And shouldn’t it be a power generator
In: Physics
Refrigerators move heat. They move it from inside the box, to outside the box. Doing work like that will always require energy to accomplish.
Refridgerators work by squishing a liquid to make it stop moving and be cold. Then it goes inside the refridgerator and the warm air inside makes it start moving. It goes back down and then it gets the heat squished out of it again.
Squishing a liquid is hard work so it makes the refridgerator make heat just like you do when you run fast on the playground
Cooling to the ambient surrounding temperature is just losing energy. Cooling *below* the ambient temperature (which is what fridges and freezers do) requires effort and that’s why the energy is needed.
To pump the refrigerant through the pipes that take the heat away. And power the little light that we use to find stuff.
Propane-based fridges don’t use power. They have a small pilot at the bottom of the cooling system that heats the refrigerant so that it evaporates, condenses at the top, and then circulates and takes heat out of the cooling compartment.
The system needs something to force the refrigerant to circulate, be it electricity to power a pump or a heat source to cause the evaporation-condensation cycle.
Edit because I forgot a word.
Cooling to the ambient surrounding temperature is just losing energy. Cooling *below* the ambient temperature (which is what fridges and freezers do) requires effort and that’s why the energy is needed.
Energy is needed to lose energy because by moving energy from within the refrigerator to outside it, an energy gradient is set up which usable energy can be extracted from. There is a concept called “entropy” which is basically the observed behavior of the universe to trend towards equilibrium; concentrations of energy spread out until everything is evenly distributed.
So because energy cannot be created or destroyed the heat within the refrigerator must be moved outside, and this reversal of entropy requires energy to perform.
Have you ever taken a can of compressed air and just held it down to shoot air for a while? You will find when you do this that the can gets very cold. You might even see Frost develop. What’s happening is a very compressed Gas is being allowed to escape the can and expand freely all at once. The technical term for this kind of expansion is ‘adiabatic’ but it just basically means that the gas is allowed to expand back to its full volume before it has time to slowly absorb heat from the environment. The result is that you formerly had a very small volume of compressed gas at room temperature, and after the expansion you now have the same amount of heat energy that was in that small volume spread out into a much bigger volume. This results in it having a lower temperature.
The whole process described here so far doesn’t really cost energy aside from the small amount used to open the valve. But in order to get that very compressed room temperature air, you have to use a pump to compress a gas into a very small hot lump, and allow that to cool itself off down to the temperature of the ambient air. If the heat from that lump was allowed to come back into the original room where it was compressed, air conditioners wouldn’t work, because the amount of heat created by compressing is more then the amount of cooling you get by letting the gas expand back to its previous volume. This is largely because the compression process is imperfect (friction on the piston, etc). So the refrigerator or air conditioner really works because it’s moving heat from one place to another. That’s why air conditioners are put in windows – to vent that heat – and part of the reason why refrigerators are so well insulated.
The cooling action of your refrigerator works just like an AC. In order for it to cool what inside, it has to pump heat out into the room, which takes energy. If you look at your refrigerator it should have a radiator somewhere, you’ll notice that this radiator is hot.
We can’t effectively turn heat into electricity when it’s at that low of a temperature.
In order to understand this, you’ll have to understand the second law of thermodynamics. Basically, the entropy (randomness) of the universe as a whole increases with every action.
Cooling a cold thing down, and heating a hot thing up conserves energy, but decreases entropy. So, in order to do that, you need to use energy from outside of the system.
So, a fridge has to take that extra energy in and spit it out somewhere.
Energy is never lost, it’s converted or moved. In this case the energy is moved from inside to outside, and the process of moving it isn’t that efficient.
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