I'm trying to figure out how to plan/start this homework question for my principles of energy engineering class, but I'm stuck on this one and I'm not really sure where to start or even what the general process would be. I tried looking through the notes but I didn't find anything that jumps out at me as being an obvious solution. I've also looked online and haven't found any similar questions. Here's the question:
1) General Electric Co. has developed an advanced fuel-cell battery that will supply the primary power needed during orbit by space capsules. The peak load delivered by the battery will be just under 2kW. The facility will be assembled from ion-exchange-membrane cells, in which the membranes are sheets of a tough, undisclosed plastic.
The fuels supplied to the cells will be hydrogen and oxygen. Though fed in the gaseous state during battery operation, these two elements will be sorted as liquid, to conserve space.
The equipment is inherently reliable because it is simple, and it achieves 60% thermal efficiency under normal load. Also, the battery will yield a by-product that is highly valuable in space-flight---- a pint of pure drinkable water for each kilowatt-hour of operation.
If the O2 and the H2 are stored as saturated liquids at their normal boiling point, what is the enthalpy change per g mol of O2 between the liquid storage tank and the state of which the O2 enters the fuel cell (1.5 atm, 27oC)