Anti-microwave oven?

[Ivan Viehoff]

I have a dream that there could be a device as convenient as a microwave oven, but for cooling stuff down. Could it exist?

The microwave oven is a fairly compact, fast and (relatively) efficient method of heating food items up, which itself does not get particularly hot. Even a conventional oven, which gets hot, eg, 200K above room temperature, is a fast (K/s) method of heating something up in comparison to the speed at which things can be cooled in a domestic freezer, which is only about 40K different from room temperature, hence its slowness in cooling relative to the heating speed of an oven. Both microwave and conventional oven avoid the inconvenient requirement for packing hot or cold liquids or solids around the item to be heated/cooled.

From time to time, it would be convenient to have a fast and efficient method of cooling food down, and I don't consider bathing it in a salt-and-ice bath is such a convenient technology, any more than I would cook much food in hot liquid baths. For items other than liquids, they would have to be sealed in a waterproof bag before they could be introduced to the bath. TV chefs have been shown cooling stuff very fast with liquid nitrogen, but this neither cheap nor a technology available to the non-pro. Electric icecream-makers, only work for cooling liquids, and in small quantities at that, and the liquid often needs to have been pre-cooled in a fridge, as the cooling capacity of the ice-cream makers is often modest, especially the ones that require putting a cooling bowl in the freezer in advance.

Why is there no generic fast and quick method available of cooling stuff down comparable, ideally, to the microwave oven, or at least to the conventional oven? Is it just much more technologically difficult to cool stuff down? Or is it the much smaller market which means that it simply hasn't benefit of the level of R&D that would be required to develop some practical household item?

[Shaula]

Essentially I guess you would be looking at a variant of doppler cooling. This is not an efficient process and requires very finely tuned narrowband energy to be used. It also normally targets electronic transitions. I guess you could use one that targeted molecular vibrations. Never seen it done though. At a guess the cooling would be slow, you'd need a good way to get rid of the microwaves produced (having them bounce around the compartment would rather defeat the idea - you would need a high efficiency absorber and something to cool that). Suspect you'd end up with a very complex power hungry system. Interestingly high-tech kitchen idea though!

[Ivan Viehoff]

The essential features are that it would be efficient, fast and convenient, like a microwave oven. No other parallel with microwaves required.

[noncryptic]

Maybe Peltier elements could do the trick?

on edit:

Google has revealed there are such things as Thermoelectric coolers using Peltier element and heat exchanger, going down to as much 30 degrees Celcius below ambient.

[Swift]

I can't think of a physical principle that would work (though that may be my limitations). The various quantum mechanical cooling methods, like laser cooling, will only work on very small, simple systems, like a cloud of atoms; I can't think how they could work on something like a container of ice cream.

Evaporative cooling works pretty fast (Swift's Home Vacuum Chamber, only $79.95), but it would tend to ruin the ice cream, by removing water and other volatiles.

As you mention, you could always take whatever you want to cool and drop it in liquid nitrogen (LN2). You say it isn't cheap nor available to the average person; I haven't priced my company's contract for LN2, but it is not that big a deal to set up a contract with a local supplier in most areas.

But there are two problems with LN2. One, it is actually too cold for what most people want. Second, you are still limited by the rate of heat transfer through whatever you wish to cool. The advantage of microwaves for heating is that this is a bulk effect, the whole object (at least the water in it) is heated, so you are not limited by the rate of heat transfer through the bulk.

[JustAFriend]

The trouble with people now days is they want to think of electronics technology for everything. ;-)

Get a $2 foam cooler and some dry ice (-80F) from any supermarket....

[geonuc]

The trouble with people now days is they want to think of electronics technology for everything. ;-)

Get a $2 foam cooler and some dry ice (-80F) from any supermarket....

Hardly convenient, though. Recall, the OP wants the convenience of a microwave, which does not require a trip to the market.

[HenrikOlsen]

Hmmm, I don't know any supermarket that stocks dry ice.

[JustAFriend]

No fish markets or fishing bait stores in Denmark either?

[cjameshuff]

Electromagnetic refrigeration techniques only work for particular targets. For general refrigeration, you're stuck with conduction, which means something like a chilled brine bath or liquid nitrogen and items with low enough volume for their surface area and high enough thermal conductivity that they can cool quickly. To get faster cooling you need lower temperatures, which means more uneven cooling of large food items. You could perhaps pierce the food with heat exchanger needles of some sort, but removing them from the food and cleaning them would be a real joy.

For something more specialized, you could have a heat exchanger that dips directly into a drink, or a drinking glass directly cooled by laser fluorescence...

[Nick Theodorakis]

Hmmm, I don't know any supermarket that stocks dry ice.

There is one here that sells it, but I don't know if it's a stock item or one they order.

Nick

[Jeff Root]

Releasing compressed gas gives instant cold.

Years ago, in The Whole Earth Catalog, I saw a nozzle
which could be attached to a compressed air tank which
caused the released air to spin around and separate by
centrifugal force into warmer and colder fractions, so
that extremely cold air came out.

-- Jeff, in Minneapolis

[cjameshuff]

Releasing compressed gas gives instant cold.

Yes, but now you're just back to sticking it in the freezer for a while.

Years ago, in The Whole Earth Catalog, I saw a nozzle
which could be attached to a compressed air tank which
caused the released air to spin around and separate by
centrifugal force into warmer and colder fractions, so
that extremely cold air came out.

The wirbelrohr: http://en.wikipedia.org/wiki/Vortex_tube

It's just another way to do the same thing that conventional refrigerators do.

[IsaacKuo]

You could perhaps pierce the food with heat exchanger needles of some sort, but removing them from the food and cleaning them would be a real joy.

You don't have to remove and clean the needles if they sublimate away.

I suggest something that casts dry ice into a bunch of long needle shapes--sort of like a bed of nails. A mechanism impales the food with this bed of nails, very quickly cooling it.

[PetersCreek]

What few people know is that polarized appliance plugs—you know, the ones you can plug in only one way—were originally developed when home-use microwave ovens first came on the scene. You see, if you could reverse the polarity on a microwave oven, you could freeze food really fast. Since microwave and refrigerator manufacturers didn't want more competition in their market segments, the cooperated in standardizing the polarized plug as a "safety measure".

Once upon a time, I almost had a gullible coworker convinced this is true.

[Swift]

What few people know is that polarized appliance plugs—you know, the ones you can plug in only one way—were originally developed when home-use microwave ovens first came on the scene. You see, if you could reverse the polarity on a microwave oven, you could freeze food really fast. Since microwave and refrigerator manufacturers didn't want more competition in their market segments, the cooperated in standardizing the polarized plug as a "safety measure".

Once upon a time, I almost had a gullible coworker convinced this is true.

Yes, those plugs solved so many problems. I used to hate it when I'd plug in a lamp with the plug flipped, turn on the light bulb, and it would suck all the photons out of the room, leaving me in the dark.

[trinitree88]

I have a dream that there could be a device as convenient as a microwave oven, but for cooling stuff down. Could it exist?

The microwave oven is a fairly compact, fast and (relatively) efficient method of heating food items up, which itself does not get particularly hot. Even a conventional oven, which gets hot, eg, 200K above room temperature, is a fast (K/s) method of heating something up in comparison to the speed at which things can be cooled in a domestic freezer, which is only about 40K different from room temperature, hence its slowness in cooling relative to the heating speed of an oven. Both microwave and conventional oven avoid the inconvenient requirement for packing hot or cold liquids or solids around the item to be heated/cooled.

From time to time, it would be convenient to have a fast and efficient method of cooling food down, and I don't consider bathing it in a salt-and-ice bath is such a convenient technology, any more than I would cook much food in hot liquid baths. For items other than liquids, they would have to be sealed in a waterproof bag before they could be introduced to the bath. TV chefs have been shown cooling stuff very fast with liquid nitrogen, but this neither cheap nor a technology available to the non-pro. Electric icecream-makers, only work for cooling liquids, and in small quantities at that, and the liquid often needs to have been pre-cooled in a fridge, as the cooling capacity of the ice-cream makers is often modest, especially the ones that require putting a cooling bowl in the freezer in advance.

Why is there no generic fast and quick method available of cooling stuff down comparable, ideally, to the microwave oven, or at least to the conventional oven? Is it just much more technologically difficult to cool stuff down? Or is it the much smaller market which means that it simply hasn't benefit of the level of R&D that would be required to develop some practical household item?

Here ya go. SEE:http://www.google.com/imgres?q=carbo...r:11,s:0,i:163

[Ivan Viehoff]

[QUOTE=trinitree88;2016076]Here ya go.[QUOTE]
Quite apart from the drawbacks other posters have already mentioned, I don't like the prices per kWh implicit here: http://www.fireandsafetycentre.co.uk...Extinguishers/

[Ivan Viehoff]

Electromagnetic refrigeration techniques only work for particular targets. For general refrigeration, you're stuck with conduction...

When you say electromagnetic refrigeration techniques only work for particular targets, one could say the same of microwave ovens for the non-conductive heating techniques. But fortunately most of the things we are interested in heating have O-H bonds in them (sugars absorb even more heat than water in a microwave), and we can tune a microwave oven to them.

So are you saying that we don't know of any electromagnetic cooling techniques that focus on O-H bonds, or do we know that no such could practicably exist? Ie, is it possible that a discovery that could yet be made, or do we know it is impossible?

But even when it comes to cooling by conductive/convective techniques, it is a lot less convenient than heating by conductive/convective techniques. I can turn my oven on and it is ready to provide conductive/convective heating at 200K above room temperature within 20 minutes. If I turn my freezer on from room temperature, it takes it several hours to get to a mere 40K below room temperature. (Unfortunately owing to my fridge freezer repeatedly malfunctioning, this is a period of time I know only too well.) When I prime my ice cream maker (I don't have the expensive instantaneous one) I have to put it in the freezer for at least 12 hours, preferably 24 hours before hand, and even then I have to put the liquid to be ice-creamed in the fridge to cool it to 5C for some hours beforehand, and even then it is easy to overload the cooling capacity of the ice-cream maker by putting too much liquid in it.

People have referred to purchasing pre-cooled or compressed gases for conductive/convective cooling, but the cost per kWh of these methods is very high, it would appear.

[Jeff Root]

Move off-Earth.

-- Jeff, in Minneapolis

[profloater]

The fact that a microwave oven can heat a whole pie really fast but there is no direct equivalent for radiating the energy away again quickly, shows that there IS a direction for time's arrow and QED needs improving to catch up with hot pies.

[cjameshuff]

When you say electromagnetic refrigeration techniques only work for particular targets, one could say the same of microwave ovens for the non-conductive heating techniques. But fortunately most of the things we are interested in heating have O-H bonds in them (sugars absorb even more heat than water in a microwave), and we can tune a microwave oven to them.

So are you saying that we don't know of any electromagnetic cooling techniques that focus on O-H bonds, or do we know that no such could practicably exist? Ie, is it possible that a discovery that could yet be made, or do we know it is impossible?

"Absorbs microwaves effectively" is a much looser requirement. Microwaves need only be in the right general area of the spectrum to heat common materials. Fluorescence cooling requires a material that fluoresces at extremely high quantum efficiency when illuminated by narrow band coherent light. Doppler cooling, Raman cooling, etc requires a cloud of already ultra-cold atoms in near vacuum with particular interaction properties with very finely controlled lasers.

[Ivan Viehoff]

The fact that a microwave oven can heat a whole pie really fast but there is no direct equivalent for radiating the energy away again quickly, shows that there IS a direction for time's arrow and QED needs improving to catch up with hot pies.

Maybe you are correct, but so far whilst it has been asserted that there is no such equivalent rapidly cooling the pie, it don't see a demonstration that there could be no such device. And it isn't clear to me that heating/cooling are like time's arrow. Whilst heating is faster than cooling in the kitchen, this does not seem to be the case in the garden.

For when I look at the temperature/time graphs reported by weather stations for sunny days/clear nights, at least in my own location, I notice no particular difference between the gradient of the increase of temperature in the morning and reduction of temperature in the evening. (I'm not looking at the cloudy situation, because it is clear that clouds can insulate against the loss of temperature more than they insulate against the increase in temperature because of the different wavelengths of the relevant radiation.) In fact, if anything, looking at the termperature time graph last few nice clear days (late March...) we had in our area if anything the temperature fell faster in the evening than it increased in the morning.

[Swift]

For when I look at the temperature/time graphs reported by weather stations for sunny days/clear nights, at least in my own location, I notice no particular difference between the gradient of the increase of temperature in the morning and reduction of temperature in the evening.

First, it is a completely different heat transfer system, it is convective heat transfer and most outside thermometers are in effect only measuring the "surface" temperature. For heating and cooling of food items, you are trying to get bulk heating and cooling and as discussed, there is no good mechanism to get bulk cooling, except by conductive heat transfer to the outside surface of the item.

Second, the rates of heating and cooling of the air temperature during a 24 hour cycle are much lower than the heating or cooling rate you are trying to achieve in an oven or your hypothetical anti-oven. I suspect typical air temperature rates are a degree or a few per hour. A typical microwave problably heats at hundreds of degrees per hour.

[Jeff Root]

A typical microwave oven probably heats at over ten thousand
degrees per hour, for a minute or so, on the right-size item.

A microwave oven acts like quintillions of tiny bullets going
into the food and hitting the electrons. Each bullet can hit
only one electron. When the electron is hit it makes the atom
or molecule it is attached to spin around. To cool the food
off, instead of bullets you need quintillions of miniature
vise-grip pliers tethered by threads. The pliers grab onto
the electrons and hold them, and the thread, connected to
something at the opposite end, damps the electron's motion
and thus slows the atom or molecule's spin.

It's easier to hit swarming electrons with bullets than to
grab them with pliers, I think.

-- Jeff, in Minneapolis

[Jens]

What few people know is that polarized appliance plugs—you know, the ones you can plug in only one way—were originally developed when home-use microwave ovens first came on the scene. You see, if you could reverse the polarity on a microwave oven, you could freeze food really fast. Since microwave and refrigerator manufacturers didn't want more competition in their market segments, the cooperated in standardizing the polarized plug as a "safety measure".

I thought they introduced them because kids were accidentally plugging in their record players backwards when the White Album was on, and were hearing the "turn me on, dead man" lyrics as the record played backwards. Paul's death was supposed to be secret.