In thermodynamics, a refrigerator is an open system that dispels heat from a closed space to a warmer area, usually a kitchen or another room. It is essentially a heat pump that cools a region instead of heating it. The Second Law of Thermodynamics states that heat will always flow spontaneously from hot to cold, and never the other way around. A refrigerator causes heat to flow from cold to hot by inputting work, which cools the space inside the refrigerator. The refrigeration cycle is entirely based on thermodynamics, and it involves the process of removing heat from a body and cooling it to a lower temperature than the actual. The common refrigerator which we have in our homes works on the principle of evaporation, and it has four components: evaporator, compressor, condenser, and expansion valve. The refrigerant fluid arrives on the liquid state and under low pressure to the evaporator, during which it is changing phase again, from liquid to gas. When you change phase, it absorbs the heat present in the conditioned items in the refrigerator case and returns to the compressor.