Usually that means either a fan or compressor pump is making a metal panel resonate; the pump itself is usually pretty quiet, and the fan is pretty much the same as a PC fan. You can usually add a sticky foam panel to the metal backpanel to eliminate the vibration.

Get one with an inverter compressor, they are very quiet. They have a compressor that can be run at varying power levels, so instead of having one that goes of noisy at 100%, then sits off for a while, you have one that runs for example at 10% most of the time.

Interesting. Is this better or worse for compressor life span?

From what I know it's better for the life span. Less load, fewer start-stop cycles, less vibration.

They're not energy efficient so I'm not sure that type of fridge is available to buy now.

Energy efficiency is secondary, that can be mitigated by solar power plus some thermal mass inside. That is actually most efficient use of solar from my pow.

Their bane is hydrogen partial pressure dropping due to it leaking through the metal of the tubes. That .. is problematic. OTOH it'll last for like 20 years before you'd need to replenish.

The Einstein-Szilard device doesn't use hydrogen, did the USSR device use it ?

in the US you can still buy hydrogen/ammonia/water gas absorption refrigerators such as "EZ Freeze". Propane/Natural Gas refrigerators use this cycle. I'm sure you can get them all over the world, the cycle is older than the one in the article.

You can buy them almost anywhere where there is a need to keep food cold without electricity.