Henning wrote: In vacuum? 15m^2 for 5MW? Really? Sorry, I just didn’t know.
Not exactly.
When you are relying strictly on radiation for heat rejection and can’t use convection, as is the case in space, then the efficiency of the radiator varies as the fourth power of the radiator temperature.
from my worksheet:
kWe 5062.98
kWt 5062.98
stefan’s 5.67E-008
emissivity 0.85
temp (c) 1000
radiator area (m2) 40
double-faced (m2) 20
sqrt 4.47 meters per side.
…………. now let’s cool things down a bit ……….
kWe 5004.6
kWt 5004.6
stefan’s 5.67E-008
emissivity 0.85
temp (c) 450
radiator area (m2) 380
double-faced (m2) 190
sqrt 13.78 meters per side.
Henning wrote: So with atmosphere you’ll wouldn’t need a water-driven colling tower. That’s great! Or am I missing something?
Still working on the parameters for the DPF portable container but no, the point of an open-system water cooling tower at a power station is to get rid of massive quantities of heat for as little energy expenditure as possible… and when you can evaporate water and discard it that’s easy.
A presumably closed system such as a disaster response power plant or a desalinization plant requires a bit more fiddling but even for the DPF container my Transformer(tm)-like cooling tower is a closed loop water system akin to nothing so much as a big car radiator… a car radiator cubic meters in volume and using several tons of a standard water-antifreeze mix 🙂
.
.