1. The Principle of Refrigerator
Cycle Principle of Refrigeration Compression System
Overview of 1.1 Refrigeration System
Two processes of refrigeration system.
Refer to the following schematic diagram: 1 - 1, divided into: refrigerants and lubricants.
One is the refrigerant cycle: the refrigerant gas discharged from the compressor passes through the evaporator, which is a closed cycle.
The second is the lubrication cycle used for lubricating compressors: lubricating oil from the oil separator, through the compressor, this circuit is also a closed cycle.
The refrigeration system consists of two circuits, and the equipment of each circuit is necessary.
Fig. 1‐1
1.2 Refrigerant Cycle in Refrigeration System
The refrigeration unit uses the evaporative latent heat of refrigerant to cool the refrigerant. The refrigerant cycle in this refrigeration equipment provides uninterrupted cooling of the refrigerant carrier. The following is a schematic explanation of refrigerant refrigeration equipment.
Evaporation process
Low-temperature and low-pressure liquid refrigerants in the evaporator shell, through heat transfer with the carrier, evaporation into low-temperature and low-pressure refrigerant gas.
(2) Pressure process
Fine foreign matter in low-temperature and low-pressure refrigerant vapor is intercepted by an aspiration filter.
Refrigerant gas, after inhaling compressor, is pressurized into high-pressure refrigerant gas (exhaust refrigerant vapor).
The discharge is a mixture of refrigerant and oil, so it is separated in the oil-gas separator and discharged into the water condenser.
(3) Condensation process
The high-pressure refrigerant gas enters the shell side of the water-cooled condenser, and the refrigerant of gas and liquid exchanges heat with the cooling water in the heat exchanger tube.
(4) Expansion process
The high-pressure refrigerant from the storage space enters the expansion valve.
The refrigerant liquid throttled by expansion valve becomes low pressure, and the refrigerant of low temperature and low pressure enters the evaporator.
In addition to the above, in order to maintain the suction pressure of the compressor, refrigerant gas is drawn from the condenser to maintain the suction pressure (hot gas bypass) of the compressor when the refrigerated water load is small.
In this kind of refrigeration equipment, refrigerant pipeline and its necessary equipment are more like a closed cycle.
2.3 Lubricant Cycle in Refrigerant System
In addition to refrigerant pipelines, lubricants are mainly used for compressor lubrication in the system.
The following illustration is combined with the schematic diagram.
Oil separator
The high-pressure gas entering the oil separator is a mixture of oil and refrigerant, and the mixed refrigerant gas is divided into refrigerant and oil in the oil-gas separation.
High-pressure oil is discharged from below the oil and flows into the oil cooler.
Oil cooling
The lubricant enters the cylindrical oil cooler and exchanges heat with the chilled water in the heat exchanger tube to cool to a temperature suitable for lubrication with viscosity.
(3) Supply compressor
Small debris in the pipeline is intercepted when passing through the oil filter, and oil enters the suction port of the oil pump.
Oil is supplied to the compressor by increasing the pressure of the oil pump. The main lubricating part is the compressor bearing.
In addition, some lubricants at the outlet of some oil pumps are used for adjustable solenoid valve drive. Lubrication oil supply sliding valve, after adjustable operation, return to the suction port.
Compressor lubrication
Bearing, lubricating oil supply bearing protection, mixed with refrigerant gas in the compressor, into the oil separator.
For energy control lubricating oil, mixed refrigerant gas enters the compressor, then compresses, and is discharged into the suction side of the compressor.
2.4 Lubrication Mechanism
Lubricating oil provided to compressors has the following uses:
A Lubricated Rotor and Bearing
B. Clearance between sealed rotor and housing
C-cooled compressed gas
