COOL-DOWN TIME OF SOLID OXIDE FUEL-CELLS INTENDED FOR TRANSPORTATION APPLICATION

To provide answers to the concern as to how quickly the temperature of solid oxide fuel cells (SOFCs) for transportation application will dr op, a thermal analysis of the cool-down time of an SOFC stack during v ehicle idle or stand-by has been carried out. Because a large amount o f thermal energy is stored in high-temperature SOFC stacks, it is impo rtant to select suitable thermal insulations to reduce heat loss. Thre e typical kinds of thermal insulating materials have been selected in the present calculations. The results indicate that a high-performance , vacuum-multifoil thermal insulation can be applied to significantly reduce heat loss and to maintain temperature uniformity across a cell stack. Consequently, the cool-down time from 1000 to 800 degrees C is extended from 2 h (with a 5 cm thick conventional material) to about 3 1 h (with a 1 cm thick high-performance material).