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Abstract:For improving the performance of stationary PEFC (polymer electrolyte fuel cell) system, the cell operating temperature up to 90 °C will be preferred in Japan during the period from 2020 to 2030. To understand the operation of the PEFC system under relatively high temperature conditions, detail heat and mass transfer analysis is required. The purpose of this study is to analyze the impact of relative humidity of supply gas on temperature distribution on the backside of separator in single cell of PEFC using Nafion membrane at higher temperature e.g. 90 °C. The in-plane temperature distribution when power was being generated was measured using thermograph with various relative humidity of supply gases. It was found that the in-plane temperature distribution at the anode was more even than that at the cathode irrespective of the relative humidity of supply gas at the anode and the cathode. The temperature elevated along gas flow through the gas channel at the cathode irrespective of relative humidity of supply gas at the anode and the cathode. The in-plane temperature distribution at the cathode was narrower with the increase in T ini irrespective of relative humidity of supply gas at the cathode, while it was not observed when changing the relative humidity of supply gas at the anode. When the relative humidity of supply gas at cathode decreased, the in-plane temperature distribution at the anode was wider compared to decreasing the relative humidity of supply gas at the anode. The study concluded that the impact of relative humidity of supply gas at both anode and cathode had little impact on the in-plane temperature distribution at the cathode.

Polymer Electrolyte Fuel Cell (PEFC) is desired to be operated at temperature around 90 °C for stationary applications during the period from 2020 to 2025 in Japan. It can be expected thinner polymer electrolyte membrane (PEM) and gas diffusion layer (GDL) would promote the power generation performance of PEFC at this temperature. The aim of this study is to understand the impact of thickness of PEM and GDL on the temperature profile of interface between PEM and catalyst layer at the cathode (i.e., the reaction surface) in a single PEFC with an initial operation temperature (T ini). An 1D multi-plate heat transfer model based on temperature data of separator measured using thermograph in power generation process was developed to evaluate temperature of the reaction surface (T react). This study investigated the effect of T ini , flow rate and relative humidity of supply gas on T react distribution. The study finds that when using thin GDL, the even distribution of T react-T ini is obtained irrespective of thickness of PEM, T ini and relative humidity conditions. T react-T ini using Nafion 115 is higher than the other thin PEMs irrespective of T ini and relative humidity conditions. It can be concluded that the even temperature distribution could be achieved by using thin PEM and GDL.

This study is to understand the impact of operating condition, especially initial operation temperature (T ini ) which is set in high temperature range, on the temperature profile of the interface between PEM (polymer electrolyte membrane) and catalyst layer at the cathode (i.e., the reaction surface) in a single PEFC (polymer electrolyte fuel cell). A 1D multi-plate heat transfer model based on the temperature data of separator measured using thermograph in a power generation experiment was developed to evaluate the reaction surface temperature (T react ). This study investigated the effects of T ini , flow rate and relative humidity of supply gas as well as thickness of PEM on the temperature distribution on reaction surface. As a result, the impact of flow rate of supply gas on the temperature distribution is not significant irrespective of relative humidity conditions as well as PEM type. When operated at high temperature, the temperature distribution is relatively flat in the case of thicker PEM (Nafion 115), while T react rises from the inlet to the outlet large and the temperature distribution is wide in the case of thin PEM (Nafion 211) irrespective of relative humidity condition. Since the water transfer through PEM in the case of Nafion 211 is better than Nafion 115 due to thin PEM, the power generation is promoted along the gas flow with the aid of humidification by water produced from electrochemical reaction.

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