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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?
Why try to develop something entirely new, with the resulting time and money requirements? A few solar cells + Peltier coolers + some insulation and an ice tray. Yes, Peltiers are inefficient... but they're solid-state, at least, which I think ought to do for remote areas as far as durability. I would think you could assemble a decent mini-freezer out of things portable enough to carry anywhere:
1) Flexible solar panels (less efficient but more portable than glass)
2) A handful of Peltiers... they're pretty small
3) A couple of cans of "Great Stuff" spray-in insulation, or cans of A-B component expanding insulation
One of my friends went to Peru to assemble a non-electric solar water purifier, and anything they couldn't carry on their backs on 30-mile-a-day hikes for a week didn't go. Now that's a design constraint!
The Romans used to make ice in the deserts of Palestine and North Africa. It seems to me they were around before electricity and Frigidaire.
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http://www.madsci.org/posts/archives/nov99/941723
Of course, the large temperature difference between the day and night in the desert it what drives it. That method probably won't work in tropical climates.
-Charles
Learning HOW to think is more important than learning WHAT to think.
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.
Back when I lived in an African village, 1989-92, we had a kerosene refrigerator. All I had to do was trim the wick occasionally and keep feeding it fossil fuel and it kept things cold/frozen for me. A co-worker of mine in another location converted his to burn butane by putting a bunsen burner in place of the kerosene wick.
Although we certainly used our fridge for food and ice, it was also very important to refrigerate meds for the clinic in our village.
1. A freeze/thaw cycle kills many (not all) microorganisms--ice crystals shred cell membranes, and freezing can mangle the protein coat on viruses. A number of tropical parasitic organisms aren't well adapted to the cold, either.
2. You can remove some dissolved chemical contaminants if you don't freeze all the water. As water freezes, the assembly of regular ice crystals tends to force impurities out into the remaining liquid. If you stop after you've frozen four-fifths of the water, then you can throw out that last twenty percent that contains the concentrated contaminants. Ice that forms on bodies of salt water is almost pure water, because the salt is driven into the liquid phase by the freezing process.
~Idarubicin
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
First of all, the states asked for aid, and Bush signed a state of emergency, BEFORE Katrina hit. There was no question about authority. FEMA and the federal government had all the authority and responsibility in this situation.
That's not how the system is set up. FEMA had authority to act, but only where specifically requested to act by state government. The governer can call of FEMA for help with any problem state and local responders can't handle, but FEMA can't act except where specific help is requested. What *usually* happens is that the state EMA says "command and control is something we can't handle, please take that over", and FEMA does, allowing them to use their own initiative. This did *not* happen in LA, and still hasn't happened.
Also, using the national guard for policing (which was desperately needed) is outside of FEMA entirely unless the president invokes the insurrection act, which would have been a very scary precedent! The governer must effectively deputize the guardsmen, as there is no martial law in the LA constitution. The governer must also directly request guardsmen from other states (they were offered, bu not requested).
Basically, Blanco refused to give up control to people who actually had a plan. It takes more than just declaring a state of emergency (which is a prerequisite), you also have to *explicitly* relinquish command and control to FEMA if you want them to run the show.
Socialism: a lie told by totalitarians and believed by fools.
There are several ways to move heat energy. The method being demonstrated here is infrared radiation. All things radiate and accept radiant infrared heat, which is slightly different than infrared light.
All other things being equal, if an object is absorbing more infrared heat radiation than it is releasing, then it gains heat. This one of the forms of radiation the sun puts out that heats the earth's surface (though lots of radiation is harmlessly bounced off the atmosphere or converted before it reaches the ground).
Since the clear night sky contributes little radiation to the earth the earth's surface radiates and cools off more quickly than it heats up. By using reflectors one can increase the surface area of the radiation and gain greater cooling, just as solar collectors with reflectors can gain greater energy with the sun shining on them.
-Adam