According to the statistical analysis of the "2013-2017 China Refrigerator Industry Market Outlook and Investment Opportunity Analysis Report", refrigerators can be classified into the following 9 working principles: compression type refrigerators: This type of refrigerator is powered by an electric motor and works on the refrigeration system through a compressor. The refrigeration system is made by utilizing the principle of absorbing heat during evaporation and vaporization of low boiling point refrigerants. Its advantages are long lifespan and easy to use, with 91-95% of refrigerators in the world falling into this category. The commonly used refrigerators use a refrigerant called R600a refrigerator as a hot "mover" to transport the "heat" from the refrigerator to the outside. Absorption refrigerator: This type of refrigerator can use heat sources (such as gas, kerosene, electricity, etc.) as power. The purpose of refrigeration is achieved through the continuous absorption diffusion process using a mixed solution of ammonia water hydrogen. Its drawbacks are low efficiency and slow cooling, which has gradually been phased out. Refrigerator: It is a refrigerator that utilizes the principle of generating the Peltier effect at nodes by applying direct current to PN type semiconductors to achieve refrigeration. Chemical refrigerator: It is a refrigerator that utilizes strong heat absorption when certain chemicals dissolve in water to achieve cooling effects. Electromagnetic vibrating refrigerator: It is a refrigerator that uses an electromagnetic vibrator as the main power to drive the compressor. Its principle and structure are basically the same as compression refrigerators. Solar refrigerator: It is a refrigerator that uses solar energy as a cooling energy source. Adiabatic demagnetization refrigeration refrigerator. Radiation cooled refrigerator. Solid state refrigeration refrigerator