Back in the olden days, before modern refrigeration techniques, people used different methods to preserve their food. Pickling, salting, and canning were common ways to keep food for longer periods of time. But now we have a fancy piece of technology called a refrigerator which allows us to keep our food fresher, longer. In this article I will explain how a refrigerator works.
water dispenser bottle The first thing you need to know about refrigeration is the Second Law of Thermodynamics which states: “When two surfaces of different temperatures come in contact with each other, the surface that is at higher temperature cools and the surface at lower temperature warms.” Also, another principle to know is that as gas expands it gets colder in temperature. So now that you understand that, let’s move on and I’ll explain the different parts of a refrigerator and how they work.
The first part you should know about is the refrigerant; this is the part of the refrigerator that is used for cooling. In older styles of refrigerators Freon was used, now the refrigerant is usually ammonia or HFC’s. As the liquid refrigerant changes its temperature and pressure it results in keeping the refrigerator cold. The refrigerant evaporates at a low temperature and that helps keep your fridge cool. Next I’ll tell you about the evaporator; basically all it does is absorb heat from inside the refrigerator. There are also heating coils that encompass the entire back of the refrigerator, they carry the refrigerant throughout the machine. The compressor is a heavy piece of metal that is powered by a motor, and its function is to raise the pressure of the refrigerant and in doing so, increasing the temperature of it. The condenser condenses the vaporized refrigerant, converts it into liquid, and lowers its temperature. The expansion valve is a thin copper wire which reduces the pressure of the refrigerant in its liquid state. Next I’ll explain the process of how a refrigerator works while it’s running.
Refrigerators have a cycle that changes the pressure, temperature, and state of matter of the refrigerant, and here is how it works. The refrigerant as a gas starts out going through the compressor, as the gas is compressed it increases in temperature and pressure, and here it becomes a heated vapor. Next, the refrigerant passes through the heating coils that surround the refrigerator, as heat is released the temperature of the refrigerant decreases due to heat loss. Now the refrigerant passes through the condenser, again reducing its temperature. The pressure though, remains the same and then the refrigerant returns again to its liquid state. As it now passes through the expansion valve, it reduces the pressure of that refrigerant, causing some of it to evaporate and expand; yet again reducing its temperature. During this evaporation the refrigerant is present in the evaporator and it absorbs the heat from the food inside the refrigerator, cooling it. Aka: The Second Law of Thermodynamics. Next the refrigerant heats up again to its gaseous state and the cycle then repeats.