Defrosting method of multi-combination type air conditioning unit

Abstract

The invention discloses a defrosting method of a multi-combination type air conditioning unit. The defrosting method comprises that starting operation is carried out, temperature T0 of a frosted side of a coil pipe of an outdoor heat exchanger (1) of each outdoor machine is measured, when T0 of a certain outdoor machine is judged to be lower than -12 degrees, an air conditioning main controller sends a defrosting command to start to defrost the outer machine, reversing direction is carried out on a four-way reversing valve (2) and rotation of an outdoor fan is stopped at the same time, the outer fan is operated in an inverted mode, when a defrosting temperature sensor of the outdoor machine for carrying out defrosting detects temperature of a defrosting side of the coil pipe of the outdoor heat exchanger (1) of the outdoor machine to be larger than or equal to 12 degrees, defrosting is finished, after frequency of an inverter compressor (3) of the outdoor machine is reduced to reversing frequency, the frequency is kept being operated for 10 seconds, then the four-way reversing valve (2) is reversed in direction, and the whole air conditioning unit is switched back to be operated in a heating mode. The defrosting method is short in defrosting time, high in defrosting efficiency and rapid in defrosting speed.

Description

technical field [0001] The invention relates to a multi-connected air-conditioning unit, in particular to a defrosting method for a multi-connected air-conditioning unit. Background technique [0002] The multi-connected air conditioner unit in the prior art includes one or more outdoor units, a plurality of indoor units connected in parallel, and two refrigerant circulation main pipes connecting each indoor unit and each outdoor unit. If there is one outdoor unit, the outdoor unit is connected to multiple indoor units connected in parallel through two refrigerant circulation main pipes; if there are multiple outdoor units, multiple outdoor units are connected in parallel, and the parallel outdoor units pass through two refrigerant circulation main pipes Connect with the indoor units connected in parallel. [0003] Each outdoor unit includes compressor, oil separator, four-way reversing valve, outdoor heat exchanger (evaporator in heating mode), throttling device, liquid re...

AI Technical Summary

Problems solved by technology

[0007] The traditional defrosting method has the following defects: 1. Because the coil of the outdoor heat exchanger generally frosts on the frosting side, but the non-frosting side does not frost, and the heat of the high-temperature and high-pressure gas in the coil is frosting. The frost layer is melted on the non-frost side, but there is no frost layer on the non-frost side. The heat on the non-frost side is dissipated into the air and is wasted, and this part of the heat is not used reasonably; The frost layer attached to the coil melts, but the outer frost layer not attached to the coil does not melt. After the inner frost layer melts, a gap is formed between the outer frost layer and the coil, and the coil can only radiate outward. Heat transfer in one layer of frost layer, its heat transfer efficiency is low, it is difficult to melt the outer layer of frost layer, the defrosting efficiency is low, and the defrosting time is too long, which affects the heating efficiency of the whole unit; 3. The water formed after the frost melts penetrates between the coils 4. During the defrosting process, the outdoor fan stops, resulting in insufficient heat exchange of the outdoor heat exchanger, and the outdoor heat exchanger The high-temperature and high-pressure gas in the heater has a small amount of liquefaction, and long-term defrosting will easily cause the pressure and temperature in the entire system to be too high, affecting the normal operation of the air conditioner

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