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Making Ice Without Electricity
j-beda writes "Time Magazine is running an article telling us how Dave Williams is trying to make ice for third-world applications using the Hilsch-Ranque vortex-tube effect (first developed in 1930 by G.J. Ranque), where swirling air is split into hot and cold components." The method is horribly inefficient but Williams is hoping it could yield helpful results in areas where electricity is really not an option.
How can you rotate anything without moving parts?
The gas moves into the chamber under pressure. The chamber is shaped to send the gas into a whirling vortex. Then the hot molecules go one way and the cold ones go the other. But I think it takes very high pressures to produce the required speeds.
... Time really needs to get its story straight with regards to scientific reporting. This method is a) not innovative b) not practical and c) REQUIRES SIGNIFICANT ENERGY INPUT. Vortex tubes have been around forever, and they are not some form of perpetual motion. It is a well-understood effect, and one which does not violate any of thermodynamics. You put in a lot of energy via compressed air, and get output in the form of a thermal differential. The key point is that you need a lot of high pressure input...where is this going to come from? Electricity. Unless you use a combustion engine to turn the crank on a compressor, in which case that's your energy source. What are villagers in rural india going to do? Blow really hard through the tube?
For those who didn't read TFA, and haven't ever read about the operation of these devices, Tim Cockerill wrote his thesis about them. He provides an excellent reference for the thermodynamic operation of these devices. You can put down your tinfoil hats, as they do obey classical thermodynamics perfectly well.
here is a picture of one. it makes it easier to see how it works.
HERE
Or, we have found First and Second Prize winners in the "Talk out your ass without knowing anything" game.
If either one of you had bothered to look into this device for even a moment, oh I don't know, maybe here for example, you'd know that they aren't spinning anything at a million RPM. It is a device that has no moving parts. Basically, and I'll boil it down for you, you blow in one end and two streams come out, one hotter and one colder. It's the vortex inside that can reach a million RPM.
If you can find a way (and this, I assume, is what he's still working on) to get enough air through it then you can get the cold stream very cold indeed, which is useful.
I've never been to anywhere that qualifies as Third-World, but I assume that simple is better. With no moving parts this is as simple as it gets, if a way can be found to get enough gas through it. Perhaps it's wind, or volcanic gases, or storing composting gas, or simply the hot air generated by your armchair engineering, the point is that he's looking into it to try to help people, and you didn't look into it and are helping no one.
The only acceptable defense of scientific results is to say that they were the product of the Scientific Method.
From a section on the solar funnel cooker website:
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In September 1999, we placed two funnels out in the evening, with double-bagged jars inside. One jar was on a block of wood and the other was suspended in the funnel using fishing line. The temperature that evening (in Provo, Utah) was 78 F. Using a Radio Shack indoor/outdoor thermometer, a BYU student (Colter Paulson) measured the temperature inside the funnel and outside in the open air. He found that the temperature of the air inside the funnel dropped quickly by about 15 degrees, as its heat was radiated upwards in the clear sky. That night, the minimum outdoor air temperature measured was 47.5 degrees - but the water in both jars had ICE. I invite others to try this, and please let me know if you get ice at 55 or even 60 degrees outside air temperature (minimum at night). A black PVC container may work even better than a black-painted jar, since PVC is a good infrared radiator - these matters are still being studied.
I would like to see the "Funnel Refrigerator" tried in desert climates, especially where freezing temperatures are rarely reached. It should be possible in this way to cheaply make ice for Hutus in Rwanda and for aborigines in Australia, without using any electricity or other modern "tricks." We are in effect bringing some of the cold of space to a little corner on earth. Please let me know how this works for you.
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This is an experiment you can conduct yourself. It may be that without advanced insulation (maybe straw wasn't enough?) one couldn't obtain ice in the desert, but given good modern materials the physics suggests that it would work well.
-Adam