5 ms·
The equation has a ^4 to the temperature. If you raise the temperature of your radiator by ~50 degrees you double its emission capacity. This is well within the
by aunty_helen 9mo ago
The equation has a ^4 to the temperature. If you raise the temperature of your radiator by ~50 degrees you double its emission capacity. This is well within the range of specialised phase change compressors, aka fancy air conditioning pumps.
Next up in the equation is surface emissivity which we’ve got a lot of experience in the automotive sector.
And finally surface area, once again, getting quite good here with nanotechnology.
Yes he’s distracting, no it’s not as impossible as many people think.
- sfink 9mo ago> And finally surface area, once again, getting quite good here with nanotechnology. So your hot thing is radiating directly onto the next hot thing over, the one that also needs to cool down?
- PinkiesBrain 9mo agoThe inner side of the radiator would be metallized, an anti black body. Together with a bit of vacuum it would thermally be quite far from the PV&GPU. Thermal insulation is easy in space.
- sfink 9mo agoYou still can't get more surface area than a sphere without crumpling things up. And given the thermal insulation, you can only lose heat via radiation. Radiating heat from a crumpled boundary means radiating it towards another part of the boundary. If there's an "inner side", then it's a sphere (or some other convex shape, all of which have at most the surface area of a sphere). I don't think you'd want any vacuum at all between the radiator and the heat sources! Thermal insulation is the problem, not the solution. You want the radiator as thermally close to the heat sources as possible, probably via some highly heat conductive metal. Though the optimal approach might be to ditch the vacuum and use a more terrestrial configuration with circulating air or water or mercury to conduct the heat away. Space is a horrible place to do this in all ways except for... well, space. You do have plenty of room up there. (Well, and power. Lots of solar energy to play with. Which in turn causes its own problems with heat and radiation.)
- PinkiesBrain 9mo agoWith a heatpump the PV and GPU would have the evaporators, the radiator would have the condenser. You do this for two reasons, so you can run the radiator hotter (4th power and all) and because the refrigerant is a good heat spreader (better than pure liquid cooling). With a heatpump, you don't want a thermal bypass, hence the isolation. Space is not a great place to get rid of heat, but if you need lots of surface area any way for PV that almost solves itself.
- vel0city 9mo ago> Next up in the equation is surface emissivity which we’ve got a lot of experience in the automotive sector. My car doesn't spend too much time driving in vacuum, does yours?
- MillionOClock 9mo agoLet's just hope the person you are responding to isn't Elon Musk!
- vel0city 9mo agoI wouldn't say that roadster isn't doing much driving but dang is it drifting!
- aunty_helen 9mo agoEngine bays have a lot of design go into where to keep heat and where to get rid of it. You can look up thermal coatings and ceramics etc.
- jamiek88 9mo agoThis makes zero sense.
- wat10000 9mo agoRaise the temperature of your radiator by 50 degrees and you double its emission capacity. Or put your radiator in the atmosphere and multiply its heat exchange capacity by a factor of a thousand. It's not physically impossible. Of course not. It's been done thousands of times already. But it doesn't make any economic sense. It's like putting a McDonald's at the top of Everest. Is it possible? Of course. Is it worth the enormous difficulty and expense to put one there? Not even a little.
- aunty_helen 9mo agoFor thousands of years we never even looked to Mount Everest, then some bloke on the fiver said he’d give it a shot. Nowadays anyone with the cash and commitment can get the job done. Same with datacenters in space, not today, but in 1000 years definitely, 100 surely, 10? As for the economics, it makes about as much sense as running jet engines at full tilt to power them.
- tialaramex 9mo ago> some bloke on the fiver said he’d give it a shot Hillary (he features on the NZ Five Dollar note) was one of those guys who does things for no good reason. He also went to both poles. This only tells us that it is indeed possible, but not that it's desirable or will become routine.
- wat10000 9mo agoIf we define a data center as a place where computers run primarily to serve distant users, then we've had data centers in space for decades. Nobody should doubt that it's possible, since it's been done. It just doesn't make any sense to do it purely for the sake of having computers do things that could be done on the ground. There's nothing weird about using jet engines to make electricity. The design of a turbine designed to generate thrust isn't necessarily that different from a turbine designed to generate electricity. You can buy a new Avon gas turbine generator today, the same engine used in the Canberra, Comet, Draken, and many others. It makes about a million times more economic sense than putting GPUs in space to run LLMs.
- marcosdumay 9mo ago> aka fancy air conditioning pumps Yeah, pumps, tubes, and fluids are some of the worst things to add to a satellite. It's probably cheaper to use more radiators. Maybe it's possible to make something economical with Peltier elements. But it's still not even a budget problem yet, it's not plainly not viable. > getting quite good here with nanotechnology Small features and fractal surfaces are useless here.
- aunty_helen 9mo agoMy dude, heat pipes were invented for satellites and there’s people walking around with piezo pumps in their phones these days. We’re getting close. Peltiers generate a lot of heat to get the job done so even though electricity is pretty much free, probably not a sure bet.
- marcosdumay 9mo ago> We’re getting close. Oh, yes, I can agree with that. With emphasis on "getting".
- pclmulqdq 9mo agoPeltiers and heat pipes don't remove heat, they just move it. You still need the radiator.
- stackghost 9mo agoEven if you create a material with surface emissivity of 1.0: - let's say 8x 800W GPUs and neglect the CPU, that's 6400W - let's further assume the PSU is 100% efficient - let's also assume that you allow the server hardware to run at 77 degrees C, or 350K, which is already pretty hot for modern datacenter chips. Your radiator would need to dissipate those 6400W, requiring it to be almost 8 square meters in size. That's a lot of launch mass. Adding 50 degrees will reduce your required area to only about 4.4 square meters with the consequence that chip temps will rise by 50 degrees also, putting them at 127 degrees C. No CPU I'm aware of can run at those temps for very long and most modern chips will start to self throttle above about 100
- aunty_helen 9mo agoHence the fancy air conditioning pumps
- stackghost 9mo ago... on satellites?
- aunty_helen 9mo agoYes, that’s what we’re talking about. Data centers in space. You put the cold side of the phase change on the internal cooling loop, step up the external cooling loop as high temp as you can and then circulate that through the radiators. You might even do this step up more than once. Imagine the data center like a box, you want it to be cold inside, and there’s a compressor, you use to transfer heat from inside to outside, the outside gets hot, inside cold. You then put a radiator on the back of the box and radiate the heat to the darkness of space. This is all very dependent on the biggest and cheapest rockets in the world but it’s a tradeoff of convenience and serviceability for unlimited free energy.
- abenga 9mo agoWhy not use the unlimited free energy on terrestrial data centers then? You can use solar power as we speak, no?