Cooling Technologies

I was looking to discuss different cooling technologies and their proficiencies/deficiencies in the following areas:

  1. Energy efficiency
  2. Cost
  3. Environmental Impact (chemicals)
  4. Longevity (repair costs)
  5. Size
  6. Noise (dB)

If any of these cooling methods peak anyone’s interest I can put some numbers to the above criteria. Looking forward to people’s input!

Traditional Refrigerant/Compressor Setups



Thermoacoustic Refrigeration



Thermoelectric Cooling



Evaporative Cooling

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I can figure how this works in theory, but do you have a real world application\numbers? Curiousity has gotten the better of me, as I’ve played with all the others at home before, but not seen this one…

There is this as well. But you wont be using ti to cool anything big.

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Thermoelectric has the advantage of already being mass produced for automotive 12v refrigerated cooler’s. Condensation is a prob.

Air conditioning is not just cooling but also dehumidification. You need to calculate the volume of space and thermal capacity of the ac unit. If you cool too fast you won’t dehumidify the air.

Generally phase change units follow a SEER rating, the higher the better.

Things to consider…

When it breaks, who will fix it and what’s the cost of repairs.

Here are some concepts from 1993

The first application of thermoacoustic refrigeration was originally a project at Penn State University sponsored by Ben & Jerry’s as an alternative to fluorocarbon refrigerant-based compressor systems. The 19% efficient prototype, at 24.5 liters in volume, was used to cool a 200 liter refrigerator to -24.6 ºC.

A manufacturing scale version of a thermoacoustic generator was produced by Aster Thermoacoustics in 2016. This unit uses waste heat from manufacturing processes to generate electricity. No data is provided for efficiency and cost, however.

It does appear that these higher-efficiency solutions have high initial costs since there are some complicated structures internally that aid in thermal exchanges via fluid mechanics of the internal gas. As far as repair costs go, the only things that can break are the pressure seals (unlikely at only 10 atm) and the speaker / driving circuitry.

Some simplier, low-effiency models can be made from PVC pipe and a loudspeaker. This unit is horribly leaky, but a sealed unit produces a low hum at the resonant frequency.

Ultimately these are a usable solution for small appliance-like units that are fairly well-sealed and low-volume such as household refrigerators and freezers. For anything larger the required resonance chamber to achieve the right cooling power becomes unreasonably large.

So sounds interesting, but cooling power of 0.81 times its electrical use says currently not doing better than the solid state TEC stuff, and it doesn’t sound like it’d be cheaper either…

The most efficient cooling block is space.

Correct. This was a cool, functional project at a university, but the numbers don’t add up as for this being a better chlorofluorocarbon replacement as heavily doped semiconductor junctions (TECs).

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I didn’t realize that Thermoelectric Cooling had already been rolled out into so many markets. They are also available in wine-cooling units and tailgate/camping style coolers. I don’t see any large scale thermoelectric cooling units but that area is more dominated by evaporative coolers.

I would like to see these thermoelectric plates put into personal temperature-controlled body-suits like for race car drivers.

I’m not suprised you don’t find big TEC units, even in portable fridges you notice the lower efficiency of a TEC over a compressor unit… but lower cost, lighter weight, having the only moving part the hotside fan, and having no working fluid is worth it for small consumer applications.

Another neat area is with Ammonia, forget exactly how it works but the 2 applications I know of are large food distribution warehouses and older RV campers using propane. I believe it was the first refrigeration technology invented that did not use shipping ice from the arctic. My Dad talked about delivering ice from my Grandfathers ice truck to homes and restaurants. This was before health inspections :slight_smile:

It took awhile for the thermoelectric coolers to take off. 30 years ago they were advertised in the back of magazines as “NASA technology!” General Snus decided they would like to try to market their product in the states. They built and deployed a ton of these tiny refrigeration units to convenience stores across the US. No idea what method they use.

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Its just a refrigerant (called R717) in a normal compressor or absorption system (where water can be the solvent), it was the most common before freons took over, but is still used on large scale systems where its low cost, high efficiency and aseptic nature are advantageous but its flammability and toxicity can be mitigated.

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