Somebody 'splaina me something...

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SSLtech

SSLtech

Well-known member
Joined
Jun 3, 2004
Messages
5,447
Location
Florida (Previously UK)
On the "How does it work" basic physics thing:

Frost-Free Refregerators.

A complete mystery to me, living in a high-humidity envoronment, how do my two giant refrigerators at home (One of which is in a non-air-conditioned garage, devoted entirely to the task of keeping all of my brewski's frosty!) keep from being consumed by the dreaded Ice monster?

The little under-the-counter thingie here at work manufactures huge concrete-overcoat-sized blocks of ice on a pretty much weekly basis, and I get how the "ice monster" forms and begins its quest to take over the refrigerator... I fail to see how it doesn't form in the frost-free versions.

In fact, during this rather busy hurricane season, I filled one of the freezers with Ice. Since bags of cubed ice were impossible to buy (everyone had the same thought... power outages = spoiled beer) by filling several dozen plastic carrier bags with water, tying knots in them and outting them in the freezer a few days before the hurricane finally arrived. One bag leaked before it froze, and the resulting elongated icicle actually slowly disappeared, instead of getting bigger.

How the hell?

Keith
 
Maybe something in there absorbs or sucks up moisture?

(maybe you've got a bunch of those "DO NOT EAT" Silica Gel packets in your freezer! :grin: )
 
i know that they keep the air dry by taking moisture out. put a loaf of bread on the counter and one in the fridge and see which one is stale(not rotten) quicker. the one in the fridge always is. if you look under/behind the fridge you will see a large pan, usually attached to the compressor. the pan will usually have a tube that comes down from somewhere inside the fridge and drips the excess water onto the pan. the compressor's waste heat warms the pan and the water evaporates quickly. however this is where my knowledge stops.. i don't know how the fridge separates the moisture from the air..
 
The basic idea is: couple times a day, the system shifts from cold to hot, and melts the frost.

To keep from melting your food, frost-free usually do not have the coils in the food chamber, but in a hidden chamber. Fanned cold air cools the food; in defrost mode the fan is stopped.

This steady super-chilled breeze is also why your ice-cubes shrink.

The melt-water runs into a disgusting pan under the reefer, and another fan blows over it to evaporate-away the water with compressor heat.
 
Amazing to think that my parents had ice delivered for their fridge. Dad was a pretty clever guy. He drilled a hole in the kitchen floor for a drain pipe. Most people had to empty pans.
 
Wait a minute, I thought ice cubes shrank due to the process of sublimation, i.e. there are always some water molecules on the surface of the ice with sufficient kinetic energy to escape as water vapor.
 
> I thought ice cubes shrank due to the process of sublimation

True. When we were on Pike's Peak, my mom hung wet wash on the line in freezing weather. Took about 3 days to dry, but it did dry.

But ice-cubes shrink a LOT faster in a frost-free than in a manual-defrost reefer because of the breeze. I don't recall any real shrinkage in the frost-boxes: I bet the frost keeps the moisture balanced. In a frost-free, the cold is in the super-chilled wind, which comes off the coils bone-dry. And after catching any loose water molecules on the surface of the ice-cubes, goes around the loop again where any humidity is condensed-out on the chiller coils and drips into the pan.
 
[quote author="buttachunk"]without doing a web-search (or paper search), who can name the inventor of the refridgerator ??


you get 10 cool points for posting this without cheating.[/quote]

Wayne Newton! :green: :green: :green:
 
Hmmmm... I just did a quick Google after posting... seems like it depends how you define a refrigerator. There were various stages of invention it appears, each refining upon the previous, until the modern refrigerator finally became its recognizeable self.

Keith

BTW, thanks for the explanation! -It seems so completely counter-intuitive to heat the cooling coil! :green:
 
> who can name the inventor of the refridgerator ??

Which refrigerator?

I did not know Einstein had one. But that is clearly not the common type.

I know more about air conditioning, which is claimed by everyone from Romans to Tommy Jefferson to a doctor in Florida. It is clearly a lot of steps from a lot of workers. In much of the US in the first half of the 20th century (and even today), air conditioning is water-based, not freon. Carrier made a LOT of these machines, and they were state-of-the-art in 1929 when the music building was built. Work very well from LA east to about St Louis, and made movie-houses bearable and popular. In the swampy east, a swamp-cooler won't pull the thermometer down much, so they claimed it would be unhealthy to do so. Even so, a Carrier really was "air conditioning", not just "cool air", and possibly better than the cheap Freon machines.

Compressor evaporator machines operated on ammonia (the pure stuff, not the 4%) long before Freon was invented. The technology was used to make ice, and grew from there.

I don't know about Kelvinator, but I bet it is just a rip on the name of Lord Kelvin, who figured out a LOT about heat and gases (and got his name on a thermometer scale). He may have outlined the thermal cycle that freon machines use, but I don't think built any refrigerators.

If you mean "the American Home Refrigerator", grand-dad of your beer-box, the answer is clearly GE. GE introduced the mechanical reefer that displaced the ice-box in most upper middle class US homes. Hot-coils and compressor were on top. My parents were low-mid-class, but by the 1950s they had hand-me-down top-coil GEs still running (though dad says you had to jam a tennis-ball behind the motor so it would not rattle, and once a month in the middle of the night that ball would work loose, shoot-out, bounce around the kitchen, and the motor would bang-bang-bang.)
 
I'm not gonna Google-cheat (yet) so off the top of my head, Einstein's refrigerator worked on magnetic principles and was not commercially successful. The Florida doctor PRR refers to wanted to make ice to cool rooms where he was treating yellow fever victims and was the one who came up with the compression-expansion idea.
 
My great-grandmother lived in the apartment above us when I was a young child. I have a very vague recollection of her owning a GAS-powered refrigerator. (Our building was a late 1800s brownstone that had gas piping for lamps and fireplaces). The 'fridge was considered an antique even back then.
 

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