Multiple-on-line system and liquid return prevention control method thereof

Abstract

The invention discloses a multiple-on-line system and a liquid return prevention control method thereof, wherein the method comprises the following steps of: controlling the multiple-on-line system to switch to a defrosting mode to operate to defrost when the multiple-on-line system is in heating operation and if an outdoor unit receives a defrosting instruction; detecting gas exhaust pressure, gas return pressure and a gas exhaust temperature of a compressor in real time; after defrosting is completed, sending a defrosting completion signal to a flow-splitting device by the outdoor unit, controlling the compressor to reduce frequency and a plurality of electric-control valves to open, and controlling any one of the electric-control valves to open and the rest of the electric-control valves to close during reversing of a four-way valve, thereby reducing amount of a refrigerant returned to a low-pressure gas-liquid separator; and regulating number of the open electric-control valves according to the gas exhaust pressure, the gas return pressure and the gas exhaust temperature. According to the method disclosed by the invention, liquid return risk of the compressor after defrosting is completed can be avoided, and the safety reliability of the system is greatly improved.

Description

technical field [0001] The invention relates to the technical field of air conditioning, in particular to a liquid back-prevention control method for a multi-connection system and a multi-connection system. Background technique [0002] The multi-split system is generally used for cooling and heating in four seasons. When the multi-split system is in heating operation, the system transfers heat from outdoor to indoor. The outdoor heat exchanger is used as an evaporator, and the indoor unit is used as a condenser. The high-temperature exhaust gas exchanges heat with the air on the indoor side and condenses, transfers the heat to the indoor air, returns to the outdoor unit after passing through the throttling device, exchanges heat with the outdoor air, and then evaporates. [0003] When the ambient temperature of the outdoor unit is lower than the freezing point, the water vapor in the outdoor air will condense and form frost on the surface of the evaporator. The frosting of...

AI Technical Summary

Problems solved by technology

The first switch of the four-way valve turns the system into a cooling reverse cycle. When the frost in the outdoor heat exchanger is defrosted, the second switch of the four-way valve turns the system into heating or main heating mode. A large amount of liquid refrigerant may quickly return to the low-pressure gas-liquid separator at the suction port of the compressor, resulting in a large amount of liquid return from the compressor

Therefore, it is difficult for the current multi-connected system to perform defrosting control on the premise of ensuring the safe and reliable operation of the system

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