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Reminds me of this company: https://www.blueheartenergy.com/ https://www.blueheartenergy.com/ The claims are pretty amazing. High efficiency, efficient over a
by rocqua 4y ago
Reminds me of this company: https://www.blueheartenergy.com/ https://www.blueheartenergy.com/
The claims are pretty amazing. High efficiency, efficient over a wide range of temperature difference, high temperature differences possible.
The operating principle is totally different. It is based on acoustic waves. Not using phase-changes but just the ideal gas law (pressure and temperature are proportional). I tried to get my head around it, and I got it with a standing sound wave. But they use a traveling wave, for which I could not find explanations I understood.
The general idea is "lower air pressure and move gas to cold side so the gas heats up" followed by "raise air pressure and move gas to warm side so the gas cools down". That means the low pressure needs to be low enough that the gas gets colder than the cold side, and the high pressure needs to be high enough that the gas gets hotter than the hot side. Luckily that is 'just' a matter of amplitude of the sound wave. I think this is how they achieve their wide range of efficient temperature deltas.
That wide range is the main difference with a phase-change based unit. The phase change happens at a much more difficult to change temperature.
- deleted 4y ago[deleted]
- lifty 4y agoReally curious what kind of COP this technique can achieve. Cool tech if real, since it doesn’t need any refrigerant. Wondering if there are other downsides.
- dr_dshiv 4y agoFascinating. I wish my physics courses had focused more on waves. https://en.wikipedia.org/wiki/Thermoacoustics https://en.wikipedia.org/wiki/Thermoacoustics
- honksillet 4y agoWhen you get past freshman physics it is all waves! (Mostly)
- WJW 4y agoAll of it is also particles! (Mostly)
- londons_explore 4y agoNon phase change systems are inherently more efficient because every heat exchanger (air/air, air/coolant and coolant/water) can be counterflow, allowing substantially greater efficiency. In phase change systems, the 'hot side' and 'cold side' are all at the same temperature, which means any gradient in whatever you are heating/cooling is lost energy.
- thinkingkong 4y agoThis same mechanism is also how the james webb space telescope stays cold!
- babyshake 4y ago> The general idea is "lower air pressure and move gas to cold side so the gas heats up" followed by "raise air pressure and move gas to warm side so the gas cools down". This sounds like Maxwell's Demon, where the work required to prevent the system from reaching thermodynamic equilibrium is equal to or greater than the extra energy. How does this differ from that?
- chroem- 4y agoEnergy input in the form of compressor work. It's not even remotely similar to Maxwell's Demon.
- huffmsa 4y agoNot at all. You use a compressor or some other means to increase the pressure. That's what the electricity is for.
- Dylan16807 4y agoCan you explain in more detail how it sounds like Maxwell's Demon? There's nothing that sounds like it sorts the air particles, so I don't see the connection.
- rocqua 4y agoMaxwell says that the effort you put in is more than the work you can get out. So the heat difference you get, even if converted perfectly to other kinetic energy, will always be less than the electricity input. But we aren't after kinetic energy, or work. We are after heat.
- taeric 4y agoI thought heat was a form of kinetic energy? Specifically, it is a measure of the kinetic energy of an object's particles, independent of the kinetic energy of the object as a whole. That not accurate?
- rocqua 4y agoIt technically is, but not really. The correct term is 'work' which means something like useful change in kinetic energy. Your idea of 'kinetic energy of the object as a whole' is probably quite close.
- jabl 4y agoAnother non-phase change method is the reverse Brayton cycle. Kind of like running a gas turbine in reverse. I think it is somewhat widely used in cryocooling, and in jet airliner cabin AC, but it seems to not have caught on for domestic heat pump applications. Presumably the traditional phase change approaches are more efficient in the relevant temperature ranges.
- pkaye 4y agoThis video shows how a thermoacoustic engine works. But I don't know if it can be good enough to cool an entire house. https://www.youtube.com/watch?v=abswNCqnMRQ https://www.youtube.com/watch?v=abswNCqnMRQ