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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.
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.
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"
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!
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."