Most air conditioners and refrigerators use the compression cooling circle. The basic thermodynamic principle lies in deflation of gases and liquids: When a gasliquid deflates it extracts heat from its environment. Extracting heat means cooling. So when a gasliquid deflates, it creates a cool environment.The cooling cycle now has to provide a high pressurised gasliquid which can deflate. The higher the pressure of the gasliquid, the more cooling will be achieved.