What Are the Different Refrigeration Jobs?

There are two ways to achieve refrigeration: natural refrigeration and artificial refrigeration.

There are two ways to achieve refrigeration: natural refrigeration and artificial refrigeration.

Natural refrigeration: Deep well water or natural ice cools objects, and generally can reach temperatures above 0 ° C.

Artificial cold source: liquid vaporization method, gas expansion method, thermoelectric method, solid adiabatic demagnetization method, etc. Different refrigeration methods are suitable for obtaining different temperatures. There are many types of artificial cooling, with different forms. The energy used for refrigeration is also different. Some use electric energy as the energy source, such as compression refrigerators that use ammonia, fluorine, and other refrigerants to achieve the refrigeration cycle. There are steam-based energy sources, such as steam-type lithium bromide absorption refrigeration. There are other thermal energy sources for cooling, such as hot water lithium bromide refrigerators, lithium bromide refrigerators that directly burn oil or natural gas, and solar absorption refrigerators. It is to consume a certain amount of energy in exchange for transferring the heat of a low-temperature object to a high-temperature object, thereby obtaining a low temperature. Liquid vapor endothermic refrigeration is a refrigeration method commonly used at home and abroad.

Chinese name

Cooling method

Foreign name

Refrigeration

1. Electric compression refrigeration

At present, the refrigeration methods widely used in China are compression refrigerators, which include piston, centrifugal and screw refrigerators.

Compression refrigerators commonly used in air-conditioning engineering, whether piston, centrifugal or screw chiller, the principle of refrigeration is that the refrigeration compressor draws the low-pressure and low-temperature gaseous working medium (ammonia or freon) in the evaporator into the compressor Inside, the compressor performs work through compression, so that it becomes a gas with higher pressure and temperature and is discharged into the condenser. In the condenser, high-pressure, high-temperature refrigerant gas exchanges heat with cooling water or air, and transfers heat to the cooling water (water-cooled method) or air (air-cooled method). As a result, the gaseous working medium condenses into a liquid. The high-pressure liquid enters the evaporator after being depressurized by the throttle valve. In the evaporator, the low-pressure refrigerant liquid is vaporized, and the heat of the surrounding medium (such as refrigerant water) must be absorbed during vaporization, thereby reducing the temperature of the refrigerant water, thereby preparing the required low-temperature cold water. The low-pressure, low-temperature gas formed by the vaporization in the evaporator is sucked and compressed by the refrigeration compressor. This cycle is repeated, and the cold and low-temperature water is continuously produced.

2. Lithium bromide absorption refrigeration

Lithium bromide absorption refrigeration has the same principle as vapor compression refrigeration. It also uses liquid refrigerant to evaporate and vaporize the heat load of the refrigerant under low temperature and low pressure conditions to produce a cooling effect. The difference is that the lithium bromide absorption refrigeration uses the "lithium bromide-water" binary solution as the working fluid to complete the refrigeration cycle. Wherein water is the refrigerant and lithium bromide is the absorbent, the specific process is divided into two parts: In the first part, the lithium bromide aqueous solution is heated and boiled by the heat source in the generator, and the refrigerant vapor generated is condensed into refrigerant water in the condenser. The refrigerant water is throttled into the evaporator through a U-shaped tube, and sprayed under low pressure by the evaporator pump. The refrigerant water evaporates, absorbing the heat of the refrigerant, and generating a cooling effect. The condensation heat generated in the condensation process is carried outside the refrigeration system by the cooling water. In the second part, the concentrated solution and intermediate concentration solution from the generator are pumped and sprayed by the absorber pump, and the refrigerant vapor evaporated from the refrigerant water in the evaporator is converted into a dilute solution. The dilute solution is transported by the generator pump to the generator, and is heated again by the heat source to generate refrigerant vapor to form a concentrated solution again, and enters the next cycle.