Control method and system for multi-connected air conditioner under cooling condition

Abstract

The invention provides a control method and system for a multi-connected air conditioner under the refrigeration working condition. The multi-connected air conditioner comprises a multi-connected air-conditioning unit and a fresh air unit; the multi-connected air-conditioning unit comprises a plurality of indoor units; and the fresh air unit comprises an indoor heat exchanger and a valve body usedfor controlling a flow rate of a refrigerant which enters the heat exchanger. The control method for the multi-connected air conditioner under the refrigeration working condition comprises the following steps of after receiving a refrigeration turning-on command, acquiring an air return temperature of the fresh air unit; calculating a current superheat degree according to preset calculation requirements corresponding to the air return temperature; and calculating a regulation opening degree of the valve body according to a difference between the current superheat degree and a target superheatdegree, and controlling the valve body according to the regulation opening degree. Aiming to different air return temperatures, the current superheat degrees are calculated according to different calculation requirements, and the opening degree of the valve body is controlled through the difference between the current superheat degree and the target superheat degree, so that the problem that during high-temperature refrigeration or low-temperature refrigeration, the fresh air unit occupies too much or too little refrigerant to influence the refrigeration effect of the multi-connected air conditioner is solved.

Description

technical field [0001] The present invention belongs to the technical field of air-conditioning equipment, and specifically relates to a control method of a multi-connected air conditioner under refrigeration conditions, a control system of a multi-connected air conditioner under refrigeration conditions, a computer device and A computer readable storage medium. Background technique [0002] At present, more and more new fans are introduced into the multi-connected air-conditioning system, which plays a vital role in improving indoor air quality. However, since the fresh air fan introduces outdoor air, when the high-temperature cooling returns air, the evaporation temperature of the indoor heat exchanger of the fresh fan is much higher than that of other indoor units in the multi-connected air-conditioning system. The evaporation temperature of the heat exchanger is much lower than that of other internal units. In this case, if the conventional internal refrigerant flow co...

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Problems solved by technology

In this case, if the conventional internal refrigerant flow control method in the industry is directly used, such as the cooling superheat control method (superheat = evaporating temperature of the indoor heat exchanger - evaporating temperature of the indoor heat exchanger), it will lead to high-temperature refrigeration. (For example, when the return air temperature is 43°C), the steaming temperature of the indoor heat exchanger of the fresh fan is very high, the degree of superheat is large, the opening of the electronic expansion valve is too large, and the flow of refrigerant is seriously biased towards the fresh fan. The indoor air unit will lack the refrigerant flow, and the cooling effect will become poor; when the cooling temperature is low (for example, when the return air temperature is 5°C), the evaporation temperature of the indoor heat exchanger of the fresh fan is very low, and the degree of superheat is close to 0 or negative. The opening will be misadjusted to the minimum opening, and a large amount of refrigerant will be biased towards other indoor units in the multi-connected air conditioning system, especially the small-capacity indoor units will be frequently protected by the low temperature of the evaporator, resulting in drastic fluctuations in the outlet air temperature

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