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In our day-to-day life, many processes procure/release heat like: burning of fuel, friction, heat losses while converting one form of energy to another, natural processes even in our body tends to release/generate heat.

I know that there is 2nd law of thermodynamics : Heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time.

But I am looking for any easy process by means of which we can absorb the heat or produce cooling!

Consider if you feel cold then there are innumerable process with the help of which you can get heat. e.g. match. But consider if you feel hot, there is there any easy process that can absorb heat in order to produce cooling (e.g match that will cool!)?

Note that I am not talking about air conditioning which requires work. I am talking about a process which can continue once you start/trigger.

Pandya
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  • Hi. May I ask how you understand heat? Thanks. – Constantine Black Jun 14 '15 at 09:11
  • one type of energy – Pandya Jun 14 '15 at 09:13
  • I take it you mean "absorb heat from the environment at room temperature"? Otherwise cooking an egg (or anything else) would be an example - the coking reactions absorb heat, resulting in the pan being very slightly cooler than it would be otherwise, but still quite hot. For an easy process that absorbs heat at room temperature, you might try evaporation of water. (Or of anything else - ethanol evaporates faster, producing a more dramatic cooling effect.) – N. Virgo Jun 14 '15 at 09:59
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    This is too broad, since you ask for an open ended list of example processes. Additionally, it is a bit unclear, because the rigorous meaning of "heat" in physics is thermodynamical transfer of energy, while I suspect you are using the colloquial meaning of thermal energy. – ACuriousMind Jun 14 '15 at 10:00
  • come to chat-room for clarification – Pandya Jun 14 '15 at 10:05

3 Answers3

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I don't know if I have understood your question well.

Well, you absorb heat from the sun. Also, if you touch something more hot than you, you will absorb heat until you and the object have reach thermal equilibrium, that is your temperature will be equal to it's temperature. But also you radiate EM radiation to your environment and that one of the mechanism the body has to keep it's temperature constant(but maybe this internally requires some process from the organism).

Heat from the sun comes as electromagnetic radiation, that is a very big amount of quantum particles called photons that carry momentum and energy, and all together form a classical electromagnetic field that also has momentum and energy. You can show that the power of such a have is given by the pointing vector. You also of course treat the photons as a excitations of a quantum field that reduces to the classical

When you touch an object, heat is transfered to you by the electromagnetic interactions or percussions of the objects atoms with you. Note also that the object possibly radiates electromagnetic radiation too.

A very interesting phenomenon is when an object has a negative absolute temperature. The object then is more hot than an object with positive temperature but when the two come in contact it's the object with the positive temperature that will give heat to the object with the negative temperature. If you are interested have a look at this Showing existence of negative temperature for a quantum system and my answer therein.

I don't know any process where the heat would flow physically from the colder to the wormer. I think that's one of the reasons of the second law.

EDIT:

@Pandya I think you ask for a spontaneous or automatic endothermic process. That means the process requires energy to occur, and to continue to absorb energy it needs to have some deficit in energy, that is lower energy than it's environment. An exothermic reaction gives energy(let's say fuel) because it has a lot more energy that the environment when you trigger a reaction with fire(the chemical bonds break releasing their stored potential energy).

Hope this helped.

Community
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Constantine Black
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You can pump heat out of an object using a Peltier cooler Easy enough to buy one on eBay and play around with it

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There are two problems here.

1- You are taking up wrong examples. A match will NOT continue to heat its surroundings. Reason being that fire requires fuel and fuel is not limitless. Once the fire has run out of fuel, the flame will extinguish and the process of "creating" heat (in fact releasing stored heat) will stop. Object for object, you can use a block of ice as a "cold match". It is a consumable (like match) and it changes the temperature of its surroundings (like match), but in the opposite direction than the match.

2- If you are looking for a process that can take almost anything as a fuel (just like fire flames can consume 80% of things in common use) and tends to lower the environment temperature than increase it, you are in a world of surprise here. It's happening all the time! Green plants continuously use sun's energy (heat) for glucose production. As a result of this reaction, the temperature of environment decreases. There are also several other chemical processes (known as endothermic processes) which consume heat and hence decrease the temperature of their environment. For example, thermally breaking any chemical bond that was formed with release of heat (for example splitting water into hydrogen and oxygen), would consume heat. Similarly several physical changes (melting of ice, evaporation etc) also consume heat.

The error in your surmising is (as depicted above) that you are expecting a finite process to continue for infinity, which is not possible.

Youstay Igo
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