According to refrigeration, mainly have compression refrigeration, absorption refrigeration and thermoelectric refrigeration (also known as semiconductor refrigeration) and so on. Compression refrigeration USES a compressor to compress the gaseous refrigerant in the closed system. The refrigerant expands and evaporates after condensing, drying, filtering, throbbing and evaporating in the circulating flow to realize the refrigeration function. It can be powered by electric motors or electromagnetic oscillations. Absorption refrigeration USES the continuous diffusion absorption of ammonia, hydrogen and water into the closed system to realize the refrigeration function. It can use electricity, gas, kerosene, liquefied petroleum gas, natural gas, solar energy and other energy as power. Thermoelectric refrigeration USES the Peltier effect of semiconductor materials to achieve refrigeration.