As I am going through building the virtualized ship systems I have seen waste heat expulsion rear it’s ugly head a few times. Since we are primarily operating in the atmosphere for the foreseeable future I am going to document my findings here, solicit feedback, and move on.
I plan to have three coolant loops (two primary, one standby) each with their own pump and reservoir. Each device in unpressurized sections of the craft will have a heat exchanger (oil to coolant) or a heat sink. Anhydrous ammonia was suggested for it’s vaporization properties in the temperature realm I am needing.
The idea is then to take fuel and/or oxidizer out of cryogenic storage using the excess heat carried by the coolant.
Since the fuel cell creates water as a byproduct, we could also dump hot water overboard.
Superficial heat exchangers (coolant to air) could be mounted inside the exterior plating but that leaves the system vulnerable (military operation, after all) and it only works in the atmosphere.
I heard that the space shuttle radiates heat from a shiny surface on the inside of the payload bay doors? I thought that materials which absorb heat best (matte black) were also the best radiators (why some engine manufacturers powder coat their engine blocks).
I have also been researching the holy grail of waste heat management – thermopiles.