Low Temperature Fuel Batteries on the Moon

Fuel battery systems have been evaluated as to their ability to reject heat while operating in earth orbit and at the 240°F temperature expected on the lunar equatorial surface at noon. Analysis of the earth orbiting condition has led to the conclusion that, if an adequate vehicle surface area is available, the temperature at which fuel battery is rejected is not a significant factor. Solutions to the lunar application have included high temperature components or heat rejection systems using the specific heat and latent heat of vaporization of gases and liquids. The use of geometrically designed radiators to provide for low temperature heat rejection under these hostile conditions represents an area where further study and evaluation can provide significant weight and simplicity advantages. Proper radiator design will allow a fuel battery system to operate at 140°F with a radiator whose total surface area is approximately 60 ft2/kw even when the most severe lunar thermal conditions are considered.