What Is Mechanical Refrigeration?

Mechanical refrigeration relies on mechanical or thermal effects to cause changes in the state of the refrigerant (including state changes), complete the refrigeration cycle, and use the temperature rise or state changes of the refrigerant at low temperatures to perform refrigeration. Mechanical refrigeration can be divided into two types of vapor refrigeration and gas refrigeration according to the way it realizes the refrigeration cycle. Modern refrigeration technology mainly uses the vapor refrigeration method. ^[1]

Mechanical refrigeration can be divided into two types of vapor refrigeration and gas refrigeration according to the way it realizes the refrigeration cycle. In the steam refrigeration method, the vapor of the working medium is first compressed to a relatively high pressure, cooled by an external cooling medium (cooling water or air), and then converted into a liquid. After throttling, the pressure and temperature are reduced at the same time. Cooling can be obtained by evaporation of the liquid. When using this refrigeration method, the working medium used must have such characteristics; it can be liquefied at normal temperature or ordinary low temperature. ^[1]

According to the method of realizing the vapor compression process, vapor refrigeration has vapor compression refrigeration, absorption refrigeration and vapor jet refrigeration. Vapor compression refrigeration is used to complete the compression process of working medium vapor with various types of compressors. It is the most widely used refrigeration method. Absorption refrigeration is the process of compressing the working medium vapor by thermo-chemical method, and it is also a refrigeration method commonly used in modern times. Steam jet refrigeration uses a steam ejector to complete the process of compressing the working medium vapor (water vapor). This refrigeration method has been applied once and is now in the position of being eliminated. ^[1]

The vapor compression refrigeration system is composed of four main parts: compressor, condenser, throttling device, and evaporator. The working fluid is circulated and connected by pipes at once to form a completely closed system. The refrigerant is in this closed refrigeration system. The system circulates in a fluid state. Through phase change, it continuously draws heat from the evaporator and releases heat in the condenser to achieve the purpose of cooling. Vapor compression refrigeration has a history of more than 100 years since its inception, and it has developed to a fairly complete level. It has a variety of models, with a cooling temperature from 5 ° C to -150 ° C, and a single unit cooling capacity from about 100 W to thousands of kilowatts. It has been widely used in air conditioning, cold processing and refrigeration of various refrigerators, food, transportation, construction Certain production processes in the engineering, chemical, petroleum, natural gas and other industries, as well as many aspects of scientific research and defense facilities. ^[1]

Absorption refrigeration is the use of certain working fluid pairs with special properties, through the absorption and release of one substance to another substance, resulting in a change in the state of the substance, which is accompanied by the process of endothermic and exothermic. Absorption refrigeration device is composed of generator, condenser, evaporator, absorber, circulating pump, throttle valve and other components. The working medium includes refrigerant for making cold capacity and absorbent for absorbing and desorbing refrigerant, both of which Working fluid pair. Absorption refrigeration also has a history of more than 100 years. Among them, lithium bromide absorption refrigeration has been widely used. It uses water as a refrigerant and the refrigeration temperature is above 0 ° C. It is used for air conditioning and production process cold water equipment. The production of refrigeration and air-conditioning equipment has accounted for a considerable proportion in the mechanical processing industry, and the power consumption of refrigeration and empty-word equipment has also accounted for a significant proportion of the total power consumption. ^[1]