19 ms·
Peltier vs. compressor-based cooling (2019)
- athenot 4y agoI 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.
- radicality 4y agoDo 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?
- londons_explore 4y agoPeltier costs a lot more in energy costs. Inverter fridges are good for quietness.
- tomatocracy 4y agoInteresting. For wine, vibration can also be a problem so this sounds like a sensible application all around.
- zasdffaa 4y ago?
- Wistar 4y ago" Although researchers still don’t agree on why vibration ruins wine, they have found that certain kinds of vibration impact how bottles age." https://blog.vinfolio.com/2016/09/13/does-vibration-ruin-wine/ https://blog.vinfolio.com/2016/09/13/does-vibration-ruin-win...
- JabavuAdams 4y agoJust going off of general chemistry knowledge, vibration may be speeding up the chemical reactions that are happening in the wine (aging). Same as stirring. EDIT> For a reaction A + B -> C, the more chances molecules of A and B have to get into contact, the faster the reaction could run since chemistry is just atoms bumping into atoms. Stirring or shaking can bring more unreacted A's and B's together.
- londons_explore 4y agoIf you live in Europe right now, beware that unless you're a big drinker, that wine fridge will be costing you more in electricity than the wine you put into it. European energy is super expensive right now, fridges normally use quite a lot of energy, and peltier fridges use quite a lot more than normal fridges.
- ReptileMan 4y agoFridges barely use any energy in Europe. Something like 4-5 euro/month. Everything sold in last fifteen years is A class or better for efficiency.
- BenjiWiebe 4y agoI think their point is that a Peltier refrigerator will be much less efficient than a compressor refrigerator.
- ReptileMan 4y agoI agree. It should be around 3 times less efficient. My guess is that people that are into wine enough to buy a dedicated fridge probably plow to way more than 30 euro a month of wine.
- ThePadawan 4y ago> Everything sold in last fifteen years is A class or better for efficiency. In case you are unaware: The European efficiency rating system is in fact percentile-based on some fictional reference appliance which is adjusted every few years [0]. A fridge with an "A" rating you bought 15 years ago would not get an A rating today. (This sounds weird, but fights the problem that when the system was based on absolute values instead of percentiles, nearly fridges started being rated A, A+, A++ or A+++ to the point that the scale was very opaque to consumers.) [0] https://en.wikipedia.org/wiki/European_Union_energy_label#Refrigerating_appliances https://en.wikipedia.org/wiki/European_Union_energy_label#Re...
- 4y ago
- derkades 4y ago> 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 4y agoYea, 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.
- londons_explore 4y agoEven with a low temperature difference, gas compressors still win. I'm not aware of any point in the input/output temperature chart where peltier wins on efficiency.
- toast0 4y agoIt'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.
- samatman 4y agoSomeone wanted to add an "on the bright side!" to a sentence which wanted to be "Peltier coolers are less efficient, and also less powerful: they will burn more electricity while moving less heat".
- jmount 4y agoThe 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 4y agoYou 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 4y agoBut 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 4y agoI 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).
- tengbretson 4y agoI 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.
- alexose 4y agoPeltier 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 https://www.amazon.com/dp/B07KZLJ7PB
- dvirsky 4y agoI have a similar one, slightly bigger than this. They are cheap and quiet but don't really cool that much.
- Baeocystin 4y agoNo. 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.
- rsaxvc 4y agoThey're semi-practical today in niche applications. You can get a small peltier car cooler , and the inefficiencies aren't huge compared to the rest of the car's electric usage. They're not great though, and many are poorly made.
- alexose 4y agoI 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_ 4y agoThere 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
- hinkley 4y agoAre those a variety of thermoacoustic heat pump? I remember Ben & Jerry's threw some money at a group working on TAHPs and then... nothing.
- xani_ 4y agoSame thing different name. I said ultrasonic because that's the wavelength you need for it to be compact The basic way of working it is basically * lowering the pressure of gas causes it to cool, increasing it causes it to heat * creating standing wave in a gas in pipe means the low pressure part will be cold, high pressure part will be hot, and the difference will equal to basically pressure induced thermal difference sooo a fancy speaker in the tube. Already stuff that can be bought, just didn't get to the level required for consumer stuff. Supposedly they can be pretty efficient too. Would also be basically noiseless, as the ultrasonics are limited to the cooling tube and easier to dampen anyway.
- alexose 4y agoThis is extremely cool! Here's a video I found where someone makes a DIY thermoacoustic cooler: https://www.youtube.com/watch?v=kkBBkQ8jFRY https://www.youtube.com/watch?v=kkBBkQ8jFRY
- akira2501 4y agoMost 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 4y agoHere'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 http://www.sparkbangbuzz.com/els/refrig2-el.htm Their other experiments are worth a read as well :)
- metadat 4y agoWhy did they need to pinch the copper tubing shut?
- tdeck 4y agoHere's my reading of it as a non-expert. The tubing isn't pinched shut, it's just pinched to restrict the flow. I believe it's to create a bottleneck where pressure can build up between the "hot side" and the "cold side" of the refrigerator. Before the pinch the compressor is driving gas into the pipe, where it meets resistance at the pinch point and compresses to liquid, shedding heat. Then after that point a narrow jet of compressed refrigerant squirts into a lower pressure part of the pipe and starts to evaporate, expanding and taking in thermal energy again. Of course, the refrigerator already has some valve to do this, but the author mentions that it may not be designed for the pressure differential needed for propane, so you can make your own with a pinched tube.
- GistNoesis 4y agoSee also https://en.wikipedia.org/wiki/Absorption_refrigerator https://en.wikipedia.org/wiki/Absorption_refrigerator
- ResNet 4y agoIt's worth mentioning the recent development of extremely miniaturized (soda can-sized) refrigeration compressors, such as those from Aspen Systems [1]; these allow for efficient cooling in small spaces that just can't be achieved with Peltier-based solutions. An interesting project I've seen using one of them is this portable chiller suit to cool the human body on-the-go, intended for relief of Multiple Sclerosis symptoms [2]. For DIY/prototyping, there are a bunch of Chinese manufacturers now producing compressors of these sizes along with the appropriate driver board for the variable-speed AC motor [3]. I'm excited to see how this technology will be applied elsewhere in time. [1] https://aspensystems.com/vapor-compression-refrigeration/ https://aspensystems.com/vapor-compression-refrigeration/ [2] https://hackaday.io/project/4729-bringing-cool-relief-to-multiple-sclerosis https://hackaday.io/project/4729-bringing-cool-relief-to-mul... [3] https://web.archive.org/web/20220916231432/https://www.aliexpress.com/wholesale?SearchText=micro+refrigeration+compressor https://web.archive.org/web/20220916231432/https://www.aliex... (archived as of time posted for future readers)
- hinkley 4y agoI remember Adam Savage got something like these to keep from baking his noodle when he made the No Face costume for Comicon. I wondered when those sorts of things would show up for more general usage. Isn't part of what makes these work also linear compressors? The old on/off models have gotten better over time, but when we were kids, some of them would practically cause brownouts on the electrical circuit. Too much startup current. So for electronics you need someone with a smoother transition.
- deleted 4y ago[deleted]
- londons_explore 4y ago> practically cause brownouts on the electrical circuit That's because a compressor has an odd property... The motor requires substantially more starting torque than running torque. That's because the cylinder can be stuck on the compression cycle pushing against a cylinder of gas, and has no momentum to get it through. Also, the very first compression typically has far more gas in it (because the 'cold side' is actually warm before it starts). If nothing were done to compensate, the motor would stall, overheat, and burn out. Designers of fridge compressors have instead added a very high current starting coil, which will provide massive amounts of torque to get the thing going for a few seconds. Sometimes that might be 20 amps or more for a few seconds. When the motor is spinning fast enough, that coil gets disconnected.
- hinkley 4y agoWhy are Peltier coolers still so far below their theoretical efficiency?
- userbinator 4y agoThe resistive losses generate a lot of heat.
- kodt 4y agoI miss the days of people over clocking using Peltiers or even better, stacked Peltiers.
- londons_explore 4y ago> 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. This means that there may be some savings in terms of air conditioning load in the area where the unit is housed, which could help offset the energy efficiency differential. Either I am misunderstanding what is being said there, or the article author misunderstands how physics works.
- deleted 4y ago[deleted]
- LoganDark 4y agoYeah, that also looks sus to me. According to my very limited understanding of how this works, compressor-based systems (actually more like phase-change systems) only have to pump heat energy from one place to another. Peltier systems have to do this while also fighting thermal conductivity from one side of the module to the other. Intuitively, the latter probably generates more waste heat...
- dtgriscom 4y agoBut, compressor-based systems have to deal with friction (both mechanical and fluid). I'd still bet on their efficiency over Peltiers, though, unless it's a really small system.
- Panzer04 4y agoPeltiers are less efficient. Ergo, in a closed room, they will generate more heat, regardless of any other factors in play.
- deleted 4y ago[deleted]
- rsaxvc 4y agoThe compressor isn't located on the cooling chamber - it's on the other side of the insulation so the heat can be dumped to the room. The self heating (for better or for worse) of a peltier is generated at the cooling chamber edge.
- elric 4y agoPeltiers used to be hot stuff in CPU overclocking circles in the early 2000s. Heatpipes and increased CPU efficiency seem to have made them redundant.
- ReptileMan 4y agoCan you use peltier elements for diy home clear ice block installation? Or mini compressor.
- deleted 4y ago[deleted]
- FunnyBadger 4y agoPeltiers simply can not scale. But compressor refrigeration easy can.
- tanking 4y agoDo you endure the mid year heat like the vast majority of us? You could surrender and concede that environmental change is negatively affecting Australia's summers. And afterward, where will we as a whole be when winter comes? then visit https://ductscleaning.com.au/service/evaporative-coolor-cleaning-service/ https://ductscleaning.com.au/service/evaporative-coolor-clea...