[HN Gopher] Peltier vs. Compressor-Based Cooling
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Peltier vs. Compressor-Based Cooling
Author : arkj
Score : 24 points
Date : 2022-09-16 19:14 UTC (3 hours ago)
(HTM) web link (labincubators.net)
(TXT) w3m dump (labincubators.net)
| alexose wrote:
| I wish there were better options for inexpensive, miniaturized
| heat pumps. I can think of all sorts of applications where it'd
| useful to have them. Plunge pools, hot tubs, trailers,
| greenhouses, dog houses, etc.
| xani_ wrote:
| There are ultrasonic heat pumps (used in JWST for example,
| precisely because of vibraiton issue), but it will take time
| till it will be mass produced. No refrigerant needed either
| akira2501 wrote:
| Most modern residential and commercial refrigerants aren't
| particularly flammable in air, they only score about a 1 on the
| NFPA 704 when under pressure. Also most technicians will "recover
| the charge" when possible during maintenance or decommissioning.
| There's been quite a bit of development in the equipment space in
| the past two decades.
|
| On the other end, you can for some applications, use "R-290"
| which is just highly pure propane. Typically waist high
| commercial ice cream freezers will use a fully sealed R-290
| system.
|
| And finally there is also "ammonia phase change" refrigeration,
| which can be done with a compressor, but also a "generator" which
| is essentially just a propane or electrical boiler which creates
| the high pressure side of the system, also with no moving parts.
| You will typically find these in highly portable and mobile
| applications, such as RVs.
| tdeck wrote:
| Here's a great website where the author charged an ordinary
| refrigerator with propane and got it
| working:http://www.sparkbangbuzz.com/els/refrig2-el.htm
|
| Their other experiments are worth a read as well :)
| metadat wrote:
| Why did they need to pinch the copper tubing shut?
| athenot wrote:
| I have a wine fridge that uses Peltier cooling and it feels like
| the perfect application, since the target temperature is not as
| low as a normal refrigerator, and quietness is important.
| tomatocracy wrote:
| Interesting. For wine, vibration can also be a problem so this
| sounds like a sensible application all around.
| radicality wrote:
| Do you have any recommendations? I live in a 1-bedroom
| apartment (so noise level is important) and have been looking
| for some quiet wine fridge (or perhaps a wine+canned beverage
| combo fridge). Any brands I should be looking at or avoiding?
| If I also want to store cans should I be avoiding Peltier
| coolers?
| derkades wrote:
| > Peltier systems require more energy input than comparable
| compressor-based systems. However, while heat is emitted from
| Peltier systems, it is comparatively less than in compressor-
| based systems.
|
| How is it possible to use more energy, but produce less heat? Are
| they comparing a tiny peltier cooling box to a full sized
| refrigerator?
|
| EDIT: I guess you could argue it produces less heat if it moves
| less heat from inside the refrigerator, but that's not really an
| upside
| StingyJelly wrote:
| Yea, that was weirdly worded sentence. Peltier cooling can
| probably be more efficient (not clear) when there's low
| temperature difference so if one wants slightly colder drinks
| than the room temperature there's an advantage. E: As someone
| here mentioned, wine fridge seems to be that perfect
| application.
| toast0 wrote:
| It's hard to separate the heat generated by the equipment from
| the heat transferred from the conditioned space to the
| unconditioned space when talking about the heat produced. So
| I'm guessing, they're effectively saying the peltier system
| uses more energy while transferring less heat. It makes sense
| for some applications where noise and vibration are important
| or required capacity is low or compressors are otherwise
| unsuitable, but compression based refrigeration is usually the
| default.
| tengbretson wrote:
| I wonder if a refrigerator that uses Peltier cooling could ever
| be practical by taking all of the space savings of getting rid of
| the compressor and using it to increase insulation or thermal
| mass, offsetting some of the relative inefficiencies of the
| underlying tech.
|
| It doesn't appear this article will make it clear if such a thing
| is possible, since it lacks any hard numbers relating to the
| technologies it is comparing.
| Baeocystin wrote:
| No. The efficiency is so terrible compared to what heat pumps
| can do it's ridiculous. Think a few percent vs 2-300%.
|
| Peltier coolers have one thing going for them- they have no
| moving parts*. That's it. Which means they still have their
| niche! But everything else about them is awful compared to
| other cooling solutions.
|
| *in practice most applications use fans for the heat sinks.
| alexose wrote:
| Peltier fridges definitely exist, although the poor efficiency
| means that they're best suited for small capacity.
|
| Here's an example: https://www.amazon.com/dp/B07KZLJ7PB
| dvirsky wrote:
| I have a similar one, slightly bigger than this. They are
| cheap and quiet but don't really cool that much.
| GistNoesis wrote:
| See also https://en.wikipedia.org/wiki/Absorption_refrigerator
| jmount wrote:
| The usual observation is the Peltier system moves the heat about
| one millimeter, and then one needs a conventional cooler to
| remove the heat from that location.
| marcosdumay wrote:
| You need a conventional cooler to remove the heat from the hot
| side of both. The only difference is that the compression one
| can move the heat further away.
| atoav wrote:
| But just because of the bigger surface area of the radiator.
| A conventional compressor with the same surface area of its
| radiator as the peltier system will perform the same
| (provided they are at the same temperature).
|
| This is why heatsinks on CPUs have fins: to increase the
| surface area where the heatsink is in contact with the
| (hopefully cooler) surrounding air. The windings of a
| radiator are very much the same idea.
| atoav wrote:
| I think there is a difference in technical concepts that you
| are mixing up. What you are talking about is convection
| cooling. Both compressor based systems and peltier coolers need
| to transfer the removed heat to the environment. This is
| usually done with big surface areas and potentially fans to
| produce airflow.
|
| In a traditional compressor based system this huge surface area
| is the radiator in the back and technically it also only "moves
| the heat" to the surface of that radiator. But give the size of
| that radiator it will be effective at transfering that heat to
| the surrounding air.
|
| A peltier cooler with a smaller surface area needs a heat sink
| and or some form of active cooling (airflow, water etc).
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