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Refrigerators To Cool With Sound (Cool!)
T-Kir writes "A very interesting report from the BBC where researchers at Penn State University are developing a prototype fridge that cools using metal plates and sound waves. If successful, this technology would help remove the dependance on gases that contribute to global warming. Talk about Cool!"
Check out their article here. Unfortunately, no mention of peoples' hair igniting.
Thankfully, even if the fridge cracks open the vast sounds generated within will not escape because the intense noise can only be generated in the pressurised gas locked inside the cooling system. Thats a damn scary sounding (no pun) fridge!
Paul Lenhart writes words!
I have been waiting for this for ages. I first read the paper by Backhaus and Swift (and here is a more recent one) four years ago, and whichever site that directed my attention to that "promised" commercialization in the near future. Not exactly swift in high tech time, but still very much welcomed.
Too bad I just bought a fridge for my dorm room. )=
Werd
Engineers also speak PDE, only in a different dialect.
Though the BBC didn't get his name right (Garrett), I actually worked for his research lab at PSU. Very interesting stuff.
There's more information about other projects the group is working on here.
The article specifically mentions that the sound intensity necessary can only be generated in a super-compressed gas. The sound wouldn't be audible to you at all. Or to your dog, for that matter. It would only exist inside the compression tube.
"Times have not become more violent. They have just become more televised."
-Marilyn Manson
The dominant effect of CFCs was to eat away at the Ozone Layer. However, CFCs are also greenhouse agents and actually far better at it than CO2.
Most of the compounds we have now introduced to replace CFCs are also greenhouse agents.
Best wishes,
Mike.
So let's see then (simple arithmatic)
...
173
-120
-----
53
Hardly what I would call "tens of thousands"
http://www.howstuffworks.com/question124.htm
"On the decibel scale, the smallest audible sound (near total silence) is 0 dB. A sound 10 times more powerful is 10 dB. A sound 100 times more powerful than near total silence is 20 dB. A sound 1,000 times more powerful than near total silence is 30 dB. Here are some common sounds and their decibel ratings:"
Decibel is a logarithmic scale, not a linear one.
So yes, 53db is 100,000x louder. Hundreds of thousands, actually.
I don't need no instructions to know how to rock!!!!
Except the dB scale is logarithmic.
+3 dB = 2 x as loud
+10 dB = 10 x as loud
53 = 10 + 10 + 10 + 10 + 10 + 3 = 10*10*10*10*10*2 times as loud = 200000 times as loud. So actual its much more than "tens of thousands"
Thought this article might provide some interesting background on thermoacoustics.
I feel compelled to lay to rest all of these posts about people going deaf from these refrigerators...
Thankfully, even if the fridge cracks open the vast sounds generated within will not escape because the intense noise can only be generated in the pressurised gas locked inside the cooling system.
Think about it for a moment. To generate the 120 dB in front of the speakers at a rock concert, you need some serious wattage. Those are powerful blasters, my friends. Also realize that the Decibel scale is logarithmic, meaning that the amount of "sonic energy" or volume -- whatever you want to call it -- between say 20 and 30 dB is a lot less than the amount between 120 and 130 dB. We're talking about a difference between 120 and 173 dB, which is, as the article points out, "tens of thousands of times more intense than any rock concert." I'm not a physicist or anything, but I'd assume that's why the sounds generated in the cooling unit work within a highly pressurized atmosphere -- so the sounds can (1) be created more efficiently and (2) carry through the gas properly. Open the unit into normal air and I don't believe it works anymore -- the atmosphere is too thin to produce those kinds of levels. On top of that, the unit is probably insulated in a vacuum anyhow, so as to prevent sound from escaping.
You won't go deaf. Your animals won't go crazy. The most you'll probably ever hear is a soft hum.
On Slashdot, we don't say "thank you." We say "that's enough..." -_-;
Einstein fridge
quick quote: It's basically an absorption-type refrigerator that uses ammonia, water and butane to create a chemical phenomenon that allows you to run the whole thing at a constant pressure, so you don't need moving parts like a pump or a compressor
I'd rather be sailing...
A small team of 10 or so in conjunction with Lawrence Livermore National Laboratory built a thermo-acoustic refridgerator. It didn't work to well but it sure did make a hell of alot of noise. :)
Our most successful aspect of the project was the prototyping of the stack. We discovered that a form of carbon areogel had some very cool properties that made isolating the heat exchanges easy. To test the new stack we created a "hooter-tube" (or holfer tube) which is the opposite of the refridgerator. We created a difference in temeperature to generate sound. We dipped one end of the tube in liqued nitrogen and then heated the other end with a blow dryer. It was a blast to play with becuase it was about the size of a light saber and becuase the open end was the cold end the air around the tip would condense and allow you to "see" the sound wave (well, a quarter of it anyway).
here are some photos and other stuff:
photo of hooter tube
photo of working refridgerator (very similar to ours)
Navy page with lots of info
BUNNY OF DEATH!
Heat engines convert temperature -differences- into mechanical energy. If you plop one inside a furnace, it'll just sit there getting warm. Reversible in this case means that you can convert mechanical energy into a temperature difference, and so it can be used as either a heat pump or as a refrigeration unit, depending on which end of the output you're interested in.
Just because it works, doesn't mean it isn't broken.
Cold storage: cooling phase change materials by running the cooling system at night, then using the cold material for daytime cooling (lower nighttime electric rates, better efficiencies due to cooler nighttime air temp)
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http://www.cogeneration.net/thermalenergystorag
Using high efficiency solid state thermionics for no-moving-parts cooling:
http://web.mit.edu/newsoffice/nr/2001/electrici
Storing nighttime coolness in phase change materials embedded in drywall:
http://doityourself.com/wall/phasechangedrywall
Windows which can switch on and off to reject or transmit infrared radiation:
http://www.consumerenergycenter.org/homeandwork
CO2 based automobile air conditioning system:
http://www.spacedaily.com/2002/021204065123.7v5
This research made some noise (ha!) about ten years ago. A company called Macrosonix holds the patents. Even NPR has covered this in the past ten years.
The best explanation of the technology I've seen is in "Fluid Power Journal."