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As we know fridge can't cool room in which it is (according to Second Law of Thermodynamics, heat emitted by fridge is greater than heat absorped).

However, when we go next to the fridge in supermarket we can feel coldness. Why?

Thanks!

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Well, you can feel it because you're on the cooled side, and the low temperature of course removes some heat from your body, too. This is increasingly strong if you actually open a fridge in the supermarket - or at home. You're right that the cooling devices have to heat something else up, but it's on a different side, and moreover, the whole supermarkets, and not just the fridges, usually have cooling systems that keep the whole area cooler than normal. Again, this is overcompensated by some heating outside the building etc. –  Luboš Motl Sep 28 '12 at 18:10
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The difference is that a domestic fridge has the heat output on the coils at the back. While a commercial system in the supermarket will eject the heat outside eg a heat exchanger on the roof –  Martin Beckett Sep 29 '12 at 22:01

2 Answers 2

Cooling Tower Australia

The idea here is like in cooling towers in Australia. But what makes the difference? Heat Exchangers.

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It would be helpful if you explained your ideas instead of a brief post about one part (where the heat goes) of the answer. –  LDC3 May 30 at 3:21

The cool air you feel near a supermarket fridge is due to imperfect insulation — or someone just opened the door :-)

Though it is true that a fridge can't cool a sealed room that it is completely in, just like air-conditioning, the heat is pumped via coolant to a radiator to be dissipated reasonably far away from the fridge so as to not heat up the surroundings of the fridge.

In other words, there is net heat loss in the vicinity of the fridge, but not in the whole universe!

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protected by Qmechanic May 30 at 6:10

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