1.5 kW HT-PEFC stack with Composite MEA for Combined Heat and Power Application

The co-generation systems appear to be one of the most efficient solutions to reduce polluting emissions and primary energy consumption. They consist in the generation of sequential or simultaneous two different forms of energy (mechanical and/or electrical and thermal) starting from a single energy source, in a single integrated system, where the thermal energy can be used to produce hot water, steam, hot or cold water for cooling processes. Among the different configurations of systems for combined heat and power (CHP) generation, one based on fuel cells, able to produce electrical and thermal energy, has assumed in recent years great interest, so as to bring some companies to produce prototypes. The growing interest in this technology for use in co-generation systems has prompted the search, on the one hand to increase the operating temperature, the other one to use as fuel not only pure hydrogen, but also gaseous mixtures rich in hydrogen. In this work, the feasibility of a high temperature (HT) PEFC stack for co-generation application was investigated. A 3 kW stack composed of two 1.5 kW modules was designed and one module was manufactured and tested. The stack is an upgrade of a previously realized 500W HT-PEFC [1] working at 120°C and 3 abs. bar with low reactants humidification levels (75%RH). The 1.5 kW module is composed of 40 cells with 150 cm2 active area. The stack architecture is based on a serpentine flow field, a parallel gas distribution, a Z-shape gas path and a water cooling system. Graphite was used for process and cooling plates manufacturing. Composite MEAs for high temperature, based on Nafion/Zirconia membranes [2], were realized and used to assembly the stack. Tests were performed in both pure hydrogen and in H2/CO2 mixture, simulating the exit gas from a methane fuel processor and in different conditions of humidification. Power rate of 1560 W was obtained by feeding the stack with H2/CO2 mixture and air and at 95% RH for fuel and 49% RH for oxidant.