Operation method and system for secondary throttle intermediate incomplete cooling refrigeration system

Abstract

The invention discloses an operation method and system for a secondary throttle intermediate incomplete cooling refrigeration system, and aims to provide a method and system for defrosting low-temperature evaporators through a low-pressure-stage compressor heat pump cycle. Each low-pressure-stage unit is provided with a medium-temperature evaporator and the corresponding low-temperature evaporator, the medium-temperature evaporators are used for achieving medium-temperature refrigeration, and the low-temperature evaporators are used for achieving low-temperature refrigeration or defrosting. When the certain low-temperature evaporators need to be defrosted, through valve switching, low-pressure-stage compressors for achieving the defrosting function are converted into high-pressure-stage compressors for operation, low-temperature compressors for achieving the defrosting function in the low-pressure-stage units absorb medium-pressure superheated steam from low-pressure-stage compressorsfor achieving the refrigeration function, and after being compressed, the medium-pressure superheated steam conducts condensation heating on the to-be-defrosted low-temperature evaporators to achievedefrosting. The low-temperature evaporators are defrosted through the low-pressure-stage compressor heat pump cycle, temperature fluctuation is small, the defrosting efficiency is high, and the cooling capacity of a refrigeration room and a freezing room can be provided.

Description

technical field [0001] The present invention relates to the technical field of refrigeration, and more specifically relates to an operation method and refrigeration system of a secondary throttling intermediate incomplete cooling refrigeration system with a medium temperature evaporator and adopting heat pump defrosting. Background technique [0002] In cold storage, when the cooling surface of the heat exchanger is covered by frost, if it is not removed in time, the accumulated frost will reduce the suction temperature of the compressor, increase the exhaust temperature, block the air passage, reduce the heat transfer area, and reduce the air flow rate. The flow resistance increases significantly, the heat transfer efficiency decreases sharply, and the operating performance of the refrigeration device decreases. The quality of the defrosting effect is also the key to give full play to the equipment capacity of the cold storage, reduce the cost of overhaul, save electricity ...

AI Technical Summary

Problems solved by technology

Since this defrosting method operates a single-stage compression heat pump cycle during defrosting, when the two-stage compression refrigeration cycle is converted to a single-stage compression heat pump defrosting cycle, the working pressure difference of the compressor participating in the defrosting of the single-stage compression heat pump cycle is greatly increased. It will cause impact on the compressor and damage the compressor, and the temperature of the working medium entering the evaporator for this single-stage compression heat pump defrosting cycle is low, the defrosting speed is slow, and the time for heat diffusion around the evaporator is long, resulting in a high defrosting efficiency. In addition, when defrosting the evaporator, a large amount of liquid working fluid condensed by the evaporator flows into the gas-liquid separator. After long-term accumulation, these liquid working fluids are easily sucked by the low-pressure stage compressor, forming a wet compression of the compressor. Cause compressor damage, resulting in economic loss

[0005] In addition, the existing cold storage generally can only achieve a single cooling temperature, and the cooling capacity of the cold storage room or the freezing room is provided according to the needs of use, which is inconvenient to use

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