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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."
Not at all. Microwave works by emitting electromagnatic waves that exite water molecules, thus making them and (indirectly) whatever they are a part of warmer.
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.
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...
https://www.gnu.org/philosophy/free-sw.html
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
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.
What?
I'm using an unmodified AVG 8 - it performs the Slashdotting for me.
If you were blocking sigs, you wouldn't have to read this.
...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).
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.
Flappinbooger isn't my real name
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 did a lot of HVAC systems in the past, and many were large scale water source heat pump systems. This is, as expected, where the air handler cools the air in the space to, say, 55 F at the coil.
The fluids go to a condensing unit (compressor) which, instead of going to a coil with a fan directly to outside air, goes instead to a heat exchanger with water. The water runs throughout the building taking heat away from all of the water source heat pumps.
Typically, what I remember, the water will gain 10 degrees from the loop and dump 10 degrees at the cooler. The cooler will either be an evaporative cooling tower or a "fluid cooler" but it is basically always dumping 10 degrees of heat multiplied by however many gallons per minute of flow.
Yeah, the individual space gets a larger than 10 degree F temperature difference, and the SYSTEM gets "just" 10 degrees, but it's apples and oranges, different flow rates of fluids, CFM, BTU's, etc. Energy is energy, the temperature difference is only one part of the equation.
So, my point, and I do have one, is that ~20 degrees C or ~20 degrees F or whatever, it's enough if applied correctly.
Flappinbooger isn't my real name
"...although 'pure' chlorine is more of an irritant..."
Yes, having your eyes and lungs dissolved by chlorine gas can be very irritating.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
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.)
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