Refrigeration systems are technologies used to remove heat from a designated area, keeping it cool. They work by circulating a refrigerant, a special fluid that absorbs heat as it evaporates and releases it when it condenses. Common applications include household refrigerators, air conditioning units, and industrial chillers. These systems typically consist of four main components: a compressor, condenser, expansion valve, and evaporator. The compressor compresses the refrigerant, raising its pressure and temperature. The condenser then cools the refrigerant, allowing it to condense into a liquid. The expansion valve reduces the pressure, and the evaporator absorbs heat, completing the cycle.