Defrosting method of variable-frequency air source heat pump unit

Abstract

The invention provides a defrosting method of a variable-frequency air source heat pump unit. The defrosting method comprises the following steps that when a defrosting condition is reached, a compressor is reduced to the lowest frequency and kept for 5 seconds, a defrosting mode is started, the frequency of the compressor is increased to the defrosting frequency, the expansion opening degree is adjusted to the defrosting opening degree, then the defrosting frequency is reduced by 5Hz every 30 seconds, the defrosting opening degree is reduced by 4%, and the adjustment is stopped until the frequency is reduced to the defrosting lower limit frequency; and the air exchange temperature, the unit high-pressure value and the defrosting duration are monitored, when any one of the three parametersexceeds a set value, the unit exits the defrosting mode, the frequency of the compressor is reduced to the lowest frequency and kept for 5 seconds, a fan is started and waits for 5 seconds, and the unit is switched back to normal heating. The method can reduce the defrosting switching impact of the air source heat pump, improves the unit safety, and reduces the noise. Meanwhile, the real-time matching of the defrosting heat demand and the unit heat supply can be kept, the total defrosting time is shortened, and the defrosting energy consumption is reduced.

Description

technical field [0001] The invention relates to the technical field of air source heat pumps, in particular to a defrosting method for frequency conversion air source heat pumps. Background technique [0002] Defrost has always been a problem hindering the further development and popularization of air source heat pumps. On the premise of maintaining reliable operation of the unit, accelerating the defrosting speed and reducing the energy consumption of defrosting are the core of defrosting technology. At present, the mainstream air source heat pump units use fixed-frequency scroll compressors and R410A refrigerants. The defrosting control method is generally: after reaching the defrosting conditions, after the unit stops for a period of time, switch the four-way valve, and then turn on the compressor for defrosting. . During defrosting, the heat exchanger temperature is detected, and when the temperature exceeds a certain value, the unit stops defrosting. At this time, aft...

AI Technical Summary

Problems solved by technology

The compressor needs to be started and stopped twice for one defrost. When the frost is severe, there will be 1 or 2 defrosts within 1 hour, which will inevitably affect the safe operation of the compressor.

On the other hand, fixed-frequency scroll compressors are generally started directly, and the noise is relatively large, which also affects user satisfaction.

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