The refrigeration compressor is the most important equipment in the industrial chiller refrigeration system, which is equivalent to the "heart" of the refrigeration system. Its role is to suck the refrigerant vapor from the evaporator, increase its temperature and pressure, and discharge it to the condenser.
Refrigeration compressors can be divided into volumetric and speed type categories. Positive displacement compressors have reciprocating piston type, screw type (single screw, twin screw), scroll type, sliding vane type and rolling rotor type compressor. Speed compressors are mainly centrifugal compressors. According to the form of the seal structure, the compressor can be divided into an open type compressor, a semi-hermetic type compressor and a totally enclosed type compressor.
1. Piston Refrigeration Compressors
Piston refrigeration compressors use the reciprocating motion of the piston in the cylinder to compress the gas in the cylinder. Usually, the crank rod linkage mechanism is used to convert the rotational motion of the prime mover into the reciprocating linear motion of the piston. Therefore, it is also referred to as reciprocating. Refrigerant compressors, which rely on the variable working volume consisting of cylinders, valves, and pistons that reciprocate in the cylinder, complete the suction, compression, and discharge of the refrigerant gas. Although there are many kinds of piston compressors and the structure is complex, the basic structure and the main components are basically the same, including the body, crankshaft, connecting rod components, piston components, cylinders, and intake and exhaust valves.
Piston compressors are widely used in small and medium chiller refrigeration equipment.
2. Screw refrigeration compressors
The screw refrigeration compressor is a volumetric rotary compressor. According to the number of screw rotors, the screw compressor has two kinds of twin screw and single screw. Twin screw compressors are simply referred to as screw compressors. Mainly used in screw chillers. The structure of the screw refrigeration compressor is mainly composed of the yin and yang rotors, the body (including the cylinder block and the suction and exhaust end seats), the bearings, the shaft seals, the balance piston and the energy adjustment device.
Screw refrigeration compressors work with a pair of intermeshing rotors (screws). The rotor has a special helical tooth shape. The convex tooth is called the male rotor, and the concave shape is called the female rotor. In general, the male rotor is the active rotor, which is directly connected with the prime mover, and the female rotor is the driven rotor. The male rotor is generally made of 4 teeth, and the female rotor is made of 6 teeth. The two rotors perform counter-rotary motion in the cylinder, and a V-shaped sealed space is formed between the rotor tooth groove and the cylinder block. With the rotation of the rotor, the volume of the space changes constantly, and the suction and exhaust ports can accurately connect or block the slots of the rotor and the suction and exhaust chambers as required, and the suction, compression, and exhaust processes are periodically performed.
The screw refrigeration compressor has a simple structure, compactness, and few wearing parts. It has a high volumetric efficiency under high compression ratio conditions. However, due to the current use of oil-injected screw compressors, the lubrication system is relatively complicated and the auxiliary equipment is relatively Big. Our country stipulates the series of screw refrigeration compressors. Under the standard operating conditions, the range of cooling capacity is between 100~2300kw, between the piston compressor and the centrifugal compressor.
