[Mechanical Equipment Technology Edition] Daily Question 20180202: Common Faults in Refrigeration Systems (8.9)
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This post was last edited by YORK Industrial Refrigeration on 2018-2-5 at 17:28. Starting from now, in order to enhance communication among members, a \"Question of the Day\" campaign has been launched on the Mechanical Equipment Technology forum. We hope everyone will participate actively to progress and improve together! ! ! Rewards: 3 points for active participation, 10-15 points for correct answers. This question is valid for two days; no score will be assigned if more than two days pass. Regarding screw compressors, how do the teachers understand the concepts of internal pressure ratio and external pressure ratio? Firstly, the internal pressure is fixed at the time of manufacture, and the internal pressure ratio (exit pressure to inlet pressure) is controlled by an energy regulation device. The external pressure ratio refers to the ratio of exhaust pressure to suction pressure, which can be seen on the display screen. ============================== Premium promotions: Mechanical equipment——York screw compressors: Maintenance procedures https://bbs.hcbbs.com/thread-1806833-1-1.html Mechanical equipment——Upgrading York Quinton control centers https://bbs.hcbbs.com/thread-1804837-1-1.html Mechanical equipment——GEA Grasso screw compressors: Major repairs https://bbs.hcbbs.com/thread-1800467-1-1.html Mechanical equipment——British HOWDEN screw compressors: Disassembly and maintenance https://bbs.hcbbs.com/thread-1832529-1-1.html Mechanical equipment——Japanese Maekawa MYCOM screw compressors: Disassembly and maintenance https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=
The internal pressure ratio refers to the degree of pressure increase imposed by the rotor of the screw compressor itself, whereas the external pressure ratio is determined by the condenser and evaporator together; external pressure ratio = condensation pressure / evaporation pressure = (discharge pressure + 0.1) / (suction pressure + 0.1). When the external pressure ratio is greater than the internal pressure ratio, it is referred to as under compression; when the external pressure ratio is less than the internal pressure ratio, it is called over compression. In both cases, the efficiency of the unit decreases (this refers to efficiency other than that of the compressor – it’s also easy to get confused between the overall efficiency of the unit and the efficiency of the compressor).
The internal pressure ratio refers to the final compression pressure/inlet pressure, while the external pressure ratio is the exhaust pressure/inlet pressure.
The internal pressure ratio refers to the degree of pressure increase imposed by the rotor of the screw compressor itself, whereas the external pressure ratio is determined by the condenser and evaporator together; external pressure ratio = condensation pressure / evaporation pressure = (discharge pressure + 0.1) / (suction pressure + 0.1). When the external pressure ratio is greater than the internal pressure ratio, it is referred to as under compression; when the external pressure ratio is less than the internal pressure ratio, it is called over compression. In both cases, the efficiency of the unit decreases (this refers to efficiency other than that of the compressor – it’s also easy to get confused between the overall efficiency of the unit and the efficiency of the compressor).
Regarding screw compressors, how do you teachers understand the concepts of internal pressure ratio and external pressure ratio? Answer: The internal pressure ratio refers to the degree of pressure increase imposed by the rotor of the screw compressor itself, whereas the external pressure ratio is determined by the condenser and evaporator together; the external pressure ratio = condensing pressure / evaporating pressure = (discharge pressure + 0.1) / (suction pressure + 0.1). When the external pressure ratio is greater than the internal pressure ratio, it is called undercompression; when the external pressure ratio is less than the internal pressure ratio, it is called overcompression
The internal pressure ratio refers to the degree of pressure increase imposed by the rotor of the screw compressor itself, whereas the external pressure ratio is determined by the condenser and evaporator together; external pressure ratio = condensation pressure / evaporation pressure = (discharge pressure + 0.1) / (suction pressure + 0.1). When the external pressure ratio is greater than the internal pressure ratio, it is referred to as under compression; when the external pressure ratio is less than the internal pressure ratio, it is called over compression. In both cases, the efficiency of the unit decreases (this refers to efficiency other than that of the compressor – it’s also easy to get confused between the overall efficiency of the unit and the efficiency of the compressor).
The internal pressure ratio refers to the degree of pressure increase imposed by the rotor of the screw compressor itself, whereas the external pressure ratio is determined by the condenser and evaporator together; external pressure ratio = condensation pressure / evaporation pressure = (discharge pressure + 0.1) / (suction pressure + 0.1). When the external pressure ratio is greater than the internal pressure ratio, it is referred to as under compression; when the external pressure ratio is less than the internal pressure ratio, it is called over compression. In both cases, the efficiency of the unit decreases (this refers to efficiency other than that of the compressor – it’s also easy to get confused between the overall efficiency of the unit and the efficiency of the compressor).
The internal pressure ratio refers to the degree of pressure increase imposed by the rotor of the screw compressor itself, while the external pressure ratio is determined by the condenser and evaporator together; external pressure ratio = condensing pressure / evaporating pressure = (discharge pressure + 0.1) / (suction pressure + 0.1)
The external pressure ratio is the ratio of the condensing pressure to the evaporating pressure in a refrigeration system (i.e., the condensing pressure in the external condenser to the evaporating pressure in the evaporator). The internal pressure ratio is the ratio of the pressure in the discharge chamber to the pressure in the suction chamber of the refrigeration compressor (i.e., the pressure inside the cylinder at the end of suction and at the end of discharge). The internal pressure ratio refers to the degree of pressure increase imposed by the rotor of the screw compressor itself, whereas the external pressure ratio is determined by the condenser and evaporator together; external pressure ratio = condensation pressure / evaporation pressure = (discharge pressure + 0.1) / (suction pressure + 0.1). When the external pressure ratio is greater than the internal pressure ratio, it is referred to as under compression; when the external pressure ratio is less than the internal pressure ratio, it is called over compression. In both cases, the efficiency of the unit decreases (this refers to efficiency other than that of the compressor – it’s also easy to get confused between the overall efficiency of the unit and the efficiency of the compressor).
The internal pressure ratio refers to the degree of pressure increase imposed by the rotor of the screw compressor itself, whereas the external pressure ratio is determined by the condenser and evaporator together; external pressure ratio = condensation pressure / evaporation pressure = (discharge pressure + 0.1) / (suction pressure + 0.1).
The internal pressure ratio refers to the degree of pressure increase imposed by the rotor of the screw compressor itself, whereas the external pressure ratio is determined by the condenser and evaporator together; external pressure ratio = condensation pressure / evaporation pressure = (discharge pressure + 0.1) / (suction pressure + 0.1).