Three-tube multi-split air-conditioning system oil return or defrosting control method and system thereof

Abstract

The invention relates to a three-tube multi-split air-conditioning system oil return or defrosting control method and a system thereof. The method includes the following steps that step 1, the temperature T1 of outlet water of a water heat exchanger is detected in real time; step 2, when an air-conditioning system conducts oil return or defrosting, a heat recovery unit is switched to a refrigerating mode; step 3, when it is detected that the outlet water temperature T1 is larger than the low temperature T, an electromagnetic expansion valve of a throttling part is opened to the set fixed opening degree, and after the system receives the ending signal of oil return or defrosting, the heat recovery unit is switched to be the mode before oil return or defrosting; step 4, when it is detected that the outlet water temperature T1 is lower than the low temperature T, the electromagnetic expansion valve of the throttling part of the heat recycling device is turned off, a bypass electromagnetic valve is turned on, and after the system receives the ending signal of oil return or defrosting, the heat recycling device is switched into the mode before oil return or defrosting. By means of the three-tube multi-split air-conditioning system oil return or defrosting control method and the system thereof, the situation that water in the water heat exchanger is frozen under the temperature of oil return or defrosting, so that user use comfort and system operation reliability are affected is avoided.

Description

technical field [0001] The invention relates to the technical field of air-conditioning equipment, in particular to a method and system for controlling oil return or defrosting of a three-pipe multi-connected air-conditioning system. Background technique [0002] At present, in order to improve the comfort of air conditioners, there may be different demands for cooling and heating in transitional seasons. For a single set of multi-connected air conditioning system, it must be able to meet the cooling and heating demands at the same time. In the prior art, three The controlled multi-connected air-conditioning system can meet this demand, and multiple indoor units can simultaneously turn on two different modes of cooling or heating. [0003] In the heating mode of the air conditioner, frosting is inevitable. The current practice of most manufacturers is to switch the internal unit to cooling mode once it enters the defrosting mode. In order to reduce the defrosting time, the e...

AI Technical Summary

Problems solved by technology

In this way, the refrigerant will flow through the internal unit, making the coil temperature of the internal unit very low. For the multi-connected system with heat recovery, if a water circulation system is used, when returning oil or defrosting, the refrigerant will pass through the heat recovery device and will be absorbed from the water Heat, resulting in a decrease in the temperature of the outlet water, in the case of low temperatures, may even cause the water in the heat recovery device to freeze, affecting user comfort and system reliability

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