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Researchers Pave Way For Compressor-Free Refrigeration 218

Posted by Soulskill
from the cool-science dept.
Hugh Pickens brings news that scientists from Penn State have developed a new method for heat-transfer that may replace the common compressor-based system used in household appliances. Quoting: "Zhang's approach uses the change from disorganized to organized that occurs in some polarpolymers when placed in an electric field. The natural state of these materials is disorganized with the various molecules randomly positioned. When electricity is applied, the molecules become highly ordered and the material gives off heat and becomes colder. When the electricity is turned off, the material reverts to its disordered state and absorbs heat. The researchers report a change in temperature for the material of about 22.6 degrees Fahrenheit... Repeated randomizing and ordering of the material combined with an appropriate heat exchanger could provide a wide range of heating and cooling temperatures."
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Researchers Pave Way For Compressor-Free Refrigeration

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  • Kind of (Score:3, Interesting)

    by iminplaya (723125) <> on Sunday August 10, 2008 @08:02PM (#24550349) Journal

    a "reverse" microwave?

  • Efficiency (Score:4, Interesting)

    by EmbeddedJanitor (597831) on Sunday August 10, 2008 @08:02PM (#24550353)
    Unless this is more efficient than at least Peltier it won't become commercially viable.
    • by ThosLives (686517)

      Yeah, this was my thought as well. TFA is, as usual, slim on the technical details...

      • Re: (Score:3, Insightful)

        by frito_x (1138353)

        well... i can see benefits in areas like this method being quieter, also it sounds like it won't produce as much heat as the conventional gas compression method.

        but then it doesn't sound like arranging these molecules into a crystal-like structure won't require considerable amounts of electric power.

        only time will tell. and even then, remember that new technologies' worst rivals are the ones they're trying to replace. even in a best case scenario, it'll probably need many years to become mainstream. gas com

        • by g0dsp33d (849253)
          I don't think anyone asks about the compressor when buying a fridge. If it has the right volume and features, they will buy it. Bonus points if the salesman can say that there's no moving parts to break.
      • Re: (Score:3, Funny)

        by RobertM1968 (951074)

        Yeah, this was my thought as well. TFA is, as usual, slim on the technical details...

        Yeah, but does that really matter? You are one of the three people on slashdot that actually reads the articles (which I think is against the rules here). I know I didnt read it.


        • by Peyna (14792) on Sunday August 10, 2008 @08:49PM (#24550755) Homepage

          You are one of the three people on slashdot that actually reads the articles (which I think is against the rules here).

          Reading of articles is strictly prohibited. However, clicking on the link and loading the article is required. This is how the Slashdot effect and ignorance of content can co-exist.

        • by mortonda (5175)

          Yeah, this was my thought as well. TFA is, as usual, slim on the technical details...

          Yeah, but does that really matter? You are one of the three people on slashdot that actually reads the articles (which I think is against the rules here). I know I didnt read it.


          But if it weren't for those few people, I wouldn't know that TFA is slim on details ... now I know that I may as well not RTFA. So thanks, article-reading-person! You're our hero!

    • Re: (Score:3, Insightful)

      by RuBLed (995686)
      and if it isn't capable of totally drying my clothes during sunless days, it won't become commercially viable. ^^
    • Re:Efficiency (Score:5, Insightful)

      by kesuki (321456) on Sunday August 10, 2008 @08:37PM (#24550637) Journal

      and since it uses PVC (plus a few more elements) it's quite toxic should it catch on fire.

      ahh the smell of chlorine gas in the morning... i can see a couple problems with this material 1. it can only change 21 degrees a cycle, this means you need multiple separate units of the stuff to cycle on and off to cool more, and since it's toxic when burned, it can't do high temperature heating. it also can't do refrigeration in an environment where it might reach it's melting point. yeah you can use heat sinks on the hot side, do you really think heat sinks are cheaper than reliable, safe, CHEAP compressor technology? if there is a significant savings on energy usage (not discussed) then yeah it's great, it's also since it's a polymer easily made into clothing articles, but they seemed to add a number of ideas that don't make sense like 'fire fighter equipment' if it's highly flammable, and creates toxic chlorine gas, it's not suitable for firefighting! and basic electric heating of gloves* is already possible, what advantage does this device have? that it can't raise the temp of your gloves by more than 21 degrees F of the temp outside? um yeah... neat, cool, new way to cool or heat stuff, doesn't mean it has any commercial value, unless it's properties are better than what we're using now.

      * = or perhaps of whole snow mobile suits, as i've seen for some modern snow mobiles...

      • Re:Efficiency (Score:5, Interesting)

        by flappinbooger (574405) on Sunday August 10, 2008 @09:51PM (#24551109) Homepage
        Nah, man, a 21 degree dT is great. A typical cooling tower or hydronic HVAC operates at a 10 degree dT.

        If they can force a 21 degree temperature drop to occur with some fancy plastic and some electricity... that's awesome. The challenge will be to APPLY this to a SYSTEM that will CAPITALIZE on the TECHNOLOGY.

        Move it from the lab to the Walmart or the appliance store or the house or the car.
      • by MrNaz (730548) on Monday August 11, 2008 @12:29AM (#24551901) Homepage

        do you really think heat sinks are cheaper than reliable, safe, CHEAP compressor technology?

        What was he thinking? We all know that a compressor is cheaper than a lump of metal.

      • Re: (Score:3, Interesting)

        by DeadChobi (740395)

        Well, to be honest, there are things in your home and/or appliances which are just as toxic when burned. Hell, plastic water piping is PVC. So unless you make it a point to light your refrigerator on fire at the end of its lifecycle you really don't have a case there.

        And in general anything that replaces mechanical parts(a compressor) with electrical parts will achieve an increase in energy efficiency because of the absence of mechanical friction in the system.

        Also there are already heat sinks on the back o

      • Various materials (Score:3, Informative)

        by phorm (591458)

        "These polarpolymers include poly(vinylidene fluoride-trifluoroethylene) and poly(vinylidene fluoride-trifluoroethylene)-chlorofluoroethylene, however there are other polarpolymers that exhibit the same effect."

        It doesn't say what the "others" are, but perhaps there's something that can be used that would be more tolerant of high heat (or less toxic). Alternately, perhaps it could be used in a heatsink type scenario wherein the sink is cooled as it absorbs heat, but doesn't become superheated itself.

    • Adsorption (Score:3, Insightful)

      by quenda (644621)

      Or Adsorption! Those fridges are very common where silent operation is needed: hotel mini-bars, offices. They're just not efficient.
          The article is useless without mentioning efficiency. Inefficient alternatives are nothing new.

      • Re:Adsorption (Score:5, Informative)

        by infolib (618234) on Monday August 11, 2008 @05:12AM (#24553177)
        I work in a group researching magnetocaloric refrigeration at room temperature. I read the Science paper [], and this is about the same, except with electrical polarization instead of magnetic. It's promising in some ways, but have some potentially fatal problems.

        1. 12 deg C is a really large temperature change, we have to do with 1-3C. My group would kill for a material like that, $EVIL_GENIUS_LAUGHTER. (With a design like this [], it's possible to have a much greater cumulative change of temperature than what any single piece of material does, so that's how to cool from +25 to -18 C).

        2. The hysteresis [] is not too high, look at fig. 1 in the paper. This is important, because hysteresis means you're converting electricity to heat inside your fridge. Many materials have great change in entropy and temperature when you put an electric or magnetic field on them, but it's killed for practical purposes by hysteresis.

        3. You need a really high electric field. The curves in the paper are done at 100-200 MegaV/m, meaning that you need 100-200 kV to polarize a layer of 1 mm thickness. A CRT uses voltages of around 20 kV, and so it's plausible to use thin layers, or just live with the fact that you'll only get 1-2 C temperature change. (Which means it has to compete with magnetic refrigeration on an even footing).

        4. It's hard to polarize and depolarize the material without electric losses. (This is a problem for ferroelectric cooling in general). You're basically charging and discharging a huge capacitor, and you'll lose the charge on the capacitor every round. This could be fixed by putting it as the "C" in an oscillating (LCR) circuit with some inductance, but it's not easy to get an inductance (L) high enough, unless you run at high frequency. This material looks to work at high frequency (the hysteresis curves are taken at 1kHz), but how do you transport the heat into/out of it? If you run at 1kHz, you'll have less than half a ms to transfer heat to the cooling fluid, which means you'll need to use a very thin layer indeed. (Incidentally this will make it easier to get a strong field gradient). Then there's the problem of moving the cooling fluid back and forth over many layers of sub-mm thickness polymer. I'm not saying it can't be done, and there might very well be smart solutions I haven't thought of, but it's not trivial. (And btw, magnetic cooling doesn't have this problem, because we can use a permanent magnet with a several cm gap, and balance material moving into the gap with material moving out.)
    • Re: (Score:3, Interesting)

      by Skater (41976)

      Am I the only one who remembers absorption refrigerators []? Actually they are still widely used in RVs because they can run on any heat source (such as propane) without requiring electricity. They're also extremely energy efficient and have no moving parts.

      The downsides to them are that they rely on the temperature differential between the coils and the ambient air, so on extremely hot days they aren't that good keeping cool (or if you are opening the door frequently).

    • Re:Efficiency (Score:4, Interesting)

      by Smidge204 (605297) on Sunday August 10, 2008 @08:46PM (#24550725) Journal

      Well, peltier stacks use electric current. This method uses electric fields. In other words, it sounds like they use the polymer as a dialectric in a capacitor that is constantly charged and discharged. I know peltiers eat a lot of current, so depending on the capacitance of this new system the total power should be quite a bit less.

      Actually transporting the heat is another matter...

    • by nospam007 (722110)

      Especially since millions of small refrigerators (minibars, camping car refr., cooling boxes), etc are already compressor-free with peltier elements.

    • by Dare nMc (468959)

      If it's cheap to manufacture, I can think of at least one use that doesn't depend on efficiency. Radiant floor heating, if you could smear a thin layer in flooring apply electric, heat the floor at night, cool the house by day...
      granted metals do this heating fine today, but no cooling, and likely not as lightweight.

    • Not only that, but the randomization of the polarpolymers, that's increasing the disordered information of the universe.


  • by ZombieEngineer (738752) on Sunday August 10, 2008 @08:20PM (#24550513)

    This could feasibly be used to make a practical air conditioner by having a segmented disk shape block that allows air to pass through.

    Outside air would pass through one half of the disk that is currently energised (the electric field orders the polymer and thus releases heat).

    The inside air would pass through the other half that is currently not energised (the relaxation of the electric field allows the material to absorb heat).

    The disk rotates with segments shifting between the outside / inside halves, the electric field is applied by a simple electric comutation.

    This is not a true "no moving parts" system but it has the potential to be an order of magnitude quieter than the current air conditioning units.


    • by TheSHAD0W (258774)

      Yup. Given the material's properties, I can't see any way of utilizing it without SOME mechanical action, which means the article's stated idea of a flat-panel refrigerator with no moving parts will never happen, at least not using this material.

    • Re: (Score:3, Insightful)

      by Locke2005 (849178)
      Sort of my thought too... you need some sort of heat "valve" to enforce one-directional heat transfer with this technology (Maxwell's daemon, anyone?), otherwise the heat just flow back in the same direction with you reverse the electric field. I can't think of any way of doing this without moving parts, so I feel the "solid state refrigerator" claim is a bit of a misnomer.
  • by PPH (736903)
    From TFA:

    These polarpolymers include poly(vinylidene fluoride-trifluoroethylene) and poly(vinylidene fluoride-trifluoroethylene)-chlorofluoroethylene, ...

    I'd like one of those poly-pola-try-viyl, er, I mean fluoro-frikkin-flora,.....

    Ah, screw it. Gimme a fridge with a compressor.

  • Being solid-state, one can hope this tech is silent. The buzz of our fridge-freezer is a pain.
  • I am not a physicist, so feel free to flame me if my question is stupid. But the article mentions a design concept that would hook multiple devices up in a sequence or series, in order to continuously move a temperature in either direction. This concept would make sense if the principle of the phenomenon is based upon a relative temperature range, instead of an absolute range. But if that was true, that this phenomenon could alter an oven at 330 up to 350, or a refrigerator at 50 down to 30 freezing, and I
    • by robbak (775424)

      The article talks about a temperature difference: The see a 22 F (12.22.. C for sane persons) difference between its energized state and its unenergized state.

      So, if it is sitting at room temperature (20C), and you power it up, its temperature raises to 32 C. If you then let it cool down to room temperature and then turn it off, its temperature will cool to 8C.

      With heat exchangers to dump heat into it when it is cold, and strip heat off it when it is hot, you could stack these devices to provide whatever

      • by robbak (775424)
        Re-Reply: Yes, efficiency is the target, and the collection of heat exchangers and these devices does not sound particularly efficient to me. But then again, peltiers and compressors are also inefficient, so there is a lot of room to improve on them.
      • by atamido (1020905)

        Is there any reason you could not stack several flat versions of this directly on top of each other and then initialize them in sequence? Or do you simply need a way to temporarily insulate the layers from one another to ensure the heat is transferred the correct direction?

        I think that if the layers sat in a vacuum then you would only need to shift the layers ever so slightly so that they made contact with one side or not with the other.

  • It sound like they have essentially developed a solid refrigerant. That has got to be far less useful than a liquid refrigerant that can me moved around to where it is needed. Not to mention since there is no phase change involved you need a buttload more of this fancy polymer to get the same heat capacity.

    Nah. This will never be economically competitive.

    • by Urkki (668283)

      It sound like they have essentially developed a solid refrigerant. That has got to be far less useful than a liquid refrigerant that can me moved around to where it is needed.

      I think more useful point of view is, they have developed a refridgerant that can change temperature without moving parts, by just application of electric field.

      And presumably they do it quite efficiently, since otherwise this would not be news. Then again, inefficiency might be precisely the reason they don't tell any numbers...

      Anyway, this particular substance is solid, but just imagine if they managed to make a liquid version... No more compressor, just passing the liquid through electric field at one po

      • by infolib (618234)

        Anyway, this particular substance is solid, but just imagine if they managed to make a liquid version... No more compressor, just passing the liquid through electric field at one point of a simple closed loop with heat sinks attached to it... Elegant.

        That's actually a good point, but I'd take a wild guess and say it's hard to develop it to show this effect while being liquid. Instead, make a powder of this plastic, and put it in a suspension. There'll be a few problems with the field though - in the article they use 200 MV/m, so you'd need to put 100s of kV over a pipe of a few mm diameter, and a length of many cm. There'd be some NASTY caps to burn yourself on if you take a fridge like that apart!

  • I could be wrong, but it sounds to me that without the compressor machinery, this could enable smaller, quieter cooling units and lead to products like battery-powered thermoses or air-conditioned clothing. Do any engineers have a take on this?

    • by robbak (775424)

      Maybe: but this is about making the same thing get hotter or colder. More machinery is needed to use that to make a flow of heat from one place to another.

      A simple way: take two blocks of this stuff. Energise A, it becomes hot: allow it to cool.
      Place A and B Together, energise B and de-energize A. A cools off, pulling all the heat from B.
      Seperate them again, energise A again to dispose of the heat pulled from B. De-energize B, and you have achieved refrigeration. Rinse and repeat.

      No doubt there are better w

    • by mikael (484)

      Some people were experimenting with thermoaccoustic cooling []. The idea is that pressure waves in air and fluids can give off heat (compression) and move heat around (standing waves?).

      This idea of solid thermoelectric blocks seems to be comparable to sliding around trays of ice-cubes or solid CO2, except that you would need a secondary refrigerator unit to convert the water or gas back into a solid.

  • Oh, oh, oh! I have an idea. Let's combine this idea with a stirling engine and see what kind of synergies come out.

    Polymer on each end of the engine, alternating current synchronized with the displacer, etc. etc. etc.

    Whaddya think?

  • The researchers report a change in temperature for the material of about 22.6 degrees Fahrenheit, in today's (Aug. 8) issue of Science.

    ...weird, you'd only expect the weatherman to do that (or the yellow press trying to inflate a figure).

    Tribute to Lord Kelvin [], anyone?

  • Reminds me of something I learned about low-temp cryocooling way back in P.Chem:

    Adiabatic Demagnetization [].

  • by istartedi (132515) on Monday August 11, 2008 @12:45AM (#24552009) Journal

    I'm not sure how close they come to reverse Carnot in a modern "fridge", but they are very durable. It seems like we had two refridgerators the whole time I was growing up, and the only reason we got the 2nd one was because we were in a different house. It's not exactly like they were being fixed all the time either. In fact, aside from the fact that the fridge we had when I was a kid required manual defrost, I don't think they ever required maintenance. The HVAC unit in my old condo had to be pulled. This was in 2006. When the tech opened it up, we discovered it was build in 1979. These units are essentially refrigerators too, with compressors. Now, that was a good old USA unit, with a steel housing and everything. I'm not sure if the cheapo plastic jobs they installed will hold up as well, but that's an implementation issue, not a problem inherent with the underlying tech.

    The point is, can this new technology be as efficient as a compressor, as cheap as a compressor and as DURABLE as a compressor?

    That said, perhaps it will find applications outside of keeping your OJ cool and your brow dry. If it does, great; but the current tech is pretty good. I wish they were silent, but even at that, a modern fridge is pretty quiet too.

    • by Arimus (198136)

      For car based Air Con it might improve the ~ 10% fuel efficiency penalty...

      • Re: (Score:3, Informative)

        by Sandbags (964742)

        most new cars only have a 2-3% AC penalty (4-5% on max AC setting). With the adoption of variable nozzle compressor technology (called variable displacement), the AC system in most cars only make air as cold as you're requesting it to, and the unit automatically disconnects during acceleration, allowing a smaller engine to feel like it has more power.

        In fact, most cars, actually get better fuel economy with the AC than with windows open, when driving over 50 MPH. In stark contract, SUVs actually get less

  • by nickovs (115935) on Monday August 11, 2008 @04:25AM (#24552967)

    Researchers Pave Way For Compressor-Free Refrigeration

    Actually, we've had usable refrigeration without a compressor for most of the last century. It's the gas absorption refrigerator [] and they are in RVs, dorm rooms and offices all over the world. In fact most small (as opposed to tiny) fridges don't have a compressor.

  • Ehh. solid state? (Score:3, Interesting)

    by rew (6140) <> on Monday August 11, 2008 @08:34AM (#24554247) Homepage

    So now you have a material that can cool on command by an electrical signal. Nice.

    So now you make it touch your fridge, and tell it to go to the "cool state". Next it absorbs heat (that leaked through the walls of the fridge), and you need to expell that heat. So now you turn it to the "warm" state, Now it's heating your fridge? No you need to make it insulated from the fridge, and thermally connected to the outside to pump the heat out. How are you going to do that?

    The easiest way would be to have two of those electro-thermal-active-plastics built as a heat exchanger. One of them (the one in the "hot" state) circulates an appropriate fluid with the heat exchanger on the back. The other circulates the fluid with the heat exchanger inside the fridge.

    So, how about we get rid of those nasty ozone-layer-affecting CFKs? Nice try, but no go! These ARE CFKs we're talking about. Maybe easier to contain than CFK gasses, but CFKs notheless.

    Next, when your element is exchanging heat with the fridge, and it has come to an equilibirium.... Then you change it to the "warm" state. Now it becomes 12.5 degrees centigrade warmer! So my fridge is 4 degrees, and the element becomes 16.5 But in the summer my home is warmer than that (actually in the winter as well!). It has to become warmer than the environment to expell heat. So we're going to need a two-step heatpump.

    So instead of a fridge with one pump, two heat exchangers, and a replacement for the CFKs for the old days, we might go to a frige with three pumps, two valves, and four CFK -containing active essential elements!

    I predict that everyone will have one of these in their house in 5 years! Not!

  • More details needed (Score:3, Interesting)

    by SnarfQuest (469614) on Monday August 11, 2008 @02:55PM (#24558859)

    There are a lot of issues that need to be known before this could be considered useful technology.

    1. Price. Is the initial outlay too expensive?

    2. Lifetime. Will it last as long as a current unit.

    3. Efficiency. Does it require more or less power than current units.

    4. Cooling. Can it freeze ice cubes in 80 degree weather?

    5. Size. Will it fit into the same space?

    All the article says it that it is quieter. People live with a noisy AC turned on for many hours a day, and a fridge is much quieter than that, so noise isn't that much of a factor.

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