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The physics problem regarding radiator arrays isn't unsolved, but it's not a problem that scales up gracefully. Small-scale radiators could get by via passive c

by kibwen 3mo ago

The physics problem regarding radiator arrays isn't unsolved, but it's not a problem that scales up gracefully. Small-scale radiators could get by via passive cooling, but large-scale radiators need active cooling, and now you need fluid, pipes, and pumps that all represent additional launch mass and points of failure (and the pumps are generating heat of their own, so now you need more radiators...).

AnthonyMouse 3mo ago
Doesn't active cooling provide counterbalancing options to improve efficiency though? For example, use multi-stage heat pumps with different refrigerants so that you can make the hot side very hot and thereby need less mass for radiators.
aeternum 3mo ago
Thermal dissipation scales quartically with T, that's about as graceful as you can get from a physics POV, very few things scale at that rate. COTs GPUs throttle at about 90-100C but that's because they have plastic parts and solder that melts. Those are relatively easy to eliminate. We haven't tried much to scale up operating temp.
- rcxdude 3mo ago
  Apple tried the damnedest at that during their intel era. Silicon gets exponentially leakier at higher temperatures, and that will outpace quadratic growth easily. (Electronics that works at 200C do exist, but they're not gonna meet a modern smartphone's specs, let alone a datacenter)
  - aeternum 3mo ago
    >Apple tried the damnedest at that during their intel era. The story I heard was intel failed to deliver on die shrinks that were supposed to increase thermal efficiency. The fan also had poor routing and basically did nothing. Apple was clearly not at the top of their game for that design, nor would you expect them to be as the decision was likely already made to move to apple silicon.
nkrisc 3mo ago
So what’s the unsolved physics problem? Everything you’re describing are engineering challenges.

by kibwen 3mo ago

AnthonyMouse 3mo ago

Doesn't active cooling provide counterbalancing options to improve efficiency though? For example, use multi-stage heat pumps with different refrigerants so that you can make the hot side very hot and thereby need less mass for radiators.

aeternum 3mo ago

Thermal dissipation scales quartically with T, that's about as graceful as you can get from a physics POV, very few things scale at that rate. COTs GPUs throttle at about 90-100C but that's because they have plastic parts and solder that melts. Those are relatively easy to eliminate. We haven't tried much to scale up operating temp.

rcxdude 3mo ago
Apple tried the damnedest at that during their intel era. Silicon gets exponentially leakier at higher temperatures, and that will outpace quadratic growth easily. (Electronics that works at 200C do exist, but they're not gonna meet a modern smartphone's specs, let alone a datacenter)
- aeternum 3mo ago
  >Apple tried the damnedest at that during their intel era. The story I heard was intel failed to deliver on die shrinks that were supposed to increase thermal efficiency. The fan also had poor routing and basically did nothing. Apple was clearly not at the top of their game for that design, nor would you expect them to be as the decision was likely already made to move to apple silicon.

nkrisc 3mo ago

So what’s the unsolved physics problem? Everything you’re describing are engineering challenges.