Thermoacoustic heat pump?

BigEHead

What do you think of this? Promising? Game-changer? Believe it when you see it? Or just a marketing gimmick? I personally think it's super exciting but would love to hear your thoughts.

https://www.pv-magazine.com/2023/01/02/residential-thermo-acoustic-heat-pump-produces-water-up-to-80-c/

Thanks!

Hot_water_fan

“We have the same efficiency as traditional heat pumps, but we have better modulation thanks to acoustic transfer,” said Loyer.

Intriguing! I imagine it probably ends up significantly less efficient than existing tech if its COP is 3 now at an unspecified sink & source temp. I don’t think it’ll improve by commercial offering. Okay modulation already exists, maybe it can improve a bit, but that’s hardly valuable since most people don’t pay for modulation and there are diminishing returns. So can it match the price of a single speed heat pump for mass market? Or compete against higher end modulating heat pumps without the economies of scale that Trane/Carrier/Mitsubishi have?  

 I don’t think it pairing well with geothermal means anything, that’s extremely niche and expensive. It must work well with air source to be useful. 

Most impressed by the noise, that’s a huge improvement. Another downside of many water to water and air to water heat pumps is their high required flow rates and high head loss. If the heat exchanger needs less flow and is less restrictive that’s a big deal. If it doesn’t need a dedicated circulator at all, that would be great! 

Jamie Hall

Either there's a good deal more going on in there than a speaker, or it's wishful thinking.

TonKa

Jamie Hall said:

Either there's a good deal more going on in there than a speaker, or it's wishful thinking.

It's really not a lot more to it than a speaker in a carefully constructed chamber with baffles. The science is sound. (Yeah, pun intended.)  If you are curious, search for "thermoacoustic engine".

Whether this can be reliably used in this application and manufactured at scale and economically is a whole other set of problems. That may be the "wishful thinking" part.

BigEHead

Yes pretty fascinating. I saw another technology very recently called ionocaloric cooling (https://newscenter.lbl.gov/2023/01/03/cool-new-method-of-refrigeration/) but the thermoacoustic one seems to be much further along.

The no refrigerant requirement is huge. The French company already has a prototype but who knows if/when it'll go on sale in France. I'd be very interested when the tech gets here!

Dave Carpentier

Cool idea.
The principle might be;
In a standing wave of sound, there are higher pressure and lower pressure zones.
They could steer the position of the peaks and troughs by a change in the frequency of the sound.
For helium, at a 3000 hz sound, the distance from peak to trough is around 6".
(no idea what theyre using, just plugged an example into an online calc)

I wonder why the -15c limitation ?