Patent ID: 7906244

Claim:
A method of homogenizing waste heat in a fuel cell stack, comprising: providing a fuel cell stack having an internal coolant circulation loop that distributes coolant between a coolant inlet and a coolant outlet, and providing a coolant circulating mechanism placed in said stack and located in said internal coolant circulation loop and between said coolant inlet and said coolant outlet for circulating coolant internally within said fuel cell stack and within said internal coolant circulation loop; operating said fuel cell stack; distributing a coolant through said fuel cell stack and through said internal coolant circulation loop, at least some of said coolant entering said fuel cell stack externally of said fuel cell stack through said coolant inlet; terminating operation of said fuel cell stack; retaining an amount of said coolant in said fuel cell stack and in said internal coolant circulation loop by closing said coolant inlet and closing said coolant outlet in order to prevent flow of coolant into and out of said fuel cell stack; and using said coolant circulating mechanism to circulate said amount of retained coolant internally within said fuel cell stack and within said internal coolant circulation loop upon start-up and while said coolant inlet and coolant outlet remain closed.