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Researchers Pave Way For Compressor-Free Refrigeration
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."
a "reverse" microwave?
What?
Unless this is more efficient than at least Peltier it won't become commercially viable.
Engineering is the art of compromise.
Congratulations on not even reading the whole fucking summary.
So, will this pave the way for a new style of super-cooling for the home computer overclocking enthusiast? ...
... cuz if not, I'm not really interested.
Wait, the fridge keeps my red-bull cold...
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.
ZombieEngineer
It really doesn't matter so long as there is a Delta. It sounds like this can absorb and release heat as fast as an electrical switch can be flipped and mankind has made some pretty snappy switches that could repeat REALLY fast.
The real question is how much power is lost. Peltier coolers for instance are horrendously inefficient. If this isn't more efficient and/or cheaper than compressor technology it will never happen. Since compressor technology isn't cheap to produce the only thing that will likely stand in the way of cheapness is greed on the part of the patent-holder. We shall see.
I tried making my own beverage cooler out of Peltiers once, it kept my beverage nice and cold but it burnt the shit out of my hand.
Wanna fight ? Bend over, stick your head up your ass, and fight for air.
It's still based on compression (and out of Penn State, licensed to Ben and Jerry's, of course), but it's a much *faster* compression, at the frequency of the sound waves used, and it takes advantage of air's intrinsic nonlinearity at high acoustic amplitudes, rather than the much slower effects inherent in traditional refrigeration techniques.
http://www.acs.psu.edu/thermoacoustics/refrigeration/benandjerrys.htm
If your current fridge is too loud, then I suggest shopping for a new one. Many of the newer units feature far quieter compressors.
While you're at it, I'd suggest looking for an energy star one.
I don't read AC A human right
...the second law of thermodynamics that states that the entropy of all isolated systems always increases.
There. Fix'd it for you.
When external energy is applied to the system (like, say, electricity), then the system isn't isolated.
You can freeze and melt water quite a few times before it wears out.
Engineering is the art of compromise.
Did you try using it without putting shit in your hand?
Nerd rage is the funniest rage.
TFA is written very poorly and describes a phenomena involving polymers that is already widely known. There are many examples. Here is one you can try using something far less exotic than the polymers mentioned in the article.
For this example, take a rubber band. Stretch it out. Touch the stretched rubber band to your lips. It will feel warm. Hold it in the stretched position for a few seconds to let it cool down to room temperature. Now let the rubber band relax, and once again touch it to your lips. You should now notice that it will feel cool.
The above process uses exactly the same principles described in TFA. Stretching the rubber band causes reduction of disorder by aligning the polymer chains. It also warms the rubber band because of the work applied. As you hold the rubber band in the stretched state it will cool to room temperature releasing some of the energy needed to heat it. This is equivalent to the step where the electrical field is applied.
Now release the rubber band. The polymer chains now revert back to a disordered state, cooling the rubber. Since the rubber band started in a stretched room temperature state the relaxed rubber band will now be below room temperature. this is equivalent to turning off the electric field as mentioned in the article.
Voila. This is a wonderful new refrigeration system that will replace all existing known cooling systems. NOT.
There are so many issues with practical application of this it is not funny. If these issues didn't exist we would have been using rubber band refrigerators for many decades already.
Also, please note that from a thermodynamics point of view this is essentially how a conventional refrigeration system works (albeit fat far more efficiently).
Going by the rough description in TFA, it sounds like electricity's effect on the ferropolymer causes its bonds to strengthen, or perhaps to magnetically align, increasing rigidity, reducing the material's potential for containing kinetic energy.
If the material's new state caps the amount of kinetic energy it can store, it has to move on - first law of thermodynamics and all.
This may be the next interesting bit in applying their discovery - finding a compatible heat conductor, and also learning the optimal frequency, voltage, current etc. at which to apply voltage.
O lord, bless this thy holy hand grenade, that with it thou mayest blow thine enemies to tiny bits, in thy mercy.
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.
For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
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.)
Any sufficiently advanced libertarian utopia is indistinguishable from government.