[HN Gopher] Equium: Acoustic Heat Pumps
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       Equium: Acoustic Heat Pumps
        
       Author : arsalanb
       Score  : 26 points
       Date   : 2023-01-03 21:27 UTC (1 hours ago)
        
 (HTM) web link (www.equium.fr)
 (TXT) w3m dump (www.equium.fr)
        
       | aaron695 wrote:
       | [dead]
        
       | kragen wrote:
       | probably if you are trying to understand how this works it would
       | be useful to read
       | https://en.wikipedia.org/wiki/Thermoacoustic_heat_engine
        
       | NegativeLatency wrote:
       | Kinda fuzzy on how this works/what the tradeoffs are?
       | 
       | Looks like it's creating a standing pressure wave and then
       | tapping into the colder or hotter part as appropriate?
       | 
       | Based on the diagrams it seems like it would need a radiator or
       | something for larger surface area?
       | 
       | Also curious as to how loud it is.
        
         | arsalanb wrote:
         | It uses the acoustic wave to expand and contract pressurized
         | helium, and then conduct heat created from the subsequent
         | pressure oscillation.
         | 
         | Source: https://www.pv-magazine.com/2023/01/02/residential-
         | thermo-ac...
         | 
         | Which I just noticed was posted a few hours ago, here:
         | https://news.ycombinator.com/item?id=34233719
        
         | twobitshifter wrote:
         | Same question about how loud it is. Wikipedia says
         | thermoacoustic engines work at 180db, which is the sound of a
         | pound of TNT being detonated 15 feet away.
        
           | MayeulC wrote:
           | Meh. This is a pressure wave. I wouldn't be surprised if
           | tapping your finger on the table creates more pressure than
           | that. Or hammering a nail, at least1.
           | 
           | Even your TNT figure has a distance indication. Pressure
           | decreases with the square of the distance when it dissipates
           | as a sphere. Doubling the distance = -6 dB
           | 
           | 1 20*log(k)=180 => k=1e9, factor to reach between rest state
           | and max pressure, I think.
        
           | arsalanb wrote:
           | Probably not. A similar acoustic heat pump company
           | (https://www.blueheartenergy.com/ourtechnology) claims 30 db,
           | so this is probably going to be in the ball park.
        
           | pjerem wrote:
           | > 180db, which is the sound of a pound of TNT being detonated
           | 15 feet away.
           | 
           | Sounds like that can be a bit annoying
        
             | elliottkember wrote:
             | Fortunately, they're only annoying for a very short time
        
               | brnt wrote:
               | Plus, it'll be the last time ever you hear anything
               | annoying at all.
        
           | dcroley wrote:
           | Equium claims that the heat pump system is completely silent,
           | despite the use of a speaker to generate the acoustic wave.
           | The level of noise is reportedly lower than 30 dB - the
           | equivalent of a whisper.
           | 
           | "The sound our system produces stays confined inside the
           | core, so you cannot hear it from outside," said Loyer.
        
             | arsalanb wrote:
             | I imagine this is possible because of better modulation of
             | the acoustic and pressure controllers to minimize energy
             | loss..
        
       | MayeulC wrote:
       | What's the efficiency compared to traditional compressors? I
       | imagine there are a lot of opportunity for thermal energy to leak
       | on the sides...
       | 
       | Edit: 20-30%, up to 40%, according to wikipedia.
        
         | idiotsecant wrote:
         | I am building right now and my state (washington) recently
         | decided no more natural gas heat, heat pumps only. That's great
         | for the warmer side of the state but most heat pumps don't work
         | great when it's 10 below - they approach zero efficiency the
         | colder it gets. Blueheart seems to claim they can output 60C on
         | the hot end when the cold end is -20C. In addition, EQUIUM
         | seems to claim a 30 year lifetime on their acoustic chamber
         | because it has essentially no moving parts, it's just a
         | pressure vessel. If both of these things are true it could
         | eventually be an advantage over heat pumps for people in cold
         | conditions or people who are sensitive to maintenance costs
         | once the technology is mature.
         | 
         | Or all the (very vague) specs could be marketing junk and it's
         | vaporware. Neat either way.
        
       | alexose wrote:
       | Super cool to see someone trying to commercialize this
       | technology. Fun fact is that the JWST cryocooler operates on a
       | similar principle (although the implementation is quite
       | different).
       | 
       | Relatedly, I found this fantastic video on to how to use the
       | thermoacoustic effect for heating and cooling a few months back:
       | https://www.youtube.com/watch?v=kkBBkQ8jFRY
        
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       (page generated 2023-01-03 23:00 UTC)