This is how a refrigerator works
When a liquid evaporates it takes away heat. You can feel the cold if you lick the back of your hand and blow on it to make it dry.
This effect is used to cool in a refrigerator. Inside the fridge, a long, bent tube is filled with a coolant. The coolant is a liquid with a very low boiling temperature, so even if it is already quite cold inside the fridge, it's still warm enough to make the coolant evaporate.
When a liquid evaporates it sucks up heat. That's why the tubes inside the fridge feel cold. The tube with the evaporated coolant leads out from the fridge and into a "compressor".
The compressor is a sort of pump which squeezes the vapour and pushes it onwards into another long, bent section of tube. This part is called the "condensor". When the vapour passes through it, the vapour condenses into liquid. This is the exact opposite of what happens inside the fridge, because when the coolant condenses from vapour to liquid, it releases all the heat it absorbed in order to evaporate.
That's why the tube outside the fridge feels hot. So the coolant sucks up heat inside the fridge and releases it again outside - then it flows back inside the fridge, starting the cycle all over.
The compressor keeps the circulation running. It does so by creating high pressure in the part of the tube that is outside the fridge. That pressure makes the vapour condense and release its heat. Only when the coolant has become a liquid can it flow through the very narrow tube and into the fridge again. There, the pressure is low enough that the coolant can evaporate. When you turn the crank you create a pressure difference inside the fridge which makes the liquid start circulating.