[HN Gopher] Nano-engineered thermoelectrics enable scalable, com...
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Nano-engineered thermoelectrics enable scalable, compressor-free
cooling
Research paper: https://www.nature.com/articles/s41467-025-59698-y
Author : mcswell
Score : 111 points
Date : 2025-06-30 14:51 UTC (3 days ago)
(HTM) web link (www.jhuapl.edu)
(TXT) w3m dump (www.jhuapl.edu)
| Spivak wrote:
| So it's a better Peltier element? The article only seems to
| compare it to existing thermoelectric devices and not standard
| refrigeration units so I'm going to assume they haven't gotten
| even close to that efficiency. If they had I would assume they
| wouldn't shut up about the fact.
|
| 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.
| porphyra wrote:
| One step at a time... it would be astonishing if any
| thermoelectric device can leapfrog mechanical compressors.
| adrian_b wrote:
| Also in the article, it is implied that there is no chance to
| replace mechanical compressors for great thermal powers, but
| for small thermal powers, from a few watt to a few hundred
| watt, thermoelectric devices may become preferable, due to
| small size, simplicity and reliability
| markhahn wrote:
| just noting that household fridge/freezers are in that
| power range...
| nandomrumber wrote:
| Yeah but, household freezers are typically capable of
| freezing many tens of kilograms of material down to -18
| to -24 degrees C / 0 to -10 F
|
| Peltier coolers aren't anywhere near this.
| speed_spread wrote:
| > can't move the heat very far.
|
| 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.
| adrian_b wrote:
| Heat pipes only reduce the thermal resistance between 2
| points. They cannot cool something below ambient temperature.
|
| 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.
| scotty79 wrote:
| You could have heat pipe filled with liquid that evaporates
| at 5 degrees. This way it would draw heat from ambient
| level temperature and lead it to peltier device that would
| cool it below 5 deg and liquefy it back again. This way you
| could have peltier in the middle of your thick insulation
| layer with heat pipes drawing the heat into it from the
| cooled space and drawing the heat from the other side of it
| outside (using traditional heat pipes this time).
| nandomrumber wrote:
| I think you may have just reinvented absorption
| refrigeration, previously invented by Ferdinand Carre in
| 1858.
|
| https://en.wikipedia.org/wiki/Absorption_refrigerator
| scotty79 wrote:
| Not really. The role of heatpipes is not to cool, just to
| transfer heat to and away from peltier device so it's
| easier to insulate hot and cold side.
| speed_spread wrote:
| I was suggesting combining Peltier element _and_ heat
| pipes.
| petermcneeley wrote:
| > the APL team achieved nearly 100% improvement in efficiency
| over traditional thermoelectric materials at room temperature
|
| Peltier effect refrigeration has very low efficiencies (5%) so
| while this is an amazing accomplishment it will not replace other
| more mechanical cooling methods.
| mitthrowaway2 wrote:
| For sure this doesn't replace mechanical cooling.
|
| 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.
| VladVladikoff wrote:
| IIRC there is an application in solar panels where thermo
| electric cooling could play a role if we could get the
| efficiency just slightly higher.
| audunw wrote:
| I'm not sure what they mean by "traditional materials" here,
| but from their paper the COP is in the range of 1.3 - 6.8
| depending on heat load which is similar to a modern household
| refrigerator. So yeah, it really does seem to be good enough to
| replace mechanical cooling.
|
| 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?
| johnnyjeans wrote:
| I'm not sure why we would want to replace mechanical systems. A
| portable AC unit with 10,000 BTUs uses ~650wh these days, and
| it'll turn a 50m^2 apartment into an icebox. That's not much
| more than a flagship GPU pulls. This is also about the least
| efficient class of aircon you can get.
|
| 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.
| fnordpiglet wrote:
| Thermoelectric cooling needs as much research as possible.
| Mechanical cooling is extraordinarily space consuming. CHESS has
| the potential over the next 10 years to largely replace vapor
| compression in most systems other than the most extreme gradients
| or scales. They are small enough to incorporate into most devices
| and would allow smaller devices more thermal load. In some ways I
| think efficient TEC like CHESS could be more useful than room
| temperature super conductors.
| vlovich123 wrote:
| Nah. Heat pumps are ~10-100x more efficient than
| thermoelectric. Thermoelectric is just inefficient mechanism
| and is inherently difficult to scale up as the more electricity
| gets generated so does more heat which inhibits the temperature
| gradient you're trying to utilize. There's a reason water
| cooling is preferred instead of peltier to ferry heat away from
| electronic.
|
| Magnetocaloric is super interesting though as an alternative to
| heat pumps. Likely the next big revolution in this space.
| leptons wrote:
| >Heat pumps are ~10-100x more efficient than thermoelectric.
|
| Peltier junctions are a type of heat pump.
| vlovich123 wrote:
| Mechanical heat pumps are 10x-100x more effective than
| peltier heat pumps.
| leptons wrote:
| That doesn't change the fact that Peltier junctions are a
| type of heat pump.
| nandomrumber wrote:
| Further to that, have a look at the refrigeration units on
| chest type portable fridges. They're really not very big,
| compressor smaller than a roast chicken, small low speed fan
| similar to an auxiliary cooling fan in a PC, a controller
| board, and a few meters of metal tubing.
|
| 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?
| audunw wrote:
| It's really, really weird to comment on the efficiency of
| these devices on an article like this, without actually
| checking the paper being referenced. Like, we know
| traditional thermoelectric are inefficient. But that's the
| whole point of this research. To improve it.
|
| 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.
| audunw wrote:
| It's really, really weird to comment on the efficiency of
| these devices on an article like this, without actually
| checking the paper being referenced. Like, we know
| traditional thermoelectric are inefficient. But that's the
| whole point of this research. To improve it.
|
| 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.
| perlgeek wrote:
| The abstract of the paper mentions temperature differential
| of 1.3degC and 2degC - not really inspiring for use in a
| refrigerator.
|
| 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.
| bob1029 wrote:
| > Mechanical cooling is extraordinarily space consuming.
|
| 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.
| dartharva wrote:
| Wait, won't thermoelectric cooling need a LOT more surface area
| to have any comparable cooling performance to compressor-based
| systems?
| ThrowawayTestr wrote:
| Most IR cameras use Peltier cooling so better coolers should lead
| to better cameras.
| willvarfar wrote:
| Presumably night vision on drones and missiles and things
| suddenly gets a lot smaller and deadlier?
| magicalhippo wrote:
| The paper[1] has some actual details, like this:
|
| _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 degC, 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.
|
| [1]: https://www.nature.com/articles/s41467-025-59698-y
| scythe wrote:
| From the abstract:
|
| >system-level coefficient-of-performance is ~15 for temperature
| differentials of 1.3 degC.
|
| 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.
| actinium226 wrote:
| So, these devices.... turn heat into electricity? Where does the
| electricity go, back into the system it's powering?
| doctoboggan wrote:
| > turn heat into electricity?
|
| 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.
| minimaxir wrote:
| Obligatory video on the inefficiencies of thermoelectric
| cooling/Peltier elements from Techonology Connections:
| https://www.youtube.com/watch?v=CnMRePtHMZY
| nandomrumber wrote:
| Down the heat pump rant rabbit hole we go.
| mkw5053 wrote:
| I need this for my compact compost freezer [1]
|
| [1] https://www.envirofreezely.com/
| nandomrumber wrote:
| I'll watch your video later when I get home. Mostly leaving a
| comment so I can find it easier later.
|
| Freezing food waste prior to composting it results in much
| faster breakdown in the compost.
| s_tec wrote:
| Thermoelectric cooling is pretty inefficient, because the
| materials need to balance competing requirements:
|
| - 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.
| ajb wrote:
| Twenty years ago there was a company trying to commercialise
| thermoelectric cooling based on a vacuum gap:
| https://web.archive.org/web/20031213235132/http://www.coolch...
|
| 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...
| dvh wrote:
| But isn't condensation based cooling like 500% efficient?
| cjbillington wrote:
| The Carnot limit is the theoretical upper limit of the
| efficiency of a heat pump, so the stated number is
| presumably with respect to that, not heat moved per unit
| energy input like you're quoting.
| londons_explore wrote:
| A Carnot heat pump maintains the temperature in a house at
| 20C on a day when the temperature outside is 5C. What is
| the coefficient of performance of the heat pump?
|
| 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.
| usrusr wrote:
| What if you use the technology in places where you actually
| want to maximize heat conductivity?
|
| 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?
| knowitnone wrote:
| that's an idea but would you not have to power each one which
| then destroys efficiency anyway
| metalman wrote:
| there are other alternatives for refrigeration
|
| 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.
| bigattichouse wrote:
| A lot of people throw around 5% efficiency for Peltiers, and it's
| just not true - it depends heavily on the temperature
| differential and current vs. IMax. You can (with care) drive them
| >2.0 COP.
|
| 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...
| wrigby wrote:
| I didn't know this, and it jumps out to me because 10k is
| pretty much the exact difference between room temperature and
| wine fridge tenperature - I wonder if this is actually not a
| horrible application for peltiers?
| NortySpock wrote:
| Found a wine fridge at the thrift store last month, pulled
| the model number, realized it was basically a Peltier cooler
| and a fan, and thus likely to be still operational. Powered
| up just fine, so...
|
| $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. :)
| knowitnone wrote:
| power consumption is worst than compressor system
| frankus wrote:
| I think the gotcha is that you need a beefy heatsink and fan
| (and power for the fan) to keep the hot side anywhere close
| to room temperature.
| quickthrowman wrote:
| You can get 4 COP with a regular air cooled chiller and up to 7
| COP if you add an evaporative cooling tower.
|
| 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?
| frankus wrote:
| I'm not sure of the exact reasons but you don't really see
| vapor-compression heat pumps in the tens- to low-hundreds-of-
| watts range. So I suspect there are some scaling factors
| where the reduced size/noise/complexity of a solid-state
| device starts to be more important than the extra energy that
| it uses.
|
| 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.
| londons_explore wrote:
| machining metal parts to tight tolerances when they're only
| a millimeter wide is awfully expensive.
|
| 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.
| frankus wrote:
| Thanks for the link. One of the projects I'll probably never
| get around to is a thermoelectric-augmented fan coil unit for
| air-to-water heat pump retrofits. The existing emitters (and
| crucially the in-wall distribution piping that's expensive to
| insulate and vapor seal after the fact) would stay just above
| the dew point, and then the augmented fan coil would work to
| remove latent heat (humidity) by dropping a bit below the dew
| point via thermoelectric coolers that reject heat into the
| return piping.
|
| 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.
| K0balt wrote:
| It's astonishing how here, in an ostensibly technical forum, the
| vast majority of comments are left by people who did not even
| skim the article. At least read through the informative comments
| left by those who did read it before giving your venerable
| opinion based on the information that was already in your head? I
| mean, isn't the point of an article or paper to present new,
| novel information?
| Henchman21 wrote:
| It's the day before a holiday in the US. No one is thinking,
| we're all just knee-jerk existing for another handful of hours
| and then... Then we engage in that once a year ritual of
| lighting up explosives and making a pilgrimage to the ER, where
| no one can afford proper treatment. /s
|
| Happy 4th all!
|
| (With apologies for the wildly off topic comment)
| RetpolineDrama wrote:
| HN hasn't been a good place for technical discussion in at
| least 5-6 years, maybe longer.
|
| X is much better for this kind of stuff these days (just follow
| the right people and stick to the following tab)
| marcyb5st wrote:
| I thought Magnetocaloric cooling [1] was what will kill
| "traditional" heat pumps, but if we will have something with even
| fewer moving parts that is awesome.
|
| [1] https://www.youtube.com/watch?v=qcscUoP8FNk
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