EVAPORATIVE COOLING OF FUEL CELLS EMPLOYING ANTIFREEZE SOLUTION

摘要

A fuel cell power plant (19) has a stack of fuel cells (20) cooled by a mixture of water with a non-volatile, miscible fluid that sufficiently depresses the freezing point, such as polyethylene glycol (PEG). The water and fluid are mixed in a reservoir (21), a small pump (22, 60) flows the mixture through coolant channels (28) in or adjacent water transport plates (29); heat of the catalytic reaction warms the water transport plates causing water to evaporate therefrom thereby cooling the stack. The PEG is non-volatile at stack operating temperature and does not evaporate; concentrated PEG is returned (33) to the reservoir (21). Water in the process air flow channels (41), including evaporated process water, is recovered in a condensation-rate-controlled (53, 54)) condenser (46) in communication (48) with the reservoir (21) for remixture with the concentrated PEG solution. Hydrophobic gas diffusion layers (72) shield the proton exchange membrane (70) from the PEG.