The advantages and disadvantages of screw refrigeration compressor
Screw refrigeration compressor is a rotary positive displacement compressor. It uses the change of the cogging volume and position of the screw to complete the process of vapor suction, compression and exhaust. Oil-free screw compressors came out in the 1930s and are mainly used for compressed air. Later, oil-injected screw compressors appeared in the cylinder and their performance was improved. Oil-injected screw compressors have become one of the main types of refrigeration compressors. Screw compressors are divided into two categories: twin screw and single screw. Twin screw compressors are customarily called screw compressors. This refrigeration compressor is commonly used in screw chillers.
Advantages of screw refrigeration compressor: 1) Compared with reciprocating piston refrigeration compressors, screw refrigeration compressors have a series of advantages such as high speed, light weight, small size, small footprint and low exhaust pulsation. 2) The screw-type refrigeration compressor has no reciprocating mass inertial force, good dynamic balance performance, stable operation, small vibration of the base, and the foundation can be made small. 3) The screw refrigeration compressor has a simple structure and a small number of parts. There are no vulnerable parts such as valves and piston rings. Its main friction parts such as rotors and bearings are relatively high in strength and wear resistance, and lubrication conditions Good, so less machining, low material consumption, long operating cycle, more reliable use, simple maintenance, is conducive to automation of operation. 4) Compared with the speed compressor, the screw compressor has the characteristics of forced air delivery, that is, the displacement is almost not affected by the discharge pressure, and no surge phenomenon occurs when the displacement is small. Within the range of conditions, high efficiency can still be maintained. 5) Adopt slide valve adjustment, which can realize energy stepless adjustment. 6) The screw compressor is not sensitive to liquid inlet and can be cooled by oil injection. Therefore, at the same pressure ratio, the discharge temperature is much lower than that of the piston type, so the single-stage pressure ratio is high. 7) There is no clearance volume, so the volumetric efficiency is high. Defects of screw refrigeration compressors: 1) The refrigerant gas periodically passes through the suction and exhaust orifices, leaks through the gap, etc., which makes the compressor very noisy, and measures for noise reduction and noise reduction are required. 2) The machining accuracy of the space surface of the spiral rotor of the screw chiller is high, and special equipment and tools are required to process it. 3) Due to the limitations of gap seals and rotor stiffness, screw compressors cannot currently achieve higher end pressures as reciprocating compressors.
