As the refrigerant is cooled it condenses, turning into a liquid again, and moves into the expansion valve.
As the liquid refrigerant travels through the expansion valve it is allowed to move from a high-pressure are to a low-pressure area. The low-pressure area is the part that the compressor is hooked to.
When it is not pressurized it then expands and evaporates. When the refrigerant evaporates it instantely begins to boil and vaporize, and this is what makes it cold. It drops immediately drops to 27 degrees Fahrenheit.
The second set of heat-exchanging coils inside of the refrigerator allow the refrigerant to transfer the cold and this cools the inside. There is also a fans inside and out of your refrigerator.
The on the inside helps with defrosting and more even cooling, the one on the inside cools the compressor, and blows air on the heat-exchange pipes on the back. After this process is done it continually repeats.
About every 15 minutes you can hear the refrigerator turn on. It is completing this process.
Working Process:
A refrigerator consists of two storage compartments - one for frozen items and the other for items requiring refrigeration but not freezing. These compartments are surrounded by a series of heat-exchanging pipes. Near the bottom of the refrigerator unit is a heavy metal device called a compressor. The compressor is powered by an electric motor. More heat-exchanging pipes are coiled behind the refrigerator. Running through the entire system is pure ammonia, which evaporates at -27 degrees Fahrenheit (-32 Celsius). This system is closed, which means nothing is lost or added while it is operating. Because liquid ammonia is a powerful chemical, a leaking refrigerator should be repaired or replaced immediately.
The refrigeration process begins with the compressor. Ammonia gas is compressed until it becomes very hot from the increased pressure. This heated gas flows through the coils behind the refrigerator, which allow excess heat to be released into the surrounding air. This is why users sometimes feel warm air circulating around the fridge. Eventually the ammonia cools down to the point where it becomes a liquid. This liquid form of ammonia is then forced through a device called an expansion valve. Essentially, the expansion valve has such a small opening that the liquid ammonia is turned into a very cold, fast-moving mist, evaporating as it travels through the coils in the freezer. Since this evaporation occurs at -27 degrees F (-32 degrees Celsius), the ammonia draws heat from the surrounding area. This is the Second Law of Thermodynamics in effect. Cold material, such as the evaporating ammonia gas, tend to take heat from warmer materials, such as the water in the ice cube tray.
As the evaporating ammonia gas absorbs more heat, its temperature rises. Coils surrounding the lower refrigerator compartment are not as compact. The cool ammonia still draws heat from the warmer objects in the fridge, but not as much as the freezer section. The ammonia gas is drawn back into the compressor, where the entire cycle of pressurization, cooling and evaporation begins anew.
