I'm trying to invent a distillation apparatus that runs solely on electricity. Suddenly, I realized that cooling things is really hard, while heating them up is so easy.
Actually, it seems that there are just three ways to cool something down:
- Peltier modules (incredibly ineffective)
- Compressing and expanding gasses (hard to make at home, the device is too big)
- Some rare endothermic reactions, such as dissolving $KNO_3$ in water
My question, however, is not how to solve my issue. I want to know why there are so limited cooling options and why they are so expensive and tricky.
For heating, the options are much easier:
- Current flow (just pick a wire and a battery)
- Rubbing things
- Burning/dissolving acids in water and other chemistry (if you're lucky, you get so much heat you won't need any more in your life)
- Absorbing el-mag waves
I, for one, blame the second law of thermodynamics.
Best Answer
It is because of the second law of thermodynamics. There are many irreversible processes that can be used to heat something. It is the natural flow of things because entropy will increase in isolated systems, and much of the internal energy of objects can be dissipated as heat (and this heat used to heat something that is colder). However, to cool something you need to perform work in order to decrease the entropy of the subsystem. There is a maximum efficiency for work to be used to cool something by removing heat from one source at lower temperature and move it to a source at a larger temperature. So both processes, heating and cooling are not symmetrical in our universe with a thermodynamic arrow of time.