Vapor Compression Refrigeration System：
It is the most widely used refrigeration cycle to use the latent heat produced by the phase change of working medium to realize refrigeration through the closed cycle of compression, condensation, throttling and evaporation.
Compressor: absorb the refrigerant vapor in the evaporator, compress it to the condensation pressure, and then discharge it to the condenser.
Condenser: condenses the high-pressure refrigerant vapor from the compressor into liquid. In the process of condensation, the heat released by the refrigerant vapor is taken away by the cooling water or air.
Throttle valve: when the refrigerant liquid passes through the throttle valve, the pressure decreases from the condensation pressure to the evaporation pressure, and part of the liquid flashes into vapor.
Evaporator: the throttled refrigerant liquid evaporates into gas in the evaporator and absorbs the heat of the object to be cooled. The object to be cooled can be liquid refrigerant or air.
1. Screw Compression Refrigerator
Advantages: small volume, light weight; simple structure, less vulnerable parts, high reliability; small torque change, less vibration, stable operation; can withstand certain liquid hammer; energy can be stepless adjustment; high compression efficiency, low exhaust temperature after rotor oil injection, good air tightness.
Disadvantages: the surface of rotor parts is curved, and the machining accuracy is high; a huge oil separator is needed to separate the oil injected into the machine, and the auxiliary equipment is complex.
2. Centrifugal Compression Refrigerator
Advantages: high coefficient of performance, large refrigeration capacity; unit power unit light weight, small volume; easy to achieve multi-stage compression and throttling; high degree of automation; can be imported guide vane or frequency conversion, automatic stepless adjustment of refrigeration capacity, wide range of adjustment; the amount of lubricant mixed with refrigerant in the refrigerator is small, which has little impact on the heat transfer effect of heat exchanger.
Disadvantages: high speed, must be suitable for large flow occasions, not suitable for the occasion of small cooling capacity; centrifugal compression refrigerator inherent low load vibration phenomenon can not be effectively solved.
3. Piston Compression Refrigerator
Advantages: the earliest model; high thermal efficiency, high speed; multi cylinder, adjustable energy; suitable for a variety of refrigerants, easy to manufacture, low price, easy to operate and manage.
Disadvantages: complex structure, many vulnerable parts, short maintenance cycle; large inertia of reciprocating motion, discontinuous gas transmission, pulsating exhaust pressure, large equipment vibration.
4. Scroll Compression Refrigerator
Compared with reciprocating piston type, it has the characteristics of high efficiency, low noise, less parts, light weight, small volume, energy saving and small vibration.