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Staying cool without refrigerants: Next-generation Peltier cooling

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Re: Staying cool without refrigerants: Next-generation Peltier cooling

#11

Post by PaulHoule »

rurban wrote: post #7
PaulHoule wrote: post #3

Earlier quoted context omitted.

I remember one objection to Peltier coolers in that application is that could possibly cool the CPU below the dew point and cause water condensation, something a fan can't do.

For this we calculate the dew point with 2 sensors and react accordingly in my temperature controller. I'd really like to try out these better peltiers, our current ones suck. And the fans to remove the heat are huge and loud.

There are other ways of building refrigerant-free refrigerators too

https://en.wikipedia.org/wiki/Magnetocaloric_effect

and

https://en.wikipedia.org/wiki/Elastocaloric_materials

of course they also have the dew point problem, but so do ordinary refrigerators and freezers.

Re: Staying cool without refrigerants: Next-generation Peltier cooling

#13

Post by szvsw »

throwaway81523 wrote: post #10

I thought Peltiers can't lower the temperature by more than 40 degrees F, in practice less than that. This is not cold enough for a refrigerator on a warm day.

FWIW, in a typical apartment or single-family home, refrigeration uses a fraction of the energy that space cooling (also via a refrigeration/vapor compression cycle) requires on a warm day (and probably year round too unless in very mild climates). The psychrometric chart path is different so there are of course differences in the amount of energy required for the sensible and latent components, but the real difference is just the volume of air that needs to be dealt with.

My point being that at least from an energy and carbon perspective, lowering the space cooling demand via more effective building envelopes or increasing the space cooling supply efficiency - eg via membrane or dessicant dehumidification, better heat pumps etc) is far more impactful on a macro scale than better refrigeration.

Granted refrigeration in a warehouse eg is really also space cooling, but I’m just making the distinction between the dT=0-25F context and the dT>25F context. If I could only choose one technology to arrive at scale to improve the efficiency, it would be for the former context.

Re: Staying cool without refrigerants: Next-generation Peltier cooling

#14

Post by marcusb »

PaulHoule wrote: post #3
WarOnPrivacy wrote: post #2

I used peltier coolers on K6 processors 1M computer years ago. They worked great and lasted about as long as the PCs did. Not long after I bought mine, they disappeared from cooler offerings. I've wondered what became of the tech.

I remember one objection to Peltier coolers in that application is that could possibly cool the CPU below the dew point and cause water condensation, something a fan can't do.

A friend had a Peltier cooler on a late 90s/early 2000s CPU and had the condensation problem. The cooler (or maybe CPU, or both; I can't remember which) had an algae-like growth all over it.

Re: Staying cool without refrigerants: Next-generation Peltier cooling

#15

Post by closewith »

szvsw wrote: post #13
throwaway81523 wrote: post #10

I thought Peltiers can't lower the temperature by more than 40 degrees F, in practice less than that. This is not cold enough for a refrigerator on a warm day.

FWIW, in a typical apartment or single-family home, refrigeration uses a fraction of the energy that space cooling (also via a refrigeration/vapor compression cycle) requires on a warm day (and probably year round too unless in very mild climates). The psychrometric chart path is different so there are of course differences in the amount of energy required for the sensible and latent components, but the real differen…

Definitely not the volume of air. The thermal mass of air is tiny.

The difference is in the thermal mass of the building and the surface area exposed to the sun.

Re: Staying cool without refrigerants: Next-generation Peltier cooling

#17

Post by bluGill »

anticensor wrote: post #4

Did they solve the inefficiency problem of peltiers?

They claim 75% better. I doubt this is better than compressors in general but they seem to be going for a niche where a high power compressor does the high load part but when only a litte cooling is needed the compressor is now very inefficient and so the peltier is better. Normal fridges just let the temperature have a wider swing which is good enough for most needs.

Re: Staying cool without refrigerants: Next-generation Peltier cooling

#18

Post by dayjah »

I worked on a scientific instrument a while ago, it had a Peltier heater on it to raise the sample to 60c from whatever residual environment temp was (approx. 20c in a lab). It was pretty amazing to see my old overclocking cooling solution come back around and be used in my professional career some 20+ years later

Re: Staying cool without refrigerants: Next-generation Peltier cooling

#19

Post by nine_k »

cosmotic wrote: post #9
anticensor wrote: post #4

Did they solve the inefficiency problem of peltiers?

The article says they have made peltiers 75% more efficient than existing ones.

OK, a typical Peltier device has 3.5% coefficient of performance, that is, it produces 35 W of cooling per 1 kW consumed.

Fine, let's expect that the new tech doubles the efficiency, to 7%. Still, to my mind, pretty wasteful, on par with a steam railway engine. A Peltier element is good in cases where you can afford a large heat removal device, but need precise temperature control and no moving parts. For a home fridge, I'll take the sound of the compressor and the temperature fluctuations of a 400% efficient compressor-based heat pump over a Peltier element any day.

Re: Staying cool without refrigerants: Next-generation Peltier cooling

#20

Post by ethan_smith »

anticensor wrote: post #4

Did they solve the inefficiency problem of peltiers?

Traditional Peltier devices operate at ~10% efficiency (COP of 0.5-0.7) compared to vapor-compression systems (COP of 2-4), but recent advances in thermoelectric materials like bismuth telluride alloys and segmented elements have pushed lab efficiencies to ~15-20%.
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