Fuel cell thermal management with thermoelectric coolers

Thermoelectric coolers are utilized along the periphery of a bipolar plate in a proton exchange membrane (PEM) fuel cell to cool the adjacent membrane exchange assemblies (MEA) where the majority of the waste heat is generated. These solid-state microcoolers (MIC) can be built in many configurations for unusual applications where parasitic thermal energy management is required. A fuel cell application is ideal with the cell powering the MICs. A thermal model is developed to use the bipolar plate as the cold junction plate of the MICs. The heat generated in the cell membrane is modelled as a uniform flux on the bipolar plate´s surface, which is manifested as a generation term in the heat conduction equation. Therefore the temperature field can be modelled in the bipolar plate, predicting the MIC´s cooling effect on it and in adjacent MEAs, and provide the temperature distribution throughout the selected design of the plate. Thus the temperature field in the MEA region, as well as the temperature gradient in the fuel cell, can be predicted. Minichanneling is used in the design of the bipolar plate gas flow channels to take advantage of the high heat transfer coefficients that take place. The model shows that the MICs´ improved heat management of the fuel cell maintains the cell stack operating temperature between 45°C and 60°C, an acceptable range that precludes the need for any internal liquid cooling or external humidification of feed gases.