4 ms·
Seems like N2 would be a better choice unless absolute molecular weight is important. Helium is hard to keep confined. Reading up a bit, it seems like this has
by moloch-hai 4y ago
Seems like N2 would be a better choice unless absolute molecular weight is important. Helium is hard to keep confined.
Reading up a bit, it seems like this has to be a traveling-wave device to get the efficiency advertised: standing wave devices seem limited to a Carnot cycle, where a traveling wave device can operate a Stirling cycle.
- makomk 4y agoAbsolute molecular weight is important. Can't remember why off-hand but if I recall correctly there's a pretty substantial efficiency hit from using heavier gas molecules and conventional Stirling engines have a similar issue.
- jfengel 4y agoCould you elaborate on that? I'm curious and thermodynamics was a while ago...
- Nosep82828 4y ago[flagged]
- moloch-hai 4y agoWikipedia will be more helpful here than I can be.
- hasmanean 4y agoYeah a large scale solution involving helium will not scale. Helium cannot be produced by any process other than hydrogen nuclear fusion, and has to be harvested in nature from natural gas wells. Using it in nuclear reactors is one thing, but at home? Since most of the worlds natural gas is in Qatar and Iran, the world will just have a helium resource crunch if this becomes widespread. Maybe a better working gas to use would be ammonia or desiccated propane. Maybe the ultimate solution is to have neighbourhood heating/cooling units that serve multiple and pipe hot/cold water to them.
- fsh 4y agoThis is a common misconception. Helium and hydrogen leaking into ultra-high vacuum systems is a problem since even trace amounts spoil the vacuum. The leakage out of a storage vessel is completely negligible.