An air conditioning system and a method for detecting and recovering refrigerant leaks therein.

Abstract

This invention discloses an air conditioning system and its refrigerant leakage detection and recovery control method. The refrigerant leakage detection and recovery control method includes: when the air conditioning system enters a stable operating state, detecting a first operating parameter of the air conditioning system and determining whether there is a refrigerant leak based on the changing trend of the first operating parameter; if a leak is detected, detecting a second operating parameter of the air conditioning system and comparing the second operating parameter with a threshold operating parameter to determine the refrigerant leakage point; after obtaining the refrigerant leakage point, adjusting the on / off state of each valve in the air conditioning system according to the operating mode of the air conditioning system to switch the refrigerant recovery path. Compared with the prior art, this invention can accurately determine whether there is a refrigerant leak and achieve intelligent and safe refrigerant recovery using an idle heat exchanger, and solve the risk of low-temperature freezing damage through flow path switching.

Description

Technical Field

[0001] This invention relates to the field of refrigeration or air conditioning, and in particular to an air conditioning system and a method for detecting and recovering refrigerant leaks. Background Technology

[0002] In air conditioning systems, refrigerant leakage is a significant factor affecting system stability and energy efficiency. Current technologies determine whether to activate the refrigerant recovery mechanism by measuring refrigerant concentration and adjust compressor frequency based on the leakage rate to accelerate recovery. However, relying solely on refrigerant concentration has a time lag, and while increasing compressor frequency can speed up recovery, it may exacerbate the leakage rate, posing safety hazards. Other existing technologies calculate refrigerant leakage using refrigerant flow rate change, temperature, and operating power differences, but these methods do not clearly define how to achieve efficient and safe refrigerant recovery.

[0003] In addition, existing methods for determining refrigerant leakage rely heavily on changes in condensing pressure. However, these changes can be affected by non-leakage factors such as changes in ambient temperature and dust accumulation on heat exchanger fins, leading to a high risk of misjudgment.

[0004] Therefore, how to propose a method for detecting and recovering refrigerant leaks in air conditioning systems and refrigerant systems that can more accurately, safely and efficiently detect and recover refrigerant leaks is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] To address the problem of inaccurate refrigerant leakage detection in existing technologies, this invention proposes an air conditioning system and a method for detecting and recovering refrigerant leakage.

[0006] The technical solution of this invention is to propose a method for detecting and controlling refrigerant leakage in an air conditioning system, comprising:

[0007] When the air conditioning system enters a stable operating state, the first operating parameter of the air conditioning system is detected, and the air conditioning system is judged to have refrigerant leakage based on the changing trend of the first operating parameter.

[0008] If the determination is yes, then the second operating parameter of the air conditioning system is detected, and the second operating parameter is compared with the threshold operating parameter to determine the refrigerant leakage point of the air conditioning system;

[0009] After identifying the refrigerant leak point in the air conditioning system, the on / off state of each valve in the air conditioning system is adjusted according to the operating mode of the air conditioning system to switch the refrigerant recovery path.

[0010] Furthermore, the first operating parameters include at least: the compressor's discharge pressure, the compressor's suction temperature, the coefficient of performance of the air conditioning system, the heat recovery water temperature of the air conditioning system, the refrigerant temperature after throttling, and the fin temperature of the finned heat exchanger.

[0011] Determining whether the air conditioning system is leaking refrigerant based on the changing trend of the first operating parameter includes:

[0012] Determine whether the changing trends of all the first operating parameters meet the target changing trend. If so, determine that there is a refrigerant leak in the air conditioning system.

[0013] Furthermore, when the first operating parameter is the discharge pressure of the compressor, the target change trend is: when the load of the air conditioning system increases, the discharge pressure of the compressor decreases;

[0014] When the first operating parameter is the suction temperature of the compressor, the target change trend is: when the discharge pressure of the compressor decreases, the suction temperature of the compressor increases;

[0015] When the first operating parameter is the performance coefficient of the air conditioning system, the target change trend is: when the discharge pressure of the compressor decreases and the load of the air conditioning system increases, the performance coefficient of the air conditioning system decreases;

[0016] When the first operating parameter is the heat recovery water temperature of the air conditioning system, the target change trend is: when the load of the air conditioning system increases, the heat recovery water temperature of the air conditioning system decreases;

[0017] When the first operating parameter is the refrigerant temperature after throttling, the target change trend is: when the load of the air conditioning system increases, the refrigerant temperature after throttling rises;

[0018] When the first operating parameter is the fin temperature of the finned heat exchanger, the target change trend is: when the load of the air conditioning system increases, the fin temperature of the finned heat exchanger decreases.

[0019] Furthermore, the second operating parameter includes at least: the rate of decrease of the compressor's discharge pressure and the rate of increase of the compressor's intake temperature;

[0020] Comparing the second operating parameter with a threshold operating parameter to determine the refrigerant leak point of the air conditioning system includes:

[0021] If the rate of decrease of the compressor's discharge pressure is greater than the first threshold and the rate of increase of the compressor's intake temperature is less than the second threshold, then it is determined that the refrigerant leak point of the air conditioning system is located on the high-pressure side of the air conditioning system.

[0022] If the rate of decrease of the compressor's discharge pressure is less than a first threshold and the rate of increase of the compressor's intake temperature is greater than a second threshold, then the refrigerant leak point of the air conditioning system is determined to be on the low-pressure side of the air conditioning system.

[0023] Furthermore, the air conditioning system includes at least an air conditioning water exchange plate, a high-efficiency hot water tank, and a finned heat exchanger for heat exchange.

[0024] When the air conditioning system is running, at least one of the air conditioning water exchange plate, the hot water high-efficiency tank, and the finned heat exchanger is in an idle state.

[0025] According to the operating mode of the air conditioning system, the on / off state of each valve in the air conditioning system is adjusted to switch the refrigerant recovery path, including: determining the heat exchanger in the idle state according to the operating mode of the air conditioning system, and adjusting the on / off state of each valve in the air conditioning system to make the refrigerant flow through the heat exchanger in the idle state.

[0026] Furthermore, the air conditioning system includes: a cooling mode, a heating mode, a hot water supply mode, a cooling and hot water supply mode, and a heating and hot water supply mode;

[0027] When the air conditioning system is in cooling mode, the idle heat exchanger is a high-efficiency hot water tank;

[0028] When the air conditioning system is in heating mode, the idle heat exchanger is a high-efficiency hot water tank;

[0029] When the air conditioning system is in hot water supply mode, the idle heat exchanger is an air conditioning water exchange plate;

[0030] When the air conditioning system is in cooling and hot water supply mode, the idle heat exchanger is a finned heat exchanger;

[0031] When the air conditioning system is in heating and hot water supply mode, the idle heat exchanger is an air conditioning water exchange plate and a high-efficiency hot water tank.

[0032] Furthermore, the air conditioning system includes at least: a compressor, a first four-way valve, a second four-way valve, a finned heat exchanger, a first electronic expansion valve, a second electronic expansion valve, a solenoid valve, a first electric valve, a second electric valve, an air conditioning water exchange plate, a water pump, a water tank, a high-efficiency hot water tank, a first one-way valve, a second one-way valve, a third one-way valve, a vapor-liquid separator, a refrigerant pump, a refrigerant tank, and a recovery valve;

[0033] The compressor's exhaust port is connected in series with a first one-way valve and then to the D end of the first four-way valve. The C end of the first four-way valve is connected to the D end of the second four-way valve. The C end of the second four-way valve is sequentially connected to the finned heat exchanger, the first electronic expansion valve, and the second electronic expansion valve, and then to one end of the air conditioning water exchange plate. The other end of the air conditioning water exchange plate is connected to the E end of the first four-way valve. The S end of the first four-way valve is connected to the vapor-liquid separator through the second one-way valve. The other end of the vapor-liquid separator is connected to the compressor's suction port.

[0034] One end of the solenoid valve is connected between the first electronic expansion valve and the second electronic expansion valve, and the other end of the solenoid valve is connected to one end of the high-efficiency hot water tank. The other end of the high-efficiency hot water tank is connected to the E end of the second four-way valve, and the S end of the second four-way valve is connected to the vapor-liquid separator through the third check valve.

[0035] The water pump and the water tank are respectively connected between the air conditioning water exchange plate and the high-efficiency hot water tank;

[0036] One end of the first electric valve is connected between the second electronic expansion valve and the air conditioning water exchange plate, and the other end of the first electric valve is connected between the solenoid valve and the high-efficiency hot water tank.

[0037] One end of the second electric valve is connected between the air conditioning water exchange plate and the E end of the first four-way valve and between the hot water high-efficiency tank and the E end of the second four-way valve, and the other end of the second electric valve is connected between the finned heat exchanger and the first electronic expansion valve.

[0038] One end of the recovery valve is connected to the vapor-liquid separator, and the other end of the recovery valve is connected to the refrigerant pump through the refrigerant tank.

[0039] Furthermore, when the air conditioning system is in cooling mode, the C end of the first four-way valve is connected to the D end, and the E end is connected to the S end; the C end of the second four-way valve is connected to the D end, and the E end is connected to the S end; the first electric valve is closed, and the second electric valve is open.

[0040] When the air conditioning system is in heating mode, the D end of the first four-way valve is connected to the E end, and the C end is connected to the S end; the D end of the second four-way valve is connected to the E end, and the C end is connected to the S end; the first electric valve is open, and the second electric valve is closed.

[0041] When the air conditioning system is in hot water supply mode, the C end of the first four-way valve is connected to the D end, and the E end is connected to the S end; the D end of the second four-way valve is connected to the E end, and the C end is connected to the S end; the first electric valve is open, and the second electric valve is closed.

[0042] When the air conditioning system is in cooling and hot water supply mode, the C and D ends of the first four-way valve are connected, and the E and S ends are connected. The D and E ends of the second four-way valve are connected, and the C and S ends are connected. The first electric valve is closed, and the second electric valve is open.

[0043] Furthermore, the refrigerant leakage detection and recovery control method for the air conditioning system also includes the following when performing refrigerant recovery:

[0044] The heat recovery water temperature of the air conditioning system is detected, and when the heat recovery water temperature of the air conditioning system is lower than a first threshold temperature, the refrigerant recovery rate is controlled to be 0%.

[0045] When the heat recovery water temperature of the air conditioning system is between the first threshold temperature and the second threshold temperature, the refrigerant recovery rate is controlled to be (T_water-5) × 0.04 × 100%, where T_water is the heat recovery water temperature of the air conditioning system.

[0046] When the heat recovery water temperature of the air conditioning system is greater than the second threshold temperature, the refrigerant recovery rate is controlled to be 100%.

[0047] The refrigerant recovery rate can be changed by adjusting the opening degree of the recovery valve.

[0048] The present invention also proposes an air conditioning system that employs the above-mentioned refrigerant leakage detection and recovery control method.

[0049] Compared with the prior art, the present invention has at least the following beneficial effects:

[0050] This invention dynamically correlates a thermodynamic model with the operating parameters of an air conditioning system, enabling precise determination of refrigerant leakage and accurate location of the leak point. Simultaneously, it rationally switches the on / off states of various valves based on the operating mode of the air conditioning system, achieving intelligent and safe heat recovery with zero additional heat exchangers through idle heat exchangers. Furthermore, it adjusts the refrigerant recovery rate by incorporating the heat recovery water temperature, avoiding the risk of low-temperature freezing damage. Attached Figure Description

[0051] The present invention will now be described in detail with reference to the embodiments and accompanying drawings, wherein:

[0052] Figure 1 This is a schematic diagram of the connection of the air conditioning system in this invention;

[0053] Figure 2 This is a schematic diagram of the refrigerant flow direction in the air conditioning system of the present invention when it is in cooling mode;

[0054] Figure 3 This is a schematic diagram of the refrigerant flow direction in the air conditioning system of the present invention when it is in heating mode;

[0055] Figure 4 This is a schematic diagram of the refrigerant flow direction in the hot water supply mode of the air conditioning system in this invention;

[0056] Figure 5 This is a schematic diagram of the refrigerant flow direction in the air conditioning system of the present invention when it is in cooling and hot water supply modes;

[0057] Figure 6 This is a flowchart illustrating the refrigerant leakage detection process in this invention.

[0058] Figure 7 This is a flowchart illustrating the refrigerant leak location and refrigerant recovery process in this invention;

[0059] Figure 8 This is an overall flowchart of the refrigerant leakage detection and recovery control method for air conditioning systems in this invention. Detailed Implementation

[0060] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0061] In existing technologies, refrigerant recovery schemes determine whether to activate the refrigerant recovery mechanism by obtaining the refrigerant concentration and adjust the compressor frequency according to the refrigerant leakage rate to accelerate recovery. However, relying on refrigerant concentration for judgment has a lag, and while adjusting the compressor frequency can accelerate recovery, it can also exacerbate the refrigerant leakage rate, leading to safety hazards. To address these issues, the technical solution of this invention is to dynamically correlate a thermodynamic model with the operating parameters of the air conditioning system to achieve accurate judgment of refrigerant leakage. Simultaneously, based on the operating mode of the air conditioning system, the on / off states of various valves are rationally switched, and refrigerant recovery is performed through an idle heat exchanger, avoiding the exacerbation of safety hazards caused by refrigerant leakage.

[0062] Please see Figure 8 Based on the above design concept, the refrigerant leakage detection and recovery control method for air conditioning systems proposed in this invention includes the following steps:

[0063] When the air conditioning system enters a stable operating state, the first operating parameter of the air conditioning system is detected, and the change trend of the first operating parameter is used to determine whether there is a refrigerant leak in the air conditioning system.

[0064] If the determination is yes, then the second operating parameter of the air conditioning system is detected, and the second operating parameter is compared with the threshold operating parameter to determine the refrigerant leakage point of the air conditioning system;

[0065] After identifying the refrigerant leak point in the air conditioning system, adjust the on / off state of each valve in the air conditioning system according to the system's operating mode to switch the refrigerant recovery path.

[0066] The above-mentioned scheme, which uses a first operating parameter to determine whether there is a refrigerant leak, relies on a thermodynamic model to correlate the operating parameters of the air conditioning system. For example, if the first operating parameter is the compressor's discharge pressure, according to the thermodynamic model, under normal operating conditions, when the load on the air conditioning system (such as ambient temperature) increases, the compressor's discharge pressure will also increase. However, if a refrigerant leak occurs, the opposite trend will be observed. For instance, in cooling mode, if the ambient temperature rises from 25°C to 30°C, the compressor's discharge pressure should normally rise from A psi to B psi. If the compressor's discharge pressure drops from A psi to C psi, this indicates a contradictory trend, suggesting a possible refrigerant leak.

[0067] In order to improve the accuracy of refrigerant leakage detection, this invention sets multiple first operating parameters. Only when the changing trends of multiple first operating parameters indicate the possibility of refrigerant leakage will the air conditioning system be determined to have refrigerant leakage. Based on this part of the solution, this invention can accurately determine whether refrigerant leakage exists.

[0068] The second operating parameter in the above scheme is used to locate the refrigerant leak point. Refrigerant leaks are generally divided into high-pressure side leaks and low-pressure side leaks. The second operating parameter is obtained by comparing the operating parameters of the high-pressure side and the low-pressure side with the operating parameters under normal conditions to determine whether a refrigerant leak has occurred, thereby achieving accurate location of the leak point.

[0069] After identifying the refrigerant leak point, a refrigerant recovery strategy needs to be initiated. The core of the solution in this invention lies in utilizing an idle heat exchanger for refrigerant recovery. In the air conditioning system of this invention, there are three heat exchangers: a finned heat exchanger, an air conditioning water exchange plate, and a high-efficiency hot water tank. All three heat exchangers can perform heat exchange, functioning as condensers and evaporators depending on the operating mode of the air conditioning system. Depending on their operating mode, one of the three heat exchangers will be an idle heat exchanger. The design concept of this invention is to utilize this idle heat exchanger for refrigerant recovery, while adjusting the recovery speed to avoid the risk of freezing.

[0070] Furthermore, the refrigerant recovery path in this invention is not limited to the aforementioned idle heat exchanger. To ensure refrigerant recovery efficiency, this invention also provides a refrigerant recovery path as the main path, which is realized through a refrigerant pump, a refrigerant tank, and a recovery valve. This part of the refrigerant recovery path is directly connected in series with the low-pressure side branch of the air conditioning system. The opening adjustment only affects the resistance of the recovery flow path. The recovery branch is completely independent and is not directly connected to the main cycle (compressor → condenser → expansion valve → evaporator). The outlet flows back to the rear of the compressor's suction port (not directly connected to the suction port) to avoid affecting the compressor's suction pressure.

[0071] Based on the above design, the present invention can achieve the beneficial effects described above:

[0072] This invention dynamically correlates a thermodynamic model with the operating parameters of an air conditioning system, enabling precise determination of refrigerant leakage and accurate location of the leak point. Simultaneously, it rationally switches the on / off states of various valves based on the operating mode of the air conditioning system, achieving intelligent and safe heat recovery with zero additional heat exchangers through idle heat exchangers. Furthermore, it adjusts the refrigerant recovery rate by incorporating the heat recovery water temperature, avoiding the risk of low-temperature freezing damage.

[0073] The above solution will be explained in detail below. First, before determining whether there is a refrigerant leak, this invention needs to determine whether the air conditioning system has entered a stable operating state. This is because if the air conditioning system has not entered a stable operating state, parameters will be manually changed when the air conditioning system mode is switched or the compressor is controlled to start or stop. This is unrelated to refrigerant leakage. In order to avoid misjudging whether there is a refrigerant leak due to the change of these parameters, this invention needs to determine whether the air conditioning system has entered a stable operating state before proceeding to the subsequent determination of whether there is a refrigerant leak.

[0074] The criteria for determining whether the air conditioning system has entered a stable operating state in this invention are as follows:

[0075] 1. The four-way valve in the air conditioning system has no state switching, which is used to determine that there is no mode switching in the air conditioning system;

[0076] 2. The compressor runs continuously, which is used to determine that the compressor does not start or stop.

[0077] 3. The fan in the air conditioning system is in a stable state, which is used to ensure that the heat exchanger is working properly, and there is no start-up or shutdown action;

[0078] Only when all three conditions mentioned above are met simultaneously will the air conditioning system be considered to have entered a stable operating state and will a judgment be made on whether there is a refrigerant leak. Based on this part of the solution, the present invention can avoid misjudgment caused by human adjustment of the operating state of the air conditioning system.

[0079] After determining whether refrigerant leakage exists, the system first checks the first operating parameter, and then uses this first operating parameter to determine whether refrigerant leakage exists in the air conditioning system. The first operating parameter in this invention includes at least: the compressor's discharge pressure, the compressor's suction temperature, the air conditioning system's coefficient of performance (COP), the air conditioning system's heat recovery water temperature, the refrigerant temperature after throttling, and the fin temperature of the finned heat exchanger.

[0080] In the above scheme, determining whether there is a refrigerant leak in the air conditioning system based on the changing trend of the first operating parameter includes:

[0081] Determine whether the changing trends of all the first operating parameters meet the target changing trend. If so, it is determined that there is a refrigerant leak in the air conditioning system.

[0082] The target trend here is set to the trend of the first operating parameter when there is a refrigerant leak.

[0083] For example, regarding the compressor's discharge pressure, under normal circumstances, when the compressor's load increases, the compressor's discharge pressure will also rise. However, when refrigerant leakage occurs, the compressor's discharge pressure will actually decrease. Here, the target change trend can be set as follows: when the load of the air conditioning system increases, the compressor's discharge pressure will decrease. When the compressor's discharge pressure is detected to meet the above target change trend, it is considered that there is a possibility of refrigerant leakage. Further judgment needs to be made in conjunction with the first operating parameter to accurately determine whether there is a refrigerant leakage.

[0084] Regarding the compressor's suction temperature, refrigerant leakage leads to a reduction in refrigerant volume. This reduction directly manifests as overheating during suction when the compressor's discharge pressure decreases, causing the suction temperature to rise. In other words, when there is a refrigerant leak, the suction temperature rises as the compressor's discharge pressure decreases. This is set as the target trend for the compressor's suction temperature. If the compressor's suction temperature meets this target trend, a refrigerant leak is suspected, and the process proceeds to the next step to accurately determine if a refrigerant leak exists.

[0085] Regarding the coefficient of performance (COP) of an air conditioning system, when there is refrigerant leakage, it will inevitably lead to a decrease in the energy efficiency of the air conditioning system, thereby causing a decrease in the COP. That is, when there is refrigerant leakage, i.e., a decrease in the compressor's discharge pressure, and an increase in the load of the air conditioning system, the COP of the air conditioning system will decrease. This is set as the target trend of the COP of the air conditioning system. If the COP of the air conditioning system meets this target trend, it is considered that there is a possibility of refrigerant leakage, and the next step of judgment is taken. If the COP of the air conditioning system does not decrease, it means that the air conditioning system is not affected by refrigerant leakage, and the decrease in the compressor's discharge pressure and the increase in the intake temperature may be caused by environmental factors.

[0086] Regarding the heat recovery water temperature of the air conditioning system, when refrigerant leakage occurs in the air conditioning system, it will lead to a decrease in the heat exchange efficiency of the air conditioning system. Under the same load, the heat recovery water temperature of the air conditioning system will inevitably decrease. That is, when the load of the air conditioning system increases, the heat recovery water temperature of the air conditioning system will decrease. This is set as the target change trend of the heat recovery water temperature of the air conditioning system. If the heat recovery water temperature of the air conditioning system meets this target change trend, it is determined that there is a possibility of refrigerant leakage, and then proceed to the next step of judgment.

[0087] Regarding the refrigerant temperature after throttling, when a refrigerant leak occurs in the air conditioning system, it will cause the subcooling of the air conditioning system to decrease, thereby causing the refrigerant temperature after throttling to rise abnormally. That is, when the load of the air conditioning system increases, the refrigerant temperature after throttling rises. This is set as the target change trend of the refrigerant temperature after throttling. If the refrigerant temperature after throttling meets this target change trend, it is determined that there is a possibility of refrigerant leakage, and then proceeds to the next step of judgment.

[0088] Regarding the fin temperature of a finned heat exchanger, when a refrigerant leak occurs in the air conditioning system, it will cause the thermal resistance to increase, thereby causing the fin temperature to decrease under the same load. That is, when the load of the air conditioning system increases, the fin temperature of the finned heat exchanger decreases. This is set as the target change trend of the finned heat exchanger fin temperature. If the fin temperature of the finned heat exchanger meets this target change trend, it is determined that there is a refrigerant leak in the air conditioning system.

[0089] Please see Figure 6 The flowchart for judging refrigerant leakage in this invention first judges whether the air conditioning system has entered a stable operating state. This is determined by judging whether the four-way valve in the air conditioning system has no switching state, the compressor runs continuously, and the fan is stable. When the above three conditions are judged to be true at the same time, the air conditioning system is considered to have entered a stable operating state.

[0090] Then, the system begins to determine if there is a refrigerant leak. This involves checking whether the compressor's discharge pressure meets the target trend, whether the compressor's suction temperature meets the target trend, whether the air conditioning system's coefficient of performance meets the target trend, whether the air conditioning system's heat recovery water temperature meets the target trend, whether the refrigerant temperature after throttling meets the target trend, and whether the finned heat exchanger's finned temperature meets the target trend. If all of the above checks are positive, it is determined that there is a refrigerant leak in the air conditioning system, and the next step is to determine the refrigerant leak point and initiate refrigerant recovery.

[0091] The above method ensures the accuracy of the judgment and avoids misjudgment by determining whether there is a refrigerant leak.

[0092] Once it is determined that there is a refrigerant leak in the air conditioning system, the refrigerant leak point is located. In this invention, the leak point is determined by comparing the second operating parameter with the threshold operating parameter. The refrigerant leak point is generally divided into high-pressure side leak and low-pressure side leak. In this invention, the second operating parameter includes the attenuation rate of the compressor's discharge pressure and the rise rate of the compressor's suction temperature.

[0093] If the refrigerant leak is on the high-pressure side, it will cause the compressor's discharge pressure decay rate to increase and exceed E% / min (E% / min is set according to the actual situation). As the compressor's discharge pressure decay rate increases, the compressor's suction temperature rise rate will decrease and be less than F°C / min (F°C / min is set according to the actual situation).

[0094] If the refrigerant leak is on the low-pressure side, it will cause the compressor's discharge pressure decay rate to decrease and become less than E% / min (E% / min is set according to actual conditions). As the compressor's discharge pressure decay rate decreases, the compressor's suction temperature rise rate will increase and become greater than F°C / min (F°C / min is set according to actual conditions).

[0095] In this invention, E% / min is set as the first threshold and F°C / min is set as the second threshold. The first and second thresholds correspond to the threshold operating parameters mentioned above. Then, the decay rate of the compressor's discharge pressure and the rise rate of the compressor's suction temperature are compared with the first and second thresholds to accurately determine the refrigerant leakage point of the air conditioning system.

[0096] If the rate of decrease of the compressor's discharge pressure is greater than the first threshold and the rate of increase of the compressor's suction temperature is less than the second threshold, then the refrigerant leak point of the air conditioning system can be identified as being on the high-pressure side of the air conditioning system. In this case, the leak point may be at the heat exchanger on the high-pressure side (the core component on the high-pressure side, where the rate of decrease of discharge pressure is greater than the rate of increase of suction temperature).

[0097] If the rate of decrease of the compressor's discharge pressure is less than the first threshold and the rate of increase of the compressor's suction temperature is greater than the second threshold, then the refrigerant leak point of the air conditioning system can be identified as being on the low-pressure side of the air conditioning system. In this case, the leak point may be at the pipe joint or the electronic expansion valve (the suction temperature rise is more significant when leaking on the low-pressure side).

[0098] Based on this part of the solution, the present invention can accurately determine the refrigerant leakage point, thereby providing a basis for the selection of subsequent refrigerant recovery paths.

[0099] As mentioned above, the present invention mainly utilizes idle heat exchangers for refrigerant recovery. Therefore, the air conditioning system proposed in this invention includes at least an air conditioning water exchange plate, a high-efficiency hot water tank, and a finned heat exchanger that can be used for heat exchange.

[0100] When the air conditioning system is running, at least one of the air conditioning water exchange plate, hot water high-efficiency tank, and finned heat exchanger is idle.

[0101] Based on the above-mentioned air conditioning system settings, this invention adjusts the on / off state of each valve in the air conditioning system according to the operating mode of the air conditioning system to switch the refrigerant recovery path. Specifically, this includes: determining the heat exchanger that is in an idle state according to the operating mode of the air conditioning system, and adjusting the on / off state of each valve in the air conditioning system so that the refrigerant flows through the heat exchanger that is in an idle state.

[0102] With this design approach, the present invention can achieve intelligent and safe refrigerant recovery without the need for additional heat exchangers, thus reducing design costs.

[0103] To change the operating mode of the air conditioning system by adjusting valves, and to recover refrigerant using an idle heat exchanger, please refer to [link to relevant documentation]. Figure 1 The air conditioning system of the present invention includes at least: a compressor, a first four-way valve, a second four-way valve, a finned heat exchanger, a first electronic expansion valve, a second electronic expansion valve, a solenoid valve, a first electric valve, a second electric valve, an air conditioning water exchange plate, a water pump, a water tank, a high-efficiency hot water tank, a first one-way valve, a second one-way valve, a third one-way valve, a vapor-liquid separator, a refrigerant pump, a refrigerant tank, and a recovery valve;

[0104] The compressor's discharge port is connected in series with the first one-way valve and then to the D end of the first four-way valve. The C end of the first four-way valve is connected to the D end of the second four-way valve. The C end of the second four-way valve is connected in sequence to the finned heat exchanger, the first electronic expansion valve, and the second electronic expansion valve, and then to one end of the air conditioning water exchange plate. The other end of the air conditioning water exchange plate is connected to the E end of the first four-way valve. The S end of the first four-way valve is connected to the vapor-liquid separator through the second one-way valve. The other end of the vapor-liquid separator is connected to the compressor's suction port.

[0105] One end of the solenoid valve is connected between the first electronic expansion valve and the second electronic expansion valve, and the other end of the solenoid valve is connected to one end of the high-efficiency hot water tank. The other end of the high-efficiency hot water tank is connected to the E end of the second four-way valve. The S end of the second four-way valve is connected to the vapor-liquid separator through the third check valve.

[0106] The water pump and water tank are respectively connected between the air conditioning water exchange plate and the high-efficiency hot water tank;

[0107] One end of the first electric valve is connected between the second electronic expansion valve and the air conditioning water exchange plate, and the other end of the first electric valve is connected between the solenoid valve and the high-efficiency hot water tank.

[0108] One end of the second electric valve is connected between the air conditioning water exchange plate and the E end of the first four-way valve, and between the high-efficiency hot water tank and the E end of the second four-way valve. The other end of the second electric valve is connected between the finned heat exchanger and the first electronic expansion valve.

[0109] One end of the recovery valve is connected to the vapor-liquid separator, and the other end of the recovery valve is connected to the refrigerant pump through the refrigerant tank.

[0110] In the above embodiments, the finned heat exchanger can be a water-cooled shell and tube type, a water-cooled plate and shell type, a water-evaporating type, or a fan finned coil air-cooled type. If the condenser is an air-cooled or evaporative condenser, it can be installed independently outdoors without being installed on the overall unit.

[0111] Evaporators can be plate heat exchangers, shell and tube heat exchangers, falling film evaporators, dry evaporators, coaxial evaporators, etc.

[0112] The adjustment of the first four-way valve and the second four-way valve can change the refrigerant flow direction, thereby adapting to different operating modes of the air conditioning system;

[0113] The switching of the first and second electric valves can be used to control different refrigerant storage needs and to recover refrigerant using an idle heat exchanger.

[0114] Based on the above-mentioned air conditioning system configuration, this invention can switch the operating mode of the air conditioning system by adjusting the on / off state of the first four-way valve, the second four-way valve, the first electric valve, and the second electric valve, and can also recover refrigerant by using an idle heat exchanger.

[0115] Based on the above settings, the operating modes of the air conditioning system in this invention include: cooling mode, heating mode, hot water supply mode, cooling and hot water supply mode, and heating and hot water supply mode.

[0116] When the air conditioning system is in cooling mode, the idle heat exchanger is a high-efficiency hot water tank.

[0117] When the air conditioning system is in heating mode, the idle heat exchanger is a high-efficiency hot water tank.

[0118] When the air conditioning system is in hot water supply mode, the idle heat exchanger is the air conditioning water exchange plate.

[0119] When the air conditioning system is in cooling and hot water supply mode, the idle heat exchanger is a finned heat exchanger.

[0120] When the air conditioning system is in heating and hot water supply mode, the idle heat exchanger consists of the air conditioning water exchange plate and the hot water high-efficiency tank.

[0121] The following description, in conjunction with the accompanying drawings, illustrates the various operating modes of the air conditioning system and the refrigerant recovery path in this invention:

[0122] Please see Figure 2 When the air conditioning system is in cooling mode, the C end of the first four-way valve is connected to the D end, and the E end is connected to the S end. The C end of the second four-way valve is connected to the D end, and the E end is connected to the S end. The first electric valve is closed and the second electric valve is open. At this time, the refrigerant returns to the compressor after passing through the first electronic expansion valve, the second electronic expansion valve, the air conditioning water heat exchange plate, the first four-way valve, and the vapor-liquid separator to carry out the refrigeration cycle. The opening of the second electric valve diverts part of the refrigerant to be stored in the idle heat exchanger (high-efficiency hot water tank). Then, the opening and closing of the first electric valve determines whether to discharge the refrigerant.

[0123] Please see Figure 3 When the air conditioning system is in heating mode, terminals D and E of the first four-way valve are connected, as are terminals C and S. Terminals D and E of the second four-way valve are connected, as are terminals C and S. The first electric valve is open, and the second electric valve is closed. At this time, the refrigerant passes through the air conditioning water heat exchanger, the second electronic expansion valve, the first electronic expansion valve, the finned heat exchanger, the second four-way valve, and the vapor-liquid separator before returning to the compressor for heating circulation. The opening of the first electric valve diverts a portion of the refrigerant to the idle heat exchanger (high-efficiency hot water tank), and the opening and closing of the second electric valve determines whether to discharge the refrigerant.

[0124] Please see Figure 4 When the air conditioning system is in hot water supply mode, terminals C and D of the first four-way valve are connected, as are terminals E and S. Terminals D and E of the second four-way valve are connected, as are terminals C and S. The first electric valve is open, and the second electric valve is closed. At this time, the refrigerant passes through the high-efficiency hot water tank, solenoid valve, first electronic expansion valve, finned heat exchanger, second four-way valve, and vapor-liquid separator before returning to the compressor to circulate hot water. The opening of the first electric valve diverts a portion of the refrigerant to the idle heat exchanger (air conditioning water exchange plate), and the opening and closing of the second electric valve determines whether to discharge refrigerant.

[0125] Please see Figure 5When the air conditioning system is in cooling and hot water supply mode, terminals C and D of the first four-way valve are connected, as are terminals E and S. Terminals D and E of the second solenoid valve are connected, as are terminals C and S. The first electric valve is closed, and the second electric valve is open. At this time, the refrigerant passes through the high-efficiency hot water tank, solenoid valve, second electronic expansion valve, air conditioning water exchange plate, first four-way valve, and vapor-liquid separator before returning to the compressor for cooling and hot water supply circulation. The opening of the first electronic expansion valve diverts some refrigerant to be stored in the idle heat exchanger (finned heat exchanger). The opening and closing of the second electric valve determines whether refrigerant is discharged.

[0126] For heating and hot water supply modes, the priority of air conditioning hot water and domestic hot water can be selected or scheduled. The default priority is domestic hot water, which follows the same refrigerant recovery path as the hot water supply mode. If heating priority is set, the refrigerant recovery path will be the same as the heating mode.

[0127] If the conditions for both heating and hot water production are met, the machine will start according to the set priority and stop when the conditions for stopping are met. At this time, the machine will check whether the conditions for starting the machine in another mode are met, and then start or stop the machine in that mode.

[0128] The table below shows the relationship between the operating modes of the air conditioning system, idle heat exchangers, recovery paths, and the operation of electric valves:

[0129]

[0130] Based on the above scheme, the present invention can switch the operating mode of the air conditioning system by adjusting the on / off state of the first four-way valve, the second four-way valve, the first electric valve, and the second electric valve, and can recover the refrigerant by using an idle heat exchanger.

[0131] To avoid the risk of freezing damage during refrigerant recovery, the refrigerant recovery rate is adjusted in this invention. The specific method includes: detecting the heat recovery water temperature of the air conditioning system, and controlling the refrigerant recovery rate to 0% when the heat recovery water temperature of the air conditioning system is lower than a first threshold temperature;

[0132] When the heat recovery water temperature of the air conditioning system is between the first threshold temperature and the second threshold temperature, the refrigerant recovery rate is controlled as (T_water-5) × 0.04 × 100%, where T_water is the heat recovery water temperature of the air conditioning system.

[0133] When the heat recovery water temperature of the air conditioning system is greater than the second threshold temperature, the refrigerant recovery rate is controlled at 100%.

[0134] The refrigerant recovery rate can be changed by adjusting the opening of the recovery valve.

[0135] Specifically, the first threshold temperature is set to 5°C and the second threshold temperature is set to 30°C. When the heat recovery water temperature is lower than the first threshold temperature and the water temperature drops by more than 0.25°C every 5 minutes, it is considered that there is a risk of low-temperature freezing damage.

[0136] At this point, the refrigerant recovery flow path is switched by switching the first four-way valve and the second four-way valve. Then, the high-temperature refrigerant discharged from the compressor is injected into the idle heat exchanger. When the heat recovery water temperature is greater than 5°C, indicating that there is no risk of freezing damage, the refrigerant recovery rate is adjusted.

[0137] For example, when the heat recovery water temperature of the air conditioning system is between the first threshold temperature and the second threshold temperature, the refrigerant recovery rate is controlled as (T_water-5) × 0.04 × 100%, where T_water is the heat recovery water temperature of the air conditioning system.

[0138] Within this temperature range, the refrigerant recovery rate can be further adjusted based on the magnitude of the temperature rise of the heat recovery water every 5 minutes. If the rise is greater than 0.25°C, high-speed recovery can be performed, with the recovery rate set at 80%. Conversely, if the rise is less than 0.25°C, there is a risk of overheating, so the recovery rate should be reduced to 50%.

[0139] When the heat recovery water temperature of the air conditioning system is greater than the second threshold temperature, the fastest recovery can be performed, and the refrigerant recovery rate is set to 100%.

[0140] The following table shows the setting of the refrigerant recovery rate in this invention:

[0141]

[0142] Based on this part of the solution, the present invention can adjust the refrigerant recovery rate by combining the heat recovery water temperature, thus avoiding the risk of freezing damage at low temperatures.

[0143] Please see Figure 7 This is a flowchart of the refrigerant leakage detection and refrigerant recovery process in this invention. First, the refrigerant leakage is detected. Only when all the target change trends are reached will a refrigerant leakage be detected. Then, the refrigerant leakage point is determined. If it is a high-pressure side leakage, high-pressure side priority recovery is initiated. If it is a low-pressure side leakage, standard recovery is initiated.

[0144] Then, the risk of freezing damage is assessed by checking whether the heat recovery water temperature is less than 5°C and whether the water temperature drops by less than 0.25°C every 5 minutes. If so, the flow path switching is initiated to inject high-temperature refrigerant into the idle heat exchanger. When the heat recovery water temperature is higher than 5°C, the refrigerant recovery rate is set according to the heat recovery water temperature and the rate of temperature increase every 5 minutes.

[0145] Refrigerant is recovered through idle heat exchangers in both cooling and heating modes. Idle heat exchangers are high-efficiency hot water tanks in hot water supply mode. Idle heat exchangers are air conditioning water exchange plates in both cooling and hot water supply modes. Idle heat exchangers are finned heat exchangers.

[0146] The recycling path is divided into two routes: route 1 is the main route recycling through the recycling storage tank, and route 2 is the auxiliary route recycling through the idle heat exchanger.

[0147] The present invention also proposes an air conditioning system that employs the above-mentioned refrigerant leakage detection and recovery control method.

[0148] Based on the above scheme, this invention dynamically correlates the thermodynamic model with the operating parameters of the air conditioning system, which can accurately determine whether there is a refrigerant leak and accurately locate the leak point. At the same time, according to the operating mode of the air conditioning system, the on / off state of each valve is switched reasonably. Intelligent and safe recovery of heat exchangers with zero new heat exchangers is achieved through idle heat exchangers. In addition, the refrigerant recovery rate is optimized by combining the heat recovery water temperature, avoiding the risk of low temperature freezing damage.

[0149] It should be noted that the terminology used above is for describing specific embodiments only and is not intended to limit the exemplary embodiments of the present invention. When the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. The order of execution of actions, steps, etc., in the apparatus and methods described in the specification and drawings can be implemented in any order unless a specific order is expressly specified, and as long as the output of the preceding process is not used in the subsequent process. Similar sequential terms used for ease of description do not imply that such an order must be followed.

[0150] Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as constraints. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0151] The above description is only a preferred embodiment of the present invention and is 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 within the protection scope of the present invention.

Claims

1. A method for detecting and controlling refrigerant leakage in an air conditioning system, characterized in that, include: When the air conditioning system enters a stable operating state, the first operating parameter of the air conditioning system is detected, and the air conditioning system is judged to have refrigerant leakage based on the changing trend of the first operating parameter. If the determination is yes, then the second operating parameter of the air conditioning system is detected, and the second operating parameter is compared with the threshold operating parameter to determine the refrigerant leakage point of the air conditioning system; After identifying the refrigerant leak point in the air conditioning system, the on / off state of each valve in the air conditioning system is adjusted according to the operating mode of the air conditioning system to switch the refrigerant recovery path.

2. The refrigerant leakage detection and recovery control method for an air conditioning system according to claim 1, characterized in that, The first operating parameters include at least: the compressor's discharge pressure, the compressor's suction temperature, the coefficient of performance of the air conditioning system, the heat recovery water temperature of the air conditioning system, the refrigerant temperature after throttling, and the fin temperature of the finned heat exchanger. Determining whether the air conditioning system is leaking refrigerant based on the changing trend of the first operating parameter includes: Determine whether the changing trends of all the first operating parameters meet the target changing trend. If so, determine that there is a refrigerant leak in the air conditioning system.

3. The refrigerant leakage detection and recovery control method for an air conditioning system according to claim 2, characterized in that, When the first operating parameter is the discharge pressure of the compressor, the target change trend is: when the load of the air conditioning system increases, the discharge pressure of the compressor decreases; When the first operating parameter is the suction temperature of the compressor, the target change trend is: when the discharge pressure of the compressor decreases, the suction temperature of the compressor increases; When the first operating parameter is the performance coefficient of the air conditioning system, the target change trend is: when the discharge pressure of the compressor decreases and the load of the air conditioning system increases, the performance coefficient of the air conditioning system decreases; When the first operating parameter is the heat recovery water temperature of the air conditioning system, the target change trend is: when the load of the air conditioning system increases, the heat recovery water temperature of the air conditioning system decreases; When the first operating parameter is the refrigerant temperature after throttling, the target change trend is: when the load of the air conditioning system increases, the refrigerant temperature after throttling rises; When the first operating parameter is the fin temperature of the finned heat exchanger, the target change trend is: when the load of the air conditioning system increases, the fin temperature of the finned heat exchanger decreases.

4. The method for detecting and recovering refrigerant leakage in an air conditioning system according to claim 1, characterized in that, The second operating parameter includes at least: the rate of decrease of the compressor's discharge pressure and the rate of increase of the compressor's intake temperature; Comparing the second operating parameter with a threshold operating parameter to determine the refrigerant leak point of the air conditioning system includes: If the rate of decrease of the compressor's discharge pressure is greater than the first threshold and the rate of increase of the compressor's intake temperature is less than the second threshold, then it is determined that the refrigerant leak point of the air conditioning system is located on the high-pressure side of the air conditioning system. If the rate of decrease of the compressor's discharge pressure is less than a first threshold and the rate of increase of the compressor's intake temperature is greater than a second threshold, then the refrigerant leak point of the air conditioning system is determined to be on the low-pressure side of the air conditioning system.

5. The method for detecting and recovering refrigerant leakage in an air conditioning system according to claim 1, characterized in that, The air conditioning system includes at least an air conditioning water exchange plate, a high-efficiency hot water tank, and a finned heat exchanger for heat exchange. When the air conditioning system is running, at least one of the air conditioning water exchange plate, the hot water high-efficiency tank, and the finned heat exchanger is in an idle state. According to the operating mode of the air conditioning system, the on / off state of each valve in the air conditioning system is adjusted to switch the refrigerant recovery path, including: determining the heat exchanger in the idle state according to the operating mode of the air conditioning system, and adjusting the on / off state of each valve in the air conditioning system to make the refrigerant flow through the heat exchanger in the idle state.

6. The refrigerant leakage detection and recovery control method for an air conditioning system according to claim 5, characterized in that, The air conditioning system includes: cooling mode, heating mode, hot water supply mode, cooling and hot water supply mode, and heating and hot water supply mode; When the air conditioning system is in cooling mode, the idle heat exchanger is a high-efficiency hot water tank; When the air conditioning system is in heating mode, the idle heat exchanger is a high-efficiency hot water tank; When the air conditioning system is in hot water supply mode, the idle heat exchanger is an air conditioning water exchange plate; When the air conditioning system is in cooling and hot water supply mode, the idle heat exchanger is a finned heat exchanger; When the air conditioning system is in heating and hot water supply mode, the idle heat exchanger is an air conditioning water exchange plate and a high-efficiency hot water tank.

7. The refrigerant leakage detection and recovery control method for an air conditioning system according to claim 6, characterized in that, The air conditioning system includes at least: a compressor, a first four-way valve, a second four-way valve, a finned heat exchanger, a first electronic expansion valve, a second electronic expansion valve, a solenoid valve, a first electric valve, a second electric valve, an air conditioning water exchange plate, a water pump, a water tank, a high-efficiency hot water tank, a first one-way valve, a second one-way valve, a third one-way valve, a vapor-liquid separator, a refrigerant pump, a refrigerant tank, and a recovery valve; The compressor's exhaust port is connected in series with a first one-way valve and then to the D end of the first four-way valve. The C end of the first four-way valve is connected to the D end of the second four-way valve. The C end of the second four-way valve is sequentially connected to the finned heat exchanger, the first electronic expansion valve, and the second electronic expansion valve, and then to one end of the air conditioning water exchange plate. The other end of the air conditioning water exchange plate is connected to the E end of the first four-way valve. The S end of the first four-way valve is connected to the vapor-liquid separator through the second one-way valve. The other end of the vapor-liquid separator is connected to the compressor's suction port. One end of the solenoid valve is connected between the first electronic expansion valve and the second electronic expansion valve, and the other end of the solenoid valve is connected to one end of the high-efficiency hot water tank. The other end of the high-efficiency hot water tank is connected to the E end of the second four-way valve, and the S end of the second four-way valve is connected to the vapor-liquid separator through the third check valve. The water pump and the water tank are respectively connected between the air conditioning water exchange plate and the high-efficiency hot water tank; One end of the first electric valve is connected between the second electronic expansion valve and the air conditioning water exchange plate, and the other end of the first electric valve is connected between the solenoid valve and the high-efficiency hot water tank. One end of the second electric valve is connected between the air conditioning water exchange plate and the E end of the first four-way valve and between the hot water high-efficiency tank and the E end of the second four-way valve, and the other end of the second electric valve is connected between the finned heat exchanger and the first electronic expansion valve. One end of the recovery valve is connected to the vapor-liquid separator, and the other end of the recovery valve is connected to the refrigerant pump through the refrigerant tank.

8. The method for detecting and recovering refrigerant leakage in an air conditioning system according to claim 7, characterized in that, When the air conditioning system is in cooling mode, the C end of the first four-way valve is connected to the D end, and the E end is connected to the S end; the C end of the second four-way valve is connected to the D end, and the E end is connected to the S end; the first electric valve is closed, and the second electric valve is open. When the air conditioning system is in heating mode, the D end of the first four-way valve is connected to the E end, and the C end is connected to the S end; the D end of the second four-way valve is connected to the E end, and the C end is connected to the S end; the first electric valve is open, and the second electric valve is closed. When the air conditioning system is in hot water supply mode, the C end of the first four-way valve is connected to the D end, and the E end is connected to the S end; the D end of the second four-way valve is connected to the E end, and the C end is connected to the S end; the first electric valve is open, and the second electric valve is closed. When the air conditioning system is in cooling and hot water supply mode, the C and D ends of the first four-way valve are connected, and the E and S ends are connected. The D and E ends of the second four-way valve are connected, and the C and S ends are connected. The first electric valve is closed, and the second electric valve is open.

9. The method for detecting and recovering refrigerant leakage in an air conditioning system according to claim 8, characterized in that, When performing refrigerant recovery, the refrigerant leakage detection and recovery control method of the air conditioning system further includes: The heat recovery water temperature of the air conditioning system is detected, and when the heat recovery water temperature of the air conditioning system is lower than a first threshold temperature, the refrigerant recovery rate is controlled to be 0%. When the heat recovery water temperature of the air conditioning system is between the first threshold temperature and the second threshold temperature, the refrigerant recovery rate is controlled to be (T_water-5) × 0.04 × 100%, where T_water is the heat recovery water temperature of the air conditioning system. When the heat recovery water temperature of the air conditioning system is greater than the second threshold temperature, the refrigerant recovery rate is controlled to be 100%. The refrigerant recovery rate can be changed by adjusting the opening degree of the recovery valve.

10. An air conditioning system, characterized in that, The air conditioning system implements the refrigerant leakage detection and recovery control method as described in any one of claims 1 to 9.

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