Refrigerators:Refrigerators are appliances that remove heat from their interior compartments and release it into their surroundings, resulting in lower temperatures inside.
Heat Engines:Heat engines are devices that convert thermal energy into mechanical work, typically by allowing heat to flow from a high-temperature region to a low-temperature region.
Coefficient of Performance (COP): COP is a measure of how efficiently a heat pump operates. It is defined as the ratio of desired output (heating or cooling) to the required input (electricity).