Refrigerants are a fundamental component of modern air conditioning and refrigeration systems, playing a key role in heat transfer and maintaining the required temperatures across various applications, whether in residential buildings, commercial facilities, or industrial sectors. 

The operating principle of refrigerants is based on their ability to change between liquid and gas states. They absorb heat from the area being cooled during evaporation and release this heat to the outside during condensation. This continuous cycle ensures the efficiency and stability of refrigeration systems. 

Refrigerants vary according to their chemical composition and properties. One of the most common types is hydrofluorocarbon compounds (HFCs), widely used in modern air conditioning systems. Natural refrigerants such as ammonia (NH₃) and carbon dioxide (CO₂) are also used and are considered environmentally friendly options in many industrial applications. 

Key characteristics of a good refrigerant include high heat transfer efficiency, chemical stability, safe usage, and low environmental impact. In recent years, there has been a growing global focus on using refrigerants with reduced effects on global warming and the ozone layer, in line with international environmental standards. 

Refrigerants are used in a wide range of applications, including central air conditioning systems, household refrigerators, cold storage rooms, food supply chains, and industrial facilities. They also play an essential role in preserving the quality of sensitive products such as pharmaceuticals and food items.