Air conditioning system and control method thereof

Abstract

The embodiment of the invention provides an air conditioning system and a control method thereof. The air conditioning system comprises a compressor; a first heat exchanger; the throttling device comprises a first throttling element and at least one second throttling element, and the first throttling element and the second throttling element are connected with the first heat exchanger; and the second heat exchanger comprises multiple stages of heat exchange units, the multiple stages of heat exchange units are sequentially connected in series and then connected with the first throttling element and the compressor, and the second throttling elements are connected to connecting pipelines of the upper-stage heat exchange unit and the lower-stage heat exchange unit in a one-to-one correspondence mode.

Description

Technical Field

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

[0002] In air conditioning systems, the evaporator's heat transfer coefficient and heat transfer pressure drop significantly impact its heat transfer performance. How to effectively balance these two factors is a pressing technical challenge in related technologies. Summary of the Invention

[0003] The embodiments of the present application provide an air-conditioning system and a control method thereof, which can better balance the heat transfer coefficient and the heat transfer pressure loss, and effectively improve the evaporation heat transfer effect of the evaporator.

[0004] On the one hand, an embodiment of the present application provides an air-conditioning system, comprising: a compressor; a first heat exchanger; a throttling device, comprising a first throttling element and at least one second throttling element, the first throttling element and the second throttling element being respectively connected to the first heat exchanger; a second heat exchanger, comprising a multi-stage heat exchange unit, the multi-stage heat exchange units being connected in series in sequence and then connected to the first throttling element and the compressor, and the second throttling elements being connected one-to-one to the connecting pipes of the upper and lower stages of the heat exchange units.

[0005] In some embodiments, the second heat exchanger includes at least one mixer, which is arranged on the connecting pipeline of the upper and lower heat exchange units; when the second heat exchanger serves as an evaporator, the mixer is configured to evenly mix the refrigerant flowing out of the heat exchange unit of the upper level and the refrigerant flowing into the connecting pipeline from the second throttling device, and output the evenly mixed refrigerant to the heat exchange unit of the next level.

[0006] In some embodiments, the mixer is a refrigerant mixing tank, and the mixer is further provided with an air outlet, which is connected to the air intake of the compressor.

[0007] In some embodiments, the air conditioning system further includes a third throttle member connecting the outlet of the mixer and the suction port of the compressor.

[0008] In some embodiments, the air-conditioning system includes at least one micro-flow bypass branch, one end of the micro-flow bypass branch is connected to the connecting pipeline of the upper and lower heat exchange units, and the other end is connected to the intake port of the compressor. The connection point between the micro-flow bypass branch and the connecting pipeline is located between the refrigerant outlet of the heat exchange unit of the upper level and the connection point between the second throttling device and the connecting pipeline, so that the micro-flow bypass branch will lead part of the refrigerant flowing out of the heat exchange unit of the upper level to the intake port of the compressor; a fourth throttling device and an electric heater are provided on the micro-flow bypass branch, the fourth throttling device is connected to the intake port of the compressor, and the electric heater is arranged between the fourth throttling device and the intake port to heat the refrigerant flowing from the fourth throttling device to the intake port.

[0009] In some embodiments, the second heat exchanger includes a multi-stage distributor, and the multi-stage distributors and the multi-stage heat exchange units are arranged in a one-to-one correspondence; the heat exchange unit includes a plurality of heat exchange branches arranged in parallel, and the distributor is respectively connected to the plurality of heat exchange branches; when the second heat exchanger is used as an evaporator, the distributor is configured to evenly distribute the refrigerant to the plurality of heat exchange branches.

[0010] In some embodiments, the heat exchange area ratio of the heat exchange unit of the previous stage to the heat exchange unit of the next stage is 0.25-1.

[0011] On the other hand, an embodiment of the present application provides an air-conditioning system control method for controlling the air-conditioning system described in any of the above embodiments, including: determining whether the outlet dryness of the heat exchange unit is within a target dryness range; when it is determined that the outlet dryness of the heat exchange unit is outside the target dryness range, determining an opening adjustment amount according to the outlet dryness of the heat exchange unit; adjusting the opening of the throttling device corresponding to the heat exchange unit according to the opening adjustment amount to adjust the outlet dryness of the heat exchange unit to within the target dryness range.

[0012] In some embodiments, before determining whether the outlet dryness of the heat exchange unit is within the target dryness range, the air-conditioning system control method includes: obtaining the outlet pressure, outlet temperature and outlet flow of the heat exchange unit; and determining the outlet dryness of the heat exchange unit based on the outlet pressure, outlet temperature and outlet flow of the heat exchange unit.

[0013] In some embodiments, obtaining the outlet flow of the heat exchange unit includes: obtaining the outdoor ambient temperature, the indoor ambient temperature and the set temperature; determining the capacity requirement percentage of the air-conditioning system based on the outdoor ambient temperature, the indoor ambient temperature and the set temperature; determining the outlet flow of the heat exchange unit based on the capacity requirement percentage of the air-conditioning system and the full load mass flow of the heat exchange unit.

[0014] In some embodiments, the air-conditioning system includes at least one micro-flow bypass branch, one end of the micro-flow bypass branch is connected to the connecting pipeline of the upper and lower heat exchange units, and the other end is connected to the air intake of the compressor, and the connection point between the micro-flow bypass branch and the connecting pipeline is located between the refrigerant outlet of the heat exchange unit of the upper stage and the connection point of the second throttling member and the connecting pipeline, so that the micro-flow bypass branch will lead part of the refrigerant flowing out of the heat exchange unit of the upper stage to the air intake of the compressor; a fourth throttling member and an electric heater are provided on the micro-flow bypass branch, and the fourth throttling member is connected to the air intake of the compressor. Then, the electric heater is arranged between the fourth throttle member and the air intake port to heat the refrigerant flowing from the fourth throttle member to the air intake port; before determining whether the outlet dryness of the heat exchange unit is within the target dryness range, the air-conditioning system control method includes: adjusting the opening of the fourth throttle member connected to the refrigerant outlet of the heat exchange unit to allow the refrigerant in the micro-flow bypass branch where the fourth throttle member is located to completely evaporate; when the refrigerant in the micro-flow bypass branch where the fourth throttle member is located is completely evaporated, obtaining the refrigerant flow of the micro-flow bypass branch; and determining the outlet dryness of the heat exchange unit based on the refrigerant flow of the micro-flow bypass branch.

[0015] The embodiment of the present application sets multiple throttling parts and a second heat exchanger including a multi-stage heat exchange unit. When the second heat exchanger is used as an evaporator, the refrigerant condensed by the first heat exchanger can be diverted to each throttling part to form multiple parts of refrigerant. The first part of the low-temperature and high-pressure liquid refrigerant is throttled by the first throttling part and flows into the first-stage heat exchange unit for evaporation. The i-th part of the refrigerant is throttled by the i-1th second throttling part and is evenly mixed with the refrigerant evaporated by the i-1th stage heat exchange unit, and then flows into the i-stage heat exchange unit for evaporation. On the one hand, it can be achieved by The heat exchange pressure loss can be reduced by diverting the refrigerant and performing multi-stage evaporation. On the other hand, the opening of the first throttling device can be controlled to control the dryness of the first-stage heat exchange unit within the corresponding target dryness range, and an appropriate amount of liquid refrigerant that has not yet been evaporated can be added to the i-th stage heat exchange unit through the i-1th second throttling device to control the dryness of the i-th stage heat exchange unit within the corresponding target dryness range. The heat transfer coefficient of each stage of the heat exchange unit can be improved through dryness control, thereby better balancing the heat transfer coefficient and heat exchange pressure loss, and effectively improving the evaporation heat exchange effect of the evaporator. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 This is a connection structure diagram of an air conditioning system provided by some embodiments of the present application;

[0018] Figure 2 is another partial connection structure diagram of the air-conditioning system provided in some embodiments of the present application;

[0019] Figure 3 is another connection structure diagram of the air conditioning system provided in some embodiments of the present application;

[0020] Figure 4 This is another connection structure diagram of the air conditioning system provided in some embodiments of the present application;

[0021] Figure 5 This is another connection structure diagram of the air conditioning system provided in some embodiments of the present application;

[0022] Figure 6 This is another connection structure diagram of the air conditioning system provided in some embodiments of the present application;

[0023] Figure 7 is a flow chart of an air conditioning system control method provided by some embodiments of the present application;

[0024] Figure 8 is a partial flow chart of an air-conditioning system control method provided by some embodiments of the present application;

[0025] Figure 9 is another partial flow chart of the air-conditioning system control method provided by some embodiments of the present application;

[0026] Figure 10 This is another partial flow chart of the air-conditioning system control method provided in some embodiments of the present application.

[0027] Description of main component symbols:

[0028] 10-compressor, 20-first heat exchanger, 30-throttling device, 31-first throttling element, 32-second throttling element, 40-second heat exchanger, 41-heat exchange unit, 411-heat exchange branch, 42-distributor, 50-mixer, 51-air outlet, 60-third throttling element, 70-micro-flow bypass branch, 71-fourth throttling element, 72-electric heater, 80-four-way valve. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0030] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0031] “A and / or B” includes the following three combinations: A only, B only, and a combination of A and B.

[0032] The use of "suitable for" or "configured to" in this application is intended to be open and inclusive language, and does not exclude devices that are adapted or configured to perform additional tasks or steps. In addition, the use of "based on" is intended to be open and inclusive, as a process, step, calculation, or other action that is "based on" one or more stated conditions or values ​​may, in practice, be based on additional conditions or values ​​beyond those stated.

[0033] In this application, the word "exemplary" is used to mean "serving as an example, illustration, or illustration." Any embodiment described in this application as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. The following description is given to enable any person skilled in the art to implement and use the present application. In the following description, details are listed for the purpose of explanation. It should be understood that one of ordinary skill in the art can recognize that the present application can be implemented without using these specific details. In other instances, well-known structures and processes are not elaborated in detail to avoid obscuring the description of the present application with unnecessary details. Therefore, the present application is not intended to be limited to the embodiments shown, but is consistent with the widest scope consistent with the principles and features disclosed in this application.

[0034] like Figures 1 to 6 As shown, on the one hand, an embodiment of the present application provides an air-conditioning system, which includes a compressor 10, a first heat exchanger 20, a throttling device 30 and a second heat exchanger 40, which can better balance the heat transfer coefficient and the heat transfer pressure loss, and effectively improve the evaporation heat transfer effect of the evaporator.

[0035] The throttling device 30 includes a first throttling member 31 and at least one second throttling member 32, each of which is connected to the first heat exchanger 20. The second heat exchanger 40 includes a multi-stage heat exchange unit 41, which is sequentially connected in series and connected to the first throttling member 31 and the compressor 10. The second throttling members 32 are connected to the connecting pipes of the upper and lower heat exchange units 41 in a one-to-one correspondence. The type of the first throttling member 31 and the second throttling member 32 can be determined according to actual needs, and can adopt types such as throttle valves and capillary tubes, and this embodiment of the present application is not limited to this.

[0036] In some embodiments, the throttling device 30 includes a first throttling member 31 and a second throttling member 32, and the second heat exchanger 40 includes two-stage heat exchange units 41, namely, a first-stage heat exchange unit 41 and a second-stage heat exchange unit 41. The exhaust port of the compressor 10, the first heat exchanger 20, the first throttling member 31, the first-stage heat exchange unit 41, the second-stage heat exchange unit 41, and the intake port of the compressor 10 are connected in sequence. One end of the second throttling member 32 is connected to the first heat exchanger 20, and the other end is connected to the connecting pipeline between the first-stage heat exchange unit 41 and the second-stage heat exchange unit 41.

[0037] When the second heat exchanger 40 functions as an evaporator, high-temperature, high-pressure gaseous refrigerant is output from the exhaust port of the compressor 10 to the first heat exchanger 20, where it is condensed into low-temperature, high-pressure liquid refrigerant. The low-temperature, high-pressure liquid refrigerant then flows to the first throttle member 31 and the second throttle member 32, respectively. A portion of the low-temperature, high-pressure liquid refrigerant is throttled by the first throttle member 31 and flows into the first-stage heat exchange unit 41 for evaporation. The remaining portion of the low-temperature, high-pressure liquid refrigerant is throttled by the second throttle member 32 and uniformly mixes with the refrigerant evaporated from the first-stage heat exchange unit 41. The uniformly mixed refrigerant then flows into the second-stage heat exchange unit 41 for evaporation.

[0038] In other embodiments, the throttling device 30 includes a first throttling member 31 and m second throttling members 32, and the second heat exchanger 40 includes multiple stages of heat exchange units 41, namely, 1st to m+1st stage heat exchange units 41, where m is a positive integer greater than or equal to 2. The exhaust port of the compressor 10, the first heat exchanger 20, the first throttling member 31, the 1st to m+1st stage heat exchange units 41, and the intake port of the compressor 10 are connected in sequence, one end of the first second throttling member 32 is connected to the first heat exchanger 20, and the other end is connected to the connecting pipeline between the first-stage heat exchange unit 41 and the second-stage heat exchange unit 41, the i-th second throttling member 32 has one end connected to the first heat exchanger 20, and the other end is connected to the connecting pipeline between the i-th stage heat exchange unit 41 and the i+1st stage heat exchange unit 41, where i is a positive integer greater than or equal to 2 and less than or equal to m.

[0039] When the second heat exchanger 40 serves as an evaporator, the high-temperature and high-pressure gaseous refrigerant is output from the exhaust port of the compressor 10 to the first heat exchanger 20, and is condensed into a low-temperature and high-pressure liquid refrigerant in the first heat exchanger 20. The low-temperature and high-pressure liquid refrigerant flows to the first throttling member 31 and each second throttling member 32 respectively. The first part of the low-temperature and high-pressure liquid refrigerant is throttled by the first throttling member 31 and flows into the first-stage heat exchange unit 41 for evaporation. The second part of the low-temperature and high-pressure liquid refrigerant is throttled by the first second throttling member 32 and is evenly mixed with the refrigerant evaporated by the first-stage heat exchange unit 41. The evenly mixed refrigerant flows into the second-stage heat exchange unit 41 for evaporation. The third part of the low-temperature and high-pressure liquid refrigerant is throttled by the second second throttling member 32 and is evenly mixed with the refrigerant evaporated by the second-stage heat exchange unit 41. The evenly mixed refrigerant flows into the third-stage heat exchange unit 41 for evaporation. By analogy, the i-th part of the low-temperature and high-pressure liquid refrigerant is throttled by the i-1-th second throttling member 32 and is evenly mixed with the refrigerant evaporated by the i-1-th heat exchange unit 41. The evenly mixed refrigerant flows into the i-stage heat exchange unit 41 for evaporation.

[0040] Compared with the related art, the air-conditioning system provided in the embodiment of the present application is provided with a plurality of throttling elements and a second heat exchanger 40 including a multi-stage heat exchange unit 41. When the second heat exchanger 40 is used as an evaporator, the refrigerant condensed by the first heat exchanger 20 can be diverted to each throttling element to form multiple parts of refrigerant. The first part of the low-temperature and high-pressure liquid refrigerant is throttled by the first throttling element 31 and flows into the first-stage heat exchange unit 41 for evaporation. The i-th part of the refrigerant is throttled by the i-1-th second throttling element 32 and is evenly mixed with the refrigerant evaporated by the i-1-stage heat exchange unit 41, and after being evenly mixed, flows into the i-stage heat exchange unit 41 for evaporation. Evaporation, on the one hand, can reduce the heat exchange pressure loss by diverting the refrigerant and performing multi-stage evaporation; on the other hand, the opening of the first throttling member 31 can be controlled to control the dryness of the first-stage heat exchange unit 41 within the corresponding target dryness range, and an appropriate amount of liquid refrigerant that has not yet been evaporated is added to the i-th stage heat exchange unit 41 through the i-1th second throttling member 32, so that the dryness of the i-th stage heat exchange unit 41 is controlled within the corresponding target dryness range. The heat transfer coefficient of each stage of the heat exchange unit 41 is improved through dryness control, thereby better balancing the heat transfer coefficient and heat exchange pressure loss, and effectively improving the evaporation heat exchange effect of the evaporator.

[0041] In some embodiments, the second heat exchanger 40 may include at least one mixer 50, which is disposed on the connecting pipeline between the upper and lower heat exchange units 41. When the second heat exchanger 40 functions as an evaporator, the mixer 50 is configured to evenly mix the refrigerant flowing out of the upper heat exchange unit 41 and the refrigerant flowing into the connecting pipeline from the second throttling member 32, and output the evenly mixed refrigerant to the lower heat exchange unit 41. In other words, the refrigerant flowing out of the i-1th heat exchange unit 41 is a gas-liquid mixed refrigerant that has been evaporated by the i-1th heat exchange unit 41, and the refrigerant flowing into the connecting pipeline from the i-1th second throttling member 32 is a liquid refrigerant that has not yet been evaporated. The above two parts of refrigerant can respectively enter the i-1th mixer 50 for even mixing to form a gas-liquid mixed refrigerant, which can then further flow to the i-th heat exchange unit 41 and be evaporated by the i-th heat exchange unit 41. In this way, the inlet dryness of the i-th stage heat exchange unit 41 can be controlled within the corresponding target dryness range, so that the outlet dryness of the i-th stage heat exchange unit 41 can also be controlled within the corresponding target dryness range.

[0042] The type of the mixer 50 can be determined according to actual needs, and can be, for example, a tank body, a mixing tube, etc., which is not limited in the embodiments of the present application. In some examples, the mixer 50 can be a refrigerant mixing tank. The mixer 50 can also be provided with an air outlet 51, which is connected to the air intake of the compressor 10. In this way, after the refrigerant is mixed in the mixer 50, at least part of the gaseous refrigerant can be discharged from the air outlet 51 of the mixer 50 and then flow back to the air intake of the compressor 10, which can not only achieve the effect of replenishing air and increasing enthalpy, but also reduce the gaseous refrigerant discharged from the mixer 50 to the next level heat exchange unit 41, and then reduce the refrigerant dryness discharged from the mixer 50 to the next level heat exchange unit 41, thereby further controlling the inlet dryness of the i-th level heat exchange unit 41 to be within the corresponding target dryness range.

[0043] Exemplarily, the air conditioning system may further include a third throttle member 60, which connects the outlet of the mixer 50 and the air intake of the compressor 10. The type of the third throttle member 60 can be determined according to actual needs, and can adopt types such as a throttle valve, a capillary tube, etc., which are not limited in the embodiments of the present application. The third throttle member 60 can throttle the refrigerant discharged from the air outlet 51 of the mixer 50, and can adjust the outlet dryness of the mixer 50 by adjusting the opening of the third throttle member 60. Exemplarily, the third throttle member 60 can be completely cut off.

[0044] In some embodiments, the air conditioning system may include at least one micro-flow bypass branch 70. One end of the micro-flow bypass branch 70 is connected to the connecting pipeline of the upper and lower heat exchange units 41, and the other end is connected to the air intake of the compressor 10. The connection point between the micro-flow bypass branch 70 and the connecting pipeline is located between the refrigerant outlet of the upper heat exchange unit 41 and the connection point between the second throttle member 32 and the connecting pipeline, so that the micro-flow bypass branch 70 can guide part of the refrigerant flowing out of the upper heat exchange unit 41 to the air intake of the compressor 10. A fourth throttle member 71 and an electric heater 72 are provided on the micro-flow bypass branch 70. The fourth throttle member 71 is connected to the air intake of the compressor 10. The electric heater 72 is arranged between the fourth throttle member 71 and the air intake to heat the refrigerant flowing from the fourth throttle member 71 to the air intake.

[0045] Here, the opening of the fourth throttle member 71 can be adjusted to completely evaporate the refrigerant in the micro-flow bypass branch 70. When the opening of the fourth throttle member 71 is adjusted to completely evaporate the refrigerant in the micro-flow bypass branch 70, the refrigerant flow rate of the micro-flow bypass branch 70 can be obtained. Furthermore, the outlet quality of the heat exchange unit 41 of the previous stage connected to the micro-flow bypass branch 70 can be determined based on the refrigerant flow rate of the micro-flow bypass branch 70. For example, if one end of a micro-flow bypass branch 70 is connected to the connecting pipeline between the i-1 stage and the i-stage heat exchange unit 41, the outlet quality of the i-1 stage heat exchange unit 41 can be determined based on the refrigerant flow rate of the micro-flow bypass branch 70 when the refrigerant in the micro-flow bypass branch 70 completely evaporates. In this way, the outlet quality of the i-1 stage heat exchange unit 41 can be measured through the micro-flow bypass branch 70.

[0046] In some embodiments, the second heat exchanger 40 may include a multi-stage distributor 42, which is arranged in a one-to-one correspondence with the multi-stage heat exchange unit 41. The heat exchange unit 41 may include multiple heat exchange branches 411 arranged in parallel, and the distributor 42 is respectively connected to the multiple heat exchange branches 411 of the heat exchange unit 41. When the second heat exchanger 40 functions as an evaporator, the distributor 42 is configured to evenly distribute the refrigerant to the multiple heat exchange branches 411, further reducing heat exchange pressure loss.

[0047] In some embodiments, the heat exchange area ratio between the upper heat exchange unit 41 and the lower heat exchange unit 41 can be set to 0.25 to 1, for example, 0.25, 0.35, 0.45, 0.5, 0.55, 0.65, 0.75, 0.85, 0.95, or 1. By setting the heat exchange area ratio between the upper and lower heat exchange units 41 within the above range, both the upper and lower heat exchange units 41 can be in an optimal evaporation state, thereby improving the overall heat exchange effect of the second heat exchanger 40.

[0048] In some embodiments, the air conditioning system may further include a four-way valve 80. The four-way valve 80 is connected to the exhaust port and the intake port of the compressor 10, the first heat exchanger 20, and the second heat exchanger 40, respectively, and can change the circulation direction of the refrigerant in the air conditioning system.

[0049] like Figures 1 to 7 As shown, on the other hand, an embodiment of the present application provides an air-conditioning system control method, which includes S10 to S30 and is used to control the air-conditioning system provided by any of the above embodiments.

[0050] S10: Determine whether the outlet quality of the heat exchange unit 41 is within the target quality range.

[0051] Here, the outlet dryness of heat exchange unit 41 can be directly measured using a dryness meter, or indirectly calculated and determined using S01-S02 or S03-S05 described below. A target dryness range can be pre-set in the air conditioning system controller and can be predetermined based on experimental test data and / or historical operating data of the air conditioning system to determine whether the heat transfer coefficient of heat exchange unit 41 is at a high level. When the outlet dryness of heat exchange unit 41 is within the target dryness range, the heat transfer coefficient of heat exchange unit 41 is high.

[0052] S20 : ​​When it is determined that the outlet quality of the heat exchange unit 41 is outside the target quality range, the opening adjustment amount is determined according to the outlet quality of the heat exchange unit 41 .

[0053] If the outlet dryness of heat exchange unit 41 is determined to be outside the target dryness range, it can be determined that the outlet dryness of heat exchange unit 41 is too high or too low, and the heat transfer coefficient of heat exchange unit 41 is low. In this case, the opening adjustment amount can be determined based on the outlet dryness of heat exchange unit 41 based on a preset opening calculation model. If heat exchange unit 41 is a first-stage heat exchange unit 41, the opening adjustment amount of first throttling device 31 can be determined based on the outlet dryness of first-stage heat exchange unit 41; if heat exchange unit 41 is an i-th-stage heat exchange unit 41, the opening adjustment amount of i-1th second throttling device 32 can be determined based on the outlet dryness of i-th-stage heat exchange unit 41.

[0054] S30: adjusting the opening of the throttling member corresponding to the heat exchange unit 41 according to the opening adjustment amount, so as to adjust the outlet dryness of the heat exchange unit 41 to within the target dryness range.

[0055] After determining the opening adjustment amount, the opening of the throttling device corresponding to the heat exchange unit 41 can be adjusted according to the opening adjustment amount. When the outlet dryness of the heat exchange unit 41 is too low, the outlet dryness of the heat exchange unit 41 is increased. When the outlet dryness of the heat exchange unit 41 is too high, the outlet dryness of the heat exchange unit 41 is reduced, so as to adjust the outlet dryness of the heat exchange unit 41 to within the target dryness range.

[0056] like Figure 8 As shown, in some embodiments, before S10, the air conditioning system control method may include S01 to S02, determining the outlet dryness of the heat exchange unit 41 by flow rate measurement.

[0057] S01: Obtain the outlet pressure, outlet temperature and outlet flow of the heat exchange unit 41.

[0058] Here, the outlet pressure of the heat exchange unit 41 can be determined by measuring the refrigerant output by the heat exchange unit 41 with a pressure sensor, the outlet temperature can be determined by measuring the refrigerant output by the heat exchange unit 41 with a temperature sensor, and the outlet flow can be determined by measuring the refrigerant output by the heat exchange unit 41 with a flow meter.

[0059] S02: Determine the outlet quality of the heat exchange unit 41 according to the outlet pressure, outlet temperature and outlet flow of the heat exchange unit 41.

[0060] Here, the outlet quality of heat exchange unit 41 can be determined based on a predetermined outlet quality calculation model according to the outlet pressure, outlet temperature, and outlet flow rate of heat exchange unit 41. The outlet quality calculation model uses the outlet pressure, outlet temperature, and outlet flow rate of heat exchange unit 41 as input variables and outputs the outlet quality of heat exchange unit 41.

[0061] like Figure 9 As shown, in some embodiments, S01 may include S011 to S013 to obtain the outlet flow of the heat exchange unit 41 .

[0062] S011: Get the outdoor ambient temperature, indoor ambient temperature and set temperature.

[0063] Here, the outdoor ambient temperature can be determined by measuring with a temperature sensor installed outdoors, the indoor ambient temperature can be determined by measuring with a temperature sensor installed indoors, and the set temperature can be input by the user through a control terminal such as a remote control, a control panel, or a smart mobile terminal.

[0064] S012: Determine the capacity requirement percentage of the air conditioning system based on the outdoor ambient temperature, indoor ambient temperature and set temperature.

[0065] Here, the air conditioning system's capacity requirement percentage can be determined based on the outdoor ambient temperature, indoor ambient temperature, and set temperature using a predetermined capacity requirement ratio calculation model. The capacity requirement ratio calculation model uses the outdoor ambient temperature, indoor ambient temperature, and set temperature as input variables and outputs the air conditioning system's capacity requirement percentage. The air conditioning system's capacity requirement percentage refers to the percentage of the air conditioning system's heat exchange capacity requirement under current operating conditions compared to the air conditioning system's heat exchange capacity requirement under full load.

[0066] S013 : Determine the outlet flow rate of the heat exchange unit 41 according to the capacity requirement percentage of the air-conditioning system and the full-load mass flow rate of the heat exchange unit 41 .

[0067] Here, the full-load mass flow rate of heat exchange unit 41 refers to the mass flow rate of heat exchange unit 41 under full load conditions, which corresponds to the heat exchange capacity requirement of the air conditioning system under full load conditions. The outlet flow rate of heat exchange unit 41 can be determined based on the air conditioning system's capacity requirement percentage and the full-load mass flow rate of heat exchange unit 41.

[0068] In some embodiments, the air conditioning system may include at least one micro-flow bypass branch 70. Figure 10As shown, before S10 , the air conditioning system control method may include S03 to S05 , determining the outlet dryness of the heat exchange unit 41 by a bypass measurement method.

[0069] S03: Adjust the opening of the fourth throttle member 71 connected to the refrigerant outlet of the heat exchange unit 41 to completely evaporate the refrigerant in the micro-flow bypass branch 70 where the fourth throttle member 71 is located.

[0070] S04: When the refrigerant in the micro-flow bypass branch 70 where the fourth throttle element 71 is located is completely evaporated, the refrigerant flow rate of the micro-flow bypass branch 70 is obtained.

[0071] S05: Determine the outlet quality of the heat exchange unit 41 according to the refrigerant flow rate of the micro-flow bypass branch 70.

[0072] For example, if one end of a micro-flow bypass branch 70 is connected to the connecting pipeline between the i-1th stage and the i-th stage heat exchange unit 41, the fourth throttle element 71 of the micro-flow bypass branch 70 can be controlled to ensure that the refrigerant in the micro-flow bypass branch 70 is completely evaporated. Then, the outlet quality of the i-1th stage heat exchange unit 41 is determined based on the refrigerant flow rate of the micro-flow bypass branch 70. In this way, the outlet quality of the i-1th stage heat exchange unit 41 can be measured through the micro-flow bypass branch 70.

[0073] The above is a detailed introduction to the air-conditioning system and control method thereof provided in the embodiments of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core idea of ​​the present application. At the same time, for technical personnel in this field, based on the ideas of the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. An air conditioning system, characterized in that: include: compressor; a first heat exchanger; a throttling device, comprising a first throttling element and at least one second throttling element, wherein the first throttling element and the second throttling element are respectively connected to the first heat exchanger; The second heat exchanger includes a multi-stage heat exchange unit, which is connected in series in sequence and then connected to the first throttling device and the compressor, and the second throttling device is connected to the connecting pipelines of the upper and lower heat exchange units in a one-to-one correspondence.

2. The air conditioning system according to claim 1, characterized in that The second heat exchanger includes at least one mixer, which is arranged on the connecting pipeline of the upper and lower heat exchange units; when the second heat exchanger serves as an evaporator, the mixer is configured to evenly mix the refrigerant flowing out of the heat exchange unit of the upper level and the refrigerant flowing into the connecting pipeline from the second throttling device, and output the evenly mixed refrigerant to the heat exchange unit of the next level.

3. The air conditioning system according to claim 2, characterized in that The mixer is a refrigerant mixing tank, and the mixer is also provided with an air outlet, and the air outlet is connected to the air intake of the compressor.

4. The air conditioning system according to claim 3, characterized in that The air conditioning system further includes a third throttle element connecting the outlet of the mixer and the suction port of the compressor.

5. The air conditioning system according to claim 1, characterized in that The air conditioning system includes at least one micro-flow bypass branch, one end of the micro-flow bypass branch is connected to the connecting pipeline of the upper and lower heat exchange units, and the other end is connected to the air intake of the compressor, and the connection point of the micro-flow bypass branch and the connecting pipeline is located between the refrigerant outlet of the upper heat exchange unit and the connection point of the second throttling member and the connecting pipeline, so that the micro-flow bypass branch guides part of the refrigerant flowing out of the upper heat exchange unit to the air intake of the compressor; A fourth throttling device and an electric heater are provided on the micro-flow bypass branch. The fourth throttling device is connected to the air intake of the compressor. The electric heater is arranged between the fourth throttling device and the air intake to heat the refrigerant flowing from the fourth throttling device to the air intake.

6. The air conditioning system according to claim 1, characterized in that The second heat exchanger includes a multi-stage distributor, and the multi-stage distributors and the multi-stage heat exchange units are arranged in a one-to-one correspondence; the heat exchange unit includes a plurality of heat exchange branches arranged in parallel, and the distributor is respectively connected to the plurality of heat exchange branches; when the second heat exchanger is used as an evaporator, the distributor is configured to evenly distribute the refrigerant to the plurality of heat exchange branches; the heat exchange area ratio of the upper-level heat exchange unit and the lower-level heat exchange unit is 0.25 to 1.

7. A method for controlling an air conditioning system, characterized in that: For controlling the air conditioning system according to claim 1, comprising: determining whether the outlet quality of the heat exchange unit is within a target quality range; When it is determined that the outlet dryness of the heat exchange unit is outside the target dryness range, determining the opening adjustment amount according to the outlet dryness of the heat exchange unit; The opening of the throttling member corresponding to the heat exchange unit is adjusted according to the opening adjustment amount to adjust the outlet dryness of the heat exchange unit to within the target dryness range.

8. The air conditioning system control method according to claim 7, characterized in that: Before determining whether the outlet dryness of the heat exchange unit is within a target dryness range, the air conditioning system control method includes: Obtaining the outlet pressure, outlet temperature and outlet flow of the heat exchange unit; The outlet quality of the heat exchange unit is determined according to the outlet pressure, outlet temperature and outlet flow of the heat exchange unit.

9. The air conditioning system control method according to claim 8, characterized in that: Obtaining the outlet flow of the heat exchange unit, comprising: Get outdoor ambient temperature, indoor ambient temperature and set temperature; determining a capacity requirement percentage of the air conditioning system according to the outdoor ambient temperature, the indoor ambient temperature, and the set temperature; The outlet flow rate of the heat exchange unit is determined according to the capacity requirement percentage of the air conditioning system and the full load mass flow rate of the heat exchange unit.

10. The air conditioning system control method according to claim 7, characterized in that: The air conditioning system includes at least one micro-flow bypass branch, one end of the micro-flow bypass branch is connected to the connecting pipeline of the upper and lower heat exchange units, and the other end is connected to the air intake of the compressor, and the connection point of the micro-flow bypass branch and the connecting pipeline is located between the refrigerant outlet of the upper heat exchange unit and the connection point of the second throttling member and the connecting pipeline, so that the micro-flow bypass branch guides part of the refrigerant flowing out of the upper heat exchange unit to the air intake of the compressor; A fourth throttle element and an electric heater are provided on the micro-flow bypass branch, the fourth throttle element is connected to the air intake of the compressor, and the electric heater is provided between the fourth throttle element and the air intake to heat the refrigerant flowing from the fourth throttle element to the air intake; Before determining whether the outlet dryness of the heat exchange unit is within a target dryness range, the air conditioning system control method includes: adjusting the opening of a fourth throttle element connected to the refrigerant outlet of the heat exchange unit so that the refrigerant in the micro-flow bypass branch where the fourth throttle element is located is completely evaporated; When the refrigerant in the micro-flow bypass branch where the fourth throttling element is located is completely evaporated, obtaining the refrigerant flow rate of the micro-flow bypass branch; The outlet dryness of the heat exchange unit is determined according to the refrigerant flow rate of the micro-flow bypass branch.

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