Nano-engineered thermoelectrics enable scalable, compressor-free cooling
jhuapl.edu
Research paper: https://www.nature.com/articles/s41467-025-59698-y
jhuapl.edu
- Good thermal insulator - Good electrical conductor - Good semiconductor
This is because the hot & cold sides are sandwiched closely together as a PN junction, so once you move heat from one side to the other, it just leaks right back. Mechanical cooling doesn't have this problem, because the hot & cold sides are separated by thin bits of tubing. This makes the thermal leakage a "minor annoyance" in a mechanical system as opposed to "literally the whole problem we're trying to solve" as it is with thermoelectrics.
One work-around is to stack lots & lots of thermoelectric coolers on top of each other. That reduces the temperature difference at each individual PN junction, which in turn lowers the leakage. That's what this team is doing, but using layers that are only a few nanometers thick, so they can fit dozens or hundreds of junctions in a single package.
They claimed 55% Carnot efficiency based on a 30-100 angstrom gap maintained by piezoelectric controllers, and a method to construct large electrodes with matched surfaces so that the gap could be maintained over a large area. It all sounded plausible but never went anywhere as far as I know.
Incidentally that means all their patents will have expired...
The coefficient of performance (COP) of the Carnot heat pump is 19.5.
The coefficient of performance of a typical heat pump in a british home is around 4.
There is obviously a huge difference between 4 and 19.5 - although a good chunk of this is explained by large temperature differentials in the condenser and evaporator, and a british desire to use a water heating loop.
I'm thinking of the separation walls in counterflow heat exchangers (only useful at the end where the incoming stream is closer to its end temperature than the delta offered by thermoelectrics I guess). Can it do whatever it does across a temperature gradient?
This isn't anything like a compressor or heatpump system, but Peltiers get a bad rap... they move heat really well if you're not pushing them to the edge.
Here's a nice chart. At 10k difference and 0.1 current max, you're over 2.5 COP. https://www.meerstetter.ch/customer-center/compendium/71-pel...
$10 and an hour of deep cleaning later, and now we have a wine cooler in our basement. I don't recall the specs or power consumption offhand, but it does keep my beverage-of-choice a few degrees cooler than ambient. :)
Variable frequency drives have made running pumps and fans a lot more efficient, even residential HVAC equipment is starting to get EC motors or VFD driven A/C motors. I can run my 10,000 BTU (1kW) window unit at 68F for an entire month in the summer and it only costs $50 due to the variable speed fans and compressor pump.
What’s the use case for peltier coolers, wearable cooling?
I think most of the commercial bed cooling systems are thermoelectric (ChiliPad, Eight Sleep) and they seem to work fine, but by the time you get to the scale of a small fridge or dehumidifiers the products are generally awful.
But making tiny things with lithography is really cheap (in volume).
The middle ground is what one needs for a 10 watt vapor compression pump. And to my knowledge nobody has built a 1 watt pump with lithography - although an array of electrostatic scroll compressors does look like it could work.
It's a relatively small delta-T and in most climates a relatively small fraction of the overall cooling load, so it might just barely pencil out.
Magnetocaloric is super interesting though as an alternative to heat pumps. Likely the next big revolution in this space.
It seems like they achieve a CoP of 1.3-6.8 (depending on heat transfer load) versus e.g. - CoP of 2-4 which is common for a household refrigerator. So we are already in similar territory.
The article also references a Samsung refrigerator already in the market using a hybrid system with thermoelectric to achieve higher efficiency. So clearly commercial thermoelectics are already efficient enough to have a role in efficient cooling.
https://news.samsung.com/global/samsung-unveils-new-refriger...
I think the role of the peltier is to allow them to design the compressor to be more efficient in a temperature maintenance mode.. so their peltier is probably not more efficient than the compressor in low heat transfer mode. That’s exactly the mode where the CHESS device is making massive improvements, so clearly it unlocks the potential for a thermoelectric-only refrigerator that’s more efficient than one using a compressor
The article has the CoP numbers for the thermoelectric element used in that Samsung refrigerator as well, if you’re interested.
I find it odd that people respond with knowledge gained in the past to a new research article without reading it and doing some investigation first as to the roadmap behind the research and what the expected endpoints are. It’s like using the first release of BERT and declaring LLMs a dead end.
Neither the article nor the abstract go out of their way to compare the efficiency of the new system to traditional heat pumps. Makes it kinda hard for a lay person to really assess the situation.
It seems like they achieve a CoP of 1.3-6.8 (depending on heat transfer load) versus e.g. - CoP of 2-4 which is common for a household refrigerator. So we are already in similar territory.
The article also references a Samsung refrigerator already in the market using a hybrid system with thermoelectric to achieve higher efficiency. So clearly commercial thermoelectics are already efficient enough to have a role in efficient cooling.
https://news.samsung.com/global/samsung-unveils-new-refriger...
The article has the CoP numbers for the thermoelectric element used in that Samsung refrigerator as well, if you’re interested.
They typically consume around the 50 to 80 watts while the compressor and fan are running, and generate two to four times that in cooling capacity.
Surely people have adapted these in to PC cooling units?
Peltier junctions are a type of heat pump.
You'd wind up taking up even more space with a TEC solution at these efficiencies. To replace a 5-ton condensing unit you'd have to reject on the order of 50-100kW of heat.
Peltier effect refrigeration has very low efficiencies (5%) so while this is an amazing accomplishment it will not replace other more mechanical cooling methods.
But efficiency is extremely important in this context, not just for saving energy, but because the inefficiency manifests as heat generated, which undermines the intended refrigeration. So as far as Peltiers go, a doubling of efficiency is like a 3x ~ 4x improvement in effectiveness. Peltiers are already used for cooling in some contexts (eg. cooling CCDs) and this greatly grows the envelope for where they can be effectively employed.
Sure less energy usage is always better, and if we could get the same out of mere single digit wh power draws that would be cool. But I don't think thermoelectrics are ever going to get us there.
The paper also references a Samsung hybrid refrigerator that already uses a thermoelectric device to improve efficiency (probably by letting the compressor operate in a more efficient mode most of the time).
According to the paper Samsung uses a bulk TEC device with a COP of 1.2 - 3 depending on heat load. That’s already fairly close to mechanical cooling. If it wasn’t it wouldn’t have made sense for Samsung to use it in a refrigerator whose whole selling point is efficiency.
I mean, clearly the 100% improvement is for the high heat load COP relative to that Samsung device, right? From 3 to 6.. and I think 6 is better than most commercially viable mechanical cooling solutions, no?
Also one of the biggest if not the biggest downside of these chips is, unlike a split refrigeration circuit, the front gets cold while the back gets hot which means you can't move the heat very far.
Peltier coolers aren’t anywhere near this.
Heat pipes (as in CPU heatsinks) can passively move the heat up to a feet away. Far enough to allow effective insulation between cold and hot side. From there you can move the heat further away with a fan.
Thermoelectric coolers do not compete with heat pipes. They are useful only when you want to obtain a temperature lower than the ambient temperature. Otherwise, heat pipes or liquid flow cooling are the right solutions.
X is much better for this kind of stuff these days (just follow the right people and stick to the following tab)
Happy 4th all!
(With apologies for the wildly off topic comment)
Under low-heat-pumping, with minimal role of parasitics, TFTEC modules offer four times the Coefficient of Performance (CoP) advantage over bulk devices. As an example, system-level CoP with a 16-couple TFTEC module is ~ 15 for small temperature differentials of 2 °C, pumping about 1.2 W heat load using 80 mW of electric power. Such small-scale high-CoP cooling is relevant for distributed refrigeration or compartmentalized refrigeration as well as for use in future electronic thermal management
They also note that the maximum cooling power density depends inversely on thickness, and this is where the thin-film TECs like this gets most of their improvements from, compared to millimeter thick regular TECs.
Just a quick scan before going to bed, but looks interesting for certain applications.
Freezing food waste prior to composting it results in much faster breakdown in the compost.
https://en.wikipedia.org/wiki/Thermoacoustic_heat_engine
it should be pointed out that thermoelectric cooling that was able to outperform mechanical pumps, would still be mostly useless for on device cooling as it cant move heat any distance, with it's own heat stuck in the same box or package, making design pivot around that limitation.
>system-level coefficient-of-performance is ~15 for temperature differentials of 1.3 °C.
There's a long way to go. As far as I know, the leader in condensed-phase refrigeration cycles is still the sodium iodide ionocaloric method, which blew past all of the competing methods (magnetocaloric, elastocaloric, thermoelectric) when it was announced in 2022:
https://www.science.org/doi/10.1126/science.ade1696
...but the temperature drop of 25 C is just barely practical for air conditioning in warm (but not desert) climates.
No, they turn a temperature gradient into electricity. If one side is heated and the other cooled, you can get current flow on the two leads. And as with many electrical devices, it can also be run in reverse: if you put a voltage across the leads then one side will get hot and the other side will get cold.