Starlink

[3930dave]

up there? like in space? cooling?

Cooling is entirely radiative in space, and very difficult to manage.

Ok, never built satellites myself...... just thinking of Ambient temp.....

On the ground, it's gotten a bit better (source heat) over time, but I'm old enough to remember main-frame cooling, using outdoor water fountains.....

Rgds, D.

 

[ning]

Ok, never built satellites myself...... just thinking of Ambient temp.....

On the ground, it's gotten a bit better (source heat) over time, but I'm old enough to remember main-frame cooling, using outdoor water fountains.....

Rgds, D.

Water is a fantastic coolant (especially if you can use the phase change like in a steam turbine) and is a "conductive cooler" (gets rid of heat by conduction - you directly heat something you're touching), but you either need to be able to dump the hot water elsewhere and keep taking in new cooler water to do the cooling, or you have to cool the water (see power plants, cooling towers)..
... in space, you're in a vacuum, so you're really not touching much, so conductive cooling doesn't work because you can't hand off that heat energy to anything directly.

Instead, you use "black body radiation" which is the radiation given off by everything dependent on how hot it is - hotter stuff give off higher energy (possibly into the visible - like "red hot" or "white hot" - or even into UV and X-Ray if super hot) and cooler stuff lower energy (infra red for your not-overfired-wood-stove), so you're limited to cooling by emitting this radiation.

You can still use cooling fins - not as conductive radiators do in air (where the increased surface area means you're in contact with more air to conduct the heat away), but to increase the surface area that's radiating away the heat energy with photons carrying it away.

It works, but not nearly as well - probably a 1000x difference.