Two-stage compression refrigerating unit for multi-temperature refrigeration storage and control method thereof

Abstract

The invention discloses a two-stage compression refrigerating unit for a multi-temperature refrigeration storage and a control method thereof. The two-stage compression refrigerating unit comprises alow-pressure compressor unit, a high-pressure compressor unit, an oil separator, a condenser, a high-pressure liquid storage device, a subcooler and an oil cooler. An oil cooling loop of the oil cooler uses the gravity difference between a high-level-energy refrigerant liquid and gas as power, and the reliable and economical oil cooling circulation is achieved; a bypass and a flow regulating valveare arranged between an oil outlet pipeline and an oil return main pipeline of the oil separator to accurately control the oil supply temperature of a compressor; and two different working modes areset to solve the problem that due to the frequent changes and the seasonal changes of the load of each storehouse of the multi-temperature refrigeration storage, the too high return air pressure of arefrigerant possibly occur to easily cause the damage of the high-pressure compressor unit.

Description

technical field [0001] The invention relates to the field of refrigeration and low temperature engineering, in particular to a two-stage compression refrigeration system for multi-temperature cold storage widely used in the cold chain logistics industry and a control method thereof. Background technique [0002] In the refrigeration compressor, the lubricating oil plays the role of lubrication, cooling, sealing and cleaning; the temperature of the lubricating oil rises during the operation of the compressor. Excessively high lubricating oil temperature will cause the performance index of the lubricating oil to attenuate, the lubricating effect is weakened, and the sealing In severe cases, it will cause excessive wear of the compressor, shorten the working life, or damage the compressor. Therefore, the lubricating oil discharged from the compressor must be cooled to maintain the best oil supply temperature for the compressor. System reliability and work efficiency are very im...

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Problems solved by technology

[0007] In order to avoid the shortcomings of the above-mentioned prior art, the present invention provides a two-stage compression refrigeration unit for multi-temperature cold storage and its control method, in order to realize reliable and economical operation of the oil cooling cycle and precisely control the supply of the compressor. Oil temperature, so that each compressor returns oil evenly; and solve the problem that due to frequent and seasonal changes in the multi-temperature cold storage load, the load distribution of each warehouse is uneven, and the high pressure of the refrigerant return air may cause damage to the high-pressure compressor unit

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