Hybrid Cooled Metal Stack Technology (HCMST) for HT PEM fuel cell stack for Combined Heat and Power

Abstract

High Temp PEM fuel cell technology is very well suited for technology CHP applications. The operating temperature is high enough for the integrated system with a matching reformer to produce high value heat, that can be used for district heating and hot water production. At the same time the high temperature polymer membranes, when operating in the range 160 to 200 degrees C, are very forgiving regarding CO content in the reformate, end this fact makes it possible to design and build a much simpler and cheaper reformer than I the cast for a conventional low temp PEM fuel cell system. However, until now very few robust designs have seen daylight, and the power density of HT PEM fuel cells has been very low. Metacon has developed a novel design, made to provide very high reliability and long life, at the same time as giving high power density. This novel design is founded in the understanding of the real operating conditions of such a fuel cell. It is easy to see that the conditions of a HT PEM fuel cell are very similar to those of an engine for a modern personal car: The temperature is cycled between ambient temperature and around 200 deg C, there are also pressure changes and stresses due to thermal expansion and temperature gradients during start- up and stop. The design developed and patented by Metacon is taking full consequences of these facts. The internal stack cooling is based on pressurized casing, high speed air circulation, and the external cooling uses circulating water, exactly as in a modern diesel engine.