Cool-down time of solid oxide fuel cells intended for transpotation application

To provide answers to the concern as to how quickly the temperature of solid oxide fuel cells (SOFCs) for transportation application will drop, a thermal analysis of the cool-down time of an SOFC stack during vehicle idle or stand-by has been carried out. Because a large amount of thermal energy is stored in high-temperature SOFC stacks, it is important to select suitable thermal insulations to reduce heat loss. Three 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°C is extended from 2 h (with a 5 cm thick conventional material) to about 31 h (with a 1 cm thick high-performance material).