
A device that removes heat from a system to lower or maintain its temperature.A refrigerator is a device that transfers heat from a colder interior to a warmer exterior, using external work to drive the process. It operates on the principles of thermodynamics, specifically the second law, which states that heat naturally flows from hot to cold — a refrigerator reverses this flow by doing work. The key measure of its performance is the coefficient of performance (COP), which is the ratio of heat removed to work input.
The first practical vapor-compression refrigerator was built by Jacob Perkins in 1834, building on earlier experimental work by Oliver Evans. The concept of mechanical refrigeration dates back to the 18th century.
A typical refrigerator uses a working fluid (refrigerant) that undergoes a cycle of compression, condensation, expansion, and evaporation. The refrigerant absorbs heat from the interior when it evaporates at low pressure, then releases that heat to the surroundings when it is compressed and condensed at high pressure. The compressor provides the work needed to maintain the pressure difference.
Refrigerators are used everywhere from household kitchens to industrial cold storage, and in scientific research for cooling detectors and samples to cryogenic temperatures.
The most efficient refrigerators approach the Carnot limit, but real ones typically achieve only 30-50% of that theoretical maximum efficiency.












