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Hang Guo
MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Beijing Key Laboratory of Heat Transfer and Energy Conversion, College of Energy and Power Engineering, Beijing University of Technology, Beijing, 100124, China

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Fuel cell
electrolysis
organic Rankine cycle
Power generation of renewable energy
photovoltaic
Parabolic trough collector field

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Journal article
Published: 28 April 2021 in International Journal of Hydrogen Energy
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Orientated-type flow channels of proton exchange membrane fuel cells cause non-Darcy effect occurring in flow regions. Therefore, the species transportation is affected by inertial effect. However, how the inertial force affects convection and diffusion of different species has not been discussed before. Thus, a modified two-dimensional, non-isothermal, two-phase and steady state model considering non-Darcy effect is employed in this study, and reactants and products transportations through diffusion and convection under inertial effects are quantitatively analyzed for the first time. Simulation results reveal that the convective transportation of reactants increases more under the influence of inertial force; water vapor transportation through convection increases the water content in porous regions. At the same time, liquid water expels more rapidly from gas diffusion layers under baffle regions, and enlarging baffle volumes increases the regions where the liquid water is rapidly removed under the inertial effect.

ACS Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma. Improving two-phase mass transportation under Non-Darcy flow effect in orientated-type flow channels of proton exchange membrane fuel cells. International Journal of Hydrogen Energy 2021, 46, 21600 -21618.

AMA Style

Hao Chen, Hang Guo, Fang Ye, Chong Fang Ma. Improving two-phase mass transportation under Non-Darcy flow effect in orientated-type flow channels of proton exchange membrane fuel cells. International Journal of Hydrogen Energy. 2021; 46 (41):21600-21618.

Chicago/Turabian Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma. 2021. "Improving two-phase mass transportation under Non-Darcy flow effect in orientated-type flow channels of proton exchange membrane fuel cells." International Journal of Hydrogen Energy 46, no. 41: 21600-21618.

Review paper
Published: 04 April 2021 in International Journal of Energy Research
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Improving energy utilization efficiency and exploiting renewable energy source have become more crucial with the growing concern on energy crisis and environmental problem. Organic Rankine cycle, a clean, low‐cost, and efficient energy utilization technology, is eliciting increasing attention. In this study, the recent research studies on organic Rankine cycle configuration modifications integrated with pure organic fluid are summarized from the perspectives of nomenclature, configuration modifications, theoretical and numerical methods, and experimental development. Results reveal that the nomenclature on the common organic Rankine cycle configurations is confusing; the research studies on organic Rankine cycle configurations are mainly focused on numerical research studies, and theoretical and experimental research studies are relatively limited. The experimental and numerical studies are mostly related to organic Rankine cycle with a recuperator due to its higher thermal and exergy efficiencies. Most experimental research studies are contributed by Chinese scholars, which indicate that China has paid much attention to improving the global environment. More theoretical and experimental research studies on other organic Rankine cycle configurations are urgently needed.

ACS Style

Jun Fen Li; Hang Guo; Biao Lei; Yu Ting Wu; Fang Ye; Chong Fang Ma. An overview on subcritical organic rankine cycle configurations with pure organic fluids. International Journal of Energy Research 2021, 45, 12536 -12563.

AMA Style

Jun Fen Li, Hang Guo, Biao Lei, Yu Ting Wu, Fang Ye, Chong Fang Ma. An overview on subcritical organic rankine cycle configurations with pure organic fluids. International Journal of Energy Research. 2021; 45 (9):12536-12563.

Chicago/Turabian Style

Jun Fen Li; Hang Guo; Biao Lei; Yu Ting Wu; Fang Ye; Chong Fang Ma. 2021. "An overview on subcritical organic rankine cycle configurations with pure organic fluids." International Journal of Energy Research 45, no. 9: 12536-12563.

Journal article
Published: 16 January 2021 in International Journal of Hydrogen Energy
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Orientated-type flow channels having porous blocks enhance the reactant transfer into gas diffusion layers of proton exchange membrane fuel cells. However, because of the blockages accounted by baffles and porous blocks in channel regions, pumping power increases. In this study, with the aim of further reducing the pumping power in flow channels with porous-blocked baffles, an orientated-type flow channel with streamline baffles having porous blocks is proposed. By employing an improved two-fluid model, cell performance, liquid water distribution and pumping power in a single flow channel are numerically studied. The simulation results show that the baffles with porous blocks increase the cell performance, and the streamline baffles with larger volumes further increase the performance; the produced water in porous regions is ejected more under inertial effect, especially at the regions near to baffles in gas diffusion layers and inside porous blocks. In addition, by using the streamline baffles, the excessive increase in power loss is further reduced. Moreover, the location and porosity effects of baffles with porous blocks are analyzed. Simulation results show that the location exhibits obscure effects on reactant transfer and cell performance, while the liquid water can be removed more when the porous blocked baffles are concentrated at downstream. The net power is enhanced more when using three porous blocks with the porosity of 0.00.

ACS Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma. A numerical study of orientated-type flow channels with porous-blocked baffles of proton exchange membrane fuel cells. International Journal of Hydrogen Energy 2021, 1 .

AMA Style

Hao Chen, Hang Guo, Fang Ye, Chong Fang Ma. A numerical study of orientated-type flow channels with porous-blocked baffles of proton exchange membrane fuel cells. International Journal of Hydrogen Energy. 2021; ():1.

Chicago/Turabian Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma. 2021. "A numerical study of orientated-type flow channels with porous-blocked baffles of proton exchange membrane fuel cells." International Journal of Hydrogen Energy , no. : 1.

Journal article
Published: 19 December 2020 in International Journal of Hydrogen Energy
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Reactants and products distribute unevenly in flow channels of proton exchange membrane fuel cells, therefore, the baffle heights and locations in flow channels exhibit effects on species transportation. In this study, a two-dimensional, two-phase, non-isothermal, and steady state model is developed to study the baffle heights and locations effects on mass transportation and performance of the fuel cells with orientated-type channels. Simulation results show that: uniformly distributing baffles in a flow channel can both enhance the reactants transportation and help expel more liquid water, resulting in higher net powers; although using a big baffle at the upstream segment of a channel enhances the performance more, while the water accumulating is also increased more. Reducing the baffle heights accounts for weaker reactants transfer enhancements and worse liquid water expelling; moving the baffles backwardly also causes the decrease in reactant transportation, while the liquid water expelling process is increased.

ACS Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma. A numerical study of baffle height and location effects on mass transfer of proton exchange membrane fuel cells with orientated-type flow channels. International Journal of Hydrogen Energy 2020, 46, 7528 -7545.

AMA Style

Hao Chen, Hang Guo, Fang Ye, Chong Fang Ma. A numerical study of baffle height and location effects on mass transfer of proton exchange membrane fuel cells with orientated-type flow channels. International Journal of Hydrogen Energy. 2020; 46 (10):7528-7545.

Chicago/Turabian Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma. 2020. "A numerical study of baffle height and location effects on mass transfer of proton exchange membrane fuel cells with orientated-type flow channels." International Journal of Hydrogen Energy 46, no. 10: 7528-7545.

Journal article
Published: 09 December 2020 in Sustainability
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In this study, two schemes of solar electrical power generation are designed and compared according to solar collection area minimization. The one comprises the parabolic trough collector, dual-tank of molten salt heat storage, and Organic Rankine cycle. The other consists of photovoltaic cell, polymer electrolyte membrane water electrolyzer, and polymer electrolyte membrane fuel cell. The effects of irradiation value, environmental temperature, and energy storage type on thermodynamic performance were investigated. The results indicated that the solar irradiation value had a more obvious effect on the PV (photovoltaic) cell performance than environmental temperature, and the PTC (parabolic trough concentrator) performance was improved with the increases of solar irradiation value and environmental temperature. The environmental temperature effect was negligible; however, the influence of irradiation value was obvious. Irradiation value had a positive effect on the former system, whereas it demonstrated the opposite for the latter. The latter system had much lower efficiency than the former, due to the low conversion efficiency between hydrogen energy and electrical energy in the polymer electrolyte membrane water electrolyzer and fuel cell. Stated thus, the latter system is appropriate for the power generation system with non-energy storage, and the former system is promising in the power generation system with energy storage.

ACS Style

Junfen Li; Hang Guo; Qingpeng Meng; Yuting Wu; Fang Ye; Chongfang Ma. Thermodynamic Analysis and Comparison of Two Small-Scale Solar Electrical Power Generation Systems. Sustainability 2020, 12, 10268 .

AMA Style

Junfen Li, Hang Guo, Qingpeng Meng, Yuting Wu, Fang Ye, Chongfang Ma. Thermodynamic Analysis and Comparison of Two Small-Scale Solar Electrical Power Generation Systems. Sustainability. 2020; 12 (24):10268.

Chicago/Turabian Style

Junfen Li; Hang Guo; Qingpeng Meng; Yuting Wu; Fang Ye; Chongfang Ma. 2020. "Thermodynamic Analysis and Comparison of Two Small-Scale Solar Electrical Power Generation Systems." Sustainability 12, no. 24: 10268.

Journal article
Published: 01 December 2020 in Journal of Energy Engineering
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A better-designed flow channel can enhance the mass transfer and improve the performance of a proton exchange membrane fuel cell. An orientated-type flow channel can achieve guidance on reactant and product transfers, resulting in an increase in the mass transfer flux and the rapid removal of the product (especially liquid water). In this study, flow fields with different orientated-type gas flow channels having different baffles are fabricated, and their effects on the current density outputs of proton exchange membrane fuel cells under various heating temperature and reactant flow rate conditions are investigated using a self-constructed testing system. The experimental results indicate that cell performance can be increased when using orientated-type flow channels with baffles having longer leeward sides, and cell performance is increased more under a suitable heating temperature. Moreover, the increase in the current densities of proton exchange membrane fuel cells with smaller baffles is limited when increasing the reactant flow rates. This limitation can be avoided when using the orientated-type flow channels with baffles having longer leeward sides.

ACS Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma. Experimental Investigations on Cell Performance of Proton Exchange Membrane Fuel Cells with Orientated-Type Flow Channels. Journal of Energy Engineering 2020, 146, 04020062 .

AMA Style

Hao Chen, Hang Guo, Fang Ye, Chong Fang Ma. Experimental Investigations on Cell Performance of Proton Exchange Membrane Fuel Cells with Orientated-Type Flow Channels. Journal of Energy Engineering. 2020; 146 (6):04020062.

Chicago/Turabian Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma. 2020. "Experimental Investigations on Cell Performance of Proton Exchange Membrane Fuel Cells with Orientated-Type Flow Channels." Journal of Energy Engineering 146, no. 6: 04020062.

Research article
Published: 30 November 2020 in International Journal of Energy Research
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The transfer processes of reactants and products affect each other in proton exchange membrane fuel cells (PEMFCs), because they have contrast transfer directions between flow channels and gas diffusion layers (GDLs). In this study, a two‐dimensional, two‐phase, non‐isothermal and steady state model is developed to analyze the species transportation behaviors through diffusion and convection in PEMFCs with orientated‐type flow channels. Five conventional shape baffles effects on mass transfers are compared, and the relationships between convection and diffusion of reactants and produced water vapor are discussed. Simulation results reveal that baffle shapes affect the mass transportation through the baffles leading angles and volumes, and larger leading angles enhance the reactants and the water vapor convective transferring into GDLs; meanwhile, larger baffle volumes enhance the reactant transferring into GDLs and water vapor transferring out from GDLs through diffusion processes. In addition, transportation processes of reactants and vapor affect each other, where more reactants convectively transferring into GDLs causes more water vapor entering GDLs; enhancing the reactants diffusively transferring into GDLs reduces water vapor diffusive transportation out from GDLs.

ACS Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma. A numerical study on convection and diffusion of mass transfer in proton exchange membrane fuel cells with orientated‐type flow channels. International Journal of Energy Research 2020, 45, 5659 -5678.

AMA Style

Hao Chen, Hang Guo, Fang Ye, Chong Fang Ma. A numerical study on convection and diffusion of mass transfer in proton exchange membrane fuel cells with orientated‐type flow channels. International Journal of Energy Research. 2020; 45 (4):5659-5678.

Chicago/Turabian Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma. 2020. "A numerical study on convection and diffusion of mass transfer in proton exchange membrane fuel cells with orientated‐type flow channels." International Journal of Energy Research 45, no. 4: 5659-5678.

Journal article
Published: 30 July 2020 in International Journal of Hydrogen Energy
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In this study, a two-dimensional, two-phase, non-isothermal and steady-state modified model of proton exchange membrane fuel cells is developed. The Forchheimer's effect (Non-Darcy effect) is coupled in the model, and its impact on liquid water removing process in flow channels with baffles having different shapes is discussed. Simulation results show that the liquid water is able to be removed more at the regions around baffles. At the same time, the baffle shapes reform the liquid water distribution. When using the baffles having larger dimensions (e.g. using rectangular baffles or trapezoidal baffles), the flow spaces around baffles decrease more and the liquid water is removed more because of the increase in local flow velocity. As a result, the concentration polarization is weakened and cell performance is improved more. Moreover, a streamline baffled flow channel that is designed for the purpose of both increasing the cell performance and avoiding excessive increase in pressure drops is discussed. Simulation results show that this flow channel design can both avoid too much increase in pressure drop and facilitate the liquid water removing out from the fuel cell.

ACS Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma. Forchheimer's inertial effect on liquid water removal in proton exchange membrane fuel cells with baffled flow channels. International Journal of Hydrogen Energy 2020, 46, 2990 -3007.

AMA Style

Hao Chen, Hang Guo, Fang Ye, Chong Fang Ma. Forchheimer's inertial effect on liquid water removal in proton exchange membrane fuel cells with baffled flow channels. International Journal of Hydrogen Energy. 2020; 46 (3):2990-3007.

Chicago/Turabian Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma. 2020. "Forchheimer's inertial effect on liquid water removal in proton exchange membrane fuel cells with baffled flow channels." International Journal of Hydrogen Energy 46, no. 3: 2990-3007.

Journal article
Published: 24 June 2020 in Journal of Power Sources
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The pressure drops and pumping powers in flow channels of proton exchange membrane fuel cells are major standards to evaluate flow channel structures. Baffled flow channels provide higher performance, while the pressure drop and pumping power both aggravate. In this work, the impact of baffle leeward length on power output and pressure drops of proton exchange membrane fuel cells are experimentally studied. The pumping power, net power and power efficiency are calculated as well. Experimental results indicate that pressure drops increase when adding baffles in channels, and longer leeward lengths result in lower pressure drops. Higher cell temperature results in lower pressure drops. The time consuming for stabilizing pressure drop are shortened when using baffles having longer leeward lengths. The net power is increased when using larger baffles, and the highest net powers occur under the temperature of 333K or 343K. In addition, raising the cell temperature can increase the power efficiency, and when the leeward lengths of baffles are decreased, the power efficiency is also decreased. When using baffle without sloping leeward sides, the power efficiency can be decreased to 45.14% under lower cell temperature of 323K.

ACS Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma. An experimental study of cell performance and pressure drop of proton exchange membrane fuel cells with baffled flow channels. Journal of Power Sources 2020, 472, 228456 .

AMA Style

Hao Chen, Hang Guo, Fang Ye, Chong Fang Ma. An experimental study of cell performance and pressure drop of proton exchange membrane fuel cells with baffled flow channels. Journal of Power Sources. 2020; 472 ():228456.

Chicago/Turabian Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma. 2020. "An experimental study of cell performance and pressure drop of proton exchange membrane fuel cells with baffled flow channels." Journal of Power Sources 472, no. : 228456.

Research article
Published: 23 January 2020 in International Journal of Energy Research
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Solar thermal electricity generating technology is an alternative solution to energy crises and environmental problems, which has caused wide concern in recent decades. In this paper, a molten salt parabolic trough‐based concentrated organic Rankine cycle system is proposed and investigated. A quadribasic nitrate salt with low melting temperature is employed as a heat transfer and storage medium. A stable heat transfer and economic model is established with Matlab. The radial and axial temperature distributions in the collector tube are obtained, and the impact of condensation and evaporation temperatures on the heat transfer area is analyzed. Results show that the temperature along the axial direction linearly increases, and the temperature at the collector tube exit decreases with the increase of molten salt mass flow rate. The maximum temperature difference along the radial direction of the collector tube happens in the annular gap. Heat transfer and thermodymanic analysis indicates that condensation temperature has a more evident effect on heat transfer area than that of evaporation temperature. An increase in condensation temperature leads to a decrease in the evaporator area, the condenser area increases, and the total area decreases. Economic analysis indicates the collector cost plays a predominant role in total capital costs, and decreasing molten salt mass flow rate can considerably reduce collector cost. Levelized energy cost sensitivity analysis indicated that operation time per year has a more evident effect than that of the four factors. Heat transfer and economic analysis on the system helps in the selection of operation parameters.

ACS Style

Jun Fen Li; Hang Guo; Qing Peng Meng; Yu Ting Wu; Fang Ye; Chong Fang Ma. Thermoeconomic analysis on a molten salt parabolic trough‐based concentrated solar organic Rankine cycle system. International Journal of Energy Research 2020, 44, 3395 -3411.

AMA Style

Jun Fen Li, Hang Guo, Qing Peng Meng, Yu Ting Wu, Fang Ye, Chong Fang Ma. Thermoeconomic analysis on a molten salt parabolic trough‐based concentrated solar organic Rankine cycle system. International Journal of Energy Research. 2020; 44 (5):3395-3411.

Chicago/Turabian Style

Jun Fen Li; Hang Guo; Qing Peng Meng; Yu Ting Wu; Fang Ye; Chong Fang Ma. 2020. "Thermoeconomic analysis on a molten salt parabolic trough‐based concentrated solar organic Rankine cycle system." International Journal of Energy Research 44, no. 5: 3395-3411.

Research article
Published: 12 December 2019 in International Journal of Energy Research
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In typical membraneless microfluidic fuel cells, the anolyte and catholyte are driven by syringe pumps, increasing the overall size of the system and limiting its miniaturization. In this study, a membraneless microfluidic fuel cell with continuous multistream flow through cotton threads was proposed. Cotton threads are simply laid in parallel to form flow channels. Multistream flow through cotton threads is formed without any external pumps. Cell performances under various operation conditions are evaluated. The results show that the middle stream could separate other two streams effectively to prevent the diffusive mixing of anolyte and catholyte. A peak power density of 19.9 mW cm−2 and a limiting current density of 111.2 mA cm−2 are delivered. Moreover, the performance improves with the sodium formate concentration rising up to 2M, while it declines at 4M fuel concentration due to the weakened convection transport and product removal caused by the low flow rate. With increasing the flow rate, the performance is enhanced because of the improved fuel transport at the anode. The good performance as well as the constant‐voltage discharging curve indicates that the microfluidic fuel cell with cotton threads as flow channels provides a new direction for miniature power sources.

ACS Style

Rui Wu; Dingding Ye; Rong Chen; Biao Zhang; Xun Zhu; Hang Guo; Zhongliang Liu. A membraneless microfluidic fuel cell with continuous multistream flow through cotton threads. International Journal of Energy Research 2019, 44, 2243 -2251.

AMA Style

Rui Wu, Dingding Ye, Rong Chen, Biao Zhang, Xun Zhu, Hang Guo, Zhongliang Liu. A membraneless microfluidic fuel cell with continuous multistream flow through cotton threads. International Journal of Energy Research. 2019; 44 (3):2243-2251.

Chicago/Turabian Style

Rui Wu; Dingding Ye; Rong Chen; Biao Zhang; Xun Zhu; Hang Guo; Zhongliang Liu. 2019. "A membraneless microfluidic fuel cell with continuous multistream flow through cotton threads." International Journal of Energy Research 44, no. 3: 2243-2251.

Conference paper
Published: 17 November 2019 in Mechanical Engineering and Materials
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The efficiencies of single screw expander and multi-stage centrifugal pump are obtained by fitting experimental data, and which substitute the constant efficiencies of the expander and the pump in most researches. Modelling analysis of four configurations of organic Rankine cycle system (conventional organic Rankine cycle, organic Rankine cycle with a regenerator, extraction organic Rankine cycle and extraction organic Rankine cycle with a regenerator) is conducted, the effects of evaporation pressure and condensation temperature on the thermal efficiency of different cycle configurations are investigated and compared. Extraction pressure and extraction ratio are introduced to analyze the thermal efficiency of the latter two cycle configurations. Result shows that the extraction organic Rankine cycle with a regenerator has the highest thermal efficiency at the same operation condition; evaporation pressure has a positive effect on the thermal efficiency, while condensation temperature has a negative effect under a certain range. This study can provide a reference for the selection of the cycle configuration and design of operation parameters for a given system.

ACS Style

Jun Fen Li; Hang Guo; Biao Lei; Yu Ting Wu; Fang Ye; Chong Fang Ma. Thermodynamic Performance Analysis on Various Configurations of Organic Rankine Cycle Systems. Mechanical Engineering and Materials 2019, 439 -446.

AMA Style

Jun Fen Li, Hang Guo, Biao Lei, Yu Ting Wu, Fang Ye, Chong Fang Ma. Thermodynamic Performance Analysis on Various Configurations of Organic Rankine Cycle Systems. Mechanical Engineering and Materials. 2019; ():439-446.

Chicago/Turabian Style

Jun Fen Li; Hang Guo; Biao Lei; Yu Ting Wu; Fang Ye; Chong Fang Ma. 2019. "Thermodynamic Performance Analysis on Various Configurations of Organic Rankine Cycle Systems." Mechanical Engineering and Materials , no. : 439-446.

Journal article
Published: 30 May 2019 in Energy Conversion and Management
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The Forchheimer’s inertial force impact is always neglected when studying the mass transfer of proton exchange membrane fuel cells in previous literatures. In this work, firstly, driving forces affecting liquid droplets on gas diffusion layer surfaces are analyzed, and it is found that the impact of Forchheimer’s inertial force becomes non-neglected when the Reynolds number is increased. Therefore, a two-dimensional, non-isothermal, steady-state and modified two-fluid model, which considers the Forchheimer’s inertial force impact, is developed for the first time. The modified two-fluid model is validated by comparing with experimental data and conventional two-fluid model results. The results indicate that the modified two-fluid model results can match the experimental data quite well under various flow rates in both the fuel cell with a straight flow channel and that with a baffled flow channel. Moreover, the liquid water saturation distribution is also studied by using the modified two-fluid model. When considering the Forchheimer’s inertial force impact, comparing with the conventional two-fluid model results, liquid water saturations in flow channels, gas diffusion layers and catalyst layers are reduced by 5.69%, 5.56% and 4.22%, respectively, in the proton exchange membrane fuel cell with baffled flow channels.

ACS Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma. Modification of the two-fluid model and experimental study of proton exchange membrane fuel cells with baffled flow channels. Energy Conversion and Management 2019, 195, 972 -988.

AMA Style

Hao Chen, Hang Guo, Fang Ye, Chong Fang Ma. Modification of the two-fluid model and experimental study of proton exchange membrane fuel cells with baffled flow channels. Energy Conversion and Management. 2019; 195 ():972-988.

Chicago/Turabian Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma. 2019. "Modification of the two-fluid model and experimental study of proton exchange membrane fuel cells with baffled flow channels." Energy Conversion and Management 195, no. : 972-988.

Journal article
Published: 30 May 2019 in Energy Conversion and Management
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A unitized regenerative fuel cell is a typical gas–liquid two-phase system that consumes oxygen and hydrogen in a fuel cell mode and liquid water in an electrolytic cell mode. Liquid water removal is crucial for a successful cell start-up after the electrolytic cell mode ends. However, investigations on two-phase transfer mechanisms for liquid water removal are limited during mode switching. To fill this research gap, a three-dimensional two-phase full-cell model is developed to describe charges, gas mixtures and liquid water transfer corresponding to operational modes of electrolytic cell, gas purging and fuel cell. The cell is assumed to being in the isothermal state. Numerical model is analyzed by using COMSOL Multiphysics 5.3a software. Furthermore, experimental and simulated results are compared to validate the proposed model. Results show that more than 84.0% of pore volume is occupied with liquid water on porous layers in an electrolytic cell mode. Although pre-switching for water removal can decrease the volume fraction of liquid water within the porous layers from 0.88 to 0.50 in a short time, more time is required for liquid water being carried away under a low level of water flooding. Purging result presents diverse influences on start-up performance in a fuel cell mode. Liquid water distribution, which is similar to that in a fuel cell mode, formed in a purging mode is encouraged for promoting a quick and stable start-up in a fuel cell mode.

ACS Style

Hang Guo; Qing Guo; Fang Ye; Chong Fang Ma; Xun Zhu; Qiang Liao. Three-dimensional two-phase simulation of a unitized regenerative fuel cell during mode switching from electrolytic cell to fuel cell. Energy Conversion and Management 2019, 195, 989 -1003.

AMA Style

Hang Guo, Qing Guo, Fang Ye, Chong Fang Ma, Xun Zhu, Qiang Liao. Three-dimensional two-phase simulation of a unitized regenerative fuel cell during mode switching from electrolytic cell to fuel cell. Energy Conversion and Management. 2019; 195 ():989-1003.

Chicago/Turabian Style

Hang Guo; Qing Guo; Fang Ye; Chong Fang Ma; Xun Zhu; Qiang Liao. 2019. "Three-dimensional two-phase simulation of a unitized regenerative fuel cell during mode switching from electrolytic cell to fuel cell." Energy Conversion and Management 195, no. : 989-1003.

Journal article
Published: 25 March 2019 in Energy Conversion and Management
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Mode switching is essential in a unitized regenerative fuel cell system. The switching of electricity, reactants, and reversible electrochemical reactions occurs, thereby affecting cell performance. During model switching, insufficient reactant supply may cause severe concentration, especially along the width of the catalyst layer which is not currently considered in a low-dimensional model. To fill this gap, a three-dimensional simulation in a proton exchange membrane unitized regenerative fuel cell is performed and validated to investigate the dynamic responses of current density and mass transfer. Results certify that reductions on current density and hydrogen generation are severe, as the cell is switched to a high electrolysis voltage. The analysis of species transfer along the width of the porous layers indicates that the deterioration is attributed to the occurrence of serious concentration polarization which is caused by the severe local water starvation on the catalyst layer, especially below the rib. A high inlet velocity for reactant and low fuel cell voltage are conducive for remitting local water starvation to improve cell performance effectively. However, a slight deterioration cannot be avoided completely before the water supply arrives, which is limited by the high rates of electrochemical reactions at a high electrolysis voltage.

ACS Style

Hang Guo; Qing Guo; Fang Ye; Chong Fang Ma; Qiang Liao; Xun Zhu. Improving the electric performance of a unitized regenerative fuel cell during mode switching through mass transfer enhancement. Energy Conversion and Management 2019, 188, 27 -39.

AMA Style

Hang Guo, Qing Guo, Fang Ye, Chong Fang Ma, Qiang Liao, Xun Zhu. Improving the electric performance of a unitized regenerative fuel cell during mode switching through mass transfer enhancement. Energy Conversion and Management. 2019; 188 ():27-39.

Chicago/Turabian Style

Hang Guo; Qing Guo; Fang Ye; Chong Fang Ma; Qiang Liao; Xun Zhu. 2019. "Improving the electric performance of a unitized regenerative fuel cell during mode switching through mass transfer enhancement." Energy Conversion and Management 188, no. : 27-39.

Special issue paper
Published: 18 March 2019 in International Journal of Energy Research
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In proton exchange membrane fuel cells, baffled flow channels enhance the reactant transfer from flow channels to gas diffusion layers. However, the reactant transfer depends on both the diffusive transfer and convective transfer, and how the baffles in flow channels affect them is still unknown. Therefore, in this work, a two‐dimensional, two‐phase, nonisothermal, and steady‐state model of proton exchange membrane fuel cells is developed, and these two transfer processes from flow channels to gas diffusion layers are comparatively studied. Simulation results show that first of all, the reactant transfer from flow channels to gas diffusion layers mainly depends on the diffusive transfer. Therefore, if the desire is to enhance the mass transfer from flow channels to gas diffusion layers, the diffusive mass transfer should be enhanced firstly. Being guided by this goal, a porous‐blocked baffled flow channel is developed. This flow channel design can further enhance the reactant transfer from flow channels to gas diffusion layers, and the cell performance can be improved. Moreover, when the porosities of porous blocks at the front place of flow channels are lower, the cell power is also increased but the pumping power can be reduced a lot.

ACS Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma; Qiang Liao; Xun Zhu. Mass transfer in proton exchange membrane fuel cells with baffled flow channels and a porous‐blocked baffled flow channel design. International Journal of Energy Research 2019, 43, 2910 -2929.

AMA Style

Hao Chen, Hang Guo, Fang Ye, Chong Fang Ma, Qiang Liao, Xun Zhu. Mass transfer in proton exchange membrane fuel cells with baffled flow channels and a porous‐blocked baffled flow channel design. International Journal of Energy Research. 2019; 43 (7):2910-2929.

Chicago/Turabian Style

Hao Chen; Hang Guo; Fang Ye; Chong Fang Ma; Qiang Liao; Xun Zhu. 2019. "Mass transfer in proton exchange membrane fuel cells with baffled flow channels and a porous‐blocked baffled flow channel design." International Journal of Energy Research 43, no. 7: 2910-2929.

Special issue paper
Published: 18 March 2019 in International Journal of Energy Research
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In this study, the cell performance of nonuniform depth and conventional straight channel in a unitized regenerative fuel cell (URFC) is compared. Various shapes of oxygen‐side channel cases are also proposed. Several parameters, such as the distribution of reactants and products and current density and powers in fuel cell (FC) and electrolytic cell (EC) modes, are investigated. A steady‐state model of two‐dimensional, two‐phase, nonisothermal, and coupled electrochemical reaction is developed. Five oxygen‐side channel shapes are also designed, in which the depth along the flow direction is narrowed. Result shows that narrowing the average channel depth can promote and guide the reactant transfer to the catalyst layer and avoid the blocking of the production. Thus, in comparison with the conventional channel, the cell performances of nonuniform depth and shallow straight channel cases are improved in both modes. In addition, with the decrease of average channel depth, the temperature uniformity gets better, which is also conductive to the improvement of cell performance. Furthermore, in FC mode at low voltage and EC mode, the cell net power basically increases with the decrease of the average channel depth ratio. And when the average channel depth is the same, the net power of straight channel is always lower than nonuniform depth case. This study introduces the round‐trip energy efficiency as an evaluation indicator of URFC. This efficiency can be increased by improving the cell performance of both modes, especially at high current density.

ACS Style

Jia Song; Hang Guo; Fang Ye; Chong Fang Ma. Mass transfer and cell performance of a unitized regenerative fuel cell with nonuniform depth channel in oxygen‐side flow field. International Journal of Energy Research 2019, 43, 2940 -2962.

AMA Style

Jia Song, Hang Guo, Fang Ye, Chong Fang Ma. Mass transfer and cell performance of a unitized regenerative fuel cell with nonuniform depth channel in oxygen‐side flow field. International Journal of Energy Research. 2019; 43 (7):2940-2962.

Chicago/Turabian Style

Jia Song; Hang Guo; Fang Ye; Chong Fang Ma. 2019. "Mass transfer and cell performance of a unitized regenerative fuel cell with nonuniform depth channel in oxygen‐side flow field." International Journal of Energy Research 43, no. 7: 2940-2962.

Journal article
Published: 04 March 2019 in Energy Conversion and Management
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In unitized regenerative fuel cells, residual water at the end of electrolysis cell mode greatly affects the cell voltage during mode switching from electrolysis cell to fuel cell mode. Therefore, the residual water removing is essential to realize the mode switching, which requires the knowledge on gas purge effect on cell voltage dynamic response. In this study, gas purge effect in oxygen and hydrogen sides on cell voltage dynamic response is investigated, respectively. In addition, the effects of fuel cell mode startup current density and electrolysis cell mode operating current density are analyzed. The results show that: the increases of gas purging time and purging gas flow rate promote the mode switching from electrolysis cell to fuel cell modes. High flow rate of purging gas is preferred than long gas purging time during mode switching when the same amount of purging gas is used. In addition, gas purging in hydrogen side is necessary. The influence of residual water in hydrogen side increases with the startup current density of FC mode, and long purging time is required for high startup current density of FC mode. Electrolysis cell mode operating current density increase leads fuel cell mode performance decrease under the same gas purge condition.

ACS Style

Xian Ming Yuan; Hang Guo; Fang Ye; Chong Fang Ma. Experimental study of gas purge effect on cell voltage during mode switching from electrolyser to fuel cell mode in a unitized regenerative fuel cell. Energy Conversion and Management 2019, 186, 258 -266.

AMA Style

Xian Ming Yuan, Hang Guo, Fang Ye, Chong Fang Ma. Experimental study of gas purge effect on cell voltage during mode switching from electrolyser to fuel cell mode in a unitized regenerative fuel cell. Energy Conversion and Management. 2019; 186 ():258-266.

Chicago/Turabian Style

Xian Ming Yuan; Hang Guo; Fang Ye; Chong Fang Ma. 2019. "Experimental study of gas purge effect on cell voltage during mode switching from electrolyser to fuel cell mode in a unitized regenerative fuel cell." Energy Conversion and Management 186, no. : 258-266.

Journal article
Published: 01 February 2019 in Journal of Energy Engineering
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Unitized regenerative fuel cells are unique devices that combine the functions of fuel cells and water electrolysis in one system. The internal mass-transport mechanisms present in a unitized regenerative fuel cell are closely related to the mode-switching method of the cell. A two-dimensional, single-phase, isothermal, multicomponent, and transient model was developed to investigate the characteristics of mass transfer coupled with electrochemical reaction in a unitized regenerative fuel cell under interval and continuous mode-switching methods. Results indicate that the average gas mass fractions in the gas-flow channel, gas diffusion layer, and catalyst layer are the same under the two different mode-switching methods. Gas mass fractions in different layers exhibit the same variation trend and gradient during the first and second cycles of interval and continuous switching. Under the two different mode-switching methods, the gradient of the gas mass fraction in fuel cell mode is larger than that in water electrolysis mode. The transient response of these layers under two different mode-switching methods is delayed by approximately 0.2 s compared with that of the operating voltage.

ACS Style

Hang Guo; Lu Lu Wang; Xu Ling Yi; Fang Ye; Chong Fang Ma. Simulation of Mode-Switching Methods’ Effect on Mass Transfer in a Unitized Regenerative Fuel Cell. Journal of Energy Engineering 2019, 145, 04018071 .

AMA Style

Hang Guo, Lu Lu Wang, Xu Ling Yi, Fang Ye, Chong Fang Ma. Simulation of Mode-Switching Methods’ Effect on Mass Transfer in a Unitized Regenerative Fuel Cell. Journal of Energy Engineering. 2019; 145 (1):04018071.

Chicago/Turabian Style

Hang Guo; Lu Lu Wang; Xu Ling Yi; Fang Ye; Chong Fang Ma. 2019. "Simulation of Mode-Switching Methods’ Effect on Mass Transfer in a Unitized Regenerative Fuel Cell." Journal of Energy Engineering 145, no. 1: 04018071.

Special issue paper
Published: 04 January 2019 in International Journal of Energy Research
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In proton exchange membrane fuel cells, baffled flow channels can enhance the reactant transfer and improve the cell performance. Many different baffled flow channels have been numerically studied in previous published papers. However, what kind of baffled flow channels can improve the cell performance most is still unknown. In this simulation work, a two‐dimensional, two‐phase, nonisothermal, and steady‐state model of proton exchange membrane fuel cells is developed. The mass transfer and cell performance of PEMFCs with different baffled flow channels have been numerically compared. Simulation results show that the rectangular baffle can enhance the reactant transfer most and improve the cell performance most; however, the power loss in rectangular baffled flow channel is also the highest. To inherit the advantages and overcome the shortages of the rectangular baffled flow channel, an optimized baffled flow channel is developed. In this newly developed baffled flow channel, the windward side is designed as the streamline shape and the leeward side is designed as the sloped shape. Results of the simulation also show that the optimized baffled flow channel can reduce the power loss accounted by the pumping power in reactant delivering process and the cell performance can be further improved.

ACS Style

Hang Guo; Hao Chen; Fang Ye; Chong Fang Ma. Baffle shape effects on mass transfer and power loss of proton exchange membrane fuel cells with different baffled flow channels. International Journal of Energy Research 2019, 43, 2737 -2755.

AMA Style

Hang Guo, Hao Chen, Fang Ye, Chong Fang Ma. Baffle shape effects on mass transfer and power loss of proton exchange membrane fuel cells with different baffled flow channels. International Journal of Energy Research. 2019; 43 (7):2737-2755.

Chicago/Turabian Style

Hang Guo; Hao Chen; Fang Ye; Chong Fang Ma. 2019. "Baffle shape effects on mass transfer and power loss of proton exchange membrane fuel cells with different baffled flow channels." International Journal of Energy Research 43, no. 7: 2737-2755.