Screw chiller-the operation process of refrigeration compressor!
Screw-type (ie twin-screw) refrigeration compressors have a pair of mutually meshing rotors with helical teeth in opposite directions. A rotor with a protruding tooth surface is called a male rotor, and a rotor with a concave tooth surface is called a female rotor. The teeth of the rotor are commensurate with the piston, and the working volume composed of the cogging of the rotor, the inner wall surface of the machine body and the end covers at both ends is commensurate with the cylinder. The two ends of the machine body are provided with suction and exhaust holes arranged diagonally. Following the rotating movement of the rotor in the body, the working volume is constantly changing due to the intrusion or disengagement of the teeth. The volume between each pair of tooth slots of the rotor changes periodically to achieve the purpose of suction, compression and exhaust. The rotors that are intermeshing each other have several identical working volumes in each movement cycle to perform the same working process in turn. This working volume is called the elementary volume. It is formed by a pair of tooth surfaces in the rotor, the inner wall surface of the machine body and the end cover. You only need to study the entire working cycle of one of the working volumes to get a complete picture of the compressor's work. Screw chiller The operation process of the refrigeration compressor starts from the suction process, then the gas is compressed in the sealed elementary volume, and finally discharged from the exhaust port. The size of the V-shaped pair of inter-tooth volumes (primary volume) formed between the female and male rotors and the machine body changes with the rotation of the rotor, and its spatial position also continuously moves. 1) Inhalation process When the rotor rotates, one tooth of the male rotor continuously disengages from a slot of the female rotor, the volume between the teeth gradually expands, and communicates with the suction orifice, and the gas enters the volume between the teeth through the suction orifice until the volume between the teeth reaches * When the value is large, it is disconnected from the suction orifice, the volume between the teeth is blocked, and the suction process ends. It is worth noting that at this time, the volume between the teeth of the male and female rotors are not connected to each other. 2) Compression process The rotor continues to rotate. Before the volume between the teeth of the male and female rotors is connected, the gas in the volume between the teeth of the male rotor is compressed by the invasion of the teeth of the female rotor; after a certain angle of rotation, the volume between the teeth of the female and male rotors is connected. A pair of interdental volumes (primitive volumes) forming a V shape. As the two rotor teeth squeeze into each other, the volume of the elementary element is gradually moved, and the volume is gradually reduced, so that the compression process of the gas is realized until the elementary volume is connected to the exhaust port, and the exhaust process begins at this moment. 3) Exhaust process As the volume of the elementary element keeps shrinking when the rotor rotates, the compressed gas is sent to the exhaust pipe, and this process continues until the volume *hour. With the continuous rotation of the rotor, the above-mentioned suction, compression, and exhaust processes are cycled, and each elementary volume works in sequence to form the refrigeration compressor working cycle of the screw chiller. From the analysis of the above process, it can be seen that the two rotors turn to the side that caters to each other, that is, the side where the convex and concave teeth cater to each other. The gas is compressed and forms a higher pressure, which is called the high pressure zone; on the contrary, the screw turns to each other. The side away from each other, that is, the side where the convex teeth and the concave teeth are separated from each other, the volume between the teeth is expanding, thereby forming a lower pressure, which is called the low pressure zone. These two areas are separated by the contact line of the shell and the rotor meshing with each other. It can be roughly considered that the axis plane of the two rotors is the interface between the high and low pressure areas. In addition, because the gas in the volume of the suction element rotates with the rotor, it moves spirally from the suction end to the exhaust end, so the suction and exhaust orifices should be arranged diagonally, and the suction orifices are located in the low pressure area. At the end, the exhaust orifice is located at the end of the high pressure zone.
