The video did not make predictions about the future, it just presented the current reality at the time. I think it is still a good introduction to set the right expectations when encountering this technology.
Maybe. However there is fundamental physics in play and so it is likely someone (not me!) can tell you the most efficiency we get from that system. I'd be curious what those people say.
I haven't watched it recently, but here are the main takeaways I remember:
Peltier coolers are neat because they're very small and quiet - as opposed to vapor compression systems solutions. However, they are an order of magnitude less energy efficient.
Also Peltier coolers still have to obey the laws of thermodynamics, which means that to cool one side of the mechanism, you must heat the other side. In order to do any substantial cooling, you need a way to dispose of that heat on the other side. This usually involves the use of radiators and fans, which negate much of the size and noise benefits.
As a result, Peltier coolers are pretty niché. Your use case would have to require only a little bit of cooling. You'd have to need a form factor that cannot accomidate a vapor cooling solution. And you'd have to be willing to make the system very energy inefficient.
For those worried about tiny COPs from these gizmos, trawling through the actual paper -- as well as the PR from JHU APL -- in this HN post [1] shows claims of COPs of ~15 for Delta Ts of 1.3°C.
A compressor based cooler gets a COP of about 4 in the real world. I'm pretty sure this is an apples to oranges comparison to an expert (I am not one of those) but a factor of 3+ increase in COP is fairly noteworthy -- if it holds up.
ugh, reading the paper, their methodology is kinda crap. They basically just guess what the thermal resistances in their system are, and use air temperature measurements to figure out the heat flow. This is not how to measure heat flow accurately. It might be OK as a comparison with whatever TEC they tested with, maybe, but it's not at all something I would trust to compare to another test setup. If their box is more insulative than they think it is, their results are gonna look better than reality. This can be validated at least approximately by just putting a heater in the box that's dissipating a known amount of heat and looking at the temperature rise, but it seems they didn't even do this. And in general the regime where you've got small temperature differences is where your systematic error in a system like this can become huge and distort the results by multiples.
(This is an area which is really hard and details matter. Heat is basically impossible to measure directly, and the indirect measurements are fraught with peril. Getting it wrong was a large part of why people thought they had demonstrated cold fusion)
The delta of 1.3C is critical there - peltier cooling drops precipitously in efficiency as the delta increases, and struggles to hit a COP of even 1 in real world scenarios. Their figure works out at about 6.5% Carnot efficiency, whereas a normal heat pump is usually nearer 45% over a much broader range of temperatures, as you can separate the hot and cold sides completely. Not so with a peltier wafer.
What they’ve done here is add a point of failure, use additional materials as well as a traditional heat pump, and called it “AI” and “eco friendly”.
The idea was just so astonishing that I ordered some from American Science and Surplus. I connected the leads to a battery and poof, one side got hot and the other got cold. Blew my mind.
I didn't actually have a use for it. It was just neat that it actually worked.
I understand the basic physics of it perfectly well. It's just one of those things where you expect basic physics to be overwhelmed by friction or something.
They're already doing great. I have a portable neck AC unit that uses peltiers and it keeps my head and neck cool in otherwise nasty desert conditions when mining. Yes the radiative heating from the sun is still a bitch but a hat basically minimizes that, and also redirects the partially-chilled air more efficiently around my head and face.
The direct-contact neck cooling plates are an absolute lifesaver. Keep the sun off the back of your neck and chill one of the best heat sink locations exposed on your clothed body.
One can only hope some kind of phonon diode material can exist that a slight voltage can overcome something so inescapable as entropy by providing it only lanes that suit us.
I believe the “apples to oranges” is the temperature gradient. AC units would routinely manage 15-20c and are rated for more than that. And some freezers manage up to 50c. The greater the gradient the worse the efficiency in general.
What about a ΔT of say 20°C? I'd reckon most refrigerators and air conditioners are around there (temp difference of refrigerant between evaporator and condenser).
Stacking a bunch of these Peltiers to give more temperature difference would give a pretty low CoP. Say, for a 13°C temperature difference you'd have to stack 10 of them and use 10x the power. It's even worse actually as the hotter ones have to also pump the waste heat from the cooler ones.
Note that a small temperature difference that is sustained very consistently over a long time using a tiny amount of electricity (let's say half of what the parent post cited, so like a COP of 8) could add up to a lot of nearly-free cooling. You'd chill your walls for weeks and when a heat wave comes with hot nights for a week, if you(r home automation) close(s) the blinds during the heat of the day, the more-powerful AC might barely have to do anything
Just an idea of course, but I'd not write new tech off as "ok but just 1.3 degrees who cares" when the claimed COP is so insanely good without first trying it out
The ΔT between evaporator (typically 2-6°C while cooling) and condenser (often 40-50°C in cooling mode) is much higher than 20°C. The condenser is often almost 20°C above ambient outside temperature.
The design ΔT of ~10°C is the typical return-to-supply air ΔT.
>in this HN post [1] shows claims of COPs of ~15 for Delta Ts of 1.3°C.
>A compressor based cooler gets a COP of about 4 in the real world.
Real life refrigeration usually isn't very interested in a difference of 1.3 C. The Carnot COP for this temperature drop near ambient conditions is, I believe, around 200. When you consider a cooling technology relative to the Carnot efficiency (or COP) you get a better idea of what the efficiency means in practice. For an AC unit blowing 10 C air on a 40 C day, the Carnot COP is about 10, while real units get less than half that. But I think that's still better than the Peltier effect getting less than 10% performance relative to Carnot limits.
You can get a COP of ~3-4 out of regular TECs, but only at pretty low temperature differences. That's the killer, fundamentally the TEC material itself is thermally conductive and heat really wants to flow back the other way, so no matter how well it moves the heat, it winds up fighting against the heat load generated by itself. A refrigerant based heat pump works much better because the heat basically only moves in the direction the refrigerant itself is moving.
COP of peltier elements can be large only when the temperature difference is small, such as the measly 1.3 degrees you quoted. When do you want to cool something by only 1.3°C compared to the surrounding temperature?
I don't understand how they could quote him saying: “This thin-film technology has the potential to grow from powering small-scale refrigeration systems to supporting large building HVAC applications, similar to the way lithium-ion batteries have been scaled to power devices as small as mobile phones and as large as electric vehicles,”
Then the entire article foregoes comparing their peltier device to traditional compressor based heat pumps.
Only if you have a cold environment into which to dump that heat into. You could maybe trickle charge your phone in the winter, if you don't mind a cold spot where the device sits on your body.
I wish they had gone into detail about what makes this device different from Peltier coolers that are available today. You can already get mini fridges that use them, but they're not very good - the total amount of cooling you can get from them is not enough to maintain the temperatures that a regular refrigerator does.
Yeah I have a cooler box with a peltier cooler, but it will only cool a few degrees, not sure I'd trust it as a standalone fridge. Plus its energy use is much higher.
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.
> Normal fridges just let the temperature have a wider swing which is good enough for most needs.
These wide swings annoy me. You hear that you shouldn't let your fridge go above 4°C, because that's dangerous. And you obviously don't want your fridge to go below 0°C. But finding a setting where the hottest part of the fridge doesn't go above 4°C (or even 5°C or 6°C) during the hottest part of the cycle and the coldest part of the fridge doesn't go near 0°C during the coldest part of the cycle is really pretty difficult, in my experience.
Would a peltier element allow for a more constant temperature? Or can you turn a peltier up and down easily? With a compressor based system it's always been "on or off", something that can ease up and down would be nice.
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%.
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.
> In the Bespoke AI Hybrid Refrigerator Samsung launched in 2024, the compressor operates under normal conditions such as routine storage and retrieval, while the Peltier device activates alongside the compressor during high-load situations — like when storing large amounts of groceries or placing hot food inside — thereby enhancing both cooling performance and energy efficiency
With home HVAC, fridges, water heaters, and dryers all using now able to use of dependent on heat pumps I wonder how long it be before we see modular appliances that connect to coolant lines where the temperature differential is supplied by a central high efficiency heat pump.
Cars already have heat scavenging that can move heat from where it's being created through losses to places where it's valuable, like the cabin or battery pre-heating. Especially in cold climates it feels like homes should be next.
It's worth noting that the very earliest electric refrigerators had a separate condensing unit outside; see this interesting 1920s Frigidaire training video for an example of what that was like: https://www.youtube.com/watch?v=W-t7DqOAMME
There were also centralised systems for apartments where one condensing unit supplied many evaporators in the refrigerator in each suite.
I used one for a couple years as my primary fridge. It was expensive, like $2k, didn't have very good temperature control and broke after 2 years and couldn't be repaired.
The latest wave of appliances is really fucking loud for some reason.
I think they're using different kinds of motor windings, bearings, insulation, etc. it's not related to the refrigerant or other system parameters. I've had older r600a fridges that were dead silent compared to anything sitting in a Best Buy showroom right now.
My wine fridge uses Peltier and is super quiet. It's the perfect application for this because wine doesn't need to be as cold as a normal fridge, and noise is a consideration.
It's not completely silent though, there's a small PC-like fan but it's way less loud than a compressor.
A hotel I was staying at had a small bar fridge that used a Peltier. I only know because it stopped working so I checked it and realized it was only a Peltier plus a heat exchanged (a cyclopropane loop).
I presume a full size fridge is outside of reach at this point.
Move it outside a cabinet, let it free stand. I found out that my nice kitchen niche for the refrigerator acted like a nice resonance chamber for the frequencies the compressor generated.
Not OP but it's a massive nuisance if you live in a studio. People don't realize how noisy a fridge is until there's one in the room that they sleep in.
Readit News
https://www.youtube.com/watch?v=CnMRePtHMZY
Peltier cooling could have a higher utility local maximum than currently used refrigerants.
Peltier coolers are neat because they're very small and quiet - as opposed to vapor compression systems solutions. However, they are an order of magnitude less energy efficient.
Also Peltier coolers still have to obey the laws of thermodynamics, which means that to cool one side of the mechanism, you must heat the other side. In order to do any substantial cooling, you need a way to dispose of that heat on the other side. This usually involves the use of radiators and fans, which negate much of the size and noise benefits.
As a result, Peltier coolers are pretty niché. Your use case would have to require only a little bit of cooling. You'd have to need a form factor that cannot accomidate a vapor cooling solution. And you'd have to be willing to make the system very energy inefficient.
Unless you want to spend more energy that you remove in heat, stick with heat pumps and cooling towers.
Thermoelectric cooling is not very good and takes a lot of energy to do.
Dead Comment
A compressor based cooler gets a COP of about 4 in the real world. I'm pretty sure this is an apples to oranges comparison to an expert (I am not one of those) but a factor of 3+ increase in COP is fairly noteworthy -- if it holds up.
[1] https://news.ycombinator.com/item?id=44424087
(This is an area which is really hard and details matter. Heat is basically impossible to measure directly, and the indirect measurements are fraught with peril. Getting it wrong was a large part of why people thought they had demonstrated cold fusion)
What they’ve done here is add a point of failure, use additional materials as well as a traditional heat pump, and called it “AI” and “eco friendly”.
Never have I seen more prime VC bait.
Deleted Comment
And you dont get to stack Peltiers to increase COP, only to increase delta T.
Still, Peltiers are super cool and I have some ideas for their use od they get slightly better. Advances are super welcome.
I didn't actually have a use for it. It was just neat that it actually worked.
I understand the basic physics of it perfectly well. It's just one of those things where you expect basic physics to be overwhelmed by friction or something.
The direct-contact neck cooling plates are an absolute lifesaver. Keep the sun off the back of your neck and chill one of the best heat sink locations exposed on your clothed body.
I'd say they are super hot, but it depends from which side you look at it.
Stacking a bunch of these Peltiers to give more temperature difference would give a pretty low CoP. Say, for a 13°C temperature difference you'd have to stack 10 of them and use 10x the power. It's even worse actually as the hotter ones have to also pump the waste heat from the cooler ones.
Just an idea of course, but I'd not write new tech off as "ok but just 1.3 degrees who cares" when the claimed COP is so insanely good without first trying it out
The design ΔT of ~10°C is the typical return-to-supply air ΔT.
>A compressor based cooler gets a COP of about 4 in the real world.
Real life refrigeration usually isn't very interested in a difference of 1.3 C. The Carnot COP for this temperature drop near ambient conditions is, I believe, around 200. When you consider a cooling technology relative to the Carnot efficiency (or COP) you get a better idea of what the efficiency means in practice. For an AC unit blowing 10 C air on a 40 C day, the Carnot COP is about 10, while real units get less than half that. But I think that's still better than the Peltier effect getting less than 10% performance relative to Carnot limits.
That said, 1.5C is tiny.
Might as well not use a refrigerator if your ambient temperature is that low.
One side would have been ~23C and the other 24.3C.
> is ~15 for temperature differentials of 1.3 °C.
Deleted Comment
Best regards,
AI
Ps.: AI
Maybe a "switch" for when things get advanced.
It's that kind of AI.
AI rebuttal about it not being AI
https://www.jhuapl.edu/news/news-releases/250521-apl-thermoe...
I don't understand how they could quote him saying: “This thin-film technology has the potential to grow from powering small-scale refrigeration systems to supporting large building HVAC applications, similar to the way lithium-ion batteries have been scaled to power devices as small as mobile phones and as large as electric vehicles,”
Then the entire article foregoes comparing their peltier device to traditional compressor based heat pumps.
These wide swings annoy me. You hear that you shouldn't let your fridge go above 4°C, because that's dangerous. And you obviously don't want your fridge to go below 0°C. But finding a setting where the hottest part of the fridge doesn't go above 4°C (or even 5°C or 6°C) during the hottest part of the cycle and the coldest part of the fridge doesn't go near 0°C during the coldest part of the cycle is really pretty difficult, in my experience.
Compressor systems use twice as much energy as an ideal system, while Peltier systems use about 10x as much.
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.
I'd choose a fridge with a larger compressor.
You can buy R600a on Amazon right now. One $60 can will charge the system ~5 times.
Cars already have heat scavenging that can move heat from where it's being created through losses to places where it's valuable, like the cabin or battery pre-heating. Especially in cold climates it feels like homes should be next.
There were also centralised systems for apartments where one condensing unit supplied many evaporators in the refrigerator in each suite.
(abandoned)
I think they're using different kinds of motor windings, bearings, insulation, etc. it's not related to the refrigerant or other system parameters. I've had older r600a fridges that were dead silent compared to anything sitting in a Best Buy showroom right now.
The advantage of the newer variable speed scroll compressors in some high end fridges is that they can run continuously at a slower speed.
It's not completely silent though, there's a small PC-like fan but it's way less loud than a compressor.
A hotel I was staying at had a small bar fridge that used a Peltier. I only know because it stopped working so I checked it and realized it was only a Peltier plus a heat exchanged (a cyclopropane loop).
I presume a full size fridge is outside of reach at this point.
I can barely hear it now.