A control method for optimizing a heat pump defrosting process and a heat pump system thereof

Abstract

A control method for optimizing a heat pump defrosting process, comprising: S1, judging whether the heat pump system needs to enter a defrosting mode, specifically: condition 1: when the coil in the heat pump system is at a first temperature, judging whether the temperature of the coil in the heat pump system is lower than the first threshold value below the ambient temperature thereof; condition 2: judging whether the compressor in the heat pump system has been continuously working for a first time period; when the above two conditions are both satisfied, the heat pump system enters the defrosting mode; otherwise, the heat pump system works in a heating mode until the above two conditions are satisfied, so as to consider that the heat pump system causes the evaporator to frost to a certain extent during the heating process and needs to be defrosted; S2, detecting whether a water pump connected with a heat exchanger for heat exchange between refrigerant and water in the heat pump system has a water pump fault, continuously detecting the water temperature of the heat exchanger, and judging whether the heat pump system is in a state without obvious water flow through the water temperature and the pressure of the return gas pipe, and protecting the heat exchanger.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of heat pumps, in particular to a control method for optimizing the defrosting process of a heat pump and a system thereof. BACKGROUND

[0002] In the prior art, when the heat pump system is in the defrosting mode, the heat exchanger through which the water flows is frozen due to the lack of water flow at a certain probability. Generally, the prior art uses a water flow switch to determine whether the water flow meets the requirements to protect the heat exchanger from being frozen. However, when the heat exchanger is frozen during the actual defrosting process of the heat pump system, the reason is that the water flow is low to a certain extent of the rated water flow, for example, less than 20%, and the entire heat pump system does not enter the protection state, or even the protection mechanism fails, thereby failing to effectively protect the heat exchanger from being frozen.

[0003] Although Chinese patent document CN116007249A discloses a control method for preventing the failure caused by the lack of water flow during the defrosting process of a heat pump on April 25, 2023, however, the technical solution has a problem of dead loop in the control process. Typically, when the control method further executes step five after executing step four in the patent document, there is a situation that makes the control method enter step twelve. When the central controller compares the detected outlet water temperature with the previously detected outlet water temperature and determines that it continues to decrease in step twelve, it will enter step four. Therefore, the patent document has a dead loop situation, i.e., step four-step five-step twelve-step four.

[0004] In addition, according to the control logic of the above-mentioned Chinese patent document CN116007249A, if the fault or abnormality is detected immediately after entering the defrosting mode, the defrosting mode is exited and the heating mode is entered, which may further cause the icing condition of the heat exchanger through which the water should flow to deteriorate. Because the reason for entering the defrosting mode is that the heat pump system has been working in the heating mode for a long time, and the heat exchanger is partially iced at a certain probability. Moreover, according to the control logic of the Chinese patent document, the outlet water temperature must be detected, which means that the outlet water temperature sensor must be in a normal state. However, in reality, there are cases of outlet water temperature sensor failure. Once such a situation occurs, the control method of the Chinese patent document will have a more serious situation than the dead loop, i.e., the entire control method cannot operate. Figure 2 Figure 2 In addition, in the prior art, an outlet water flow switch is always needed to control the outlet water. When the heat exchanger is frozen, the outlet water flow switch loses its significance.

[0005] In addition, in the prior art, an outlet water flow switch is always needed to control the outlet water. When the heat exchanger is frozen, the outlet water flow switch loses its significance.

[0006] ​Therefore, the defrosting control method of the heat pump in the prior art has the problems of little significance of the water flow switch, and the defrosting control method logic may fall into a dead loop, or even the whole control method cannot work or further worsen the local icing of the heat exchanger, which needs to be further optimized. SUMMARY

[0007] Therefore, the defrosting control method of the heat pump in the prior art has the problems of little significance of the water flow switch, and the defrosting control method logic may fall into a dead loop, or even the whole control method cannot work or further worsen the local icing of the heat exchanger, which needs to be further optimized.

[0008] The application discloses a control method for optimizing a heat pump defrosting process, comprising the following steps:

[0009] S1, judging whether the heat pump system needs to enter a defrosting mode, the judgment conditions comprising the following two conditions:

[0010] Condition 1: when a finned heat exchanger in the heat pump system is used as an evaporator, and when the ambient temperature of the finned heat exchanger is a first temperature, judging whether the temperature of the finned heat exchanger is lower than the ambient temperature by a first threshold value;

[0011] Condition 2: judging whether the compressor in the heat pump system has continuously worked for a first time period;

[0012] When the above two conditions are both met, the heat pump system enters the defrosting mode; otherwise, as long as any of the above conditions is not met, the heat pump system works in a heating mode until the above two conditions are met, so that it is considered that the evaporator is frosted to a certain degree during the heating process of the heat pump system and needs to be defrosted;

[0013] S2, the heat pump system enters the defrosting mode, and detecting whether a water pump connected with a heat exchanger for heat exchange between refrigerant and water in the heat pump system has a water pump fault:

[0014] When it is detected that the water pump has a fault, the heat pump system is shut down, and a prompt information is sent to wait for repair;

[0015] Otherwise, the next step is entered;

[0016] S3, timely detecting whether an inlet water temperature sensor and an outlet water temperature sensor of the water pump in the heat pump system have faults:

[0017] When it is detected that the inlet water temperature sensor and the outlet water temperature sensor both have faults, the heat pump system is shut down, and a prompt information is sent to wait for repair;

[0018] When it is detected that the water inlet temperature sensor is not faulty and the water outlet temperature sensor is faulty, the water inlet temperature of the water pump in the heat pump system is detected, and if the water inlet temperature is less than a second threshold value, the heat pump system exits the defrosting mode and introduces an auxiliary heat source to heat the water entering the water pump;

[0019] Otherwise, the following steps are performed:

[0020] S31, detecting the water inlet temperature of the water pump in the heat pump system:

[0021] When it is detected that the water inlet temperature is less than a second threshold value, the heat pump system exits the defrosting mode and introduces an auxiliary heat source to heat the water entering the water pump;

[0022] Otherwise, proceed to the next step S32;

[0023] S32, continuously detecting the water inlet temperature:

[0024] i) When it is detected that the water inlet temperature is almost unchanged within a second time period, it is detected whether the compressor is in a certain low-pressure condition and the pressure continues to decrease within a third time period:

[0025] If so, it is considered that the heat pump system is in a state without obvious water flow, the heat pump system exits the defrosting mode and introduces an auxiliary heat source to heat the water entering the water pump;

[0026] Otherwise, it is considered that the heat pump system is in a state with water flow, and the execution starts again from step S2;

[0027] ii) When it is detected that the water inlet temperature has a significant change within a second time period, it is determined whether the water outlet temperature continues to decrease within the third time period:

[0028] If so, it is detected whether the compressor is in a certain low-pressure condition and the pressure continues to decrease within a third time period: if so, it is considered that the heat pump system is in a state without obvious water flow, the heat pump system exits the defrosting mode and introduces an auxiliary heat source to heat the water entering the water pump; otherwise, it is considered that the heat pump system is in a state with water flow, and the execution starts again from step S2;

[0029] Otherwise, the heat pump system still works in the defrosting mode and re-executes step S32.

[0030] Preferably, the control method for optimizing the defrosting process of the heat pump, wherein:

[0031] The first temperature is above 0 degrees and below 8 degrees Celsius.

[0032] Preferably, the control method for optimizing the defrosting process of the heat pump, wherein:

[0033] The first temperature is 3 degrees Celsius.

[0034] Preferably, the control method for optimizing the defrosting process of a heat pump, wherein:

[0035] The first threshold is 5 degrees Celsius.

[0036] Preferably, the control method for optimizing the defrosting process of a heat pump, wherein:

[0037] The first time period is 45 minutes.

[0038] Preferably, the control method for optimizing the defrosting process of a heat pump, wherein:

[0039] The first temperature, the first threshold, and the first time period in step S1 can be set according to the parameters of the heat pump system. The setting principle is that it can effectively determine that the evaporator of the heat pump system has been frosted to a certain extent and needs to be defrosted, and it meets the requirement that the control method can be stably controlled without causing the system to run away during the control process of the heat pump system.

[0040] Preferably, the control method for optimizing the defrosting process of a heat pump, wherein:

[0041] The second threshold is 15 degrees Celsius.

[0042] Preferably, the control method for optimizing the defrosting process of a heat pump, wherein:

[0043] In step S3,

[0044] When it is detected that the inlet water temperature sensor has a fault and the outlet water temperature sensor does not have a fault, a prompt message is sent to alert;

[0045] When it is detected that both the inlet water temperature sensor and the outlet water temperature sensor do not have a fault, the next step S4 is entered;

[0046] S4, detecting the outlet water temperature of the water pump in the heat pump system:

[0047] When it is detected that the outlet water temperature is less than a third threshold, the heat pump system exits the defrosting mode, and an auxiliary heat source is introduced to heat the water entering the water pump;

[0048] Otherwise, the next step S5 is entered;

[0049] S5, continuously detecting the outlet water temperature:

[0050] i) When it is detected that the outlet water temperature is almost unchanged within a fourth time period, it is detected whether the compressor is in a certain low pressure condition and the pressure continues to decrease within a fifth time period:

[0051] If so, the heat pump system is considered to be in a state of no significant water flow. The heat pump system exits the defrost mode and introduces an auxiliary heat source to heat the water entering the pump.

[0052] Otherwise, the heat pump system is considered to be in a state of water flow, and the process starts again from step S2;

[0053] ii) When a significant change in the outlet water temperature is detected during the fourth time period, determine whether the outlet water temperature continues to decrease during that fourth time period:

[0054] If so, check if the compressor is in a low-pressure state and the pressure continues to drop during the fifth time period: if so, it is considered that the heat pump system is in a state with no obvious water flow, the heat pump system exits the defrost mode, and an auxiliary heat source is introduced to heat the water entering the water pump; otherwise, it is considered that the heat pump system is in a state with water flow, and the process starts again from step S2.

[0055] Otherwise, the heat pump system will remain in defrost mode, and step S5 will be executed again.

[0056] Preferably, in the method for controlling the optimized heat pump defrosting process, wherein:

[0057] The auxiliary heat source is an electric heater or a wall-mounted boiler.

[0058] Preferably, the present invention also discloses a heat pump system for performing a control method for optimizing the heat pump defrosting process, the heat pump system comprising:

[0059] The circuit is arranged in a clockwise direction as follows: finned heat exchanger - four-way valve - compressor - heat exchanger for heat exchange between refrigerant and water - liquid receiver - filter - finned heat exchanger; all flowing through the circuit is refrigerant.

[0060] in,

[0061] A heat exchanger that exchanges heat between refrigerant and water, is connected to a water pump and has a water passage through which water flows; wherein, the outlet of the heat exchanger is exempt from the need for a flow switch.

[0062] Preferred,

[0063] The heat exchanger for exchanging heat between the refrigerant and water also has a refrigerant flow path, which is used to flow the refrigerant into the heat exchanger to achieve heat exchange between the refrigerant and water, and the refrigerant flow path is also connected to the liquid storage tank and the compressor.

[0064] The present invention has the following beneficial effects:

[0065] The application always monitors the water flow during the defrosting process, even if the outlet water temperature sensor arranged at the heat exchanger where the refrigerant exchanges heat with water fails, as long as the inlet water temperature sensor arranged at the heat exchanger where the refrigerant exchanges heat with water is still normal, then the water flow loss of the heat pump system during the defrosting process can be accurately controlled according to the change of the inlet water temperature, and whether the heat pump system is safely running can be judged in time; of course, if the outlet water temperature sensor is normal, then the water flow loss of the heat pump system during the defrosting process can be accurately controlled according to the change of the outlet water temperature, and whether the heat pump system is safely running can be judged in time.

[0066] The application introduces the state of the return air pipe pressure value at the same time when the heat pump system is in the defrosting mode, especially the monitoring under the low pressure condition, reduces the misjudgment of the water flow loss caused by the error of the water temperature, and thus reduces unnecessary defrosting interruption; therefore, the heat pump system can significantly reduce the risk of the heat exchanger being damaged and improve the safety of the heat pump system when the defrosting mode is performed.

[0067] In addition, the application comprehensively considers the logic operation level, so that the outlet water flow switch arranged at the outlet of the heat exchanger where the refrigerant exchanges heat with water is no longer necessary, and thus the outlet water flow switch can be directly exempted, the expenditure of components is saved, and the robustness of the entire heat pump system is improved.

[0068] In addition, the application detects the temperature of the waterway system before defrosting and comprehensively judges whether the energy of the waterway system can meet the energy consumed in the defrosting process in combination with pressure sensing, thereby effectively avoiding the risk of the heat exchanger being damaged. And when it is judged that the heat pump system is in a state without obvious water flow, the heat pump system exits the defrosting mode, and an auxiliary heat source is introduced to heat the water entering the water pump, thereby avoiding the problem that may be caused by directly exiting the defrosting mode and directly entering the heating mode when the existing technology is abnormal in the defrosting mode: the icing condition of the heat exchanger where the water should flow may be further deteriorated.

[0069] In summary, the application has the characteristics of careful operation, safety and reliability, and cost saving. BRIEF DESCRIPTION OF DRAWINGS

[0070] Figure 1 It is a schematic diagram of the heat pump system of an embodiment of the application;

[0071] Figure 2 It is a partial enlarged schematic view of the first embodiment of the application; Figure 1 It is a partial enlarged schematic view of the first embodiment of the application;

[0072] Figures 3 to 5 It is a relationship diagram of pressure, time and temperature during the defrosting process. EMBODIMENT

[0073] The application will be further described in connection with the accompanying drawings and embodiments.

[0074] A control method for optimizing a heat pump defrosting process, comprising the following steps:

[0075] S1, judging whether the heat pump system needs to enter a defrosting mode, the judgment conditions including the following two conditions:

[0076] Condition 1: when the finned heat exchanger in the heat pump system is used as an evaporator, when the temperature of the environment in which the finned heat exchanger is located is a first temperature, judging whether the temperature of the finned heat exchanger in the heat pump system is lower than the first threshold value below the temperature of the environment in which the finned heat exchanger is located;

[0077] Exemplarily, the finned heat exchanger is arranged outdoors; preferably, the first temperature is above 0 degrees and below 8 degrees Celsius. More preferably, the first temperature is 3 degrees Celsius, i.e., slightly higher than 0 degrees, so as to be associated with the judgment of frost and ice.

[0078] As for the first threshold value, it is preferably 5 degrees Celsius. For example, the first temperature is 3 degrees, and the temperature of the coil is minus 2 degrees, which is obviously lower than 5 degrees below the first temperature; this is associated with the frost and ice of the heat exchanger and the coil which exchanges heat with the refrigerant and water.

[0079] Condition 2: judging whether the compressor in the heat pump system has been continuously working for a first time period;

[0080] When the above two conditions are both met, the heat pump system enters the defrosting mode; otherwise, as long as any of the above conditions is not met, the heat pump system works in the heating mode until the above two conditions are met, so as to consider that the heat pump system causes the evaporator to frost to a certain extent during the heating process and needs to be defrosted;

[0081] Exemplarily but not limitatively, the first time period is 45 minutes. Further descriptions of the above parameters are shown below.

[0082] S2, when the heat pump system enters the defrosting mode, detecting whether there is a water pump fault of a water pump connected to a heat exchanger which exchanges heat with the refrigerant and water in the heat pump system:

[0083] When it is detected that the water pump has a fault, the heat pump system is stopped, and a prompt information is sent to wait for repair;

[0084] Otherwise, the next step is entered;

[0085] Exemplarily, the heat exchanger which exchanges heat with the refrigerant and water is arranged indoors.

[0086] S3, timely detecting whether the water inlet temperature sensor and the water outlet temperature sensor of the water pump in the heat pump system have faults:

[0087] When it is detected that both the inlet water temperature sensor and the outlet water temperature sensor are faulty, the heat pump system is shut down and a prompt message is sent to wait for repair;

[0088] When it is detected that the inlet water temperature sensor is not faulty but the outlet water temperature sensor is faulty, the inlet water temperature of the water pump in the heat pump system is detected, and if the inlet water temperature is less than a second threshold value, the heat pump system exits the defrosting mode and introduces an auxiliary heat source to heat the water entering the water pump;

[0089] It can be understood that the auxiliary heat source plays a role of supplementing energy for the heat exchanger for heat exchange between the refrigerant and the water in the heat pump system, which is conducive to using these energies to defrost and deice.

[0090] Otherwise, the following steps are performed:

[0091] S31, detecting the inlet water temperature of the water pump in the heat pump system:

[0092] When it is detected that the inlet water temperature is less than a second threshold value, the heat pump system exits the defrosting mode and introduces an auxiliary heat source to heat the water entering the water pump; it can be understood that a certain time interval is provided between S31 and S3, so even if the inlet water temperature is not less than the second threshold value in S3, it still needs to be detected in S31, because there may be a case that the inlet water temperature is less than the second threshold value at this time. When the third threshold value is involved below, similar situations may also exist.

[0093] Otherwise, go to the next step S32;

[0094] S32, continuously detecting the inlet water temperature:

[0095] i) When it is detected that the inlet water temperature is almost unchanged within a second time period, it is detected whether the compressor is in a certain low pressure condition and the pressure continues to decrease within a third time period:

[0096] If so, it is considered that the heat pump system is in a state without obvious water flow, the heat pump system exits the defrosting mode, and an auxiliary heat source is introduced to heat the water entering the water pump;

[0097] Otherwise, it is considered that the heat pump system is in a state with water flow, and the execution starts again from step S2;

[0098] ii) When it is detected that the inlet water temperature has a significant change within a second time period, it is judged whether the outlet water temperature continues to decrease within the third time period:

[0099] For example, the second time period can be 90 seconds; more preferably, for example, 20 seconds;

[0100] If so, it is detected whether the compressor is in a certain low pressure condition and the pressure continues to drop in the third time period: if so, it is considered that the heat pump system is in a state without obvious water flow, the heat pump system exits the defrosting mode, and the auxiliary heat source is introduced to heat the water entering the water pump; otherwise, it is considered that the heat pump system is in a state with water flow, and the execution starts again from step S2.

[0101] Otherwise, the heat pump system still works in the defrosting mode, and step S32 is re-executed.

[0102] Illustratively, the third time period can be the same as the second time period, or different; the two time periods are critical to judge the trend and / or speed of change, thereby associating them with the state without obvious water flow.

[0103] Preferably, the control method for optimizing the defrosting process of the heat pump, wherein:

[0104] The first temperature, the first threshold value and the first time period in step S1 can be set according to the parameters of the heat pump system, and the setting principle is that the evaporator of the heat pump system can be effectively judged to have been frosted to a certain degree and needs to be defrosted, and the control method can be stably controlled to avoid the system runaway in the control process of the heat pump system.

[0105] Preferably, the control method for optimizing the defrosting process of the heat pump, wherein:

[0106] The second threshold value is 15 degrees Celsius. The threshold value is associated with the purpose of heat pump heating, so the threshold value is limited by the heat pump heating.

[0107] Preferably, the control method for optimizing the defrosting process of the heat pump, wherein:

[0108] In step S3,

[0109] When it is detected that the inlet water temperature sensor has a fault and the outlet water temperature sensor has no fault, a prompt information is sent to warn;

[0110] It can be understood that the timely detection of the present application includes detection at the same time interval, or detection at regular different time intervals, or more real-time detection; in short, it is not only detected once, but many times;

[0111] When it is detected that the inlet water temperature sensor and the outlet water temperature sensor have no fault, the next step S4 is entered;

[0112] S4, detecting the outlet water temperature of the water pump in the heat pump system:

[0113] When the outlet water temperature is detected to be less than the third threshold value, the heat pump system exits the defrosting mode and introduces an auxiliary heat source to heat the water entering the water pump;

[0114] Otherwise, go to next step S5;

[0115] S5, continuously detect the outlet water temperature:

[0116] i) When the outlet water temperature is detected to be almost unchanged in a fourth time period, detect whether the compressor is in a certain low pressure condition and the pressure continuously decreases in a fifth time period:

[0117] If yes, it is considered that the heat pump system is in a state without obvious water flow, the heat pump system exits the defrosting mode and introduces an auxiliary heat source to heat the water entering the water pump;

[0118] Otherwise, it is considered that the heat pump system is in a state with water flow, and the execution starts again from step S2;

[0119] ii) When the outlet water temperature is detected to have obvious change in the fourth time period, judge whether the outlet water temperature continuously decreases in the fourth time period:

[0120] If yes, detect whether the compressor is in a certain low pressure condition and the pressure continuously decreases in a fifth time period: if yes, it is considered that the heat pump system is in a state without obvious water flow, the heat pump system exits the defrosting mode and introduces an auxiliary heat source to heat the water entering the water pump; otherwise, it is considered that the heat pump system is in a state with water flow, and the execution starts again from step S2;

[0121] Otherwise, the heat pump system still works in the defrosting mode, and the step S5 is re-executed.

[0122] For example, under the condition that the outlet water temperature sensor is not faulty, the detection of the outlet water temperature is prior to the inlet water temperature.

[0123] In another embodiment, for example, the second threshold value corresponding to the inlet water temperature is greater than the third threshold value of the outlet water temperature; for example, greater than 5 degrees. That is, when the outlet water temperature threshold value is 15 degrees, the inlet water temperature threshold value can be 20 degrees.

[0124] Preferably, the control method for optimizing the heat pump defrosting process, wherein:

[0125] The auxiliary heat source is an electric heater or a wall-mounted boiler.

[0126] Preferably, the present application also discloses a heat pump system for executing a control method for optimizing the heat pump defrosting process, the heat pump system comprising:

[0127] The heat exchanger for heat exchange between refrigerant and water is connected with the water pump and has a water flow path through which water flows; and the water outlet of the heat exchanger is free of a water flow switch.

[0128] In the heat pump system,

[0129] The heat exchanger for heat exchange between refrigerant and water is connected with the water pump and has a water flow path through which water flows; and the water outlet of the heat exchanger is free of a water flow switch.

[0130] In the heat pump system, Figure 1 In the heat pump system,

[0131] The heat exchanger for heat exchange between refrigerant and water is connected with the water pump and has a water flow path through which water flows; and the water outlet of the heat exchanger is free of a water flow switch.

[0132] In the heat pump system,

[0133] The heat pump system further comprises a filter which is acted upon by the electronic expansion valve and is used for throttling.

[0134] In the heat pump system,

[0135] The heat pump system further comprises a fan which is used for forced convection.

[0136] In the heat pump system,

[0137] The finned heat exchanger is provided with a coil temperature sensor for sensing the coil temperature.

[0138] In the heat pump system,

[0139] The heat pump system further comprises a liquid storage tank which is used for dynamic storage of refrigerant when the refrigerant flow is in a low flow state to different degrees in the entire heat pump system pipeline.

[0140] In the heat pump system,

[0141] The return pipe of the compressor is provided with a pressure sensor and a return temperature sensor. In this way, not only the pressure can be monitored, but also the difference between the return temperature and the saturation temperature of the return pressure can be obtained, for example, when the difference is less than 2 degrees, the electronic expansion valve is continuously closed to make the heat pump system cope with the state that the entire heat pump system pipeline has low heat, and the heat is delayed from being consumed too quickly.

[0142] In the heat pump system,

[0143] When the pressure of the return pipe of the compressor of the heat pump system is lower than a certain low pressure, for example, lower than 0.9 MPa (100% water flow low pressure), it is determined that the low pressure state is entered.

[0144] In one embodiment, the water outlet temperature and pressure are detected continuously multiple times as shown in Table 1 below:

[0145]

[0146] For Table 1 above, it means that:

[0147] At time 1s, the water outlet temperature is measured to be 28.48 degrees Celsius, and the pressure is 0.43 MPa;

[0148] At time 35s, the water outlet temperature is measured to be 25.52 degrees Celsius, and the pressure is 0.61 MPa;

[0149] At time 199s, the water outlet temperature is measured to be 21.78 degrees Celsius, and the pressure is 1 MPa;

[0150] In combination with Figure 3 , according to experience, Table 1 above and Figure 3 described above all show that: the water outlet temperature is decreasing, the heat exchange is given to the refrigerant, the frost is removed by the refrigerant, and the return gas pipe pressure of the compressor is normally rising, which belongs to the relationship between the pressure and the water outlet temperature in the defrosting process with normal flow.

[0151] In one embodiment, the water outlet temperature and pressure are detected continuously multiple times as shown in Table 2 below:

[0152]

[0153] For Table 2 above, it means that:

[0154] At time 1s, the water outlet temperature is measured to be 29.04 degrees Celsius, and the pressure is 0.69 MPa;

[0155] At time 33s, the water outlet temperature is measured to be 28.98 degrees Celsius, and the pressure is 0.44 MPa;

[0156] At time 81s, the water outlet temperature is measured to be 28.95 degrees Celsius, and the pressure is 0.41 MPa;

[0157] In combination with Figure 4 , according to experience, Table 2 above and Figure 4The temperature is almost constant, and the water may be blocked in the heat exchanger for heat exchange between the refrigerant and the water, and there is no obvious water flow. In addition, the return gas pipe pressure of the compressor is decreasing, which has decreased from 0.69 at time 1s to 0.4, and the refrigerant flowability is poor. However, defrosting is to use the heat obtained from the heat exchanger for heat exchange between the refrigerant and the water to flow. Therefore, when the refrigerant flowability is poor and is in this low pressure state for a certain period of time, it means that the local icing or frosting of the heat exchanger and the coil will be maintained for a corresponding period of time, which is likely to cause damage to the heat exchanger and the coil. Therefore, Table 2 and Figure 4 The situation reflected is the relationship between the pressure and the outlet water temperature when there is no obvious water flow, which is an abnormal situation that should be responded to. As described in the foregoing examples, the control method of the present application includes the response to this situation.

[0158] In one embodiment, the outlet water temperature and the pressure are detected multiple times in succession as shown in Table 3:

[0159]

[0160] For Table 3, it refers to:

[0161] At time 1s, the outlet water temperature is 29.81 degrees Celsius, and the pressure is 0.82 MPa;

[0162] At time 30s, the outlet water temperature is 23.21 degrees Celsius, and the pressure is 0.61 MPa;

[0163] At time 85s, the outlet water temperature is 15.13 degrees Celsius, and the pressure is 0.53 MPa;

[0164] In combination with Figure 5 According to experience, Table 3 and Figure 5 The temperature is continuously decreasing, and there is no obvious water flow in the heat exchanger for heat exchange between the refrigerant and the water. In addition, the return gas pipe pressure of the compressor is decreasing, which has decreased from 0.82 at time 1s to 0.6 and is still decreasing, and the refrigerant flowability is poor. However, defrosting is to use the heat obtained from the heat exchanger for heat exchange between the refrigerant and the water to flow. Therefore, when the refrigerant flowability is poor and is in this low pressure state for a certain period of time, it means that the local icing or frosting of the heat exchanger and the coil will be maintained for a corresponding period of time, which is likely to cause damage to the heat exchanger and the coil. Therefore, Table 3 and Figure 5 The situation reflected is the relationship between the pressure and the outlet water temperature when there is no obvious water flow, which is an abnormal situation that should be responded to. As described in the foregoing examples, the control method of the present application includes the response to this situation.

[0165] More preferably, the low pressure state is identified when the pressure is below 0.6 MPa. Illustratively, the pressure values recorded over a 60 second period are continuously evaluated to determine if the pressure is continuously decreasing under low pressure conditions. Thus, 60 seconds is an optional value that can be set based on testing or experience to provide robust and effective system control.

[0166] In the description of the application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the application and simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application. The terms "first", "second" are only used for description purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated.

[0167] The basic principles and main features of the application and the advantages of the application are shown and described above. Those skilled in the art should understand that the application is not limited by the above examples, and the above examples and descriptions in the specification are only illustrative of the principles of the application. Without departing from the spirit and scope of the application, various changes and improvements can be made to the application, and these changes and improvements all fall within the scope of the claimed application. The scope of protection of the application is defined by the appended claims and their equivalents.

Claims

1. A control method for optimizing a defrosting process of a heat pump system, comprising the following steps: S1, judging whether the heat pump system needs to enter a defrosting mode, the judging conditions comprising the following two conditions: Condition 1: when a finned heat exchanger in the heat pump system is used as an evaporator, judging whether the temperature of the finned heat exchanger is lower than the temperature of the environment in which the finned heat exchanger is located by a first threshold value when the temperature of the environment is a first temperature; Condition 2: judging whether a compressor in the heat pump system has been continuously working for a first time period; When both of the above two conditions are satisfied, the heat pump system enters the defrosting mode; otherwise, as long as any of the above conditions is not satisfied, the heat pump system works in a heating mode until the above two conditions are satisfied, so that it is considered that the heat pump system causes the evaporator to frost to a certain extent during the heating process and needs to be defrosted; S2, after the heat pump system enters the defrosting mode, detecting whether a water pump connected to a heat exchanger for exchanging heat between refrigerant and water in the heat pump system has a water pump fault: When it is detected that the water pump has a fault, the heat pump system is shut down, and a prompt information is sent to wait for repair; Otherwise, the next step is entered; S3, timely detecting whether an inlet water temperature sensor and an outlet water temperature sensor of the water pump in the heat pump system have faults: When it is detected that both the inlet water temperature sensor and the outlet water temperature sensor have faults, the heat pump system is shut down, and a prompt information is sent to wait for repair; When it is detected that the inlet water temperature sensor does not have a fault but the outlet water temperature sensor has a fault, detecting the inlet water temperature of the water pump in the heat pump system, and if the inlet water temperature is less than a second threshold value, the heat pump system exits the defrosting mode and introduces an auxiliary heat source to heat the water entering the water pump; Otherwise, the following step is performed: S31, detecting the inlet water temperature of the water pump in the heat pump system: When it is detected that the inlet water temperature is less than the second threshold value, the heat pump system exits the defrosting mode and introduces an auxiliary heat source to heat the water entering the water pump; Otherwise, the next step S32 is entered; S32, continuously detecting the inlet water temperature: i) When it is detected that the inlet water temperature is almost unchanged within a second time period, detecting whether the compressor is in a certain low pressure condition and the pressure continuously decreases within a third time period: If yes, it is considered that the heat pump system is in a state without obvious water flow, the heat pump system exits the defrosting mode, and an auxiliary heat source is introduced to heat the water entering the water pump; Otherwise, it is considered that the heat pump system is in a state with water flow, and the execution starts again from step S2; ii) When it is detected that the inlet water temperature has a significant change within the second time period, judging whether the outlet water temperature continuously decreases within the third time period: If yes, it is detected whether the compressor is in a certain low pressure condition and the pressure continuously decreases within the third time period: if yes, it is considered that the heat pump system is in a state without obvious water flow, the heat pump system exits the defrosting mode, and an auxiliary heat source is introduced to heat the water entering the water pump; otherwise, it is considered that the heat pump system is in a state with water flow, and the execution starts again from step S2; Otherwise, the heat pump system still works in the defrosting mode, and step S32 is re-executed. 2.The control method according to claim 1, wherein: The first temperature is above 0 degrees Celsius and below 8 degrees Celsius.

3. The control method of claim 1, wherein: The first temperature is 3 degrees Celsius.

4. The control method of claim 1, wherein: The first threshold is 5 degrees Celsius.

5. The control method of claim 1, wherein: The first time period is 45 minutes.

6. The control method of claim 1, wherein: The first temperature, the first threshold, and the first time period in step S1 can be set according to the parameters of the heat pump system, and the setting principle is that the heat pump system evaporator can be effectively determined to have frost to a certain extent that requires defrosting, and the control method can be stably controlled to avoid system runaway during heat pump system control.

7. The control method of claim 1, wherein: The second threshold is 15 degrees Celsius.

8. The control method of claim 1, wherein: In step S3, When it is detected that the water inlet temperature sensor has a fault and the water outlet temperature sensor does not have a fault, a prompt message is sent to alert; When it is detected that both the water inlet temperature sensor and the water outlet temperature sensor do not have a fault, proceed to the next step S4; S4, detect the water outlet temperature of the water pump in the heat pump system: When it is detected that the water outlet temperature is less than a third threshold, the heat pump system exits the defrosting mode and introduces an auxiliary heat source to heat the water entering the water pump; Otherwise, proceed to the next step S5; S5, continuously detect the water outlet temperature: i) When it is detected that the water outlet temperature is almost unchanged within a fourth time period, detect whether the compressor is in a certain low pressure condition and the pressure continuously decreases within a fifth time period: If so, it is considered that the heat pump system is in a state without obvious water flow, the heat pump system exits the defrosting mode, and an auxiliary heat source is introduced to heat the water entering the water pump; Otherwise, it is considered that the heat pump system is in a state with water flow, and the execution starts again from step S2; ii) When it is detected that the water outlet temperature has a significant change within the fourth time period, determine whether the water outlet temperature continuously decreases within the fourth time period: If so, detect whether the compressor is in a certain low pressure condition and the pressure continuously decreases within a fifth time period: if so, it is considered that the heat pump system is in a state without obvious water flow, the heat pump system exits the defrosting mode, and an auxiliary heat source is introduced to heat the water entering the water pump; otherwise, it is considered that the heat pump system is in a state with water flow, and the execution starts again from step S2; Otherwise, the heat pump system still works in the defrosting mode, and step S5 is re-executed.

9. The control method of claim 1, wherein: The auxiliary heat source is an electric heater or a wall-mounted boiler.

10. A heat pump system for performing the control method of claim 1-9, the heat pump system comprising: The circuit is composed of the following components in the clockwise direction: finned heat exchanger-four-way valve-compressor-heat exchanger for heat exchange between refrigerant and water-storage tank-filter-finned heat exchanger circuit; and the circuit is for the refrigerant. In the circuit, The heat exchanger for heat exchange between refrigerant and water is connected with the water pump and has a water channel for water flow; and the water outlet of the heat exchanger is free of water flow switch.

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