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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 flow rate, relative humidity and type of supply gas as well as T ini on the temperature distribution on reaction surface. The results obtained in O 2 supply case show that, the temperature rise at the segments near the outlet of cell decreases with increasing T ini irrespective of relative humidity of supply gas (RH), while it is not seen in air supply case. Regarding the segments except near the outlet in O 2 supply case, T react-T ini increases with increasing T ini for 40% RH. The temperature distribution on reaction surface in O 2 supply case is wider with increasing T ini as well as decreasing RH, though that in air supply case is relatively even.

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We propose a novel type of on-wall in-tube flexible thermal sensor, which is able to measure the flow rate under both developing and fully developed flow conditions. We fabricated the thermal flow sensor on a flexible polyimide film by using polymer MEMS technologies and formed a ring-shaped on-wall in-tube sensor configuration by inserting the sensor into a tube. The resistance of the sensor linearly changed with the change in temperature. Its temperature coefficient of resistance is 0.0026 K−1. We obtained a constant and stable output signal of the sensor even though the sensor position was near the tube entrance region where the flow is developing a hydraulic flow condition. We concluded that the proposed sensor is able to measure the flow rate under both the developing and the fully developed hydraulic flow conditions.

The impact of micro porous layer (MPL) with various thicknesses of polymer electrolyte membrane (PEM) on heat and mass transfer characteristics, as well as power generation performance of Polymer Electrolyte Fuel Cell (PEFC), is investigated. The in-plane temperature distribution on cathode separator back is also measured by thermocamera. It has been found that the power generation performance is improved by the addition of MPL, especially at higher current density condition irrespective of initial temperature of cell (Tini) and relative humidity condition. However, the improvement is not obvious when the thin PEM (Nafion NRE-211; thickness of 25 μm) is used. The increase in temperature from inlet to outlet without MPL is large compared to that with MPL when using thick PEM, while the difference between without MPL and with MPL is small when using thin PEM. It has been confirmed that the addition of MPL is effective for the improvement of power generation performance of single PEFC operated at higher temperatures than normal. However, the in-plane temperature distribution with MPL is not even.

Impact of operation condition on temperature distribution in single cell of polymer electrolyte fuel cell operated at higher temperature than usual