. (2004). A novel approach for distribution of reacting gases with enhanced mass transfer in fuel cells. American Society of Mechanical Engineers, Advanced Energy Systems Division (Publication) AES, 44, 117-124.
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  Abstract: In order to improve the power output of a fuel cell, a novel approach for gas delivery and mass transfer enhancement in a gas distributor is proposed. A model analyzing the power output against the dimensions of a novel gas delivery channel and current collector is also presented. Experimental study for some proton-exchange-membrane fuel cells and numerical analysis for a planar type solid oxide fuel cell are carried out. Significant improvement of power output was obtained for the newly designed fuel cells compared to conventional ones. Both the experimental results and modeling analysis are of great significance to the design of fuel cells. Copyright © 2004 by ASME.
• Li, P. W., Chen, S. P., & Chyu, M. K. (2004). New conceptual gas distributor with mass transfer enhancing function in polymer electrolyte fuel cells. Fuel Cell Science, Engineering and Technology - 2004, 561-565.
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  Abstract: A new conceptual structure of the gas distributors in polymer electrolyte fuel cells (PEFC) or proton exchange membrane (PEM) fuel cells is developed in this work. Basically, instead of partitioned channels and non-interrupted walls, the proposed new gas distributors make use of discretized elements as the current collector in the flow fields, which can help to enhance the mass transfer in the gas flow fields while maintaining the function of transmitting current out of the fuel cell. Experimental operation without external humidification of the reactant gases for single PEM fuel cells and cell stacks using conventional and the currently presented gas distributors were conducted for comparison and verification. It was found that the maximum operational cell current, beyond which there is a sharp drop of the cell voltage, could be significantly improved when using the currently proposed gas distributors and the same membrane-electrode-assembly (MEA) sheets. Correspondingly, the output electrical power can have at least 11 percent increment for the operation with free-convective airflow and around 50 percent increment for the operation with forced convective airflow.
• Li, P. W., Uysal, U., & Chyu, M. K. (2004). Mass transfer enhancement for improving the performance of polymer electrolyte fuel cells. Proceedings of the ASME Heat Transfer/Fluids Engineering Summer Conference 2004, HT/FED 2004, 3, 87-92.
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  Abstract: The significance of mass transfer enhancement in polymer electrolyte fuel cells (PEFC) is presented and studied in this work based on experimental investigation. A novel structure of reactant gas distributors in PEFC is proposed for mass transfer enhancement purpose. For the PEFC with novel gas distributors, it is found that the large drop of the cell voltage, generally caused by a weak mass diffusion, is postponed to occur at relatively higher current density even though the same or less amount of air is fed when comparing to a PEFC with gas distributors in conventional structure. As a result, the maximum obtained electrical power in a PEFC and a PEFC stack both are dramatically improved under both free convective and forced convective airflow conditions. Copyright © 2004 by ASME.
• Li, P., & Suzuki, K. (2004). Numerical Modeling and Performance Study of a Tubular SOFC. Journal of the Electrochemical Society, 151(4), A548-A557.
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  Abstract: A quasi-2D model was proposed and made available for numerical studies on the performance of a single tubular solid oxide fuel cell (SOFC) under practical operating conditions. The model takes account of the air and fuel flow velocity fields, ohmic and thermodynamic heat generation, convective heat-transfer, mass transfer of participating chemical species including the electrochemical processes, and the electric potential and electric current in the electrodes and electrolyte. Numerical computation was carried out to test the proposed model for a single unit cell having a specific geometry being operated at a few different thermal and composition conditions for the inlet fuel and air flows. Obtained numerical results show that the quasi-two-dimensional approximation adopted in the model to mitigate the computational cost effectively can work reasonably well. At low electric current density, the cell terminal voltage was overpredicted. In order to improve the model on this point, the simple treatment adopted for the activation and concentration polarization in the model must be replaced by a more sophisticated approach in future studies. Discussions were further given concerning the obtained results for the overall cell performance and the detailed features of the velocity, thermal, and mass-transfer fields in the cell in addition to the local electrochemical characteristics. It is suggested that the air flow convective heat-transfer is important as a cooling means and that overpotential due to concentration polarization is more serious for the cathode side than for the anode side. All the presented results including the electricity conversion efficiency were observed to agree reasonably well with the popularly accepted cell performance. © 2004 The Electrochemical Society.
• Li, P., Schaefer, L., & Chyu, M. K. (2004). A numerical model coupling the heat and gas species' transport processes in a tubular SOFC. Journal of Heat Transfer, 126(2), 219-229.
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  Abstract: A numerical model is presented in this work that computes the interdependent fields of flow, temperature, and mass fractions, in a single tubular solid oxide fuel cell (SOFC). Fuel gas from a pre-reformer is considered to contain H2, CO, CO2, H2O (vapor), and CH4, so reforming and shift reactions in the cell are incorporated. The model uses mixture gas properties of the fuel and oxidant that are functions of the numerically obtained local temperature, pressure, and species concentrations, which are both interdependent and related to the chemical and electrochemical reactions. A discretized network circuit of a tubular SOFC was adopted to account for the Ohmic losses and Joule heating from the current passing around the circumference of the cell to the interconnect. In the iterative computation, local electrochemical parameters were simultaneously calculated based on the local parameters of pressure, temperature, and concentration of the species. Upon convergence of the computation, both local details and the overall performance of the fuel cell are obtained. These numerical results are important in order to better understand the operation of SOFCs. © 2004 by ASME.
• Yixin, L. u., Schaefer, L., & Peiwen, L. i. (2004). Numerical simulation of heat transfer and fluid flow of a flat-tube high power density solid oxide fuel cell. Fuel Cell Science, Engineering and Technology - 2004, 369-374.
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  Abstract: In this paper, a three dimensional numerical model to simulate the steady state heat transfer and fluid flow of a flat-tube high power density solid oxide fuel cell (HPD-SOFC) is developed. A computer code is programmed using the FORTRAN language to solve the governing equations for continuity, momentum and energy conservation. The highly coupled temperature and flow fields of the air stream and the fuel stream inside and outside a typical channel of a flat-tube HPD-SOFC are investigated. The variation of the temperature and flow fields with the current output is studied The simulation also predicts pressure drop behavior of the both the air and fuel streams. This heat transfer and fluid flow modeling of the computer code will be used to simulate the overall performance of a flat-tube HPD-SOFC in the near future, and to help optimize the design and operation of a SOFC stack in practical applications.
• Li, P., & Chyu, M. K. (2003). Simulation of the chemical/electrochemical reactions and heat/mass transfer for a tubular SOFC in a stack. Journal of Power Sources, 124(2), 487-498.
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  Abstract: The heat and species transport processes in a tubular type solid oxide fuel cell (SOFC) that works in a cell stack were analyzed and modeled. Since most of the single tubular SOFCs working in a cell stack share the same/similar chemical/electrochemical and heat/mass transfer conditions, it is plausible to assume that heat and species are not exchanged between one cell and its neighboring cells. Therefore, a surrounding fuel flow space was outlined controllable by a specific single cell, for which zero flux was assumed at its boundary in neighborhood with other cells. The numerical model subjects such a cell and its controllable fuel flow space to a two-dimensional analysis for the flow, heat/mass transfer and chemical/electrochemical performance. Computations were performed for three different tubular SOFCs having practical operating results available from publications by different researchers. The numerical results of the terminal voltages for those different SOFCs showed very good agreement with the published experimental data. It is expectable that the proposed numerical model be used to significantly help the design and operation of a SOFC stack in practical applications. © 2003 Elsevier B.V. All rights reserved.
• Li, P., Schaefer, L., & Chyu, M. K. (2003). Interdigitated heat/mass transfer and chemical/electrochemical reactions in a planar type solid oxide fuel cell. Proceedings of the ASME Summer Heat Transfer Conference, 2003, 561-568.
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  Abstract: The details of the heat/mass transfer in a planar type solid oxide fuel cell that controls the energy conversion performance are studied by employing a three-dimensional numerical computation for the fields of velocity, gas mass fractions and temperature. The SOFC under investigation is a unit working in a SOFC stack. It has the tri-layer of anode-electrolyte-cathode and inter-connects having multiple channels for fuel and air. Two designs of the tri-layer, anode-supported and electrolyte-supported, are studied. Pre-reformed fuel gas with components of H 2, H 2O, CO, CO 2 and CH 4 is arranged in cross-flow direction with airflow. Further reforming and shift reaction in fuel channels were considered at chemical equilibrium. It was found that the consumption and production of gas species are different in the different channels. High current density was located in the upstream area of fuel channels. The operation conditions of current density affected the temperature level significantly.
• Li, P., Schaefer, L., & Chyu, M. K. (2003). Investigation of the energy budget in an internal reforming tubular type solid oxide fuel cell through numerical computation. Proceedings of the 2003 International Joint Power Generation Conference, 923-930.
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  Abstract: Based on a numerical computation simultaneously solving the fields of flow, heat and mass transfer, the energy budget in a tubular type solid oxide fuel cell is delineated for better understanding of the energy conversion performance and the heat transfer characteristics. It is found that the Joule heating due to ion and electron conduction in cell components is at the same level as that of the thermal energy released from the electrochemical reaction. The energy budget varies significantly with the operating current density of the fuel cell because the Joule heating and thermal energy increase in different manner with the operating current density.
• Li, P., Schaefer, L., & Chyu, M. K. (2003). The Energy Budget in Tubular and Planar Type Solid Oxide Fuel Cells Studied through Numerical Simulation. American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD, 374(2), 429-436.
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  Abstract: The energy budget in a tubular and a planar type solid oxide fuel cell (SOFC) is studied based on numerical simulation. By solving the discretized governing equations for flow, temperature, and mass fraction of gas species in the fuel cells, the detailed local parameters determining the local electromotive forces are obtained. The energy flows of electrical power, Joule heating, thermal energy from the entropy change of the electrochemical reaction, as well as the chemical reaction heat by reforming and shift reactions are delineated and compared for the two different types of SOFCs.
• Li, P., Schaefer, L., Wang, Q., Zhang, T., & Chyu, M. K. (2003). Multi-gas transportation and electrochemical performance of a polymer electrolyte fuel cell with complex flow channels. Journal of Power Sources, 115(1), 90-100.
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  Abstract: A three-dimensional (3D) numerical model associating the heat/mass transfer and the electrochemical reaction in a proton exchange membrane (PEM) fuel cell is developed in this study, and a miniaturized PEM fuel cell with complex flow channels is simulated. The numerical computation is based on the finite-volume method. Governing equations for flow and heat/mass transfer are coupled with the electrochemical reactions and are solved simultaneously. The latent heat from the condensation of water vapor in cathode channel, if any, is considered. The perimeters of the bipolar plates are also included in the computational domain to account for their heat conduction effect. The miniaturized PEM fuel cell has a membrane electrode assembly (MEA) sandwiched by two brass bipolar plates etched with a number of winding gas channels with a flow area of 250 μm × 250 μm. The influence of anode gas humidity on the performance of the fuel cell is investigated through model prediction. Finally, field details of velocity, mass fraction and electromotive force are illustrated and discussed. © 2003 Published by Elsevier Science B.V.
• Li, P., Zhang, T., Wang, Q., Schaefer, L., & Chyu, M. K. (2003). The performance of PEM fuel cells fed with oxygen through the free-convection mode. Journal of Power Sources, 114(1), 63-69.
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  Abstract: The feasibility and restrictions of feeding oxygen to a PEM fuel cell through free-convection mass transfer were studied through theoretical analysis and experimental testing. It was understood through the theoretical analysis that the free-convection mass-transfer coefficient strongly depends on the difference in mass fraction or concentration of oxygen at the cathode surface and in the quiescent air. Thus, the mass-transfer rate has a strong dependence on the oxygen concentration at the cathode surface, which can be viewed in terms of the relationship of the fuel cell current density and the fuel cell voltage. Through this analysis, the maximum applicable current density was derived, beyond which there will be an abrupt drop in the output voltage, which results in excessively low power in the fuel cell. Experimental tests were conducted for one PEM fuel cell stack and two single PEM fuel cell units. An excessive drop in output voltage was observed when the free-convection mass-transfer mode was utilized. It was also found that the orientation of the cathode surface affects the performance of the fuel cell, which is mainly due to the fact that the free-convection mass-transfer coefficient depends on the orientation of the involved mass-transfer surface, which is analogous to free-convection heat transfer. © 2002 Elsevier Science B.V. All rights reserved.
• Zhang, T., Li, P., Wang, Q., Schaefer, L., & Chyu, M. K. (2003). Fabrication and Performance Evaluation of Miniaturized Proton Exchange Membrane (PEM) Fuel Cells. Fuel Cell Science, Engineering and Technology, 129-136.
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  Abstract: Two types of miniaturized PEM fuel cells are designed and characterized in comparison with a compact commercial fuel cell device in this paper. One has Nafion® membrane electrolyte sandwiched by two brass bipolar plates with micromachined meander-like gas channels. The cross-sectional area of the gas flow channel is approximately 250 by 250 (μm). The other uses the same Nafion® membrane and anode structure, but in stead of the brass plate, a thin stainless steel plate with perforated round holes is used at cathode side. The new cathode structure is expected to allow oxygen (air) being supplied by free-convection mass transfer. The characteristic curves of the fuel cell devices are measured. The activation loss and ohmic loss of the fuel cells have been estimated using empirical equations. Critical issues such as flow arrangement, water removing and air feeding modes concerning the fuel cell performance are investigated in this research. The experimental results demonstrate that the miniaturized fuel cell with free air convection mode is a simple and reliable way for fuel cell operation that could be employed in potential applications although the maximum achievable current density is less favorable due to limited mass transfer of oxygen (air). The relation between the fuel cell dimensions and the maximum achievable current density is also discussed with respect to free-convection mode of air feeding.
• Chyu, M. K., Uysal, U., & Li, P. (2002). Convective heat transfer in a triple-cavity structure near turbine blade trailing edge. ASME International Mechanical Engineering Congress and Exposition, Proceedings, 4, 265-272.
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  Abstract: The present study explores the internal heat transfer in a triple-cavity cooling structure with a ribbed lip for a turbine blade trailing edge. The design consists of two impingement cavities, two sets of crossover holes, a third cavity and an exit slot with eleven ribs attached to it. Local heat transfer in each subregion is determined. Results indicate that the highest heat transfer occurs in the second impingement cavity. The exit slot area between the ribs is identified as a region of low heat transfer in the overall design. A comparison with enhancement induced by arrays of pin fins and fins of other geometries reveals that the triple-cavity design represents a lesser quality cooling scheme in the range of Reynolds numbers tested. Further improvement of the convective heat transfer at the exit slot with either film cooling, or different rib geometries appears to be essential to make the triple-cavity strategy superior to those of the traditional approaches for cooling of blade trailing edge. Copyright © 2002 by ASME.
• Chyu, M. K., Uysal, U., & Li, P. (2002). Convective heat transfer in a triple-cavity structure near turbine blade trailing edge. American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD, 372(4), 265-272.
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  Abstract: The present study explores the internal heat transfer in a triple-cavity cooling structure with a ribbed lip for a turbine blade trailing edge. The design consists of two impingement cavities, two sets of crossover holes, a third cavity and an exit slot with eleven ribs attached to it. Local heat transfer in each subregion is determined. Results indicate that the highest heat transfer occurs in the second impingement cavity. The exit slot area between the ribs is identified as a region of low heat transfer in the overall design. A comparison with enhancement induced by arrays of pin fins and fins of other geometries reveals that the triple-cavity design represents a lesser quality cooling scheme in the range of Reynolds numbers tested. Further improvement of the convective heat transfer at the exit slot with either film cooling, or different rib geometries appears to be essential to make the triple-cavity strategy superior to those of the traditional approaches for cooling of blade trailing edge.
• Kawaguchi, Y., Segawa, T., Feng, Z., & Peiwen, L. i. (2002). Experimental study on drag-reducing channel flow with surfactant additives-Spatial structure of turbulence investigated by PIV system. International Journal of Heat and Fluid Flow, 23(5), 700-709.
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  Abstract: The turbulent frictional drag of water can be reduced dramatically by adding small amounts of drag-reducing materials, such as polymers or surfactants. As a percentage drag reduction of 80% can easily be achieved, this technique is thought to be the most practical method of reducing turbulent frictional drag. In this work, a double pulse particle image velocimetry (PIV) system was used to clarify the spatial velocity distribution of surfactant solution flow in a two-dimensional channel. A type of cationic surfactant cetyltrimethyl ammonium chloride (C16H33N(CH3)3Cl) mixed with the same weight of counter-ion material NaSal (HOC6H4COONa) was used as a drag-reducing additive to water at a mass concentration of 40 ppm. Instantaneous velocity distribution taken by PIV was examined to clarify the effect of surfactant. It was found that the instantaneous velocity distribution taken in water flow exhibits penetration from the low-speed fluid region into the high-speed region, which is one of the important events of turbulence energy production and turbulent mixing. Although this structure is commonly observed in water flow, it was not found in drag-reducing flow under the same Reynolds number. The strong vorticity fluctuation near the wall also disappeared and the integral length scale in streamwise direction of turbulent fluctuation had a smaller value in surfactant solution flow. © 2002 Elsevier Science Inc. All rights reserved.
• Li, P., Schaefer, L., Wang, Q., & Chyu, M. K. (2002). Computation of the Conjugating Heat Transfer of Fuel and Oxidant Separated by a Heat-generating Cell Tube in a Solid Oxide Fuel Cell. American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD, 372(7), 423-430.
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  Abstract: A numerical model is presented in this work to compute the inter-dependent fields of flow, temperature and the concentrations of multiple gases in a single tubular solid oxide fuel cell (SOFC) system. It was supposed that the fuel gas supplied to the fuel cell is from a pre-reformer and thus contains hydrogen and proportions of carbon monoxide, carbon dioxide, steam, and methane. The model takes mixture gas properties of the fuel and oxidant as functions of the numerically obtained local temperature, pressure and species concentrations, which are inter-dependent and intimately related to the electrochemical reaction in the SOFC. In the iterative computation steps, local electrochemical parameters were simultaneously calculated based on the local parameters of pressure, temperature, and concentration of the species available at each step. Upon the convergence of the computation, both local details and the overall performance of the fuel cell could be obtained. The numerical results obtained are helpful for better understanding of the operation of SOFCs.
• Li, P., Schaefer, L., Wang, Q., & Chyu, M. K. (2002). Computation of the conjugating heat transfer of fuel and oxidant separated by a heat-generating cell tube in a solid oxide fuel cell. ASME International Mechanical Engineering Congress and Exposition, Proceedings, 7, 423-430.
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  Abstract: A numerical model is presented in this work to compute the inter-dependent fields of flow, temperature and the concentrations of multiple gases in a single tubular solid oxide fuel cell (SOFC) system. It was supposed that the fuel gas supplied to the fuel cell is from a pre-reformer and thus contains hydrogen and proportions of carbon monoxide, carbon dioxide, steam, and methane. The model takes mixture gas properties of the fuel and oxidant as functions of the numerically obtained local temperature, pressure and species concentrations, which are inter-dependent and intimately related to the electrochemical reaction in the SOFC. In the iterative computation steps, local electrochemical parameters were simultaneously calculated based on the local parameters of pressure, temperature, and concentration of the species available at each step. Upon the convergence of the computation, both local details and the overall performance of the fuel cell could be obtained. The numerical results obtained are helpful for better understanding of the operation of SOFCs. Copyright © 2002 by ASME.
• Chen, M., Li, P. W., Wang, Q. W., & Tao, W. Q. (2001). Theoretical calculation on forced convective condensation heat transfer coefficient of nonazeotropic mixtures inside tube. Huagong Xuebao/Journal of Chemical Industry and Engineering (China), 52(2), 114-118.
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  Abstract: A theoretical approach to forced convective condensation heat transfer coefficient of nonazeotropic mixtures inside smooth tubes was developed. Calculations were performed for R32/R134a mixtures with the R32 mass fraction ranged from 0 to 60.1%. The results reveals that there is a reduction of heat transfer coefficient for a nonazeotropic mixture compared with that of a single component substance with the same thermophysical properties. The reduction of the heat transfer coefficient depends not only on the mass fraction of the mixture, but also on the vapor quality of the fluid. Besides, minimum heat transfer coefficients were observed at mass fractions ranging from 10% to 30% for R32/R234a mixtures.
• Li, P. W., Kawaguchi, Y., Yabe, A., Daisaka, H., Hishida, K., & Maeda, M. (2001). Experimental study of the characteristics on turbulence in drag reducing flow using surfactant additives. Hsi-An Chiao Tung Ta Hsueh/Journal of Xi'an Jiaotong University, 35(1), 37-42.
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  Abstract: The phenomenon of drag reduction of turbulence water flow added with surfactant (CTAC+NaSal)was investigated experimentally in the work. The conditions of temperature, concentration of surfactant and Reynolds number that drag reduction may occur were studied. By using LDV, the turbulence properties of the flow in a two-dimensional channel were measured. It is concluded that the low drag of surfactant solution flow can be maintained at Reynolds numbers pertinent to turbulent flow of the case for water alone if the Reynolds number does not exceed a critical Reynolds number. The critical Reynolds number however increases with the surfactant concentration and decreases with increasing the temperature of the solution. Under drag reducing flow, the main velocity profile shifts its shape to that of a laminar flow however, still remains certain level of turbulent intensities although quite weak than that of water flow under the same Reynolds number. While there are turbulent intensities, the turbulent Reynolds stress is almost zero or even has depletion, which reflects the change of correlation of turbulence intensities in different directions in the flow.
• Li, P., Kawaguchi, Y., & Yabe, A. (2001). Transitional heat transfer and turbulent characteristics of drag-reducing flow through a contracted channel. Journal of Enhanced Heat Transfer, 8(1), 23-40.
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  Abstract: Accompanying the significant reduction of drag of turbulent flow when a drag-reducing surfactant is used, there is a serious reduction of heat transfer, typically 80%. Since the drag reduction can be terminated by a large wall shear stress, the drag-reducing flow of surfactant solution has a special property of the diameter effect. Based on this, a contracted section was designed in a two-dimensional channel to control the drag-reducing flow of a surfactant solution so as to produce turbulence for heat transfer purposes when it passes through the contracted part at certain Reynolds numbers. The same level of turbulence intensity as that of water flow is approached when the surfactant solution passes through the contracted section at certain Reynolds numbers. The heat transfer coefficient thus achieves 70 to 80 percent of that of water flow in the contracted section. In the non-contracted section the friction drag keeps the low level as drag-reducing flow. It is shown that the termination of the drag-reducing effect of the surfactant solution within a heat exchanger is possible by using the present method. The studied surfactant solution is CTAC/NaSal/Water at the temperature of around 30 °C with the concentration ranging from 30 ppm to 60 ppm.
• Li, P., Kawaguchi, Y., Daisaka, H., Yabe, A., Hishida, K., & Maeda, M. (2001). Heat transfer enhancement to the drag-reducing flow of surfactant solution in two-dimensional channel with mesh-screen inserts at the inlet. Journal of Heat Transfer, 123(4), 779-789.
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  Abstract: The heat transfer enhancement of drag-reducing flow of high Reynolds number in a two-dimensional channel by utilizing the characteristic of fluid was studied. As the networks of rod-like micelles in surfactant solution are responsible for suppressing the turbulence in drag-reducing flow, destruction of the structure of networks was considered to eliminate the drag reduction and prevent heat transfer deterioration. By inserting wire mesh in the channel against the flow, the drag-reducing function of the micellar structure in surfactant aqueous solution was successfully switched off. With the Reynolds number close to the first critical Reynolds number, the heat transfer coefficient in the region downstream of the mesh can be improved significantly, reaching the same level as that of water. The region with turbulent heat transfer downstream of the mesh becomes smaller as the concentration of surfactant in the solution increases. Three types of mesh of different wire diameter and opening space were evaluated for their effect in promoting heat transfer and the corresponding pressure loss due to blockage of the mesh. The turbulent intensities were measured downstream from the mesh by using a Laser Doppler Velocimetry (LDV) system. The results indicated that the success of heat transfer enhancement is due to the strong turbulence promoted by the mesh which destroys the network of rod-like micelles by applying high shear stress and thus relaxing the shear induced state (SIS).
• Li, P., Chen, M., & Tao, W. (2000). Theoretical analysis and experimental investigation on local heat transfer characteristics of HFC-134a forced-convection condensation inside smooth horizontal tubes. Heat Transfer Engineering, 21(6), 34-43.
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  Abstract: An improved analysis model is presented for predicting the local heat transfer coefficient of forced condensation in the annular flow region inside smooth horizontal tubes. Heat transfer experiments for R-12 and R-134a are conducted inside a condensing tube with an inner diameter of 11 mm and a length of 13 m. The mass flux ranged from 200 to 510 kg/m2 s, and the vapor qualities varied from 1.0 to 0.0. Compared with the experimental data, the numerical results have a deviation of not more than 20% and 25% for 80% of the total 47 points of R-12 and 88% of the total 226 points of R-134a, respectively. Copyright © 2000 Taylor & Francis.
• Kawaguchi, Y., Yabe, A., Daisaka, H., Hishida, K., Li, P. W., & Maeda, M. (1997). Study on a thermal boundary layer of drag reducing surfactant solution - Measurements of temperature fluctuation. American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FED, 244, 375-380.
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  Abstract: In order to clarify the mechanism of turbulent heat transfer in drag reducing flow by surfactant additives, temperature in thermal boundary layer in two dimensional channel has been experimentally investigated. Time mean temperature and temperature fluctuation were examined at the Reynolds number of 1.2×10 4 using a fine wire thermocouple probe. The surfactant system tested was CTAC/NaSal/water. A high diffusivity layer near the wall was found in the thermal boundary layer of surfactant solution. The layer is formed by micellar phase change. Time scales of the temperature fluctuation in surfactant solution flow became large compared to the water flow. It suggests the role of the fluid elasticity to suppress the coherent structure near the wall. As the drag reducing additives have a direct effect on the flow structure in the buffer layer at 10
• Chen, M., Li, P. W., & Tao, W. Q. (1996). Investigation on existing correlations for prediction of HFC-134A in-tube boiling heat transfer coefficients based on experiment. International Symposium on Heat Transfer, 411-416.
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  Abstract: The present work is concerned with the saturated flow boiling heat transfer coefficients of HFC-134a inside a horizontal, smooth tube. Local-average heat transfer coefficients were measured with pure HFC-134a using a water-heated, double-tube counterflow test section. The results were compared with ten existing correlations, among whom those of Kandlikar, Wattelet et al. and Bivens & Yokozeki were found to be superior to the others, with the correlation of Wattelet et al. having the minimum absolute mean deviation. In consideration of the wide range of applicability, the correlation of Kandilkar, though gave slightly poorer agreement against present data, is suggested for use of HFC-134a in thermal design of equipment.
• Li, P. W., & Tao, W. Q. (1995). Experimental study on mass/heat transfer of circular jet impingement in cubical cavities. Journal of Enhanced Heat Transfer, 2(4), 251-261.
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  Abstract: Heat/mass transfer characteristics of a circular jet impingement in cubical cavity with flat or curved bottom surface are investigated experimentally using naphthalene sublimation technique. The effects of the distance between jet exit and bottom surface (H) and jet Reynolds number are parametrically studied. The jet Reynolds number varied from 7 × 103 to 1.1 × 105, and the ratio of H/D (D-jet delivery nozzle diameter) varied from 0.5 to 4.0. The surface averaged Sherwood numbers for the bottom and lateral walls are correlated with jet exit Reynolds number by a power law equation. In the parameter range tested, the averaged Sherwood number of the bottom surface is always lower than that of the lateral walls.
• Li, P. W., & Tao, W. Q. (1994). Effects of outflow boundary condition on convective heat transfer with strong recirculating flow. Wärme- und Stoffübertragung, 29(8), 463-470.
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  Abstract: Three practices of treating outflow boundary condition were adopted in computations for convective heat transfer of a two-dimensional jet impinging in a rectangular cavity. The three practices were local mass conservation method, local one-way method and fully developed assumption. The numerical solutions of the three methods were compared with test data obtained via, naphthalene sublimation technique. It was found that the fully developed assumption was inappropriate, and the local one-way method could provide reasonably good results for the cavity bottom, while for the lateral wall the results with this method qualitatively differed from the test data. The solution with the local mass conservation method was the best. It thus suggested that for a problem expected with a strong recirculating flow at the exit of the computation domain, the local mass conservation method be adopted to treat the outflow boundary condition. © 1994 Springer-Verlag Berlin Heidelberg.
• Li, P. W., & Tao, W. Q. (1993). Numerical and experimental investigations on heat/mass transfer of slot-jet impingement in a rectangular cavity. International Journal of Heat and Fluid Flow, 14(3), 246-253.
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  Abstract: Laminar flow and heat/mass transfer of a slot jet impinging in a rectangular cavity are studied numerically and experimentally. The discretization equations are formed by the finite-volume approach. Special attention is paid to the treatment of the outflow boundary condition. The influences of the jet-exit velocity distribution, the distance between the jet exit and the cavity bottom, and the Reynolds number on the local heat transfer distribution of the cavity bottom are investigated. In the experimental work, the local mass transfer coefficient distribution of the bottom surface is measured by the napthalene sublimation technique. The agreement between the numerical and experimental results is quite satisfactory. © 1993.

Proceedings Publications

• Hatcher, S., Farias, M., Li, J., Li, P., & Xu, B. (2023, July/Simmer).

  Numerical Study of Solar Receiver Tube With Modified Surface Roughness for Enhanced and Selective Absorptivity in Concentrated Solar Power Tower

  . In 17th International Conference on Energy Sustainability.
• Li, P. (2023). Numerical Study of Solar Receiver Tube With Modified Surface Roughness for Enhanced and Selective Absorptivity in Concentrated Solar Power Tower. In ASME 2023, 17th International Conference on Energy Sustainability.
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  https://doi.org/10.1115/ES2023-106936
• Li, P. (2023). Prediction of the Maximum Energy Harvest Considering Year-Around Sky Coverage Conditions and Optimized Setup Angles of Fixed PV Panels. In ASME IMECE conference 2023. Proceedings of the 2023 International Mechanical Engineering Congress and Exposition.
• Li, P., & Zhang, Y. (2022). Analysis of the Heat Transfer and Criterion of Freezing of Molten Salt Startup Flow in Relatively Cold Pipes. In ASME 2022 Heat Transfer Summer Conference.
• Li, P., Missoum, S., Pidaparthi, B., Hatcher, S., Khadka, R., & Xu, B. (2022). Multiphysics Numerical Study of Solar Receiver Tube for Enhanced Thermal Efficiency and Durability in Concentrated Solar Power Tower Plant. In ASME 2022 16th International Conference of Energy Sustainability.
• Haddad, F., & Li, P. (2021, 11/Winter). Entropy Generation Minimization to Optimize Heat Transfer in CSP Technologies Using Molten Salt System NaCl/KCl/MgCl₂ as Heat Transfer Fluids. In 2021 ASME International Mechanical Engineering Congress and Exposition.
• Gamil, A., Li, P., & Angel, R. (2020). Modeling of a small-scale solar central receiver with pressurized water for heat collection and storage. In 2020 AIChE Annual Meeting.
• Hu, Q., Wang, X., & Li, P. (2020). Experimental investigation to the desalination performance of a system due to integration of a solar collection chamber and a cooling chimney. In 5th Thermal and Fluids Engineering Conference (TFEC), 2020.
• Li, P., Hu, Q., & Wang, X. (2020, April). Experimental investigation to the desalination performance of a system due to integration of a solar collection chamber and a cooling chimney. In 5th Thermal and Fluids Engineering Conference (TFEC), 2020, 5-8, April , New Orleans, LA, USA, 1, 12.
• Missoum, S., Li, P., & Pidaparthi, B. (2020). Entropy-Based Optimization of Helical Fins for Heat Transfer Enhancement Inside Tubes. In ASME 2020 International Mechanical Engineering Congress and Exposition.
• Pidaparthi, B. P., Missoum, S., & Li, P. (2020). A Multi-Fidelity Approach for the Reliability Assessment of Shell and Tube Heat Exchangers. In 2020 ASME International Mechanical Engineering Congress and Exposition.
• Pidaparthi, B., Li, P., & Missoum, S. (2020). Entropy-Based Optimization of Helical Fins for Heat Transfer Enhancement Inside Tubes. In 2020 ASME International Mechanical Engineering Congress and Exposition.
• Alfulayyih, Y. M., Gwesha, A. O., & Li, P. (2019, November/Winter.).

  Optimization of Fixed PV Panel “Tilt” Angles for Maximal Energy Harvest Considering Year-Around Sky Coverage Conditions

  . In 2019 International Mechanical Engineering Congress and Exposition, IMECE2019 -10391, November 11-14, 2019, Salt Lake City, UT, USA..
• Alfulayyih,, Y. M., Li, P., & Xu, X. (2019). YEAR-ROUND SOLAR ENERGY FORECASTING AND STORAGE PREDICTION FOR NON-INTERRUPTED POWER SUPPLY. In 2019, 4th Thermal and Fluids Engineering Conference.
• Gwesha, A. O., Alfulayyih, Y. M., & Li, P. (2019). Optimization of fixed PV panel “Tilt” angles for maximal energy harvest considering year-around sky coverage conditions. In 2019 ASME International Mechanical Engineering Congress and Exposition.
• Li, P., Vasquez Diaz, G. A., Wang, K., & Wei, C. (2019, July 15-18/Summer.).

  CFD Analysis and Evaluation of Heat Transfer Enhancement of Internal Flow in Tubes With 3D-Printed Complex Fins

  . In Proceedings of the ASME Summer Heat Transfer Conference, HT2019-3630, July 15-18, 2019, Bellevue, WA, USA..
• Wei, C., Diaz, G. A., Wang, K., & Li, P. (2019). CFD analysis and evaluation of heat transfer enhancement of internal flow in tubes with 3D-printed complex fins. In 2019 ASME summer heat transfer conference.
• Li, P. (2018, March 4 – 7). Evaluation of Several Types of High Temperature Heat Transfer Fluids for Concentrated Solar Power System. In The 3rd Thermal and Fluid Engineering Conference, TFEC2018, TFEC-2018-21710, , March 4 – 7, 2018, Fort Lauderdale, FL, USA..
• Li, P. (2018, Nov.). Experimental Study of Hygroscopy of Single and Different Mixtures of MgCl2, KCl, NaCl, ZnCl2 for Ap-plication as Heat Transfer Fluids in CSP. In ASME 2018 In-ternational Mechanical Engineering Congress and Exposition.
• Li, P. (2018, Nov.). Longer Passage of Airflow in Multiple Packed-Bed Thin Tanks Versus in a Short Big Tank for Improved Thermal Storage Performance. In Proceedings of the ASME 2018 International Mechanical Engineering Congress and Exposition IMECE2018.
• Li, P., Wang, X., Zhang, S., & Xu, X. (2017). Producing Hydrogen From Jet-A Fuel in a Reactor With Integrated Autothermal Reforming and Water-Gas Shift. In ASME 2017 Power and Energy Conference and Exhibition.
• Xiao, B., Li, P., Gervasio, D., Xu, X., Wang, X., Elsentriecy, H., Li, Y., & Hao, Q. (2017). Investigation of Properties of KCl-MgCl2 Eutectic Salt for Heat Transfer and Thermal Storage Fluids in CSP Systems. In ASME 2017 Summer Heat Transfer Conference.
• Li, P., Dehghani, G., & Xu, X. (2016, June). Measurement Of The Basic Properties Of Ternary Eutectic Chloride Salts Used As High Temperature Heat Transfer Fluids And Thermal Storage Media. In ASME 2016 Power and Energy Conference and Exhibition, June 26-30, 2016, Charlotte, NC, USA..
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  Ghazal Dehghani, Xiankun Xu, Peiwen Li, Measurement Of The Basic Properties Of Ternary Eutectic Chloride Salts Used As High Temperature Heat Transfer Fluids And Thermal Storage Media, PowerEnergy2016-59190, Proceedings of ASME 2016 Power and Energy Conference and Exhibition, June 26-30, 2016, Charlotte, NC, USA.
• Li, P., Guo, P., & Li, J. (2016, November). Assessment of Water Droplet Evaporation Path in a Full Separation MED Desalination System. In ASME 2016 International Mechanical Engineering Congress & Exposition.
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  Penghua Guo, Peiwen Li, Jingyin Li, Assessment of Water Droplet Evaporation Path in a Full Separation MED Desalination System, Proceedings of the ASME 2016 International Mechanical Engineering Congress & Exposition, IMECE2016, IMECE2016-65656, Nov 11-17, 2016, Phoenix, AZ, USA.
• Li, P., Xu, X., & Dehghani, G. (2016). Measurement of the Basic Properties of Ternary Eutectic Chloride Salts Used as High Temperature Heat Transfer Fluids and Thermal Storage Media. In ASME 2016 Power and Energy Conference and Exhibition.
• Li, P., Zhang, S., & Wang, X. (2016, June). , Hydrogen Production Via Catalytic Autothermal Reforming of Desulfurized Jet-A Fuel. In ASME 2016 Power and Energy Conference and Exhibition, June 26-30, 2016, Charlotte, NC, USA.
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  Shuyang Zhang, Xiaoxin Wang, Peiwen Li, Hydrogen Production Via Catalytic Autothermal Reforming of Desulfurized Jet-A Fuel, PowerEnergy2016-59095, Proceedings of ASME 2016 Power and Energy Conference and Exhibition, June 26-30, 2016, Charlotte, NC, USA
• Peri, A., Li, P., Ma, H., & Chen, Y. (2015). Heat and Mass Transfer Analysis of a Water and Solute Separation System: Using Solar Thermal Energy for Water Desalination. In ASME 2015 Power & Energy Conversion Conference.
• Han, J., Xu, B., Li, P., Kumar, A., & Yang, Y. (2014, November 14-20). Experimental Study of a Novel Thermal Storage System Using Sands with High-conductive Fluids Occupying the Pores. In 2014 International Mechanical Engineering Congress and Exposition.
• Li, P., Xu, B., & Chan, C. (2014). Volume Sizing for Thermal Storage With Phase Change Material for Concentrated Solar Power Plant. In ASME 2014 8th International Conference on Energy Sustainability.
• Wang, K., Molina, E., Dehghani, G., Xu, B., Li, P., Hao, Q., Lucas, P., Kassaee, M. H., Jeter, S. M., & Teja, A. S. (2014, June 29-July 2). Experimental Investigation to the Properties of Eutectic Salts by NaCl-KCl-ZnC12 for Application as High Temperature Heat Transfer Fluids. In 8th International Xonference on Energy Sustainability.
• Xu, B., Li, P., & Chan, C. (2014, June 29-July 2). Fluid Charge and Discharge Strategies of Dual-media Thermal Storage Systems in the Starting-up Process of Daily Cyclic Operations. In 8th International Conference on Energy Sustainability.
• Xu, B., Li, P., & Chan, C. (2014, June 29-July 2). Volume Sizing for Thermal Storage with Phase Change Material for Concentrated Solar Power Plant. In 8th International Conference on Energy Sustainability.
• Xu, X., Zhang, S., & Li, P. (2014, June 29-July 2). Hydrogen Production of a Heavy Hydrocarbon Fuel Autothermal Reformer on NiO-Eh Based Monolithic Catalysts. In 12th Fuel Cell Science, Engineering and Technology Conference.
• Arabyan, A., Li, P., & Wang, K. (2013). Achieving Quasi-Isothermal Air Compression With Multistage Compressors for Large-Scale Energy Storage. In ASME 2013 7th International Conference on Energy Sustainability.
• Li, P., Xu, B., Tumilowicz, E., & Chan, C. L. (2013). An Enthalpy Formulation for Thermocline With Encapsulated PCM Thermal Storage and Benchmark Solution Using the Method of Characteristics. In Proceedings of the ASME 2013 Summer Heat Transfer Conference.
• Li, P., Zhang, S., & Xu, X. (2013). Desulfurization of Liquid Phase Jet-A Fuel by Selective Adsorption at Room Temperature. In ASME 2013 11th Fuel Cell Science.
• Waller, P., Li, P., & Xu, B. (2013). Optimization of the Flow Field of a Novel ARID Raceway (ARID-HV) for Algal Production. In ASME 2013 11th Energy Sustainability and Fuel Cell Science, Engineering, and Technology.
• Loy, D., Li, P., & Garza, G. (2012). Micro-Fluidic Assisted Passive Direct Methanol Fuel Cells. In 2012 ASME International Mechanical Engineering Congress & Exposition.
• Sanfelice, R. G., Li, P., Kane, P., & Mokler, M. (2012). The Effect of Solar Tracking Resolution to the Defocus of a Giant Fresnel Lens for a Solar Stove. In ASME 2012 6th International Conference on energy Sustainability and Fuel Cells..
• Waller, P., Li, P., & Xu, B. (2012). Study of the Flow Mixing in a Novel Open-Channel Raceway for Algae Production. In ASME 2012 6th International Conference on Energy Sustainability and fuel cells.
• Chan, C., Li, P., Karaki, W., Van Lew, J., Valmiki, M. M., & Stephens, J. (2011). Experimental Investigation of Thermal Storage Processes in a Thermocline Storage Tank. In ASME 2011 5th International Conference on Energy Sustainability..
• Li, P., & Liu, H. (2011). CFD Assisted Design Optimization of a Flow Distributor for Uniform Fluid Distribution. In 2011 ASME International Mechanical Engineering Congress & Exposition.
• Li, P., Ramos-Alvarado, B., Liu, H., & Hernandez-Guerrero, A. (2010). CFD Analysis of Flow and Heat Transfer in a Novel Heat Sink for Electronic Devices. In 2010 ASME International Mechanical Engineering Congress & Exposition..
• Li, P., Xu, X., Valmiki, M. M., Pradhan, S., & Liu, H. (2010). Solar Thermal Closed-Helium Brayton Cycle With High Temperature Phase-Change Thermal Storage. In ASME 2010 4th International Conference on Energy Sustainability.
• Li, P., Dhar, N., & Dumay, A. (2009). Development and Fabrication of Passive DMFCs. In FUELCELL2009, Seventh International Conference on Fuel Cell Science.
• Li, P., Milobar, D. G., & O’Brien, J. E. (2009). Analytical Study, 1-D Optimization Modeling, and Testing of Electrode Supported Solid Oxide Electrolysis Cells. In ASME 2009 2nd Micro/Nanoscale Heat & Mass Transfer International Conference.
• Li, P., Ramos-Alvarado, B., Hernandez-Guerrero, A., Juarez-Robles, D., & Rubio-Arana, J. C. (2009). Parametric Study of a Symmetric Flow Distributor. In ASME 2009 International Mechanical Congress and Exposition.
• Li, P., Sahrawat, S., Sepulveda, J. L., Loutfy, R. O., & Chang, S. (2009). An Easy-to-Approach Mathematical Model and Optimization of Planar Type Proton-Conductive SOFC. In Seventh International Conference on Fuel Cell Science, FUELCELL2009.
• Li, P., Van Lew, J. T., Chan, C. L., Karaki, W., & Stephens, J. (2009). Transient Heat Delivery and Storage Process in a Thermocline Heat Storage System. In Proceedings of the ASME 2009 International Mechanical Congress and Exposition..
• Li, P., Coopamah, D., & Dhar, N. (2008). Analysis and Optimization of Flow Distribution Channels for Uniform Flow in Fuel Cells. In 2008 ASME Fluids Engineering Conference.
• Li, P., Coopamah, D., & Ki, J. (2008). Uniform Distribution of Species in Fuel Cells Using a Multiple Flow Bifurcation Design. In Sixth international Conference on Fuel Cell Science, Engineering and Technology, ASME, New York, 2008..
• Li, P., Coopamah, D., & Ki, J. (2008, Proceedings of the Sixth international Conference on Fuel Cell Science, Engineering and Technology, ASME, New York, 2008.). Uniform Distribution of Species in Fuel Cells Using a Multiple Flow Bifurcation Design. In 2008 Proceedings of the Sixth international Conference on Fuel Cell Science, Engineering and Technology..
• Chen, C. F., Chan, C. L., & Li, P. (2007). Buoyancy-Driven Circulation Flow of an Electrical Conductive Liquid in a Rectangular Annulus. In 2007 ASME-JSME, Thermal Engineering Summer Heat Transfer Conference.
• Li, P., & Tao, G. (2007). Effect of the Geometries of Current Collectors on the Power Density in a Solid Oxide Fuel Cell. In 2007 ASME International Mechanical Engineering Congress and Exposition.

Presentations

• Li, P. (2023).

  _{Some issues and solutions to facilitate the future energy need fully relying on renewable energies}

  . Invited seminar talk. University of Wisconsin Madison: University of Wisconsin.
• Li, P. (2023, July). Heat transfer analysis of special receivers/reactors to facilitate reciprocal redox thermochemical reactions for hydrogen production. Advances in Solar Energy: Heliostat Systems Design, Implementation, and Operation. San Diego: SPIE.
• Li, P. (2016, June). High Temperature Heat Transfer Fluid and Heat Transfer in Solar Collectors—the Critical Demand for Concentrated Solar Power Technology. ASME 2016 Power and Energy Conference and Exhibition, June 26-30, 2016, Charlotte, NC, USA.. Charlotte, NC, USA.: ASME Energy Sustainability.
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  High Temperature Heat Transfer Fluid and Heat Transfer in Solar Collectors—the Critical Demand for Concentrated Solar Power Technology, Plenary keynote speech, ASME 2016 Power and Energy Conference and Exhibition, June 26-30, 2016, Charlotte, NC, USA.
• Li, P. (2016, June). Long term, large scale, wind and solar energy storage via hydrogen production (storage) using electrolyzers. School of Energy and Power Engineering, Xi’an Jiaotong University, 8:30 am, June 4, 2016.. School of Energy and Power Engineering,: Xi’an Jiaotong University.
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  Long term, large scale, wind and solar energy storage via hydrogen production (storage) using electrolyzers, School of Energy and Power Engineering, Xi’an Jiaotong University, 8:30 am, June 4, 2016.
• Li, P. (2016, June). Recent Advancement of Concentrated Solar Thermal Power Technology. Invited talk at Lanzhou Jiaotong University, 3:00 pm, June 14, 2016.. Lanzhou Jiaotong University, Lanzhou, Gansu, China.: Lanzhou Jiaotong University.
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  Recent Advancement of Concentrated Solar Thermal Power Technology, Lanzhou Jiaotong University, 3:00 pm, June 14, 2016.
• Li, P. (2016, June). Recent Advancement of Concentrated Solar Thermal Power Technology. Invited talk at University of Chinese Academy of Science. University of Chinese Academy of Science, Beijing, China: University of Chinese Academy of Science.
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  Recent Advancement of Concentrated Solar Thermal Power Technology, University of Chinese Academy of Science, 3:00 pm, June 17, 2016.
• Li, P. (2016, June). Thermal-driven Water Treatment Systems for Full Separation of Solute-Water. BIT’s 5th Annual World Congress of Advanced Materials. Chongqing, China: Chinese Material Science society.
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  Peiwen Li, Sahib Metha, Ishan Arora, Aditya Peri, Abraham Jalbout, Thermal-driven Water Treatment Systems for Full Separation of Solute-Water, BIT’s 5th Annual World Congress of Advanced Materials, June 6-8, 2016, Chongqing, China.
• Li, P. (2016, June). Thermal-driven Water Treatment Systems for Full Separation of Solute-Water. Invited talk at School of Energy and Power Engineering. School of Energy and Power engineering, Xi’an Jiaotong University, Xi'an, Shaanxi, China.: Xi’an Jiaotong University.
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  Thermal-driven Water Treatment Systems for Full Separation of Solute-Water, School of Energy and Power Engineering, Xi’an Jiaotong University, 11:00 am, June 4, 2016.
• Li, P. (2016, May). Minimum System Entropy Production for the Figure of Merit of High Temperature Heat Transfer Fluid Properties. Invited talk at School of Energy and Power Engineering, Xi’an Jiaotong University, 11:00am, May 25, 2016.. School of Energy and Power Engineering, Xi’an Jiaotong University, 11:00am, May 25, 2016.: Xi’an Jiaotong University, China.
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  Minimum System Entropy Production for the Figure of Merit of High Temperature Heat Transfer Fluid Properties, School of Energy and Power Engineering, Xi’an Jiaotong University, 11:00am, May 25, 2016.
• Li, P. (2016, May). Recent Advancement of Concentrated Solar Thermal Power Technology. Invited talk at Institute of Engineering Thermophysics, Chinese Academy of Science.. Invited talk at Institute of Engineering Thermophysics, Chinese Academy of Science.: Chinese Academy of Science..
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  Recent Advancement of Concentrated Solar Thermal Power Technology, Institute of Engineering Thermophysics, Chinese Academy of Science, 10:00 am, May 24, 2016.
• Li, P. (2016, May). Recent Advancement of Concentrated Solar Thermal Power Technology, School of Energy and Power Engineering. Xi’an Jiaotong University, May 25, 2016.. School of Energy and Power Engineering, Xi’an Jiaotong University: Xi’an Jiaotong University.
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  Recent Advancement of Concentrated Solar Thermal Power Technology, School of Energy and Power Engineering, Xi’an Jiaotong University, 8:30am, May 25, 2016.
• Li, P. (2016, May). Recent Advancement of Concentrated Solar Thermal Power Technology. Invited talk at Nanjing Tech University, 3:00 pm, May 27, 2016.. department of Materials for Energy technologies, Nanjing Tech University, 3:00 pm, May 27, 2016.: Nanjing Tech University, 3:00 pm, May 27, 2016..
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  Recent Advancement of Concentrated Solar Thermal Power Technology, Nanjing Tech University, 3:00 pm, May 27, 2016.
• Li, P. (2016, june). Solar and Wind Energy Electricity for Hydrogen Production and Large Quantity Energy Storage. Plenary keynote speech, ASME 2016 Fuel Cell Conference, June 26-30, 2016, Charlotte, NC, USA.ASME Energy Sustainability.
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  Solar and Wind Energy Electricity for Hydrogen Production and Large Quantity Energy Storage, Plenary keynote speech, ASME 2016 Fuel Cell Conference, June 26-30, 2016, Charlotte, NC, USA.
• Li, P. (2014, May 29). Halide and Oxy-halide Eutectic Systes for High Performance High Temperature Heat Transfer Fluids. DOE SunShot Workshop. Anaheim, CA: DOE.
• Li, P. (2014, October 22). Concentrated Solar Thermal Power Generation at Higher Temperatures--U of A Heat Transfer Fluid Development. GK-12 student fellows and local middle and high school teachers. Tucson, AZ: AME.