Dynamic characteristics of phosphoric-acid fuel-cell stack cooling system

The phosphoric-acid fuel-cell has advanced in power generation systems with relatively small outputs from thousands to millions of watts and several commercial plants are expcted to be built the near future. In such a system, the temperature in the cells must be kept within a certain range by a cooling system. The cooling system, employing water, would be preferable in order to obtain a uniform temperature-distribution, thereby saving the power of auxillary machines and utilizing the exhaust heat for other processes requiring heat. In this paper, the results of the numerical simulation of dynamic characteristics of this cooling system and the fuzzy approach to control the cooling system are reported. The fuzzy control system with strategies self-tuned during operation could be superior to a conventional PID control, which is difficult to tune via three parametes for a complex system.