CN211204223U - Inverter air conditioning system - Google Patents

Abstract

The utility model discloses a variable frequency air conditioning system, temperature and pressure sensor that temperature sensor detected variable frequency compressor's the side of inhaling detect variable frequency compressor's the pressure value of inhaling and all send for the controller, the controller is according to receiving information and controlling the switching of first electronic expansion valve and second electronic expansion valve. When the variable frequency compressor runs in a low frequency state for more than the preset time, the second electronic expansion valve is controlled to be closed, a part of heat exchange tube loop in the evaporator does not participate in heat exchange, the volume and the heat exchange area of a refrigerant in the evaporator are reduced, so that the evaporation pressure is reduced, the refrigerant participating in heat exchange in the evaporator is reduced, the flow rate of the refrigerant is increased on the contrary, the suction side pressure of the variable frequency compressor is reduced, and the oil return effect of the refrigerant oil is improved. In addition, because the area participating in heat exchange is reduced, the air conditioner can output smaller refrigerating capacity under the same lowest compressor frequency, and the frequent starting and stopping conditions of the variable frequency compressor caused by low room heat load are reduced.

Description

Inverter air conditioning system

technical field

The utility model relates to the technical field of air conditioners, in particular to a frequency conversion air conditioner system.

Background technique

Most of the existing air conditioning and refrigeration systems are in the form of an expansion valve connected to an evaporator. After the refrigerant is depressurized by the expansion valve, it flows through the evaporator for heat exchange. The heat exchange area of the heat exchange pipeline in the evaporator is Fixed, and in the case of ensuring the air volume and air supply distance, when the cooling demand (heat load) is very small, it is mainly achieved by reducing the operating frequency of the compressor and adjusting the opening of the expansion valve. Under the condition of constant wind distance, it is easy to cause difficulty in oil return of refrigeration oil, unsatisfactory oil return effect, and frequent start and stop of the compressor, which will eventually damage the compressor, reduce the service life of the compressor, and affect the operation safety of the air conditioning unit. When the compressor runs at a low frequency, there are still the following shortcomings:

(1) When the operating parameters of the fan remain unchanged, in order to maintain a certain degree of suction superheat, the suction pressure will increase, which will cause the compressor to easily exceed the pressure operating range and reduce the service life of the compressor;

(2) Due to the small cooling demand and the small opening of the expansion valve, the flow rate on the evaporator side is reduced, and the flow rate of the refrigerant will affect the separation effect of the refrigeration oil mixed in the refrigerant, and the low flow rate cannot effectively bring the refrigeration oil back to the compressor. It is easy to cause compressor failure. If the oil return effect is enhanced by increasing the frequency of the compressor in a short time, the heat exchange of evaporation will increase accordingly, which will easily cause large fluctuations in the supply air temperature and affect the air outlet effect;

(3) Since the pipelines involved in heat exchange in the evaporator are fixed, the corresponding heat exchange area is also fixed. When the compressor operates at a low heat load (low cooling demand) and the compressor operates at the lowest frequency, the output cooling capacity will still be higher than The heat load is too large, which causes the compressor to start and stop frequently, and the room temperature fluctuates greatly, which increases the power consumption and reduces the service life of the compressor.

Utility model content

In view of the above-mentioned technical problems in the prior art, the utility model provides a hardware structure of a variable frequency air conditioning system. After being programmed by software personnel, the variable frequency air conditioning system can easily control the flow rate of the refrigerant in the evaporator, and can meet the requirements of smaller refrigeration capacity. At the same time, avoid frequent start and stop of the compressor.

For achieving the above object, the utility model provides the following technical solutions:

A variable frequency air conditioning system is provided, including an indoor unit, an outdoor unit, a variable frequency compressor, a liquid inlet pipeline and a liquid outlet pipeline, and the outdoor unit and the indoor unit are communicated through the liquid inlet pipeline, so that the refrigerant of the outdoor unit is flow to the indoor unit; the liquid outlet pipeline connects the indoor unit, the variable frequency compressor and the outdoor unit in sequence, so that the refrigerant of the indoor unit is compressed and flows to the outdoor unit; it is characterized by:

The indoor unit includes a plurality of heat exchange tube circuits, and the liquid inlet pipeline includes a first flow path that communicates with part of the heat exchange tube loop and a second flow path that communicates with another part of the heat exchange tube loop. The first flow path is in phase with the second flow path. In parallel, the first flow path includes the first electronic expansion valve and the first liquid separator, and the outdoor unit, the first electronic expansion valve, the first liquid separator and the indoor unit are connected in sequence; the second flow path includes the second electronic expansion valve and the first liquid separator. Second liquid separator, the outdoor unit, the second electronic expansion valve, the second liquid separator and the indoor unit are connected in sequence;

A pressure sensor and a temperature sensor are connected to the liquid outlet pipeline between the indoor unit and the variable frequency compressor; the variable frequency air conditioning system also includes a controller, the pressure sensor, the temperature sensor, the first electronic expansion valve and the second electronic expansion valve are respectively Electrically connect the controller.

Specifically, if the pressure value received by the controller exceeds the preset threshold value, it controls one of the first electronic expansion valve and the second electronic expansion valve to close, and the other keeps working.

Specifically, the outdoor unit includes a condenser and a condensation side fan for blowing and dissipating heat to the condenser.

Specifically, the indoor unit includes an evaporator and an evaporation side fan for blowing heat to the evaporator.

Specifically, the heat exchange tube loops communicated with the first flow path and the heat exchange tube loops communicated with the second flow path are arranged at intervals.

The control method for the low-frequency operation of the above-mentioned variable frequency air-conditioning system includes the following steps:

First, determine the maximum operating pressure Pmax of the suction side of the variable frequency compressor according to the model of the variable frequency compressor. The controller calculates the saturated suction temperature T1 according to the detection value P1 of the pressure sensor, and the suction temperature T2 is detected by the temperature sensor. Suction superheat T=T2-T1;

When P1≦Pmax﹣ pressure deviation, the first electronic expansion valve and the second electronic expansion valve synchronously adjust the refrigerant flow into the indoor unit according to the suction superheat degree T according to the same control opening degree, so as to ensure that the suction superheat degree T is within Within the control range set by the unit operation;

When the inverter compressor runs at a low frequency for more than a preset time and P1≧Pmax, the second electronic expansion valve is completely closed until P1 is reduced to below Pmax, and then the first electronic expansion valve is adjusted according to the suction superheat degree T. refrigerant flow.

Specifically, when the inverter compressor re-enters the non-low frequency operation, and the frequency increases so that P1 satisfies the pressure deviation of P1≦Pmax﹣, the second electronic expansion valve is first opened to the minimum opening degree, and then the same as the suction superheat degree T. speed, increase the opening degree of the second electronic expansion valve, decrease the opening degree of the first electronic expansion valve, until the opening degrees of the first electronic expansion valve and the second electronic expansion valve are the same, and then simultaneously increase or decrease the first electronic expansion valve at the same speed. The opening degrees of the first electronic expansion valve and the second electronic expansion valve are so as to keep the intake superheat degree T within the set range.

Specifically, the pressure deviation is 1 bar.

Specifically, the preset time is 2 minutes.

The beneficial effects of the present utility model:

In the variable frequency air conditioning system of the utility model, after the software personnel have programmed, the temperature sensor detects the temperature on the suction side of the variable frequency compressor, and the pressure sensor detects the suction pressure value of the variable frequency compressor and sends them to the controller. The information controls the opening and closing of the first electronic expansion valve and the second electronic expansion valve. When the inverter compressor runs at a low frequency for more than a preset time, the first electronic expansion valve and the second electronic expansion valve are controlled, so that because the second electronic expansion valve is closed, part of the heat exchange pipe loop in the evaporator does not participate. Heat exchange, the refrigerant volume and heat exchange area in the evaporator are reduced, which reduces the evaporating pressure, reduces the refrigerant involved in heat exchange in the evaporator, and increases the refrigerant flow rate, thereby reducing the suction side pressure of the inverter compressor. Improve the oil return effect of refrigeration oil. In addition, because the area involved in heat exchange is reduced, under the same minimum compressor frequency, the air conditioner can output a smaller cooling capacity, reducing the frequent start and stop of the inverter compressor caused by the low heat load of the room.

Description of drawings

FIG. 1 is a schematic structural diagram of an inverter air conditioning system in an embodiment.

Reference number:

Indoor unit 1, evaporator 11, evaporation side fan 12;

Outdoor unit 2, condenser 21, condensing side fan 22;

Inverter compressor 3;

Liquid inlet pipeline 4, first electronic expansion valve 411, first liquid separator 412, second electronic expansion valve 421, second liquid separator 422;

Liquid outlet pipeline 5; pressure sensor 6; temperature sensor 7.

Detailed ways

The present utility model will be described in detail below with reference to specific embodiments and accompanying drawings.

The variable frequency air conditioning system of this embodiment, as shown in FIG. 1 , includes an indoor unit 1, an outdoor unit 2, a variable frequency compressor 3, a liquid inlet pipeline 4 and a liquid outlet pipeline 5, and the outdoor unit 2 includes a condenser 21 and a The condensation side fan 22 for blowing heat to the condenser 21 , and the indoor unit 1 includes the evaporator 11 and the evaporation side fan 12 for blowing and cooling the evaporator 11 . The condenser 21 and the evaporator 11 are communicated through the liquid inlet pipeline 4 , so that the refrigerant in the condenser 21 flows to the evaporator 11 . The liquid outlet pipeline 5 connects the evaporator 11 , the inverter compressor 3 and the condenser 21 in sequence, so that the refrigerant in the evaporator 11 is compressed and flows to the condenser 21 . The liquid inlet pipeline 4 includes a first flow path and a second flow path in parallel, the first flow path includes a first electronic expansion valve 411 and a first liquid separator 412, the condenser 21, the first electronic expansion valve 411, the first The liquid container 412 is communicated with the evaporator 11 in sequence. The second flow path includes a second electronic expansion valve 421 and a second liquid separator 422 , and the outdoor unit 2 , the second electronic expansion valve 421 , the second liquid separator 422 and the evaporator 11 are communicated in sequence. A pressure sensor 6 and a temperature sensor 7 are connected to a position of the liquid outlet pipeline 5 between the evaporator 11 and the inverter compressor 3 . The inverter air conditioning system further includes a controller, and the pressure sensor 6, the temperature sensor 7, the first electronic expansion valve 411 and the second electronic expansion valve 421 are respectively electrically connected to the controller. After the software engineer programs the controller, the system can realize that the temperature sensor 7 detects the temperature of the suction side of the variable frequency compressor 3 and the pressure sensor 6 detects the suction pressure value of the variable frequency compressor 3 and sends them to the controller to control. The controller controls the opening and closing of the first electronic expansion valve 411 and the second electronic expansion valve 421 according to the received information.

The control method for the low-frequency operation of the above-mentioned air conditioning system, the control method is completed by establishing a functional module framework, and the computer system is controlled by a computer program instruction, and the control method specifically includes the following steps:

First determine the maximum operating pressure Pmax of the suction side of the variable frequency compressor 3 according to the model of the variable frequency compressor 3, and the controller calculates the saturated suction temperature T1 according to the detection value P1 of the pressure sensor 6 (T1 can be determined according to the type of refrigerant, through P1 Checking the pressure-temperature curve table shows that the parameters are in one-to-one correspondence), the intake air temperature T2 is detected by the temperature sensor 7, and the intake superheat degree T=T2-T1 is calculated.

When P1≦Pmax﹣1bar (1bar is equal to 10^5Pa, which is used as a pressure deviation, minus 1bar is an empirical value, or it can be minus 0.5bar or 1.5bar), the first electronic expansion valve 411 and the second electronic expansion valve 421 According to the suction superheat degree T, the refrigerant flow into the indoor unit 1 is synchronously adjusted according to the same control opening degree to ensure that the suction superheat degree T is within the control range set by the unit operation. At this time, the first flow path and the second flow path are Lu Jun participated in the work, and the heat exchange area was fully utilized.

When the inverter compressor 3 runs at a low frequency for more than a preset time (experience value 2min) and P1≧Pmax, the second electronic expansion valve 421 is completely closed until P1 is reduced to below Pmax, and then the first electronic expansion valve 421 is closed. 411 Adjust the refrigerant flow according to the suction superheat degree T. During this process, since the second electronic expansion valve 421 is closed, the heat exchange tube circuit in the evaporator 11 that communicates with the second circuit does not participate in heat exchange, (the first flow path and the second flow path are respectively connected to the parallel circuits of the indoor unit 1 . A plurality of heat exchange tube loops, the outlets of the plurality of loops are integrated and communicated with the same tube and then communicated with the inverter compressor 3. The heat exchange tube loops communicated with the first flow path and the heat exchange tube loops communicated with the second flow path are arranged at intervals), The volume and heat exchange area of the refrigerant in the evaporator 11 are reduced, so that the evaporation pressure is reduced, the refrigerant participating in the heat exchange in the evaporator 11 is reduced, and the flow rate of the refrigerant is increased, thereby reducing the suction side pressure of the inverter compressor 3. At the same time Improve the oil return effect of refrigeration oil. In addition, because the area involved in heat exchange is reduced, under the same minimum compressor frequency, the air conditioner can output a smaller cooling capacity, reducing the frequent start and stop of the inverter compressor 3 due to low room heat load.

When the inverter compressor 3 re-enters the non-low frequency operation, and the frequency increases so that P1 satisfies P1≦Pmax﹣1bar, the second electronic expansion valve 421 first opens to the minimum opening degree, and then simultaneously according to the suction superheat degree T at the same speed , increase the opening degree of the second electronic expansion valve 421 and decrease the opening degree of the first electronic expansion valve 411 until the opening degrees of the first electronic expansion valve 411 and the second electronic expansion valve 421 are the same, and then increase or decrease synchronously at the same speed. The opening degrees of the first electronic expansion valve 411 and the second electronic expansion valve 421 are reduced so that the intake superheat degree T is kept within the set range.

Numerical example:

Assume that the inverter compressor 3 with Pmax=15.6bar is selected, and the unit system uses R410A refrigerant. It is assumed that the inverter compressor 3 runs at a low frequency for more than 2 minutes, and the pressure sensor 6 detects the suction side pressure of the inverter compressor 3. The value is P1=16bar, corresponding to the table, we can see that the saturated suction temperature T1=25.84℃ at this time, assuming that the temperature sensor 7 detects the suction temperature T2=32.84℃, the suction superheat degree T=T2-T1=7 °C.

Since P1≧Pmax at this time, the first electronic expansion valve 411 is closed, and only the first electronic expansion valve 411 adjusts the refrigerant flow rate according to the suction superheat degree T. At this time, the cooling capacity decreases, but the refrigerant flow rate does not decrease.

When P1 satisfies P1≦Pmax﹣1bar=14.6bar, first open the second electronic expansion valve 421 to the minimum opening degree, and then increase the opening of the second electronic expansion valve 421 at the same speed according to the suction superheat degree T at the same time. increase or decrease the opening degree of the first electronic expansion valve 411 until the opening degrees of the first electronic expansion valve 411 and the second electronic expansion valve 421 are the same, and then simultaneously increase or decrease the first electronic expansion valve 411 and the second electronic expansion valve 421 at the same speed. The opening degree of the second electronic expansion valve 421 keeps the intake superheat degree T within the set range.

Since the pressure detected by the pressure sensor 6 and the temperature detected by the temperature sensor 7 change in real time, the re-detection calculation and judgment adjustment are performed in a cycle of 30 seconds, so the suction superheat T is a dynamic process, and the entire system adjustment is also dynamic. , so as to ensure the air outlet effect and control accuracy of the unit.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the protection scope of the present invention. Persons should understand that the technical solutions of the present invention may be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.

Claims (4)

1. Inverter air conditioning system, including indoor unit, outdoor unit, inverter compressor, liquid inlet pipeline and liquid outlet pipeline. The outdoor unit and the indoor unit are connected through the liquid inlet pipeline, so that the refrigerant of the outdoor unit can flow. to the indoor unit; the liquid outlet pipeline connects the indoor unit, the variable frequency compressor and the outdoor unit in sequence, so that the refrigerant of the indoor unit is compressed and flows to the outdoor unit; it is characterized by: The indoor unit includes a plurality of heat exchange tube circuits, and the liquid inlet pipeline includes a first flow path that communicates with part of the heat exchange tube loop and a second flow path that communicates with another part of the heat exchange tube loop. The first flow path is in phase with the second flow path. In parallel, the first flow path includes the first electronic expansion valve and the first liquid separator, and the outdoor unit, the first electronic expansion valve, the first liquid separator and the indoor unit are connected in sequence; the second flow path includes the second electronic expansion valve and the first liquid separator. Second liquid separator, the outdoor unit, the second electronic expansion valve, the second liquid separator and the indoor unit are connected in sequence; A pressure sensor and a temperature sensor are connected to the liquid outlet pipeline between the indoor unit and the variable frequency compressor; the variable frequency air conditioning system also includes a controller, the pressure sensor, the temperature sensor, the first electronic expansion valve and the second electronic expansion valve are respectively Electrically connect the controller. 2 . The variable frequency air conditioning system according to claim 1 , wherein the outdoor unit comprises a condenser and a condensation side fan for blowing and radiating heat to the condenser. 3 . 3 . The variable frequency air conditioning system according to claim 1 , wherein the indoor unit comprises an evaporator and an evaporative side fan for blowing and dissipating heat to the evaporator. 4 . 4 . The inverter air conditioning system according to claim 1 , wherein the heat exchange tube loops communicated with the first flow path and the heat exchange tube loops communicated with the second flow path are arranged at intervals. 5 .

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