Researchers Pave Way For Compressor-Free Refrigeration 218
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."
Kind of (Score:3, Interesting)
a "reverse" microwave?
Efficiency (Score:4, Interesting)
Already been done? (Score:1, Interesting)
How is this different from a Peltier cooler?
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: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.
Re:Efficiency (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=
Re:Already been done? (Score:1, Interesting)
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.
How do you figure? The thermoelectric effect has crap efficiency. This sounds like it might work a lot better (although of course we need numbers to judge).
It's not strange at all. It's basically taking a material in a high entropy state (disorganized), and when an electric field is applied, it converts into a low entropy state (organized).
A natural consequence of going from high entropy to low entropy is that heat is removed from the system. Reverting back to the disorganized state increases entropy, and draws heat back into the system.
Then you just need a mechanism which can take advantage of this.
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.
Re:What about overclocking / cooling? (Score:3, Interesting)
Re:Efficiency (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 of refrigerators. How would this be a different situation? So yes, I do think this will be cheaper than bulky, loud, inefficient fluid compressors.
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.
its important for wine storage (Score:1, Interesting)
http://www.vintagecellars.com/productview.asp?productsid=652&prodcategoryID=7/ [vintagecellars.com]
When you're storing wine for a long time sediment settles out and a compressor will stir it up. Not good for the taste.
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.