3 ms·
Has anyone ever deployed a heat pump in orbit to increase the radiator temperature? T^4 is a pretty steep curve. If your usual rejection temperature was 77 C
by floxy 11mo ago
Has anyone ever deployed a heat pump in orbit to increase the radiator temperature? T^4 is a pretty steep curve. If your usual rejection temperature was 77 C / 350 K, and you could bump that up to 227 C / 500K, your radiator goes down to ~1/4 of the required area. But then you need more solar panel area to power the heat pump. And 1/4 of the area is only ~50% smaller in linear dimensions. Maybe it doesn't pencil out. Maybe instead of powering the heat pump with PV panel electricity, it is mechanically driven by a heat engine driven by concentrated sunlight. 1000 K warm end, and 500K cold end. But then you need to dissipate the waste heat from the engine as well. Fun to think about anyway.
- dekhn 11mo agoHeat pumps are used a lot in space already. They do not address data center scale heat removal.
- floxy 11mo agoWhat is a good rejection temperature to use for medium earth orbit? Assuming you would orient your radiator normal to the incoming light from the sun, and normal to the earth-shine/earth-radiation. And in the shade from your PV panels. Is 50 Kelvin a reasonable temperature? Then you could radiate 1 GW of thermal energy at 350 K using a 2.5e6 m^2 surface (assuming 0.9 for emissivity). That is a square about 1.55 km on a side. Maybe reversible computing is step one in this plan.
- floxy 11mo agoInterestingly enough, to get 1 GWe, using 30% efficient PV panels and assuming 1360 W/m^2 insolation, you'd also need ~2.5e6 m^2 of PV panels.
- floxy 11mo agoAh, for a radiator, you can use both sides; one side exposed to the solar system north, and the other side facing south. So the 1.55 km on a side gets reduce by a factor of sqrt(2), to 1.1 km on a side.