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I do believe this is the “jelly donut” myth. From How Stuff Works:
The reason a jelly donut seems to heat from the inside out is the different density of its components. Microwaves penetrate pretty evenly, but the jelly has a higher density compared to the dough, so it heats more rapidly.
If all you put into your microwave is jelly donuts, you might not notice other foods heating from the outside in or with other heat patterns.
[Homer]
Mmm…jelly donuts…
[/Homer]
I understand that microwaves work by causing the water molecules (which are polar) to vibrate in time with the microwaves. In other words, the water molecules basically “ride the microwaves”, up and down, and that’s what causes the heating effect.
Following this, couldn’t you take a MASER, tune it so you have a standing wave, and cause the water molecules to essentially lock in place, thereby cooling the object?
I guess I wasn’t very clear in my previous post, Anthracite. I took your comment
to mean just that. In other words, if you put a frozen chicken breast in the microwave, the center will be thawed first. This is a pervasive urban legend that is demonstrably untrue. I apologise for my misunderstanding of your meaning.
I was once in a grocery store that had a “wine cooler” in its huge wine section. This was a five-gallon tub filled with what looked and smelled a little like engine antifreeze. You put your bottle in and the antifreeze (obviously chilled below the freezing point of water) would circulate around it, driven by a little pump. In ten minutes your bottle was nicely chilled. Of course, it would warm up again on the drive home, so I really didn’t see the point…
What about a very powerful vacuum? It wont stop the molecules in the food from vibrating right away, but wouldn’t a perfect vacuum be bereft of kinetic energy?
Such systems exist in the industry, but they are actually rather rare. Far more common are systems that freeze with air. Basically large, souped-up versions of home refrigerators. They are called IQF systems (Instant Quick Freeze), and they generally consist of a conveyor belt (straight line or spiral) that carries the product past large evaporator coils with great big fans.
Note that they are rather too large to have one in your kitchen, though.
A vacuum is a very good insulator - putting something in an evacuated box would cool it off far more slowly than just blowing cool air over it.
That is a slight exaggeration, I think. IIRC, the temperature difference between your fingers and the liquid nitrogen would be so great that a protective layer of gaseous nitrogen would immediately form around you fingers. Of course, your fingers would rapidly loose heat, but not so quickly that you would not have time to withdraw your hand before suffering frostbite.
For the record, I did play around with liquid nitrogen in high school, dipped my bare fingers in the stuff several times, and I still have ten digits to type with. I remember that you could do all sorts of neat tricks with liquid nitrogen. The most fun was putting a tiny amount in your mouth–you could blow impressive fumes of whitish “smoke” that way.
You don’t need to tell me that those were stupid things to do. I already know that… But let’s not exaggerate how quickly liquid nitrogen would cause frostbite or make your hands fall off.
so an object placed in a vaccum would not lose heat? I am thinking of two things here: 1) space, where there are no molecul;es to heat up, is pretty cold, IIRC and 2) when to take a sealed contained and make it smaller without letting out the air, it heats up. When you decrease the pressure, it cools off. This decompression is basically what cools your fridge.
So, if you rapidly decrease the pressure of a sealed chamber by creating a vacuum, do you not decrease the temperature? Would it help to first increase the pressure (number of molecules per unit of space) then FOOOMP–decompress it?
Well, Jonas, when I’m talking to teenagers, my Mom Mode kicks in and tends to exaggerate. “Sydney, you must never, ever play with liquid nitrogen, because one touch and your fingers will freeze solid and fall off, just like a lot of frozen fish sticks…”
Ferrous, your link deals with “Small and Medium Capacity” freezers. I’m talking about the CRYO-QUICK Immersion Tunnel Freezer. I’m talking Mass Production with a capital “M-P”. And, um, far from being “relatively rare”, liquid nitrogen is actually the backbone of the frozen foods industry. And, um, it looks to me like the Instant Quick Freeze technique, the IQF, actually uses liquid nitrogen, that’s it’s not “just like a home freezer”.
http://www.dandelions.com/home.html
http://www.scenicfruit.com/strawberries.htm
http://www.trigas.com/Products&Services/FoodGroup/FoodGroups.html
http://www.tx7.com/fries/docs/info.html
http://www.niseafood.co.uk/something_fishy/seafish_story/fishproc.php3
And, Sydney, if ya wanna buy one, here’s one For Sale… With a picture, too.
Wow! Teach me to tangle with the Queen of Internet Research!
I don’t want to argue the point… But I work for a major industrial refrigeration contractor. Our clients are major food processors and distributors (I don’t know if I should mention their names, but the biggest one rhymes with Bostco) and we NEVER use liquid nitrogen systems. They’re more expensive to operate because you are constantly using up refrigerant, instead of recycling it.
The specific unit I linked to is. There are others on that site that are for larger capacities.
And if I may use a few of your own quotes, with different emphasis…
Air refrigerated with a recirculated ammonia or freon system.
The very cold liquid would be ammonia or a CFC such as freon.
Which means that 75% of the fruit is processed in a more conventional way.
To sum up, while I don’t doubt that some high-end and specialty rely mainly on liquid nitrogen, I beleive the majority use closed-system ammonia or freon systems.
Er, that should have read “…high-end and specialty users…”
I guess I did want to argue the point after all! 
Yeah, okay, I’ve been sitting here browsing frozen food websites, too, and I guess I’ll withdraw the “backbone of the industry” statement. But now I see that air-blast and plate freezing still have a place in the industry, so I stand corrected.
IQF
can also evidently mean “individually quick frozen”, not just “instant quick frozen”.
Although I did find this.
http://www.advancedfreezer.com/appraisal4.html
And this.
Damn, I love this message board! Where else can you see an argument over industrial freezers?
A vacuum has no temperature. An object floating in space will gain or lose heat by absorbtion and emission of radiation. Eventually it will reach the same temperature as its surroundings. If you’re way out in deep intergalatic space, with no sources of energy nearby, you will eventually cool off to about 3 degrees kelvin as you radiate all your heat away. It’s not the vacuum doing this, it’s the total lack of any nearby heat-generating objects.
Right, except the refridgerator is doing the compression and expansion in different places. The expansion makes cold inside the fridge, and the compression makes heat in the coils on the back. Of course, it takes the gas many cycles of expansion and compression to make any significant change in fridge temperature.
Yes, the gas would cool off as you drew it out. But, as the thermal capacity of the gas is probably mich less than the thermal capacity of the thing you’re trying to cool, the amount of cooling done to the subject material would be minimal. And once you were done, the vacuum wouldn’t suck any more heat out of the object - in fact, it will act as a pretty good insulator between it and the walls of the chamber. Eventually through radiation alone the object will reach the same temperature as the walls of the chamber - this may take a very long time however.
No, I’m afraid it is not a “jelly donut myth”. First, ask yourself - how does the microwave heat? We’re talking, in the section you quoted from me, about glass on a surface of a container versus the water containing substance within the container.
Don’t worry about it. I should have been more clear, it seems, so it is my fault.
[QUOTE]
*Originally posted by AndrewL *
**
Just to be clear, your object does not radiate heat away to the point that it reaches absolute zero. Does it stay at 3°K because it is at equilibrium with the ambient heat radiation?
Right. 3K, give or take a few tenths, is the Universal Temperature, as best as we can tell. Apparently, there is some anisotropy, so you could end up in a region that was closer to 0K, but overall…yeah, about 2.7 K.
Years ago, I saw a documentary on butler schools. One of the tricks they revealed was how to chill wine for your employer’s picnic outings quickly: wrap a full wine bottle in wet newspaper, hold the wrapped bottle out the car window, and drive around for a few minutes.
I assume this works much like sweating does for people - simple evaporative cooling, only at a higher rate due to the wind of driving. If so, how cold could one get something by doing this (or something similar in, say, a microwave-sized box)?