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Researchers Pave Way For Compressor-Free Refrigeration
Posted by
Soulskill
on Sun Aug 10, 2008 06:59 PM
from the cool-science dept.
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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Kind of (Score:3, Interesting)
a "reverse" microwave?
Re:Kind of (Score:5, Informative)
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.
Parent
Kind of like kinetic stasis for ferropolymers (Score:5, Informative)
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.
Parent
What about overclocking / cooling? (Score:4, Funny)
Wait, the fridge keeps my red-bull cold...
Parent
Re:What about overclocking / cooling? (Score:4, Funny)
Wait, the fridge keeps my red-bull cold...
The fridge? You're still using the fridge? I keep my Red Bull inside my very, very overclocked computer case. I also hang my steaks in there.
Parent
Re: (Score:3, Funny)
That explains the wired network.
Re: (Score:3, Interesting)
Efficiency (Score:4, Interesting)
Re: (Score:2)
Yeah, this was my thought as well. TFA is, as usual, slim on the technical details...
Re: (Score:3, Insightful)
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
Re: (Score:3, Funny)
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.
Re:Efficiency (Score:5, Funny)
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.
Parent
Re:Efficiency (Score:5, Funny)
Parent
Re: (Score:3, Insightful)
Re:Efficiency (Score:5, Insightful)
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...
Parent
Re:Efficiency (Score:5, Interesting)
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.
Parent
Re:Efficiency (Score:5, Informative)
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.
Parent
Re: (Score:3, Informative)
Re:Efficiency (Score:4, Funny)
What was he thinking? We all know that a compressor is cheaper than a lump of metal.
Parent
Re: (Score:3, Interesting)
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)
"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.
Re:Efficiency (Score:4, Informative)
you missed the point. polystyrene is flammable, but completely lacks the poly-vinyl-chlorine.
chlorine is an important part of many poison gasses, although 'pure' chlorine is more of an irritant combined with vinyl the chlorine gas is Quite toxic, that's the big problem, in some states it's becoming illegal to use PVC piping, because in a fire when people are trapped breathing fumes, the toxic vinyl chloride gas can kill not only trapped victims but can make onlookers and rescuer crews sick, if they survive.
I know the following link is greenpeace, but they had the most comprehensive page about why Poly vinyl chloride (PVC) is so toxic.
remember, this device is being proposed as a replacement for the compressor/gas phase of a fridge, not the outer housing.
http://www.greenpeace.org/usa/news/how-to-find-and-avoid-toxic-vi [greenpeace.org]
Parent
Re:Efficiency (Score:4, Funny)
Well that sucks.
I guess we'll have to step up the open-pit copper mining, then. Yay environmentalism!
Parent
Re:Efficiency (Score:5, Funny)
Yes, having your eyes and lungs dissolved by chlorine gas can be very irritating.
Parent
Adsorption (Score:3, Insightful)
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)
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 [iop.org], 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 [wikipedia.org] 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.)
Parent
Re: (Score:3, Interesting)
Am I the only one who remembers absorption refrigerators [wikipedia.org]? 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)
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...
=Smidge=
Parent
Possible practical implementation (Score:5, Interesting)
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
Re: (Score:3, Insightful)
Re: (Score:3, Insightful)
Then flip their states again; the outer one will dump most of that absorbed heat to the outside, since the inner one is currently rejecting heat.
I'm sorry, but there's no such thing as "rejecting heat". If the inner one is colder, it will take heat from the outer period. Your system will be nicely wasting electricity while moving heat from inner to outer and back again.
You need to set up some kind of touch/non-touch configuration, which means moving parts.
Compressors are hard to beat (Score:4, Informative)
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.
Re: (Score:3, Informative)
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
We already have compressor-free refrigerators! (Score:3, Interesting)
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 [wikipedia.org] 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)
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)
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.
Re: (Score:3, Informative)
Congratulations on not even reading the whole fucking summary.
Unless you had multiple stages (Score:2)
Re: (Score:2)
And don't forget Peltierâ"Seebeck junctions.
But perhaps it might be more efficient, which is preventing more widespread use of Peltier effect devices.
Re:compressionless is new? (Score:5, Informative)
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 [psu.edu]
Parent
Re:compressionless is new? (Score:5, Funny)
Parent
Re:compressionless is new? (Score:5, Funny)
Did you try using it without putting shit in your hand?
Parent
Re:Light (Score:5, Interesting)
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.
Parent
It's not vaporware! (Score:3, Funny)
It is anti vaporware: it is refrigeration without vapors!! No more e-vapor-ators!
Re: (Score:3, Informative)
It's pretty vague, but it sounds like it is not continuous. The Peltier effect with thermoelectric material is constant as long as electricity is applied. This new material seems to give off heat and is then able to absorb heat once the electricity is turned off.
It's sound pretty strange and not much better than thermoelectric which already has been around quite a long time. Just wait and see if we can get more technical explanations later.
Buy a new fridge... (Score:4, Insightful)
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.
Parent
Re:2nd law says no. (Score:5, Informative)
There. Fix'd it for you.
When external energy is applied to the system (like, say, electricity), then the system isn't isolated.
Parent
Depends (Score:5, Insightful)
Parent
Re:One thinks a Uni would not mangle it this bad (Score:5, Informative)
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).
Parent
Re: (Score:3, Funny)
Slashdot is the ultimate source of entropy. Nothing can come close the the random BS emitted around here.