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Comments on Saturday 8 July 2006:
Yesterday, I was surprised to be considered strange for not putting hot liquids that I want cooled into the fridge, instead cooling them to room temperature first. If I did polls I would now poll whether you people do that or not, but I don't, so I won't. What I'll do instead is provide SCIENCE!

For simplicity's sake, let's say you have one litre of water at 50°C, room temperature is 25°C and your fridge's target temperature is 0°C (but not frozen). Your fridge has a generous one third of a cubic metre capacity (slightly larger than an average fridge I think).

The specific heat of water is about 4.186 kJ per litre per °C. So if you put your litre into the fridge at 50°C instead of at 25°C, you're putting 4.186*(50-25) kJ of unnecessary energy into your fridge that will need to be dissipated. That's 104.65kJ.

The specific heat of air is an imprecise thing depending on pressure, humidity and temperature, but a decent approximation is 1kJ/kg °C. One kilogram of air is also approximately one cubic metre, conveniently three times the volume of our hypothetical fridge. So, it takes about a third of a kilojoule to raise the temperature of an entire fridgeful of air by one degree. Which means our 104.65kJ of unnecessary warmth in our single litre of water is the energy equivalent to raising the temperature of a fridgeful of air from 0°C to 314°C.

Alternatively, and more realistically, it's the equivalent of letting all the cold air out of the fridge, to be replaced with room-temperature air, more than twelve times. People are mostly reluctant to leave the fridge door open because it will let a fraction of a fridgeful of cold air out - by comparison you can see that letting out a bit of cold air is nothing compared to introducing heat unnecessarily. Especially since your fridge's target temperature isn't even really that low - all simplified figures are simplified to understate the comparison.

And that's just one litre, at a not-very-hot 50°C. I had five litres of lemon barley water, at probably closer to 70°C - if I put that in the fridge without cooling, that would be the wasted energy equivalent of heating a fridgeful of air to a fantastic 2825°C. That's over 5000 fahrenheit, for Americans.

SCIENCE! [06:18]

Serendipity
I think I'm in love. <3

RavenBlack
There's nothing sexier than SCIENCE! Except games. And maybe sex.

Nameless
I'd point out that most consumers don't really consider energy efficiancy when doing their kitchen chores on a regular basis..... Just their own personal convience being ease and speed.

Even odder is many people who are enviromentally consious are the same way.....

Another fun thing to note is the number of people who will run a clothes dryer with the airconditioner on.

For that matter if you have an airconditioner you should also have a summer kitchen.

Why aren't summer kitchens included with houses anymore?

RavenBlack
What's a summer kitchen?

In the UK the reason they aren't included is probably because UK houses are really stingy with their footprint. An extra room has no chance of getting on a standard design.

Anet
They were a separate kitchen from the main house (before AC) to keep cooking heat from the family (usually in homes that had servants). The term was also used, like in the farm I grew up on, for a kitchen in the basement.

Nameless
A small detached outbuilding that has cooking facilites to keep from overheating the house with the baking and whatnot in the summer. Also used for large gatherings where you wanted to have multiple didshes cooking at once. I wouldn't say that the majority of them were/are for homes with servants. Though they usually weren't in lowend homes. In cities where land is scarce they tended to be for the wealthy in more rural area's most farm houses have them or had them then were demolished in the states.

Some retarded Girl
I think that sounds smart. Now, could someone explain it me in laymen's terms?

Nameless
Girl in laymens terms if you put a very hot liquid in your fridge directly from the stove it'll cost you some electriciy/money plus not be particularly good for maintaining a stable temperature for your fridge....
It's better to just let it cool outside the fridge to room temperature as it takes no more effort on your part and just a bit of time....

Carina
I don't put hot things straight into the fridge, not becuase of science, but because when I was growing up my mother would get shirty if I did. I think her reasoning was based on the science, albeit less precise, so I guess mine is too, by association... or something.

cCAngel_EyesCc
I've had almost no sleep for the past four days. Reading this almost put me into a comma. However, it is a better idea to let things cool before stuffing them into your fridge.

AlexTrebek
There are two real problems I have here; the first is that you state that there is enough energy to heat the air to 314 and 2825 degrees celsius, respectively; the phrasing could be construed as a bit misleading, as it is exceedingly hard to make a substance warmer than the substance that is giving it heat (there are a few exceptions at EXTREME conditions, but this generally disobeys the laws of thermodynamics). Of course, this is excluding exothermic chemical reactions, but placing water in a fridge is unlikely to produce any of those. The truth is that your water would cool down and the air would heat up, but to a temperature between 0 and 50. To sum this up, there are two basic principles working in this problem: the initial energy is equal to the final energy (energy is conserved) and temperature flows from hot to cold until both are the same temperature.

So, [4.184 kJ/C * (50) C] + [1/3 kJ/C * (0) C] = [4.184 kJ/C * (Tfinal) C] + [1/3 kJ/C * (Tfinal) C]

This simplifies to:
209.2 kJ = [4.184 * (Tfinal)] kJ + [1/3 * (Tfinal)] kJ

From this, you can get:
209.2 kJ = [4.517 * (Tfinal)] kJ

Divide both by 4.517 kJ/C:
46.3 kJ/(kJ/C) = Tfinal = 46.3 degrees celsius

So, yes, the fridge would stay fairly warm at these conditions; however, it would not involve the fridge heating to 314 degrees celsius, as your calculations could cause a layperson to believe.

Also, there is one more problem here; you assume that the refrigerator is perfectly insulated, and give no credit to the fact that refrigerators cool things down. The rate of dissipation of heat from the water is in conflict with the cooling of the refrigerator. As for actual rates, I can say nothing. I imagine that in this case, the water would raise the temperature to the "dangerous" level for long enough (assuming, as my quotation marks signify, that this level is truly dangerous for food) to pose danger to your food. However, when using scientific methods, please try to be accurate and don't throw out wildly large numbers without explaining them.

RavenBlack
If by layperson you mean complete idiot, then I agree. I wasn't writing for those people so that's okay.
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