Primary throttling inter complete cooling refrigeration system with medium temperature evaporators

Abstract

The invention discloses a primary throttling inter complete cooling refrigeration system with medium temperature evaporators. The system is provided for turn-grade defrosting of low temperature evaporators of a defrosting cycle with high temperature hot gas discharged by low-pressure-stage compressors of a refrigeration cycle. The refrigeration system comprises a high-pressure-stage compressor set, a condenser, a first throttle valve, an intercooler and a plurality of low-pressure-stage units. Each low-pressure-stage unit comprises one low-pressure-stage compressor, a first four-way reversingvalve, a second throttle valve, one low temperature evaporator, one medium temperature evaporator, a two-way valve, a first check valve, a second check valve and a third check valve. The low-pressure-stage units are used for the refrigeration cycle or the defrosting cycle, and the refrigeration cycle and the defrosting cycle are switched through switching between connectors of the first four-way reversing valves and opening and starting of the two-way valves. Reverse cycle heat pump defrosting is achieved through the high temperature hot gas discharged by the low-pressure-stage compressors ormedium-pressure saturated vapor of the intercooler, temperature fluctuation is avoided, energy is saved, and efficiency is high.

Description

technical field [0001] The invention relates to the technical field of refrigeration, and more specifically relates to a two-stage compression refrigeration system with a medium-temperature evaporator, a throttling intermediate complete cooling, and a hot gas defrosting system. 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 and ensure the quality of food. [0003] Th...

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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