Air conditioning system and defrosting control method thereof

Abstract

An air-conditioning system and a defrost control method thereof, the air-conditioning system comprising a compressor, a four-way reversing valve, an outdoor heat exchanger, a throttle valve, a flow regulating valve, an indoor heat exchanger, a liquid reservoir, a temperature sensor, a liquid level sensor and a control module; the air-conditioning system may have a liquid hammer phenomenon during the reverse cycle defrosting process, which will increase system noise and reduce the reliability of the compressor. At the end of defrosting, a large amount of liquid refrigerant accumulates in the liquid reservoir, which is not conducive to reheating after the end of defrosting. The present invention proposes a defrost control method, which dynamically couples and controls the openings of the throttle valve and the flow regulating valve according to the defrosting situation on the surface of the outdoor heat exchanger and the liquid level height of the liquid reservoir, thereby preventing the occurrence of compressor liquid hammer phenomenon and reducing the liquid refrigerant in the liquid reservoir at the end of defrosting.

Description

Technical Field

[0001] The present invention relates to the technical field of air-conditioning systems, and in particular to an air-conditioning system and a control method thereof. Background Art

[0002] Air conditioners have been widely used in various fields due to their high system energy efficiency. However, when operating in a high humidity and low temperature environment for heating, frost will form on the surface of the outdoor heat exchanger. The growth of frost will lead to a decrease in air flow and an increase in heat transfer resistance. Therefore, reverse cycle defrosting of the air conditioning system is necessary, which is an important means to ensure the efficient operation of the air conditioning system.

[0003] When the air-conditioning system performs reverse cycle defrosting, the refrigerant entering the liquid receiver is generally two-phase refrigerant, which will cause the liquid level in the liquid receiver to continue to increase until liquid hammer occurs. The occurrence of liquid hammer will increase the noise during system operation and may damage the compressor. In addition, at the end of defrosting, a large amount of liquid refrigerant will accumulate in the liquid receiver. When the air-conditioning system starts heating again after defrosting, this part of the refrigerant can only circulate through the system in the form of flash evaporation, which will extend the time for the compressor to start and establish high and low pressure differences, which is not conducive to the air-conditioning system to quickly blow hot air, reduces the energy efficiency of the air-conditioning system, and affects the thermal comfort of the air-conditioning system. Summary of the Invention

[0004] In response to the problems existing in the air-conditioning system described above, the purpose of the present invention is to provide an air-conditioning system and a defrost control method thereof, by real-time monitoring of the surface temperature of the outdoor heat exchanger 03 to obtain the defrosting status of the surface of the outdoor heat exchanger 03, and also real-time monitoring of the liquid level height of the liquid reservoir 07 to prevent liquid hammer in the compressor 01, and by using the surface temperature of the outdoor heat exchanger 03 and the liquid level height of the liquid reservoir 07 as logical control criteria, the opening of the throttle valve 05 and the flow control valve 09 are dynamically coupled and adjusted, thereby improving the defrosting efficiency of the heat pump system and preventing liquid hammer during the defrosting process, and in the later stage of defrosting, a large amount of high-temperature exhaust gas from the compressor 01 is bypassed to heat the liquid refrigerant in the liquid reservoir 07, thereby reducing the liquid refrigerant in the liquid reservoir 07 at the end of defrosting.

[0005] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0006] An air conditioning system includes a compressor 01, a four-way reversing valve 02, an outdoor heat exchanger 03, a temperature sensor 04, a throttle valve 05, an indoor heat exchanger 06, a liquid reservoir 07, a liquid level sensor 08, a flow regulating valve 09 and a control module C1. The compressor exhaust port 100 is connected to the first port 21 of the four-way reversing valve and the flow regulating valve 09 respectively. The flow regulating valve 09 is connected to the liquid reservoir 07. The copper pipe connecting the liquid reservoir 07 and the flow regulating valve 09 extends into the liquid reservoir 07. The compressor intake port 101 is connected to the liquid reservoir outlet 72. The third port 23 of the four-way reversing valve is connected to the liquid reservoir inlet 71. The fourth port 24 of the reversing valve is connected to the indoor heat exchanger 06, and the second port 22 of the four-way reversing valve is connected to the outdoor heat exchanger 03. The outdoor heat exchanger 03 and the indoor heat exchanger (06) are connected through the throttle valve 05. The temperature sensor 04 is installed in the middle position of the outdoor heat exchanger 03, and the liquid level sensor 08 is installed inside the liquid reservoir 07 for measuring the liquid level height in the liquid reservoir 07. The control module C1 is connected to the temperature sensor 04, the throttle valve 05, the liquid level sensor 08 and the flow control valve 09, and is used to collect signals from the temperature sensor 04 and the liquid level sensor 08, and control the opening of the throttle valve 05 and the flow control valve 09.

[0007] In the defrosting control method for an air-conditioning system, the temperature sensor 04 and the liquid level sensor 08 output signals to the control module C1, and the control module C1 controls the opening of the throttle valve 05 and the flow control valve 09 according to the pre-written control logic; during the reverse cycle defrosting process of the air-conditioning system, the liquid refrigerant in the liquid reservoir 07 will gradually increase until liquid hammer occurs. Liquid hammer will cause a large noise and is not conducive to the reliability of the compressor 01. In addition, at the end of defrosting, a large amount of liquid refrigerant will accumulate in the liquid reservoir 07. When the air-conditioning system is restarted after defrosting, this Part of the refrigerant can only enter the system circulation in the form of flash evaporation, which is not conducive to the establishment of high and low pressures in the air-conditioning system and prolongs the startup phase. By dynamically coupling and adjusting the throttle valve 05 and the flow control valve 09, liquid hammer during the defrosting process can be prevented, and the exhaust gas of the compressor 01 is used to heat the liquid refrigerant in the liquid reservoir 07, reducing the liquid refrigerant in the liquid reservoir 07 at the end of the defrosting and shortening the time of the defrosting restart phase. K1 represents the temperature value measured by the temperature sensor 04, and l1 represents the liquid level measured by the liquid level sensor 08. The specific control is as follows:

[0008] In the initial stage of defrosting, the opening of the throttle valve 05 is n1, the flow regulating valve 09 is closed, and the control module C1 monitors the changes of temperature and liquid level once at a preset time. As the defrosting progresses, when the temperature k1 < k n1 , and the liquid level l1<l n1 When the temperature k1<k n1, and the liquid level l n2 ≥l1≥l n1 When the temperature k1≥k n1 , and the liquid level l1≤l n2 When the temperature k n2 >k1≥k n1 , and the liquid level l1>l n2 When the temperature k n3 >k1≥k n2 When the temperature is used as the control basis, the opening of the throttle valve 05 is kept at n4, and the opening of the flow control valve 09 is set to f3; when the temperature k1 ≥ k n3 When the air conditioning system exits the defrost mode,

[0009] The k n1 、k n2 、k n3 、 l n2 The value ranges of n1, n2, n3, n4, f1, f2, and f3 are as follows:

[0010]

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] 1. The present invention proposes an air-conditioning system and a defrost control method thereof, which can dynamically couple the openings of the throttle valve and the flow regulating valve according to the defrost condition of the outdoor heat exchanger surface and the liquid level height of the liquid reservoir to prevent the occurrence of liquid hammer.

[0013] 2. The present invention proposes a microchannel heat exchanger and a working method thereof, which can dynamically couple the opening of the throttle valve and the flow regulating valve according to the defrosting condition of the outdoor heat exchanger surface and the liquid level height of the liquid reservoir, thereby reducing the liquid refrigerant in the liquid reservoir at the end of defrosting. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The figure is a schematic diagram of the refrigerant flow in an air-conditioning system under defrosting conditions according to the present invention. DETAILED DESCRIPTION

[0015] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0016] like Figure 1The air conditioning system includes a compressor 01, a four-way reversing valve 02, an outdoor heat exchanger 03, a temperature sensor 04, a throttle valve 05, an indoor heat exchanger 06, a liquid reservoir 07, a liquid level sensor 08, a flow regulating valve 09 and a control module C1. The compressor exhaust port 100 is respectively connected to the first port 21 of the four-way reversing valve and the flow regulating valve 09, and the flow regulating valve 09 is connected to the liquid reservoir 07. The copper pipe connecting the liquid reservoir 07 and the flow regulating valve 09 is inserted into the liquid reservoir 07 and is 2 cm to 3 cm away from the bottom of the liquid reservoir 07. The compressor intake port 101 is connected to the liquid reservoir outlet 72, and the third port 23 of the four-way reversing valve is connected to the liquid reservoir inlet 7. 1, the fourth port 24 of the four-way reversing valve is connected to the indoor heat exchanger 06, the second port 22 of the four-way reversing valve is connected to the outdoor heat exchanger 03, the outdoor heat exchanger 03 is connected to the throttle valve 05, and the throttle valve 05 is connected to the indoor heat exchanger 06; the temperature sensor 04 is installed in the middle position of the outdoor heat exchanger 03, and the liquid level sensor 08 is installed inside the liquid reservoir 07 for measuring the liquid level height in the liquid reservoir 07; the control module C1 is connected to the temperature sensor 04, the throttle valve 05, the liquid level sensor 08 and the flow control valve 09, and is used to collect signals from the temperature sensor 04 and the liquid level sensor 08, and control the opening of the throttle valve 05 and the flow control valve 09.

[0017] The working process of the air conditioning system of the present invention is as follows: Figure 1 As shown, when the flow regulating valve 09 is opened, part of the high-temperature and high-pressure refrigerant coming out of the compressor 01 enters the four-way reversing valve 02, and part enters the liquid accumulator 07 to heat the liquid refrigerant. When the flow regulating valve 09 is closed, all the high-temperature and high-pressure refrigerant coming out of the compressor 01 enters the four-way reversing valve 02. The refrigerant coming out of the four-way reversing valve 02 then enters the outdoor heat exchanger 03 for defrosting. The refrigerant coming out of the outdoor heat exchanger 03 is throttled to a low-temperature and low-pressure state after passing through the throttle valve 05, and then enters the indoor heat exchanger 06 for evaporation heat exchange. The refrigerant coming out of the indoor heat exchanger 06 passes through the four-way reversing valve 02 and enters the liquid accumulator 07, and finally enters the compressor 01 for compression.

[0018] In the defrosting control method for an air-conditioning system of the present invention, the temperature sensor 04 and the liquid level sensor 08 output signals to the control module C1, and the control module C1 controls the opening of the throttle valve 05 and the flow control valve 09 according to the pre-written control logic. During the reverse cycle defrosting process of the air-conditioning system, the liquid refrigerant in the liquid reservoir 07 will gradually increase until liquid hammer occurs. Liquid hammer will cause a large amount of noise and is not conducive to the reliability of the compressor 01. In addition, at the end of defrosting, a large amount of liquid refrigerant will accumulate in the liquid reservoir 07. During the restart phase of the air-conditioning system after defrosting, This part of the refrigerant can only enter the system circulation in the form of flash evaporation, which is not conducive to the establishment of high and low pressures in the air-conditioning system and prolongs the startup phase. By dynamically coupling the throttle valve 05 and the flow control valve 09, liquid hammer can be prevented during the defrosting process. The exhaust gas of the compressor 01 is used to heat the liquid refrigerant in the liquid reservoir 07, reducing the liquid refrigerant in the liquid reservoir 07 at the end of the defrosting and shortening the time of the defrosting restart phase. K1 represents the temperature value measured by the temperature sensor 04, and l1 represents the liquid level measured by the liquid level sensor 08. The specific control is as follows:

[0019] In the initial stage of defrosting, the opening of the throttle valve 05 is n1, the flow regulating valve 09 is closed, and the control module C1 monitors the changes in temperature and liquid level every 5 seconds. As the defrosting progresses, when the temperature k1 < k n1 , and the liquid level l1<l n1 When the temperature k1<k n1 , and the liquid level l n2 ≥l1≥l n1 When the temperature k1≥k n1 , and the liquid level l1≤l n2 When the temperature k n2 >k1≥k n1 , and the liquid level l1>l n2 When the temperature k n3 >k1≥k n2 When the temperature is used as the control basis, the opening of the throttle valve 05 is kept at n4, and the opening of the flow control valve 09 is set to f3; when the temperature k1 ≥ k n3 When the air conditioning system exits the defrost mode,

[0020] The k n1 、k n2 、k n3 、 l n2The value ranges of n1, n2, n3, n4, f1, f2, and f3 are as follows:

[0021]

Claims

1. An air conditioning system, characterized in that: The invention comprises a compressor (01), a four-way reversing valve (02), an outdoor heat exchanger (03), a temperature sensor (04), a throttle valve (05), an indoor heat exchanger (06), a liquid reservoir (07), a liquid level sensor (08), a flow regulating valve (09) and a control module (C1); the compressor exhaust port (100) is respectively connected to the first port (21) of the four-way reversing valve and the flow regulating valve (09); the flow regulating valve (09) is connected to the liquid reservoir (07); the copper pipe connecting the liquid reservoir (07) and the flow regulating valve (09) is extended into the liquid reservoir (07); the compressor intake port (101) is connected to the liquid reservoir outlet (72); the four-way reversing valve third port (23) is connected to the liquid reservoir inlet (71); The fourth port (24) of the four-way reversing valve is connected to the indoor heat exchanger (06), the second port (22) of the four-way reversing valve is connected to the outdoor heat exchanger (03), and the outdoor heat exchanger (03) and the indoor heat exchanger (06) are connected via the throttle valve (05); the temperature sensor (04) is installed on the outdoor heat exchanger (03), and the liquid level sensor (08) is installed inside the liquid reservoir (07) for measuring the liquid level height in the liquid reservoir (07); the control module (C1) is connected to the temperature sensor (04), the throttle valve (05), the liquid level sensor (08) and the flow regulating valve (09), and is used to collect signals from the temperature sensor (04) and the liquid level sensor (08), and control the opening of the throttle valve (05) and the flow regulating valve (09).

2. An air conditioning system according to claim 1, characterized in that: The copper tube connecting the liquid reservoir (07) and the flow regulating valve (09) is inserted into the liquid reservoir (07) and is 2 cm to 3 cm away from the bottom of the liquid reservoir (07).

3. The air conditioning system according to claim 1, characterized in that: The temperature sensor (04) is installed in the middle of the outdoor heat exchanger (03).

4. The defrost control method for an air conditioning system according to any one of claims 1 to 3, characterized in that: The temperature sensor (04) and the liquid level sensor (08) output signals to the control module (C1), and the control module (C1) controls the opening of the throttle valve (05) and the flow control valve (09); during the reverse cycle defrosting process of the air conditioning system, the liquid phase refrigerant in the liquid reservoir (07) will gradually increase until liquid hammering occurs, which will cause noise and reduce the reliability of the compressor (01). At the end of defrosting, liquid phase refrigerant will accumulate in the liquid reservoir (07). During the restart phase after the defrosting of the air conditioning system, this part of the refrigerant can only enter the system circulation in the form of flash evaporation, which prolongs the time of the startup phase; by dynamically coupling and adjusting the throttle valve (05) and the flow control valve (09), the liquid hammer phenomenon during the defrosting process can be prevented, and the exhaust gas of the compressor (01) is used to heat the liquid phase refrigerant in the liquid reservoir (07), thereby reducing the liquid phase refrigerant in the liquid reservoir (07) at the end of defrosting and shortening the time of the restart phase of defrosting; K1 represents the temperature value measured by the temperature sensor (04), and l1 represents the liquid level measured by the liquid level sensor (08). The specific control is as follows: In the initial stage of defrosting, the opening of the throttle valve (05) is n1, the flow regulating valve (09) is closed, and the control module (C1) monitors the changes of temperature and liquid level at a preset time. As the defrosting progresses, when the temperature k1 < k n1 , and the liquid level l1<l n1 When the temperature k1<k n1 , and the liquid level l n2 ≥l1≥l n1 When the temperature k1≥k n1 , and the liquid level l1≤l n2 When the temperature k n2 >k1≥k n1 , and the liquid level l1>l n2 When the temperature k n3 >k1≥k n2 When the temperature is used as the control basis, the throttle valve (05) opening is kept at n4, and the flow control valve (09) opening is set to f3; when the temperature k1 ≥ k n3 When the air conditioning system exits the defrost mode, The k n1 、k n2 、k n3 、 l n2 The value ranges of n1, n2, n3, n4, f1, f2, and f3 are as follows:

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