Two-stage compression air-conditioning system and its control method

Abstract

The invention discloses a two-stage compression air-conditioning system and a control method thereof. The air-conditioning system includes a two-stage compressor, a four-way reversing valve, an outdoor heat exchanger, a first throttling device, a flash evaporator, a second throttling device and Indoor heat exchanger, the opening of the first and second throttling devices can be adjusted; it also includes a bypass pipeline, a heat accumulator and a control valve, and the bypass pipeline is connected to the first port of the outdoor heat exchanger and the double Between the suction ports of the two-stage compressors, the first heat exchange pipe of the heat accumulator is connected in series on the pipeline between the exhaust port of the two-stage compressor and the first end interface of the indoor heat exchanger, and the first heat exchange pipe of the heat accumulator The two heat exchange pipes are connected in series on the bypass pipe, and the control valve is used to selectively connect or disconnect the pipe and bypass pipe between the first port of the outdoor heat exchanger and the suction port of the two-stage compressor road. The two-stage compression air-conditioning system of the present invention can improve the operating efficiency of the system; moreover, the defrosting speed is fast, and the refrigerant that cannot be fully evaporated can be prevented from entering the compressor during defrosting.

Description

Technical field [0001] The present invention relates to the technical field of air conditioning, in particular to a two-stage compression air conditioning system and a control method thereof. Background technique [0002] At present, the intermediate air supplement volume of a two-stage compression air-conditioning system with flasher is not adjustable. When the compressor uses the same frequency, changes in other parameters in the system may cause the intermediate air supplement volume to fluctuate, causing the compressor to deviate from the optimal operating state Efficiency point, causing the compressor to not run at the best efficiency point. [0003] In addition, the conventional defrosting method of the two-stage compression air conditioning system is that during the heating process, when the defrosting conditions are reached, the compressor stops first, and then turns on to the refrigeration mode for defrosting. When the defrosting is over, stop the machine again, and then ...

AI Technical Summary

Problems solved by technology

Although this defrosting method can solve the above-mentioned problems existing in the traditional defrosting method, since the defrosting method uses the heat generated by the compressor to store heat, the phase change temperature point of the phase change heat storage material used will inevitably be If the temperature is lower, the heat absorption and heat release speed of the heat storage material will be slower, so that the defrosting speed will be slower, and the defrosting time will be prolonged, which will also affect the heating effect and comfort

Especially for the two-stage compression air conditioning system with defrosting function, when heating, due to the existence of the flash evaporator, the refrigerant must be subcooled again when it flows through the flash evaporator, that is, the refrigerant flowing into the outdoor heat exchanger must be at Lower temperatures than single-stage compression, so frosting will be more severe and frequent, so defrosting will be slower

Moreover, defrosting when the accumulator has insufficient heat storage will cause a large amount of refrigerant that cannot be evaporated to enter the compressor, thereby posing a fatal threat to the reliability of the compressor.

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