Subcooler throttle valve structure under low load and control method

Abstract

The subcooler throttle valve structure under the low load comprises an auxiliary subcooling heat exchanger, an electronic expansion valve, a heat exchanger evaporation side outlet temperature sensor, a heat exchanger evaporation side inlet temperature sensor, a bypass electric ball valve and a heat exchanger main path outlet temperature sensor. A first port of the auxiliary supercooling heat exchanger communicates with an auxiliary heat exchanger of the outdoor unit, a second port communicates with a liquid pipe operating valve, a third port communicates with the compressor, a heat exchanger evaporation side outlet temperature sensor is arranged on a communicating pipeline, and a fourth port communicates with the first port. The electronic expansion valve and the heat exchanger evaporation side inlet temperature sensor are arranged on the communicated pipeline, the bypass electric ball valve is connected to the two ends of a first port and a second port of the auxiliary supercooling heat exchanger in parallel, and the heat exchanger main path outlet temperature sensor is arranged on the pipeline where the auxiliary supercooling heat exchanger is communicated with the liquid pipe operating valve. When the air conditioner operates under small load, whistling of the indoor unit cannot be generated under the condition that the supercooling degree is met.

Description

Technical Field

[0001] The invention relates to the technical field of subcoolers, and in particular to a throttle valve structure and a control method of a subcooler under low load. Background Art

[0002] The current multi-split air conditioners are increasingly tending to develop in the direction of single-unit large capacity. The increase in air conditioning capacity will increase the user distribution distance, thereby lengthening the multi-split connection pipe. The lengthening of the connection pipe will increase the pressure drop, resulting in a decrease in supercooling. The consequences of the decrease in supercooling are: first, it will cause the user experience to be poor, and second, it will cause the valve opening of the indoor unit to be opened too much to form refrigerant flow noise. In order to solve these two problems, manufacturers generally pursue a large supercooling degree of the unit to improve the user experience. After the supercooling degree is increased, when the user is running at a small load, due to the good heat exchange effect, the liquid pipe temperature is low, which causes the risk of whistling noise on the user side. Summary of the invention

[0003] The object of the present invention is to provide a subcooler throttle valve structure and control method under low load, so as to solve the problem of whistling noise generated when users use the existing structure subcooler multi-split and operate under low load.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a subcooler throttling valve structure under low load, comprising an auxiliary subcooling heat exchanger, an electronic expansion valve, a heat exchanger evaporation side outlet temperature sensor, and a heat exchanger evaporation side inlet temperature sensor, the first port of the auxiliary subcooling heat exchanger is connected to the auxiliary heat exchanger of the outdoor unit, the second port is connected to the liquid pipe operating valve, the third port is connected to the compressor, and the connected pipeline is provided with a heat exchanger evaporation side outlet temperature sensor, the fourth port is connected to the first port, and the connected pipeline is provided with an electronic expansion valve and a heat exchanger evaporation side inlet temperature sensor, based on the prior art, the present invention further makes the following improvements: it also includes a bypass electric ball valve and a heat exchanger main outlet temperature sensor, the bypass electric ball valve is connected in parallel at both ends of the first port and the second port of the auxiliary subcooling heat exchanger, and the heat exchanger main outlet temperature sensor is arranged on the pipeline connecting the auxiliary subcooling heat exchanger and the liquid pipe operating valve.

[0005] The present invention also provides a control method for a subcooler throttle valve structure under low load, wherein when the indoor unit demand load is greater than 20%, the temperature difference between the actual temperature collected by the outlet temperature sensor of the heat exchanger evaporation side and the inlet temperature sensor of the heat exchanger evaporation side is calculated, and when the temperature difference is greater than the target superheat, the electronic expansion valve is opened and controlled, and when the temperature difference is less than the target superheat, the electronic expansion valve is closed and controlled; when the indoor unit demand load is less than or equal to 20%, the electronic expansion valve is controlled by the temperature collected by the main outlet temperature sensor of the heat exchanger, and the formula is as follows:

[0006]

[0007] Wherein y(t) is the control command value, i.e., the opening of the electronic expansion valve, Kp is the proportional gain, Ti is the integral constant, e(t)=x(t)-xopt(t), x(t) is the control object value, i.e., the main outlet temperature of the heat exchanger, xopt(t) is the optimum value of the control object, i.e., the target value of the main outlet temperature of the heat exchanger, and the target value of the main outlet temperature of the heat exchanger is Y=0.856*Ta-2, where Ta is the ambient temperature.

[0008] Compared with the prior art, the present invention has the following beneficial effects:

[0009] After optimizing the subcooler control, the temperature of the liquid refrigerant will not be too low while ensuring supercooling, so precise control can be achieved to avoid the generation of whistling sounds while taking into account the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of the structure of the subcooler throttle valve under low load of the present invention;

[0011] Figure 2 This is a relationship diagram between the main outlet temperature of the heat exchanger of the present invention and the ambient temperature.

[0012] In the figure: auxiliary subcooling heat exchanger 1, electronic expansion valve 2, heat exchanger evaporation side outlet temperature sensor 3, heat exchanger evaporation side inlet temperature sensor 4, auxiliary heat exchanger 5, liquid pipe operating valve 6, compressor 7, bypass electric ball valve 8, heat exchanger main outlet temperature sensor 9, heat exchanger 10, first electronic expansion valve 11, second electronic expansion valve 12, four-way valve 13, oil separator 14, one-way valve 15, oil return assembly 16, gas-liquid separator 17, first solenoid valve 18, second solenoid valve 19, air pipe operating valve 20, third solenoid valve 21. DETAILED DESCRIPTION

[0013] See also Figure 1 A subcooler throttling valve structure under low load includes an auxiliary subcooling heat exchanger 1, an electronic expansion valve 2, a heat exchanger evaporation side outlet temperature sensor 3, and a heat exchanger evaporation side inlet temperature sensor 4. The first port of the auxiliary subcooling heat exchanger 1 is connected to the auxiliary heat exchanger 5 of the outdoor unit, the second port is connected to the liquid pipe operating valve 6, the third port is connected to the compressor 7 through the third solenoid valve 21, and the heat exchanger evaporation side outlet temperature sensor 3 is arranged on the connected pipeline, the fourth port is connected to the first port, and the electronic expansion valve 2 and the heat exchanger evaporation side inlet temperature sensor 4 are arranged on the connected pipeline. Figure 1Also shown are conventional components of the outdoor unit system, including a heat exchanger 10 of the outdoor unit, a first electronic expansion valve 11 and a second electronic expansion valve 12 connected to the heat exchanger 10, a four-way valve 13, an oil separator 14, a one-way valve 15, an oil return assembly 16, a gas-liquid separator 17, a first solenoid valve 18, a second solenoid valve 19, and an air pipe operating valve 20. The specific connection relationships are all prior art and will not be repeated here.

[0014] The refrigerant is subjected to two heat exchanges with increased subcooling through the auxiliary heat exchanger 5 and the auxiliary subcooling heat exchanger 1, and the auxiliary subcooling heat exchanger 1 is the main heat exchange means for increasing the subcooling as the second subcooling heat exchange. In order to pursue a large subcooling degree, improve the online length and the user's heat exchange effect experience, one is to increase the heat exchange area of ​​the auxiliary subcooling heat exchanger 1 and the throttling capacity of the electronic expansion valve 2, and the other is to reduce the superheat of the auxiliary subcooling heat exchanger 1 in control to increase the flow. The traditional control method is to control the opening of the electronic expansion valve 2 by the temperature difference between the outlet temperature of the evaporation side of the heat exchanger and the inlet temperature of the evaporation side of the heat exchanger to perform subcooling heat exchange control. That is, the actual temperature difference between the outlet temperature of the evaporation side of the heat exchanger and the inlet temperature of the evaporation side of the heat exchanger and the target superheat are used to perform differential control of the electronic expansion valve 2. When the actual temperature difference is greater than the target superheat, the valve is opened and controlled, and when the actual temperature difference is less than the target superheat, the valve is closed. The existing method will cause insufficient subcooling under low load, resulting in refrigerant flow noise.

[0015] On the basis of the prior art, the subcooler throttling valve structure under low load of this embodiment further includes a bypass electric ball valve 8 and a heat exchanger main outlet temperature sensor 9. The bypass electric ball valve 8 is connected in parallel at both ends of the first port and the second port of the auxiliary subcooling heat exchanger 1. Other solenoid valves can also be used as bypasses, but the electric ball valve can control the flow rate with higher accuracy. The heat exchanger main outlet temperature sensor 9 is arranged on the pipeline connecting the auxiliary subcooling heat exchanger 1 and the liquid pipe operating valve 6.

[0016] Reference Figure 2 The control method of the subcooler throttle valve structure under low load of this embodiment is as follows: when the indoor unit demand load is greater than 20%, the temperature difference between the actual temperature collected by the heat exchanger evaporation side outlet temperature sensor 3 and the heat exchanger evaporation side inlet temperature sensor 4 is calculated, and when the temperature difference is greater than the target superheat, the electronic expansion valve 2 is opened and controlled, and when the temperature difference is less than the target superheat, the electronic expansion valve 2 is closed and controlled; when the indoor unit demand load is ≤20%, the electronic expansion valve 2 is controlled by the temperature collected by the heat exchanger main outlet temperature sensor 9, and the formula is as follows:

[0017]

[0018] Where y(t) is the control command value, i.e., the opening of the electronic expansion valve 2, Kp is the proportional gain, Ti is the integral constant, e(t) = x(t)-xopt(t), x(t) is the control object value, i.e., the main outlet temperature of the heat exchanger, xopt(t) is the optimal value of the control object, i.e., the target value of the main outlet temperature of the heat exchanger, the target value of the main outlet temperature of the heat exchanger is Y = 0.856*Ta-2, Ta is the ambient temperature. The implementation of this control method can avoid the whistling sound of the liquid refrigerant and the electronic expansion valve core caused by the excessively low outlet temperature of the heat exchanger at low load. When the control process causes the opening of the electronic expansion valve to be below 50PLS, the electric ball valve control is opened to ensure stability and the temperature converges.

[0019] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A subcooler throttle valve structure under low load, comprising an auxiliary subcooling heat exchanger, an electronic expansion valve, a heat exchanger evaporation side outlet temperature sensor, and a heat exchanger evaporation side inlet temperature sensor, wherein the auxiliary subcooling heat exchanger has a first port connected to an auxiliary heat exchanger of an outdoor unit, a second port connected to a liquid pipe operating valve, a third port connected to a compressor, and a heat exchanger evaporation side outlet temperature sensor is arranged on the connected pipeline, a fourth port connected to the first port, and an electronic expansion valve and a heat exchanger evaporation side inlet temperature sensor are arranged on the connected pipeline, characterized in that: It also includes a bypass electric ball valve and a heat exchanger main outlet temperature sensor. The bypass electric ball valve is connected in parallel at both ends of the first port and the second port of the auxiliary subcooling heat exchanger. The heat exchanger main outlet temperature sensor is arranged on the pipeline connecting the auxiliary subcooling heat exchanger and the liquid pipe operating valve.

2. A control method for a subcooler throttle valve structure under low load, characterized in that: The method is that when the indoor unit demand load is greater than 20%, the temperature difference between the actual temperature collected by the outlet temperature sensor of the heat exchanger evaporation side and the inlet temperature sensor of the heat exchanger evaporation side is calculated, and when the temperature difference is greater than the target superheat, the electronic expansion valve is opened and controlled, and when the temperature difference is less than the target superheat, the electronic expansion valve is closed and controlled; when the indoor unit demand load is less than or equal to 20%, the electronic expansion valve is controlled by the temperature collected by the main outlet temperature sensor of the heat exchanger, and the formula is as follows: Wherein y(t) is the control command value, i.e., the opening of the electronic expansion valve, Kp is the proportional gain, Ti is the integral constant, e(t)=x(t)-xopt(t), x(t) is the control object value, i.e., the main outlet temperature of the heat exchanger, xopt(t) is the optimal value of the control object, i.e., the target value of the main outlet temperature of the heat exchanger, and the target value of the main outlet temperature of the heat exchanger is Y=0.856*Ta-2, where Ta is the ambient temperature.

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