… That’s a very good point actually. Vacuums are rather insulating. Without convection cooling from a fluid, you’re relying on radiative heat transfer for cooling, and that’s piss poor.
Only operate when your side of the moon is dark or even near the poles where it can be coldest? I’m not sure what the plan is for daytime operations since it apparently gets really hot.
No atmosphere up there to insulate so the temperatures fluctuate to extremes
No atmosphere means very little thermal radiation is pulled from radiators.
I imagine the best bet would be to drill into the surface of the moon and sink your radiators into the ground, fill the gaps with a material that transfers heat well.
Easiest version of that would probably be to lay the radiators on or just below the surface and bury them in a regolith concrete mixture of some sort. Probably not as efficient as drilling straight in, but way less complicated I imagine.
I suppose the regolith itself could be used as a heat sink. I don’t know what its thermal properties are like?
But yeah, I imagine heat dissipation is a limiting factor. Everything I’ve read suggests the 1st gen reactors will put out something on the order of 10s of kilowatts, so rather modest by nuclear standards but still plenty for a nascent Moon base I imagine?
Heat pipes running to radiators in vacuum is how you do it in space. It’s efficient and scaleable, though it hasn’t ever been done on an industrial scale. Definitely doable though. Considering the temperature on the moon is a balmy -270°C
Yes. You need to use radiation, via radiators. It’s a shame I’m getting downvoted on this, because I really do know what I’m talking about on this one. Ammonia in heat pipes wicks the heat away from the thing you want to be cold, towards the radiator, which is usually just a dumb coil, but could be enhanced with a bimetallic thermally decoupled louver if you want to keep it cool in sunlight. Or bury it, since we’re on the moon.
From an engineering perspective it’s not that difficult to do, as the variables which affect it are well known and don’t change that much. It is for sure slower than combined conductive/convective cooling, but it’s a known quantity, so you can plan quite effectively.
It’s definitely possible, however nukes have like 30-40% efficiency so to cool even a tiny 10 kW reactor you’d need twice the capacity the ISS currently has (14kW) for just the reactor without any safety margins.
The temp is low but it is a vacuum. Vacuums are bad at dissipating heat. Think of the vacuum walled drinking vessels. They are so efficient at keeping beverages hot/cool because the vacuum insulates the majority of the surface area that heat can move across.
Likewise a cooling tank of water (typical nuclear reactor design) itself surrounded by vacuum, will not cool efficiently at all. Presumably they’d have to use piping to circulate the water over a large surface area of some other medium like the moon rock itself.
I’ve got it. Since we’re worried about rising sea levels on earth, we can just pipe the excess water to the moon and flood the moon’s surface with water and use that for cooling.
The IR band gap is high enough that you’d need really efficient heat pumps to keep things radiating well. Otherwise the heat pumps generate more heat than you can radiate.
Cooling is the process of offloading heat from one atom to another. In space and the moon, there’s very little…anything. You can’t transfer heat onto nothing - so an “air cooled” heat vent doesn’t work. Another user suggested they use the moon itself or moon dust as a heat sink, and you could do that in theory.
how would you even start with the cooling? that sounds like a nightmare
… That’s a very good point actually. Vacuums are rather insulating. Without convection cooling from a fluid, you’re relying on radiative heat transfer for cooling, and that’s piss poor.
Lots of radiators.
No wind…
That’s why it’s a nuclear plant instead of a wind turbine /jk
Lithoradiators
I suspect you would dump the heat into the Moon itself. You wouldn’t need that much power up there.
Only operate when your side of the moon is dark or even near the poles where it can be coldest? I’m not sure what the plan is for daytime operations since it apparently gets really hot.
No atmosphere up there to insulate so the temperatures fluctuate to extremes
No atmosphere means very little thermal radiation is pulled from radiators.
I imagine the best bet would be to drill into the surface of the moon and sink your radiators into the ground, fill the gaps with a material that transfers heat well.
Easiest version of that would probably be to lay the radiators on or just below the surface and bury them in a regolith concrete mixture of some sort. Probably not as efficient as drilling straight in, but way less complicated I imagine.
I read this in chief O’Brien’s voice
Unfortunately you can’t really turn off a nuclear reactor.
Russians: “Sure you can, it’s just this red button right here…”
If you have enough ice, you evaporate it.
If not, heat pump/ sink into basalt probably.
I suppose the regolith itself could be used as a heat sink. I don’t know what its thermal properties are like?
But yeah, I imagine heat dissipation is a limiting factor. Everything I’ve read suggests the 1st gen reactors will put out something on the order of 10s of kilowatts, so rather modest by nuclear standards but still plenty for a nascent Moon base I imagine?
Heat pipes running to radiators in vacuum is how you do it in space. It’s efficient and scaleable, though it hasn’t ever been done on an industrial scale. Definitely doable though. Considering the temperature on the moon is a balmy -270°C
It’s extremely difficult to cool things in space, as everything is basically insulated in a vacuum.
Yes. You need to use radiation, via radiators. It’s a shame I’m getting downvoted on this, because I really do know what I’m talking about on this one. Ammonia in heat pipes wicks the heat away from the thing you want to be cold, towards the radiator, which is usually just a dumb coil, but could be enhanced with a bimetallic thermally decoupled louver if you want to keep it cool in sunlight. Or bury it, since we’re on the moon. From an engineering perspective it’s not that difficult to do, as the variables which affect it are well known and don’t change that much. It is for sure slower than combined conductive/convective cooling, but it’s a known quantity, so you can plan quite effectively.
It’s definitely possible, however nukes have like 30-40% efficiency so to cool even a tiny 10 kW reactor you’d need twice the capacity the ISS currently has (14kW) for just the reactor without any safety margins.
you could use space that shit is called as balls
Dissipating heat in space is actually one of the major issues that comes up in designs for space applications. It’s… not easy.
The temp is low but it is a vacuum. Vacuums are bad at dissipating heat. Think of the vacuum walled drinking vessels. They are so efficient at keeping beverages hot/cool because the vacuum insulates the majority of the surface area that heat can move across.
Likewise a cooling tank of water (typical nuclear reactor design) itself surrounded by vacuum, will not cool efficiently at all. Presumably they’d have to use piping to circulate the water over a large surface area of some other medium like the moon rock itself.
I’ve got it. Since we’re worried about rising sea levels on earth, we can just pipe the excess water to the moon and flood the moon’s surface with water and use that for cooling.
Hello, Nobel prize foundation?
Yes, this man right here!
They’re also very good at not stopping infrared radiation.
The IR band gap is high enough that you’d need really efficient heat pumps to keep things radiating well. Otherwise the heat pumps generate more heat than you can radiate.
Cooling is the process of offloading heat from one atom to another. In space and the moon, there’s very little…anything. You can’t transfer heat onto nothing - so an “air cooled” heat vent doesn’t work. Another user suggested they use the moon itself or moon dust as a heat sink, and you could do that in theory.
https://en.m.wikipedia.org/wiki/Thermal_radiation
Since we’re being pedants, that’s moving heat through nothing, not transferring it to nothing.
Not that it’s a viable means of heat removal for a reactor.