CN115289613A - Method and device for preventing air source heat pump unit from freezing, air source heat pump unit and storage medium - Google Patents

Abstract

The present application relates to the technical field of smart home appliances, and discloses a method for antifreezing of an air source heat pump unit. The air source heat pump unit includes: a water circulation loop; and a refrigerant circulation loop, including a first heat exchanger; wherein, the first heat exchanger exchanging heat with the water circulation loop; the method includes: under the condition of the cooling operation of the air source heat pump unit, detecting the inlet water temperature T _wi and outlet water temperature T _wo of the first heat exchanger; calculating ΔT _w =T _wi -T _wo , obtain the temperature difference ΔT _w of the inlet water temperature and the outlet water temperature of the first heat exchanger; when ΔT _w >ΔT is _cold and the duration reaches the fourth duration T _C4 , shut down the air source heat pump unit; Among them, ΔT _cold is the first flow temperature difference threshold. The method can not only realize the antifreeze protection of the first heat exchanger, but also can reduce the frequent shutdown of the unit, so that the operation of the unit is more stable. The application also discloses an antifreeze device for an air source heat pump unit, an air source heat pump unit and a storage medium.

Description

Method and device for antifreezing air source heat pump unit, air source heat pump unit, storage storage medium

technical field

The present application relates to the technical field of smart home appliances, for example, to a method and device for antifreezing an air source heat pump unit, an air source heat pump unit, and a storage medium.

Background technique

At present, plate heat exchangers are widely used in the water side heat exchangers of air source heat pump units. If the water flow through the plate heat exchanger is insufficient or the water temperature is too low, or the evaporation temperature is too low during the cooling process, the water will The side heat exchanger is frozen and cracked. Most of the existing air source heat pump units adopt the reverse defrosting method. However, based on this defrosting method, when the air source heat pump unit switches to the defrosting mode, the refrigerant in the circuit reverses through the water side for heat exchange. The temperature of the water-side heat exchanger will drop, which will easily cause the water-side heat exchanger to freeze and crack.

In order to solve the problem that the water-side heat exchanger in the air source heat pump unit is easy to freeze and crack, the related art discloses a method for controlling the abnormal water flow of the heat pump water heater unit. By detecting the temperature of the water entering and leaving the water side heat exchanger, according to the range of the temperature difference, it is judged whether the water flow is abnormal, and the shutdown of the unit is controlled. Furthermore, it is effectively guaranteed that the water side heat exchanger will not be affected by too little water flow and cause it to be frozen and cracked.

In the process of implementing the embodiments of the present disclosure, it is found that at least the following problems exist in related technologies:

Although this technology can have a certain effect on the antifreeze of the water-side heat exchanger of the air-source heat pump unit, when it is detected that the temperature difference between the inlet and outlet water of the water-side heat exchanger is greater than the specified threshold, the air-source heat pump unit will stop immediately. Brief periods of low water flow may cause the unit to shut down frequently, resulting in erratic operation.

Contents of the invention

In order to provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is presented below. The summary is not intended to be an extensive overview nor to identify key/important elements or to delineate the scope of these embodiments, but rather serves as a prelude to the detailed description that follows.

The embodiment of the present disclosure provides a method and device for antifreezing of an air source heat pump unit, an air source heat pump unit, and a storage medium, which can not only realize the antifreeze protection of the water side heat exchanger, but also reduce the frequent shutdown of the air source heat pump unit , so that the operation of the air source heat pump unit is more stable.

In some embodiments, the air source heat pump unit includes: a water circulation loop; and, the refrigerant circulation loop includes a first heat exchanger; wherein, the first heat exchanger exchanges heat with the water circulation loop; the method includes: in the air source heat pump In the case of cooling operation of the unit, detect the water inlet temperature T _wi and the water outlet temperature T _wo of the first heat exchanger; calculate △T _w =T _wi -T _wo , and obtain the water inlet temperature and water outlet temperature of the first heat exchanger Temperature difference △T _w ; when △T _w > △T _cold and the duration reaches the fourth duration T _C4 , shut down the air source heat pump unit; where △T _cold is the first flow temperature difference threshold.

In some embodiments, the device for preventing freezing of an air source heat pump unit includes a processor and a memory storing program instructions, and the processor is configured to execute the above-mentioned air source heat pump unit when running the program instructions. Antifreeze method.

In some embodiments, the air source heat pump unit includes: a refrigerant circulation circuit, including a compressor and a first heat exchanger, and a pressure sensor is provided at the air inlet of the compressor for detecting the air inlet pressure of the compressor; The circuit includes a circulating water pump and an auxiliary electric heating device; the circulating water pump is used to start the water circulation of the air source heat pump unit; the auxiliary electric heating device is used to heat the water flowing into the first heat exchanger; wherein, the first heat exchanger and the water circulation circuit Heat exchange, the first heat exchanger includes a water inlet and a water outlet, the water inlet and the water outlet are connected to the water circulation circuit; the water circulation circuit corresponding to the water inlet is provided with a first temperature sensor for detecting the water inlet of the first heat exchanger temperature; the water circulation loop corresponding to the water outlet is provided with a second temperature sensor for detecting the outlet water temperature of the first heat exchanger; The pressure sensor, the first temperature sensor and the second temperature sensor are electrically connected.

In some embodiments, the storage medium stores program instructions, and when the program instructions are run, the above-mentioned method for preventing freezing of an air source heat pump unit is executed.

In the embodiment of the present disclosure, the air source heat pump unit is in cooling operation and the cooling capacity is constant, and the temperature difference between the inlet water temperature and the outlet water temperature of water with different flow rates after flowing through the first heat exchanger is different. The smaller the water flow, the larger the temperature difference between the inlet water temperature and the outlet water temperature. The magnitude of the water flow can be judged by judging the magnitude of the actual temperature difference between the inlet and outlet water and the corresponding first flow temperature difference threshold. If the temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger is greater than the first flow temperature difference threshold and lasts for a certain period of time, it can be determined that the water flow at this time is low. The water flow rate in the first heat exchanger is judged by comparing the temperature difference between the inlet and outlet water of the first heat exchanger and the flow temperature difference threshold, and shutting down the air source heat pump unit is controlled when the water flow rate is low. Thereby, antifreeze protection of the first heat exchanger is achieved. At the same time, the short-term low water flow may cause a large temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger, and setting the duration avoids frequent shutdowns caused by short-term low water flow. In this way, the frequent shutdown of the air source heat pump unit is reduced, and the operation of the air source heat pump unit is more stable.

The foregoing general description and the following description are exemplary and explanatory only and are not intended to limit the application.

Description of drawings

One or more embodiments are exemplified by the corresponding drawings, and these exemplifications and drawings do not constitute a limitation to the embodiments, and elements with the same reference numerals in the drawings are shown as similar elements, The drawings are not limited to scale and in which:

Fig. 1 is a schematic diagram of an air source heat pump unit provided by an embodiment of the present disclosure;

Fig. 2 is a schematic diagram of a method for preventing freezing of an air source heat pump unit provided by an embodiment of the present disclosure;

Fig. 3 is a schematic diagram of another method for preventing freezing of an air source heat pump unit provided by an embodiment of the present disclosure;

Fig. 4 is a schematic diagram of another method for preventing freezing of an air source heat pump unit provided by an embodiment of the present disclosure;

Fig. 5 is a schematic diagram of another method for preventing freezing of an air source heat pump unit provided by an embodiment of the present disclosure;

Fig. 6 is a schematic diagram of another method for preventing freezing of an air source heat pump unit provided by an embodiment of the present disclosure;

Fig. 7 is a schematic diagram of another method for preventing freezing of an air source heat pump unit provided by an embodiment of the present disclosure;

Fig. 8 is a schematic diagram of another method for preventing freezing of an air source heat pump unit provided by an embodiment of the present disclosure;

Fig. 9 is a schematic diagram of another method for preventing freezing of an air source heat pump unit provided by an embodiment of the present disclosure;

Fig. 10 is a schematic diagram of another method for preventing freezing of an air source heat pump unit provided by an embodiment of the present disclosure;

Fig. 11 is a schematic diagram of another method for preventing freezing of an air source heat pump unit provided by an embodiment of the present disclosure;

Fig. 12 is a schematic diagram of another method for preventing freezing of an air source heat pump unit provided by an embodiment of the present disclosure;

Fig. 13 is a schematic diagram of a device for preventing freezing of an air source heat pump unit provided by an embodiment of the present disclosure.

Reference signs:

1: refrigerant circulation circuit; 2: water circulation circuit; 3: circulating water pump; 4: compressor; 5: first heat exchanger; 6: auxiliary electric heating device; 7: pressure sensor; 8: first temperature sensor; 9: Second temperature sensor; 10: second heat exchanger; 11: four-way valve; 12: electronic expansion valve; 13: gas-liquid separator.

Detailed ways

In order to understand the characteristics and technical content of the embodiments of the present disclosure in more detail, the implementation of the embodiments of the present disclosure will be described in detail below in conjunction with the accompanying drawings. The attached drawings are only for reference and description, and are not intended to limit the embodiments of the present disclosure. In the following technical description, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the disclosed embodiments. However, one or more embodiments may be practiced without these details. In other instances, well-known structures and devices may be shown simplified in order to simplify the drawings.

The terms "first", "second" and the like in the description and claims of the embodiments of the present disclosure and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific sequence or sequence. It should be understood that the data so used may be interchanged under appropriate circumstances so as to facilitate the embodiments of the disclosed embodiments described herein. Furthermore, the terms "comprising" and "having", as well as any variations thereof, are intended to cover a non-exclusive inclusion.

In the embodiments of the present disclosure, the orientations or positional relationships indicated by the terms "upper", "lower", "inner", "middle", "outer", "front", "rear" etc. are based on the orientations or positional relationships shown in the drawings. Positional relationship. These terms are mainly used to better describe the embodiments of the present disclosure and their implementations, and are not used to limit that the indicated devices, elements or components must have a specific orientation, or be constructed and operated in a specific orientation. Moreover, some of the above terms may be used to indicate other meanings besides orientation or positional relationship, for example, the term "upper" may also be used to indicate a certain attachment relationship or connection relationship in some cases. Those skilled in the art can understand the specific meanings of these terms in the embodiments of the present disclosure according to specific situations.

Unless stated otherwise, the term "plurality" means two or more.

In the embodiments of the present disclosure, the character "/" indicates that the preceding and following objects are an "or" relationship. For example, A/B means: A or B.

The term "and/or" is an associative relationship describing objects, indicating that there can be three relationships. For example, A and/or B means: A or B, or, A and B, these three relationships.

The term "correspondence" may refer to an association relationship or a binding relationship, and the correspondence between A and B means that there is an association relationship or a binding relationship between A and B.

Additionally, the term "setting" should be interpreted broadly.

It should be noted that, in the case of no conflict, the embodiments and the features in the embodiments of the present disclosure may be combined with each other.

As shown in FIG. 1 , an embodiment of the present disclosure provides an air source heat pump unit, including a refrigerant circulation loop 1 , a water circulation loop 2 and a processor (not shown in the figure). Wherein, the refrigerant circulation circuit 1 includes a compressor 4 , a four-way valve 11 , a first heat exchanger 5 , an electronic expansion valve 12 , a second heat exchanger 10 and a gas-liquid separator 13 connected in sequence. The air inlet of the compressor 4 is provided with a pressure sensor 7 for detecting the pressure of the air inlet of the compressor 4 .

The water circulation circuit 2 includes a circulating water pump 3 and an auxiliary electric heating device 6 . The circulating water pump 3 is used to start the water circulation of the air source heat pump unit. The auxiliary electric heating device 6 communicates with the first heat exchanger 5 and is used for heating the water flowing into the first heat exchanger 5 . The first heat exchanger 5 exchanges heat with the water circulation circuit 2 . The first heat exchanger 5 includes a water inlet and a water outlet, and the water inlet and the water outlet communicate with the water circulation circuit 2 . The water inlet of the first heat exchanger 5 is provided with a first temperature sensor 8 for detecting the water inlet temperature of the first heat exchanger 5 . The water outlet of the first heat exchanger 5 is provided with a second temperature sensor 9 for detecting the outlet water temperature of the first heat exchanger 5 .

In the case of air-conditioning cooling operation or defrosting operation, the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 4 flows to the second heat exchanger 10 for heat exchange through the four-way valve 11 (reversible, at this time connected to the cooling state), Convert high-pressure gaseous refrigerant to high-pressure liquid refrigerant. Then, the high-pressure liquid refrigerant flows through the electronic expansion valve 12 for throttling and depressurization, and then enters the first heat exchanger 5, where the first heat exchanger 5 exchanges heat with the water in the water circulation circuit 2 (absorbs heat) and converts it into a low-temperature and low-pressure refrigerant. gaseous refrigerant. The low-temperature and low-pressure gaseous refrigerant returns to the compressor 4 through the four-way valve 11 , the gas-liquid separator 13 and the pressure sensor 7 . In the case of air conditioning and heating operation, the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 4 flows to the first heat exchanger 5 and the water circulation circuit 2 through the four-way valve 11 (reversible, and it is connected to the heating state at this time). The water performs heat exchange (heat release), converting the high-pressure gaseous refrigerant into a high-pressure liquid refrigerant. Then, the high-pressure liquid refrigerant flows through the electronic expansion valve 12 for throttling and pressure reduction, and then enters the second heat exchanger 10 , where heat exchange is performed in the second heat exchanger 10 and converted into a low-temperature and low-pressure gaseous refrigerant. The low-temperature and low-pressure gaseous refrigerant returns to the compressor 4 through the four-way valve 11 , the gas-liquid separator 13 and the pressure sensor 7 .

The processor can control the start and stop of the air source heat pump unit according to the temperature difference between the inlet and outlet water of the first heat exchanger, so as to realize the antifreeze protection of the first heat exchanger. Moreover, it can reduce the frequent shutdown of the air source heat pump unit, so that the operation of the air source heat pump unit is more stable.

In combination with the air source heat pump unit shown in FIG. 1 , an embodiment of the present disclosure provides a method for antifreezing the air source heat pump unit, as shown in FIG. 2 . The method includes:

S601. In the case of the cooling operation of the air source heat pump unit, the processor detects the inlet water temperature T _wi and the outlet water temperature T _wo of the first heat exchanger.

S602. The processor calculates ΔT _w =T _wi −T _wo to obtain a temperature difference ΔT _w between the inlet water temperature and the outlet water temperature of the first heat exchanger.

S603, under the condition that △ _Tw >△ _Tcold and the duration reaches the fourth duration T _C4 , the processor shuts down the air source heat pump unit. Wherein, ΔT _cold is the first flow temperature difference threshold. The value range of T _C4 is (0 min, 5 min]. Optionally, T _C4 is 1 min, 3 min or 5 min.

In the embodiment of the present disclosure, the air source heat pump unit is in cooling operation and the cooling capacity is constant, and the temperature difference between the inlet water temperature and the outlet water temperature of water with different flow rates after flowing through the first heat exchanger is different. The smaller the water flow, the larger the temperature difference between the inlet water temperature and the outlet water temperature. The magnitude of the water flow can be judged by judging the magnitude of the actual temperature difference between the inlet and outlet water and the corresponding first flow temperature difference threshold. If the temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger is greater than the first flow temperature difference threshold and lasts for a certain period of time, it can be determined that the water flow at this time is low. When the water flow rate is low, the shutdown control of the air source heat pump unit is carried out to realize the antifreeze protection of the first heat exchanger. At the same time, the short-term low water flow may cause a large temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger, and setting the duration avoids frequent shutdowns caused by short-term low water flow. In this way, frequent shutdowns are reduced, and the operation of the air source heat pump unit is more stable. At the same time, the air source heat pump unit no longer needs to install a flow meter separately, which reduces the cost.

Optionally, _ΔTcold is determined according to the operating frequency of the compressor. According to the experimental verification, in the case of cooling operation of the air source heat pump unit, the temperature difference between the inlet and outlet water of the first heat exchanger is related to the operating frequency of the compressor. In this way, when the operating frequency of the compressor is constant, the temperature difference between the inlet water temperature and the outlet water temperature of water with different flow rates after flowing through the first heat exchanger is different. Therefore, _ΔTcold can be determined by the operating frequency of the compressor. Determining △T _cold through the real-time operating frequency of the compressor can make the water flow judgment more accurate. Therefore, the control of the air source heat pump unit is more precise, and the antifreeze effect is better.

Optionally, determining _ΔTcold according to the operating frequency of the compressor includes: acquiring the current operating frequency f of the compressor by the processor. The processor determines ΔT _cold corresponding to the current operating frequency f of the compressor according to the corresponding relationship between ΔT _cold and the operating frequency f of the compressor. In the case of insufficient water flow in the first heat exchanger of the air source heat pump unit, the water temperature in the water cycle quickly reaches the set temperature, causing the unit to stop and restart after the water temperature drops, resulting in frequent switching of the unit. When the water flow in the first heat exchanger of the air source heat pump unit is too large, the water temperature in the water cycle cannot reach the set temperature for a long time, resulting in poor user experience. Therefore, the air source heat pump unit will set the normal operating water flow range according to the cooling capacity. The corresponding relationship between △T _cold and the operating frequency f of the compressor is to measure the corresponding inlet water temperature and outlet water temperature according to the operating frequency of multiple different compressors on the basis of ensuring the lower limit of the water flow range of the normal operation of the air source heat pump unit The temperature difference ΔT is _cold , and then the corresponding fitting formula is obtained based on multiple sets of data. _ΔTcold =12.5×(f/Q ₃ ). Among them, _Q3 is the correction value of the fitting formula. The value range of Q ₃ is [75, 85]. Optionally, _Q3 is 75, 80 or 85. Different series of products have different fitting formulas due to the influence of compressor performance or product structure. In this way, by modifying the formula through _Q3 , a more accurate flow temperature difference threshold can be obtained. Therefore, the control of the air source heat pump unit can be more precise, and the antifreeze effect is better.

Optionally, the cooling operation of the air source heat pump unit includes: the cooling operation of the refrigerant circulation loop and the operating time of the circulating water pump reaches the first operating time T _Y1 . The value range of T _Y1 is (0min, 3min]. Optionally, T _Y1 is 1min, 2min or 3min. After the running time of the circulating water pump reaches the first running time T _Y1 , then judge the water flow in the water circulation loop , can effectively ensure that the water flow in the first heat exchanger has been stabilized. Thereby, effectively avoid the shutdown of the air source heat pump unit due to the unstable water flow in the first heat exchanger when starting up, and make the operation of the air source heat pump unit more stable.

Optionally, after the processor shuts down the air source heat pump unit, the method further includes: in the case of m<M, the processor restarts the operation of the air source heat pump unit after an interval of a second waiting period T _D2 . In the case of m≥M, the processor controls the start and stop of the air source heat pump unit according to the stop times m ₁ within the second constraint time length T _S2 . Among them, m is the cumulative number of low water flow shutdowns of the air source heat pump unit, and M is the maximum number of shutdowns allowed within the second constraint duration T _S2 . The value range of T _D2 is (0min, 10min]. Optionally, T _D2 is 2min, 5min, 8min or 10min. The value range of T _S2 is (0h, 2h]. Optionally, T _S2 is 0.5h , 1h or 2h. The value range of M is [1, 5], and M is a positive integer. Optionally, M is 1, 3 or 5. After shutdown, in order to prevent the water flow in the first heat exchanger occasionally The low phenomenon affects the normal operation of the air source heat pump unit, and the air source heat pump unit will automatically restart after a certain period of time. Thus, the control of the air source heat pump unit is more reliable.

Combined with Figure 3. An embodiment of the present disclosure provides another method for preventing freezing of an air source heat pump unit, including:

S701, the air source heat pump unit starts cooling operation.

S702. The processor detects the outlet water temperature T _wo and the inlet water temperature T _wi of the first heat exchanger.

S703, the processor calculates ΔT _w =T _wi −T _wo to obtain a temperature difference ΔT _w between the inlet water temperature and the outlet water temperature of the first heat exchanger.

S704. The processor judges whether ΔT _w > _ΔTcold is satisfied and the duration reaches the fourth duration T _C4 . If yes, execute step S705. Otherwise, return to step S704.

S705, the processor shuts down the air source heat pump unit.

S706, the processor judges whether m<M is satisfied. If yes, execute step S707. Otherwise, execute step S708.

S707, the processor restarts the operation of the air source heat pump unit after an interval of a second waiting time T _D2 .

S708, the processor controls the start and stop _of the air source heat pump unit according to the stop times m1 within the second constraint time length T _S2 .

In the embodiment of the present disclosure, the water flow rate in the first heat exchanger is judged by comparing the temperature difference between the inlet and outlet water of the first heat exchanger and the flow temperature difference threshold value, and the air source heat pump unit is controlled when the water flow rate is low. Shutdown control. Thereby, antifreeze protection of the first heat exchanger is achieved. At the same time, the short-term low water flow may cause a large temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger, and setting the duration avoids frequent shutdowns caused by short-term low water flow. In this way, frequent shutdowns are reduced, and the operation of the air source heat pump unit is more stable. After shutting down, in order to prevent the occasional low water flow in the first heat exchanger from affecting the normal operation of the air source heat pump unit, the air source heat pump unit will automatically restart after a certain period of time. Therefore, the control of the air source heat pump unit is more reliable.

Optionally, the processor controls the start and stop of the air source heat pump unit according to the number of shutdowns m ₁ within the second constraint duration T _S2 , including: in the case of m ₁ ≥ M, the processor maintains the shutdown state of the air source heat pump unit. In the case of m ₁ <M, the processor restarts the operation of the air source heat pump unit after an interval of the second waiting period T _D2 . If the air source heat pump unit shuts down frequently within the constraint time, there may be a fault or other situation at present, and it is necessary to keep the shutdown state and not restart to protect the air source heat pump unit. For example, when the flow rate of water in the first heat exchanger is always low, the water in the first heat exchanger can easily cool down and freeze, causing the first heat exchanger to freeze and crack. Adopting such a shutdown control method can effectively reduce the chance of freezing cracks of the first heat exchanger and reduce the occurrence of freezing cracks.

Optionally, the method further includes: when the air source heat pump unit is in cooling operation, the processor detects the air inlet pressure P _s of the compressor. The processor determines a low pressure saturation temperature P _st corresponding to P _s . In the case of P _st <P _s-t1 , the processor controls the operation of the compressor to adjust the water temperature of the first heat exchanger. Wherein, P _s-t1 is the first low pressure saturation temperature threshold. The value range of P _s-t1 is (-5°C, -3°C). Optionally, P _s-t1 is -4.5°C, -4°C or -3.5°C. When the air source heat pump unit is in cooling operation, the air inlet pressure of the compressor will fluctuate according to the operating frequency of the compressor. The higher the operating frequency of the compressor, the lower the inlet pressure of the compressor, and the lower the corresponding low-pressure saturation temperature. If the low pressure saturation temperature is lower than a certain value, the probability of freezing of water in the first heat exchanger will increase. By controlling the operation of the compressor through the low-pressure saturation temperature of the compressor, the first heat exchanger can be prevented from being in the condition of too low temperature for a long time, and antifreeze protection for the first heat exchanger can be realized. Compared with related technologies, the embodiments of the present disclosure do not need to adjust the electronic expansion valve, which reduces the complexity of the control process and improves the reliability of the solution. Multiple methods are used to protect the first heat exchanger against freezing, which greatly reduces the probability of freezing cracks of the first heat exchanger and reduces the occurrence of freezing cracks.

Optionally, in the case of P _st <P _s-t1 , the processor controls the operation of the compressor, including: in the case of P _s-t1 >P _st ≥P _s-t2 , the processor prohibits the operation of the compressor Increased frequency. In the case of P _s-t2 >P _st ≥P _s-t3 , the processor reduces the operating frequency of the compressor. When P _st < P _s-t3 and the duration reaches the first duration T _C1 , the processor turns off the compressor. Wherein, P _s-t2 is the second low pressure saturation temperature threshold, and P _s-t3 is the third low pressure saturation temperature threshold. P _s-t1 >P _s-t2 >P _s-t3 . The value range of T _C1 is (0s, 60s). Optionally, T _C1 is 5s, 20s, 35s or 50s. Setting the duration can avoid frequent shutdowns caused by short-term low-pressure saturation temperatures that are too low, making the air source heat pump unit run more stably. The value range of P _s-t1 is (-5°C, -3°C), the value range of P _s-t2 is (-7°C, -5°C), and the value range of P _s-t3 is (-10°C °C, -6 °C). Optionally, P _s-t1 is -4.5°C, P _s-t2 is -6°C, and P _s-t3 is -8°C. Alternatively, P _s-t1 is -3.5°C, P _s-t2 is -5°C, and P _s-t3 is -7°C. Alternatively, P _s-t1 is -4.5°C, P _s-t2 is -6.5°C, and P _s-t3 is -9°C. Due to the higher operating frequency of the compressor, the lower the inlet pressure of the compressor, the lower the corresponding low-pressure saturation temperature. When the low pressure saturation temperature is in different temperature ranges, the air inlet pressure of the compressor can be controlled by prohibiting the operation frequency of the compressor from increasing or reducing the operation frequency of the compressor or shutting down the compressor. In this way, by timely controlling the operation of the compressor, the cooling rate of the water in the first heat exchanger can be reduced, the antifreeze protection of the first heat exchanger can be effectively realized, and the occurrence of frost cracking can be reduced.

Optionally, the method further includes: when the air source heat pump unit enters the defrosting operation, the processor detects the outlet water temperature T _wo of the first heat exchanger. The processor controls the operation of the auxiliary electric heating device according to the outlet water temperature T _wo , so as to adjust the water temperature of the first heat exchanger. Since the defrosting operation is basically equivalent to the cooling operation, the temperature of the first heat exchanger will drop after the air source heat pump unit changes from the heating operation to the defrosting operation. When the temperature of the refrigerant in the first heat exchanger is relatively low (below zero degrees), if the temperature of the water in the first heat exchanger is also relatively low at this time, the probability of freezing the water in the first heat exchanger will rise. In the case of defrosting operation of the air source heat pump unit, the operation of the auxiliary electric heating device is controlled by judging the outlet water temperature, so as to ensure that the water in the first heat exchanger maintains a relatively high water temperature in the case of defrosting operation. In this way, in the case of defrosting operation, the speed of decreasing the temperature of the water in the first heat exchanger is slowed down. Thereby, the probability of freezing and cracking of the first heat exchanger is reduced, and the phenomenon of freezing and cracking is reduced. Multiple methods are used to protect the first heat exchanger against freezing, which greatly reduces the probability of freezing cracks of the first heat exchanger and reduces the occurrence of freezing cracks.

Optionally, the processor controls the operation of the auxiliary electric heating device according to the outlet water temperature T _wo , including: when T _wo <T _wo2 , the processor turns on the auxiliary electric heating device. In the case of T _wo >T _wo3 , the processor turns off the auxiliary electric heating device. Wherein, T _wo2 is the second outlet water temperature threshold, T _wo3 is the third outlet water temperature threshold, T _wo3 >T _wo2 . The value range of T _wo2 is [15°C, 20°C]. Optionally, T _wo2 is 15°C, 17°C or 20°C. The value range of T _wo3 is (20°C, 25°C]. Optionally, T _wo3 is 21°C, 23°C or 25°C. In this way, the water temperature in the first heat exchanger can be kept at a higher temperature, The probability of freezing and cracking of the first heat exchanger is reduced. Thus, the phenomenon of freezing and cracking of the first heat exchanger is reduced. At the same time, when the outlet water temperature is higher than a certain value, turning off the auxiliary electric heating device can also save energy consumption.

Optionally, before the air source heat pump unit enters the defrosting operation, the method further includes: the processor judges whether T _wo satisfies the first condition for entering the defrosting operation. If yes, the processor controls the air source heat pump unit to enter the defrosting operation. Otherwise, the processor turns on the auxiliary electric heating device, and when the outlet water temperature meets the second condition for entering the defrosting operation, the processor controls the air source heat pump unit to enter the defrosting operation. In this way, by judging the outlet water temperature to control whether the air source heat pump unit enters the defrosting operation, it can ensure that the water temperature in the first heat exchanger remains at a relatively high temperature when entering the defrosting operation. Therefore, the probability of freezing and cracking of the first heat exchanger is reduced, and the occurrence of freezing and cracking phenomenon is reduced. Multiple methods are used to protect the first heat exchanger against freezing, which greatly reduces the probability of freezing cracks of the first heat exchanger and reduces the occurrence of freezing cracks.

Optionally, the first condition includes: T _wo ≥ T _wo4 . Wherein, T _wo4 is the fourth outlet water temperature threshold. The value range of _{Two wo4} is [20°C, 45°C]. Optionally, T _wo4 is 20°C, 30°C or 45°C. In this way, it can be ensured that the temperature of the water in the first heat exchanger remains at a relatively high temperature in the case of entering the defrosting operation, thereby reducing the probability of freezing and cracking of the first heat exchanger. Therefore, the phenomenon of freezing and cracking of the first heat exchanger is reduced.

Optionally, the second condition includes: T _wo6 ≤ T _wo ≤ T _wo5 and the duration reaches the fifth duration T _C5 . Or, T _wo >T _wo5 and the duration reaches the sixth duration T _C6 . Wherein, T _wo5 is the fifth outlet water temperature threshold, T _wo6 is the sixth outlet water temperature threshold, T _C5 >T _C6 . The value range of T _wo5 is [20°C, 22°C]. Optionally, T _wo5 is 20°C, 21°C or 22°C. The value range of T _wo6 is [15°C, 22°C]. Optionally, T _wo6 is 15°C, 18°C or 22°C. The value range of T _C5 is [10min, 1h]. Optionally, T _C5 is 10min, 30min or 1h. The value range of T _C6 is (0s, 60s]. Optionally, T _C6 is 10s, 30s or 60s. In this way, it can ensure that the water temperature in the first heat exchanger remains at a relatively high temperature when it enters the defrosting operation , reducing the probability of the first heat exchanger freezing and cracking, thereby reducing the occurrence of the first heat exchanger freezing and cracking phenomenon.

Optionally, during the defrosting operation of the air source heat pump unit, the method further includes: in the case of T _wo <T _wo7 , the processor controls the air source heat pump unit to exit the defrosting operation. Among them, T _{wo7 is} determined according to T _wo4 , T _wo8 and T _wo9 , T _wo7 is the seventh outlet water temperature threshold, T _wo8 is the eighth outlet water temperature threshold, and T _wo9 is the ninth outlet water temperature threshold. When the outlet water temperature of the first heat exchanger is lower than a certain temperature, the probability of freezing of the water in the first heat exchanger increases at this time, and the air source heat pump unit is controlled to exit the defrosting operation. In this way, the probability of freezing and cracking of the first heat exchanger can be reduced, and the phenomenon of freezing and cracking can be reduced. Multiple methods are used to protect the first heat exchanger against freezing, which greatly reduces the probability of freezing cracks of the first heat exchanger and reduces the occurrence of freezing cracks.

Optionally, T _wo7 is determined according to T _wo4 , T _wo8 and T _wo9 , including: T _wo7 =max(T _wo4 −T _wo8 , T _wo9 ). Among them, T _wo4 -T _wo8 are expressions of the drop range of the outlet water temperature of the first heat exchanger, and T _wo9 is the lower limit value of the outlet water temperature of the first heat exchanger. The value range of _{Two wo8} is [10°C, 15°C]. Optionally, T _wo8 is 10°C, 12°C or 15°C. The value range of _{Two wo9} is [5°C, 10°C]. Optionally, T _wo9 is 5°C, 8°C or 10°C. Among them, T _wo4 -T _wo8 are mainly aimed at the conditions for exiting the defrosting operation set when the air source heat pump unit enters the defrosting operation according to the first condition. If the defrosting operation is caused by insufficient water flow or low pressure saturation temperature If the outlet water temperature of the first heat exchanger drops too fast, the risk of freezing and cracking of the first heat exchanger is greater. _{Two wo9} is mainly for the air source heat pump unit to enter the defrosting operation according to the second condition to set the conditions for exiting the defrosting operation. If the outlet water temperature of the first heat exchanger is too low during the defrosting operation, the risk of frost cracking of the first heat exchanger is relatively high. big. In this way, the drop rate of the outlet water temperature and the lower limit of the outlet water temperature are jointly used as conditions for exiting the defrosting operation, thereby reducing the probability of the first heat exchanger being cracked by freezing. Therefore, the phenomenon of freezing and cracking of the first heat exchanger is reduced. For example, when T _wo4 is 25°C, T _wo8 is 12°C, and T _wo9 is 10°C, then T _wo7 =max(25°C-12°C, 10°C)=13°C. When T _wo4 is 21°C, T _wo8 is 15°C, and T _wo9 is 8°C, T _wo7 =max(21°C-15°C, 8°C)=8°C.

Optionally, the method further includes: when the air source heat pump unit is in heating operation, the processor detects the inlet water temperature T _wi and the outlet water temperature T _wo of the first heat exchanger. The processor calculates ΔT _w =T _wo −T _wi to obtain the temperature difference ΔT _w between the inlet water temperature and the outlet water temperature of the first heat exchanger. When ΔT _w > ΔT _hot and the duration reaches the seventh duration T _C7 , the processor shuts down the air source heat pump unit. Wherein, ΔT _heat is the second flow temperature difference threshold. The value range of T _C7 is (0min, 5min]. Optionally, T _C7 is 1min, 3min or 5min. The air source heat pump unit is in heating operation and the heating capacity is constant. The temperature difference between the inlet water temperature and the outlet water temperature after the heat exchanger is different. The smaller the water flow rate, the larger the temperature difference between the inlet water temperature and the outlet water temperature. By judging the actual inlet and outlet water temperature difference and the corresponding second flow temperature difference threshold The size of the water flow can be judged. If the temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger is greater than the second flow temperature difference threshold and lasts for a certain period of time, it can be determined that the water flow at this time is low. If the air source heat pump unit enters the defrosting operation when the water flow is low, the water in the first heat exchanger will easily cool down and freeze, causing the first heat exchanger to freeze. The source heat pump unit is shut down to realize the antifreeze protection of the first heat exchanger. At the same time, the short-term low water flow may cause a large temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger. Avoid frequent shutdowns due to short-term low water flow. In this way, frequent shutdowns are reduced and the operation of the air source heat pump unit is more stable. At the same time, the air source heat pump unit no longer needs to install a flow meter separately, which reduces costs. Multiple methods are used Together, the first heat exchanger is protected against freezing, which greatly reduces the chance of freezing cracks in the first heat exchanger and reduces the occurrence of freezing cracks.

Optionally, ΔT _heat is determined according to the operating frequency of the compressor and the outdoor ambient temperature. According to the experimental verification, in the case of heating operation of the air source heat pump unit, the temperature difference between the inlet and outlet water of the first heat exchanger is related to the operating frequency of the compressor and the outdoor ambient temperature. In this way, when the operating frequency of the compressor and the outdoor ambient temperature are constant, the temperature difference between the inlet water temperature and the outlet water temperature of water with different flow rates after flowing through the first heat exchanger is different. Therefore, ΔT _heat can be determined by the operating frequency of the compressor and the outdoor ambient temperature. The ΔT _heat is determined by the real-time operating frequency of the compressor and the outdoor ambient temperature, which can make the judgment of the water flow more accurate. Therefore, the control of the air source heat pump unit is more precise, and the antifreeze effect is better.

Optionally, determining ΔT _heat according to the operating frequency of the compressor and the outdoor ambient temperature includes: the processor acquires the current operating frequency f of the compressor and the outdoor ambient temperature T _ao . The processor determines the ΔT _heat corresponding to the current operating frequency f of the compressor and the outdoor ambient temperature T _ao according to the corresponding relationship between the ΔT _heat , the operating frequency of the compressor, and the outdoor ambient temperature. In the case of insufficient water flow in the first heat exchanger of the air source heat pump unit, the water temperature in the water cycle quickly reaches the set temperature, causing the unit to stop and restart after the water temperature drops, resulting in frequent switching of the unit. When the water flow in the first heat exchanger of the air source heat pump unit is too large, the water temperature in the water cycle cannot reach the set temperature for a long time, resulting in poor user experience. Therefore, the air source heat pump unit will set the normal operating water flow range according to the heating capacity. The corresponding relationship between △T _heat and the operating frequency of the compressor and the outdoor ambient temperature is based on the lower limit of the water flow range of the normal operation of the air source heat pump unit, and the corresponding relationship is measured according to the operating frequency of multiple different compressors and the outdoor ambient temperature. The temperature difference between the inlet water temperature and the outlet water temperature is △T _heat , and then the corresponding fitting formula is obtained based on multiple sets of data. In the case of T _ao ≥ 21°C, ΔT _heat = 20×(f/Q ₁ ). In the case of T _ao <21°C, ΔT _heat =2×(0.25×(T _ao +12)+5)×(f/Q ₂ ). Among them, Q ₁ and Q ₂ are the correction values of the fitting formula. The value range of Q ₁ is [40, 60], and the value range of Q ₂ is [75, 85]. Optionally, _Q1 is 40, 50 or 60. Optionally, _Q2 is 75, 80 or 85. Different series of products have different fitting formulas due to the influence of compressor performance or product structure. In this way, by modifying the formula through Q ₁ and Q ₂ , a more accurate flow temperature difference threshold can be obtained. Therefore, the control of the air source heat pump unit can be more precise, and the antifreeze effect is better.

Optionally, the heating operation of the air source heat pump unit includes: the heating operation of the refrigerant circulation loop and the operating time of the circulating water pump reaches the second operating time T _Y2 . The value range of T _Y2 is (0min, 3min]. Optionally, T _Y2 is 1min, 2min or 3min. After the running time of the circulating water pump reaches the second running time T _Y2 , then judge the water flow in the water circulation loop , can effectively ensure that the water flow in the first heat exchanger has been stabilized. Thereby, effectively avoid the shutdown of the air source heat pump unit due to the unstable water flow in the first heat exchanger when starting up, and make the operation of the air source heat pump unit more stable.

Optionally, after the processor shuts down the air source heat pump unit, the method further includes: in the case of i<1, the processor restarts the operation of the air source heat pump unit after a third waiting period T _D3 . In the case of i≥I, the processor controls the start and stop of the air source heat pump unit according to the number of shutdowns i ₁ within the third constraint duration T _S3 . Wherein, i is the cumulative low water flow downtime of the air source heat pump unit, and I is the maximum number of downtimes allowed within the third constraint duration T _S3 . The value range of T _D3 is (0min, 10min]. Optionally, T _D3 is 2min, 5min, 8min or 10min. The value range of T _S3 is (0h, 2h]. Optionally, T _S3 is 0.5h , 1h or 2h. The value range of I is [1,5], and I is a positive integer. Optionally, I is 1, 3 or 5. After shutting down, in order to prevent the water flow in the first heat exchanger occasionally The low phenomenon affects the normal operation of the air source heat pump unit, and the air source heat pump unit will automatically restart after a certain period of time. Thus, the control of the air source heat pump unit is more reliable.

Optionally, the processor controls the start and stop of the air source heat pump unit according to the number of shutdowns i ₁ within the third constraint duration T _S3 , including: in the case of i ₁ ≥ I, the processor keeps the air source heat pump unit in the shutdown state. In the case of i ₁ <I, the processor restarts the operation of the air source heat pump unit after a third waiting period T _D3 . If the air source heat pump unit shuts down frequently within the constraint time, there may be a fault or other situation at present, and it is necessary to keep the shutdown state and not restart to protect the air source heat pump unit. For example, if the first heat exchanger enters into a defrosting operation when the water flow rate in the first heat exchanger is low, the water in the first heat exchanger can easily cool down and freeze, causing the first heat exchanger to freeze and crack. Adopting such a shutdown control method can effectively reduce the chance of freezing cracks of the first heat exchanger and reduce the occurrence of freezing cracks.

The processor can also control the operation of the compressor according to the air inlet pressure of the compressor, so as to realize the antifreeze protection of the first heat exchanger, reduce the complexity of the control process, and improve the reliability of the scheme.

Combining with the air source heat pump unit shown in FIG. 1 , an embodiment of the present disclosure provides another antifreeze method for the air source heat pump unit, as shown in FIG. 4 . The method includes:

S201. In the case of cooling operation of the air source heat pump unit, the processor detects the air inlet pressure P _s of the compressor.

S202. The processor determines a low pressure saturation temperature P _st corresponding to P _s .

S203, in the case of P _st <P _s-t1 , the processor controls the operation of the compressor to adjust the water temperature of the first heat exchanger. Wherein, P _s-t1 is the first low pressure saturation temperature threshold. The value range of P _s-t1 is (-5°C, -3°C). Optionally, P _s-t1 is -4.5°C, -4°C or -3.5°C.

In the embodiment of the present disclosure, when the air source heat pump unit is in cooling operation, the pressure at the air inlet of the compressor will fluctuate according to the operating frequency of the compressor. The higher the operating frequency of the compressor, the lower the inlet pressure of the compressor, and the lower the corresponding low-pressure saturation temperature. If the low pressure saturation temperature is lower than a certain value, the probability of freezing of water in the first heat exchanger will increase. By controlling the operation of the compressor through the low-pressure saturation temperature of the compressor, the first heat exchanger can be prevented from being in the condition of too low temperature for a long time, and antifreeze protection for the first heat exchanger can be realized. Compared with related technologies, the embodiments of the present disclosure do not need to adjust the electronic expansion valve, which reduces the complexity of the control process and improves the reliability of the solution.

Optionally, the method further includes: when the air source heat pump unit is in cooling operation, the processor detects the outlet water temperature T _wo and the inlet water temperature T _wi of the first heat exchanger. When T _wi ≤ T _wi1 and the duration reaches the second duration T _C2 , the processor shuts down the air source heat pump unit. Or, under the condition that T _wo ≤ T _wo1 and the duration reaches the third duration T _C3 , the processor shuts down the air source heat pump unit. Wherein, T _wi1 is the first inlet water temperature threshold, and T _wo1 is the first outlet water temperature threshold. The value range of _Twi1 is [3°C, 5°C]. Optionally, T _wi1 is 3°C, 4°C or 5°C. The value range of T _wo1 is [3°C, 5°C]. Optionally, _Two1 is 3°C, 4°C or 5°C. The value range of T _C2 is [0min, 2min]. Optionally, T _C2 is 0 min, 1 min or 2 min. The value range of T _C3 is [0min, 2min]. Optionally, T _C3 is 0 min, 1 min or 2 min. In the case of cooling operation of the air source heat pump unit, the temperature of the first heat exchanger will drop. When the temperature of the refrigerant in the first heat exchanger is relatively low (below zero degrees), if the temperature of the water in the first heat exchanger is also relatively low at this time, the probability of freezing the water in the first heat exchanger will rise. When the inlet water temperature or outlet water temperature of the first heat exchanger is lower than a certain temperature for a period of time, the air source heat pump unit is shut down to avoid freezing caused by the low water temperature of the first heat exchanger. Thereby, antifreeze protection of the first heat exchanger is achieved. At the same time, setting the duration avoids the frequent shutdown of the air source heat pump unit caused by the short-term low temperature of the inlet and outlet water. In this way, frequent shutdowns are reduced, and the operation of the air source heat pump unit is more stable. Multiple methods are used to protect the first heat exchanger against freezing, which greatly reduces the probability of freezing cracks of the first heat exchanger and reduces the occurrence of freezing cracks.

As shown in FIG. 5 , an embodiment of the present disclosure provides another method for preventing freezing of an air source heat pump unit, including:

S301, the air source heat pump unit starts cooling operation.

S302. The processor detects the inlet pressure P _s of the compressor.

S303. The processor determines the low pressure saturation temperature P _st corresponding to P _s .

S304, the processor judges whether P _st <P _s-t1 is satisfied. If yes, execute step S305. Otherwise, return to step S304. Wherein, P _s-t1 is the first low pressure saturation temperature threshold.

S305, the processor controls the operation of the compressor to adjust the water temperature of the first heat exchanger.

S306. The processor detects the outlet water temperature T _wo and the inlet water temperature T _wi of the first heat exchanger.

S307. The processor judges whether T _wi ≤ T _wi1 is satisfied and the duration reaches the second duration T _C2 . If yes, execute step S309. Otherwise, return to step S307.

S308. The processor judges whether T _wo ≤ T _wo1 is satisfied and the duration reaches the third duration T _C3 . If yes, execute step S309. Otherwise, return to step S308.

S309, the processor shuts down the air source heat pump unit.

Wherein, steps S302 to S305 and steps S306 to S309 are executed synchronously, and step S307 and step S308 are executed synchronously.

In the embodiment of the present disclosure, by controlling the operation of the compressor through the low-pressure saturation temperature of the compressor, the first heat exchanger can be prevented from being in a condition of too low temperature for a long time, and antifreeze protection for the first heat exchanger can be realized. Compared with related technologies, the embodiments of the present disclosure do not need to adjust the electronic expansion valve, which reduces the complexity of the control process and improves the reliability of the solution. At the same time, by judging the temperature of the inlet and outlet water of the first heat exchanger, the shutdown control of the air source heat pump unit is performed, so as to avoid freezing caused by the water temperature of the first heat exchanger being too low. Thereby, antifreeze protection of the first heat exchanger is achieved. Setting the duration avoids frequent shutdown of the air source heat pump unit due to short-term low inlet and outlet water temperatures. In this way, frequent shutdowns are reduced, and the operation of the air source heat pump unit is more stable. Multiple methods are used to protect the first heat exchanger against freezing, which greatly reduces the probability of freezing cracks of the first heat exchanger and reduces the occurrence of freezing cracks.

Optionally, after the processor shuts down the air source heat pump unit, the method further includes: in the case of n<N, the processor restarts the operation of the air source heat pump unit after an interval of a first waiting period T _D1 . In the case of n≥N, the processor controls the start and stop of the air source heat pump unit according to the number of shutdowns n ₁ within the first constraint duration T _S1 . Wherein, n is the accumulated number of low-temperature shutdowns of the air source heat pump unit, and N is the maximum number of shutdowns allowed within the first constraint duration T _S1 . The value range of T _D1 is [8min, 15min]. Optionally, T _D1 is 8min, 10min, 12min or 15min. The value range of T _S1 is [1h, 2h]. Optionally, T _S1 is 1 h, 1.5 h or 2 h. The value range of N is [1, 5], and N is a positive integer. Optionally, N is 1, 3 or 5. After shutting down, in order to prevent the occasional low water temperature in the first heat exchanger from affecting the normal operation of the air source heat pump unit, the air source heat pump unit will automatically restart after a certain period of time. Therefore, the control of the air source heat pump unit is more reliable.

Optionally, controlling the start and stop of the air source heat pump unit according to the number of shutdowns n ₁ within the first constraint duration T _S1 includes: in the case of n ₁ ≥ N, the processor maintains the shutdown state of the air source heat pump unit. In the case of n ₁ <N, the processor restarts the operation of the air source heat pump unit after an interval of the first waiting time T _D1 . If the air source heat pump unit shuts down frequently within the constraint time, there may be a fault or other situation at present, and it is necessary to keep the shutdown state and not restart to protect the air source heat pump unit. For example, when heating operation is required in winter, the user makes a wrong operation to perform cooling operation. Due to the low water temperature in winter, if the refrigeration is operated again at this time, the water in the first heat exchanger is easy to freeze and cause the first heat exchanger to freeze and crack. Adopting such a shutdown control method can effectively reduce the chance of freezing cracks of the first heat exchanger and reduce the occurrence of freezing cracks.

The processor can also control the start and stop of the air source heat pump unit according to the inlet water temperature or the outlet water temperature of the first heat exchanger, so as to realize the antifreeze protection for the first heat exchanger. Moreover, it can reduce the frequent shutdown of the air source heat pump unit, so that the operation of the air source heat pump unit is more stable.

Combining with the air source heat pump unit shown in FIG. 1 , the embodiment of the present disclosure provides another antifreeze method for the air source heat pump unit, as shown in FIG. 6 . The method includes:

S401. In the case of cooling operation of the air source heat pump unit, the processor detects the outlet water temperature T _wo and the inlet water temperature T _wi of the first heat exchanger.

S402. Under the condition that T _wi ≤ T _wi1 and the duration reaches a second duration T _C2 , the processor shuts down the air source heat pump unit.

S403, under the condition that T _wo ≤ T _wo1 and the duration reaches a third duration T _C3 , the processor shuts down the air source heat pump unit.

Wherein, T _wi1 is the first inlet water temperature threshold, and T _wo1 is the first outlet water temperature threshold. The value range of _Twi1 is [3°C, 5°C]. Optionally, T _wi1 is 3°C, 4°C or 5°C. The value range of T _wo1 is [3°C, 5°C]. Optionally, _Two1 is 3°C, 4°C or 5°C. The value range of T _C2 is [0min, 2min]. Optionally, T _C2 is 0 min, 1 min or 2 min. The value range of T _C3 is [0min, 2min]. Optionally, T _C3 is 0 min, 1 min or 2 min.

In the embodiment of the present disclosure, when the air source heat pump unit is in cooling operation, the temperature of the first heat exchanger will decrease. When the temperature of the refrigerant in the first heat exchanger is relatively low (below zero degrees), if the temperature of the water in the first heat exchanger is also relatively low at this time, the probability of freezing the water in the first heat exchanger will rise. When the inlet water temperature or outlet water temperature of the first heat exchanger is lower than a certain temperature for a period of time, the air source heat pump unit is shut down to avoid freezing caused by the low water temperature of the first heat exchanger. Thereby, antifreeze protection of the first heat exchanger is achieved. At the same time, setting the duration avoids the frequent shutdown of the air source heat pump unit caused by the short-term low temperature of the inlet and outlet water. In this way, frequent shutdowns are reduced, and the operation of the air source heat pump unit is more stable.

As shown in FIG. 7 , an embodiment of the present disclosure provides another method for preventing freezing of an air source heat pump unit, including:

S501, the air source heat pump unit starts cooling operation.

S502. The processor detects the outlet water temperature T _wo and the inlet water temperature T _wi of the first heat exchanger.

S503. The processor judges whether T _wi ≤ T _wi1 is satisfied and the duration reaches the second duration T _C2 . If yes, execute step S505. Otherwise, return to step S503.

S504. The processor judges whether T _wo ≤ T _wo1 is satisfied and the duration reaches the third duration T _C3 . If yes, execute step S505. Otherwise, return to step S504.

S505, the processor shuts down the air source heat pump unit.

S506, the processor judges whether n<N is satisfied. If yes, execute step S507. Otherwise, execute step S508.

S507, the processor restarts the operation of the air source heat pump unit after an interval of the first waiting time T _D1 .

S508, the processor controls the start and stop of the air source heat pump unit according to the number of stop times n1 within the _first constraint duration T _S1 .

In the embodiment of the present disclosure, when the air source heat pump unit is in cooling operation, the temperature of the first heat exchanger will decrease. When the temperature of the refrigerant in the first heat exchanger is relatively low (below zero degrees), if the temperature of the water in the first heat exchanger is also relatively low at this time, the probability of freezing the water in the first heat exchanger will rise. When the inlet water temperature or outlet water temperature of the first heat exchanger is lower than a certain temperature for a period of time, the air source heat pump unit is shut down to avoid freezing caused by the low water temperature of the first heat exchanger. Thereby, antifreeze protection of the first heat exchanger is achieved. At the same time, setting the duration avoids the frequent shutdown of the air source heat pump unit caused by the short-term low temperature of the inlet and outlet water. In this way, frequent shutdowns are reduced, and the operation of the air source heat pump unit is more stable. After shutting down, in order to prevent the occasional low water temperature in the first heat exchanger from affecting the normal operation of the air source heat pump unit, the air source heat pump unit will automatically restart after a certain period of time. Therefore, the control of the air source heat pump unit is more reliable.

The processor can also control the operation of the auxiliary electric heating device of the air source heat pump unit according to the outlet water temperature of the first heat exchanger, so as to reduce the probability of freezing cracks of the first heat exchanger and reduce the occurrence of freezing cracks.

Combining with the air source heat pump unit shown in FIG. 1 , the embodiment of the present disclosure provides another method for antifreezing of the air source heat pump unit, as shown in FIG. 8 . The method includes:

S801. When the air source heat pump unit enters the defrosting operation, the processor detects the outlet water temperature T _wo of the first heat exchanger.

S802, the processor controls the operation of the auxiliary electric heating device according to the outlet water temperature T _wo , so as to adjust the water temperature of the first heat exchanger.

In the embodiment of the present disclosure, since the defrosting operation is basically equivalent to the cooling operation, the temperature of the first heat exchanger will decrease after the air source heat pump unit switches from the heating operation to the defrosting operation. When the temperature of the refrigerant in the first heat exchanger is relatively low (below zero degrees), if the temperature of the water in the first heat exchanger is also relatively low at this time, the probability of freezing the water in the first heat exchanger will rise. In the case of defrosting operation of the air source heat pump unit, the operation of the auxiliary electric heating device is controlled by judging the outlet water temperature, so as to ensure that the water in the first heat exchanger maintains a relatively high water temperature in the case of defrosting operation. In this way, in the case of defrosting operation, the speed of decreasing the temperature of the water in the first heat exchanger is slowed down. Thereby, the probability of freezing and cracking of the first heat exchanger is reduced, and the phenomenon of freezing and cracking is reduced.

As shown in FIG. 9 , an embodiment of the present disclosure provides another method for preventing freezing of an air source heat pump unit, including:

S901, the air source heat pump unit receives a defrosting operation instruction.

S902. The processor detects the outlet water temperature T _wo of the first heat exchanger.

S903, the processor judges whether the first condition for entering the defrosting operation is satisfied. If yes, execute step S906. Otherwise, execute step S904.

S904, the processor turns on the auxiliary electric heating device.

S905. The processor judges whether the second condition for entering the defrosting operation is satisfied. If yes, execute step S906. Otherwise, return to step S905.

S906, the processor controls the air source heat pump unit to enter the defrosting operation.

S907. The processor judges whether T _wo <T _wo2 is satisfied. If yes, execute step S909. Otherwise, execute step S908.

S908, the processor judges whether T _wo >T _wo3 is satisfied. If yes, execute step S910. Otherwise, return to step S907.

S909, the processor turns on the auxiliary electric heating device. Return to step S908.

S910, the processor turns off the auxiliary electric heating device. Return to step S907.

In the embodiment of the present disclosure, by judging the outlet water temperature to control whether the air source heat pump unit enters the defrosting operation, it can ensure that the water temperature in the first heat exchanger remains at a relatively high temperature when entering the defrosting operation. Therefore, the probability of freezing and cracking of the first heat exchanger is reduced, and the occurrence of freezing and cracking phenomenon is reduced. After entering the defrosting operation, controlling the switch of the auxiliary electric heating device according to the outlet water temperature can keep the water temperature in the first heat exchanger at a higher temperature, and at the same time turn off the auxiliary electric heating device when the outlet water temperature is higher than a certain value. Save energy.

Optionally, the method further includes: when the air source heat pump unit is in defrosting operation, the processor detects the air inlet pressure P _s of the compressor. The processor determines a low pressure saturation temperature P _st corresponding to P _s . In the case of P _st <P _s-t1 , the processor controls the operation of the compressor to adjust the water temperature of the first heat exchanger. Wherein, P _s-t1 is the first low pressure saturation temperature threshold. The value range of P _s-t1 is (-5°C, -3°C). Optionally, P _s-t1 is -4.5°C, -4°C or -3.5°C. In the case of defrosting operation of the air source heat pump unit, the air inlet pressure of the compressor will fluctuate according to the operating frequency of the compressor. The higher the operating frequency of the compressor, the lower the inlet pressure of the compressor, and the lower the corresponding low-pressure saturation temperature. If the low pressure saturation temperature is lower than a certain value, the probability of freezing of water in the first heat exchanger will increase. By controlling the operation of the compressor through the low-pressure saturation temperature of the compressor, the first heat exchanger can be prevented from being in the condition of too low temperature for a long time, and antifreeze protection for the first heat exchanger can be realized. Multiple methods are used to protect the first heat exchanger against freezing, which greatly reduces the probability of freezing cracks of the first heat exchanger and reduces the occurrence of freezing cracks.

Optionally, in the case of P _st <P _s-t1 , the processor controls the operation of the compressor, including: in the case of P _s-t1 >P _st ≥P _s-t2 , the processor prohibits the operation of the compressor Increased frequency. In the case of P _s-t2 >P _st ≥P _s-t3 , the processor reduces the operating frequency of the compressor. When P _st < P _s-t3 and the duration reaches the first duration T _C1 , the processor turns off the compressor. Wherein, P _s-t2 is the second low pressure saturation temperature threshold, and P _s-t3 is the third low pressure saturation temperature threshold. P _s-t1 >P _s-t2 >P _s-t3 . The value range of T _C1 is (0s, 60s). Optionally, T _C1 is 5s, 20s, 35s or 50s. Setting the duration can avoid frequent shutdowns caused by short-term low-pressure saturation temperatures that are too low, making the air source heat pump unit run more stably. The value range of P _s-t1 is (-5°C, -3°C), the value range of P _s-t2 is (-7°C, -5°C), and the value range of P _s-t3 is (-10°C °C, -6 °C). Optionally, P _s-t1 is -4.5°C, P _s-t2 is -6°C, and P _s-t3 is -8°C. Alternatively, P _s-t1 is -3.5°C, P _s-t2 is -5°C, and P _s-t3 is -7°C. Alternatively, P _s-t1 is -4.5°C, P _s-t2 is -6.5°C, and P _s-t3 is -9°C. Due to the higher operating frequency of the compressor, the lower the inlet pressure of the compressor, the lower the corresponding low-pressure saturation temperature. When the low pressure saturation temperature is in different temperature ranges, the air inlet pressure of the compressor can be controlled by prohibiting the operation frequency of the compressor from increasing or reducing the operation frequency of the compressor or shutting down the compressor. In this way, by timely controlling the operation of the compressor, the cooling rate of the water in the first heat exchanger can be reduced, the antifreeze protection of the first heat exchanger can be effectively realized, and the occurrence of frost cracking can be reduced.

Optionally, the method further includes: when the air source heat pump unit is in defrosting operation, the processor detects the inlet water temperature T _wi of the first heat exchanger. The processor calculates ΔT _w =T _wi −T _wo to obtain the temperature difference ΔT _w between the inlet water temperature and the outlet water temperature of the first heat exchanger. When ΔT _w > ΔT _cold and the duration reaches the fourth duration T _C4 , the processor shuts down the air source heat pump unit. Wherein, ΔT _cold is the first flow temperature difference threshold. The value range of T _C4 is (0min, 5min]. Optionally, T _C4 is 1min, 3min or 5min. The air source heat pump unit is in cooling operation and in the case of a certain cooling capacity, water with different flow rates flows through the first The temperature difference between the inlet water temperature and the outlet water temperature after the heat exchanger is different. The smaller the water flow rate, the larger the temperature difference between the inlet water temperature and the outlet water temperature. By judging the actual inlet and outlet water temperature difference and the corresponding first flow temperature difference threshold The size of the water flow can be judged. If the temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger is greater than the first flow temperature difference threshold and lasts for a certain period of time, then it can be determined that the water flow is low at this time. In the water When the flow rate is low, the air source heat pump unit is shut down to realize the antifreeze protection of the first heat exchanger. At the same time, the short-term low water flow rate may cause the temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger. The temperature difference is large, and the setting duration avoids frequent shutdowns caused by short-term low water flow. In this way, frequent shutdowns are reduced, and the air source heat pump unit operates more stably. At the same time, the air source heat pump unit no longer needs to install a flow meter separately, reducing The cost is reduced. Multiple methods are used to protect the first heat exchanger against freezing, which greatly reduces the probability of freezing cracks in the first heat exchanger and reduces the occurrence of freezing cracks.

Optionally, _ΔTcold is determined according to the operating frequency of the compressor. According to the experimental verification, in the case of defrosting operation of the air source heat pump unit, the temperature difference between the inlet and outlet water of the first heat exchanger is related to the operating frequency of the compressor. In this way, when the operating frequency of the compressor is constant, the temperature difference between the inlet water temperature and the outlet water temperature of water with different flow rates after flowing through the first heat exchanger is different. Therefore, _ΔTcold can be determined by the operating frequency of the compressor. Determining △T _cold through the real-time operating frequency of the compressor can make the water flow judgment more accurate. Therefore, the control of the air source heat pump unit is more precise, and the antifreeze effect is better.

Optionally, determining _ΔTcold according to the operating frequency of the compressor includes: acquiring the current operating frequency f of the compressor by the processor. The processor determines ΔT _cold corresponding to the current operating frequency f of the compressor according to the corresponding relationship between ΔT _cold and the operating frequency f of the compressor. In the case of insufficient water flow in the first heat exchanger of the air source heat pump unit, the water temperature in the water cycle quickly reaches the set temperature, causing the unit to stop and restart after the water temperature drops, resulting in frequent switching of the unit. When the water flow in the first heat exchanger of the air source heat pump unit is too large, the water temperature in the water cycle cannot reach the set temperature for a long time, resulting in poor user experience. Therefore, the air source heat pump unit will set the normal operating water flow range according to the cooling capacity. The corresponding relationship between △T _cold and the operating frequency f of the compressor is to measure the corresponding inlet water temperature and outlet water temperature according to the operating frequency of multiple different compressors on the basis of ensuring the lower limit of the water flow range of the normal operation of the air source heat pump unit The temperature difference ΔT is _cold , and then the corresponding fitting formula is obtained based on multiple sets of data. _ΔTcold =12.5×(f/Q ₃ ). Among them, _Q3 is the correction value of the fitting formula. The value range of Q ₃ is [75, 85]. Optionally, _Q3 is 75, 80 or 85. Different series of products have different fitting formulas due to the influence of compressor performance or product structure. In this way, by modifying the formula through _Q3 , a more accurate flow temperature difference threshold can be obtained. Therefore, the control of the air source heat pump unit can be more precise, and the antifreeze effect is better.

Optionally, the defrosting running of the air source heat pump unit includes: the cooling running of the refrigerant circulation loop and the running time of the circulating water pump reaches the first running time T _Y1 . The value range of T _Y1 is (0min, 3min]. Optionally, T _Y1 is 1min, 2min or 3min. After the running time of the circulating water pump reaches the first running time T _Y1 , then judge the water flow in the water circulation loop , can effectively ensure that the water flow in the first heat exchanger has been stabilized. Thereby, effectively avoid the shutdown of the air source heat pump unit due to the unstable water flow in the first heat exchanger when starting up, and make the operation of the air source heat pump unit more stable.

Optionally, after the processor shuts down the air source heat pump unit, the method further includes: in the case of m<M, the processor restarts the operation of the air source heat pump unit after an interval of a second waiting period T _D2 . In the case of m≥M, the processor controls the start and stop of the air source heat pump unit according to the stop times m ₁ within the second constraint time length T _S2 . Among them, m is the cumulative number of low water flow shutdowns of the air source heat pump unit, and M is the maximum number of shutdowns allowed within the second constraint duration T _S2 . The value range of T _D2 is (0min, 10min]. Optionally, T _D2 is 2min, 5min, 8min or 10min. The value range of T _S2 is (0h, 2h]. Optionally, T _S2 is 0.5h , 1h or 2h. The value range of M is [1, 5], and M is a positive integer. Optionally, M is 1, 3 or 5. After shutdown, in order to prevent the water flow in the first heat exchanger occasionally The low phenomenon affects the normal operation of the air source heat pump unit, and the air source heat pump unit will automatically restart after a certain period of time. Thus, the control of the air source heat pump unit is more reliable.

Optionally, the processor controls the start and stop of the air source heat pump unit according to the number of shutdowns m ₁ within the second constraint duration T _S2 , including: in the case of m ₁ ≥ M, the processor maintains the shutdown state of the air source heat pump unit. In the case of m ₁ <M, the processor restarts the operation of the air source heat pump unit after an interval of the second waiting period T _D2 . If the air source heat pump unit shuts down frequently within the constraint time, there may be a fault or other situation at present, and it is necessary to keep the shutdown state and not restart to protect the air source heat pump unit. For example, when the flow rate of water in the first heat exchanger is always low, the water in the first heat exchanger can easily cool down and freeze, causing the first heat exchanger to freeze and crack. Adopting such a shutdown control method can effectively reduce the chance of freezing cracks of the first heat exchanger and reduce the occurrence of freezing cracks.

The processor can also control the start and stop of the air source heat pump unit according to the temperature difference between the inlet and outlet water of the first heat exchanger, so as to realize the antifreeze protection of the first heat exchanger. Moreover, it can reduce the frequent shutdown of the air source heat pump unit, so that the operation of the air source heat pump unit is more stable.

Combining with the air source heat pump unit shown in FIG. 1 , the embodiment of the present disclosure provides another antifreeze method for the air source heat pump unit, as shown in FIG. 10 . The method includes:

S1001. When the air source heat pump unit is in heating operation, the processor detects the inlet water temperature T _wi and the outlet water temperature T _wo of the first heat exchanger.

S1002. The processor calculates ΔT _w =T _wo −T _wi to obtain the temperature difference ΔT _w between the inlet water temperature and the outlet water temperature of the first heat exchanger.

S1003, when △ _Tw >△Thot and the duration reaches the seventh duration T _C7 , the processor shuts down the air source _heat pump unit. Wherein, ΔT _heat is the second flow temperature difference threshold. The value range of T _C7 is (0 min, 5 min]. Optionally, T _C7 is 1 min, 3 min or 5 min.

In the embodiment of the present disclosure, when the air source heat pump unit is in heating operation and the heating capacity is constant, the temperature difference between the inlet water temperature and the outlet water temperature of water with different flow rates after flowing through the first heat exchanger is different. The smaller the water flow, the larger the temperature difference between the inlet water temperature and the outlet water temperature. By judging the magnitude of the actual temperature difference between the inlet and outlet water and the corresponding second flow temperature difference threshold, the magnitude of the water flow can be judged. If the temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger is greater than the second flow temperature difference threshold and lasts for a certain period of time, it can be determined that the water flow at this time is low. If the air source heat pump unit enters the defrosting operation when the water flow rate is low, the water in the first heat exchanger can easily cool down and freeze, causing the first heat exchanger to freeze and crack. When the water flow rate is low, the shutdown control of the air source heat pump unit is carried out to realize the antifreeze protection of the first heat exchanger. At the same time, the short-term low water flow may cause a large temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger, and setting the duration avoids frequent shutdowns caused by short-term low water flow. In this way, frequent shutdowns are reduced, and the operation of the air source heat pump unit is more stable. The air source heat pump unit no longer needs to install a flow meter separately, which reduces the cost.

As shown in FIG. 11 , an embodiment of the present disclosure provides another method for preventing freezing of an air source heat pump unit, including:

S1101, the air source heat pump unit starts heating operation.

S1102. The processor detects the outlet water temperature T _wo and the inlet water temperature T _wi of the first heat exchanger.

S1103, the processor calculates ΔT _w =T _wo −T _wi to obtain the temperature difference ΔT _w between the inlet water temperature and the outlet water temperature of the first heat exchanger.

S1104. The processor judges whether ΔT _w > ΔT _heat is satisfied and the duration reaches the seventh duration T _C7 . If yes, execute step S1105. Otherwise, return to step S1104.

S1105, the processor shuts down the air source heat pump unit.

S1106, the processor judges whether i<I is satisfied. If yes, execute step S1107. Otherwise, execute step S1108.

S1107, the processor restarts the operation of the air source heat pump unit after a third waiting time T _D3 .

S1108, the processor controls the start and stop of the air source heat pump unit according to the number of shutdowns i ₁ within the third constraint duration T _S3 .

In the embodiment of the present disclosure, in the case of heating operation of the air source heat pump unit, the water flow rate in the first heat exchanger is judged by comparing the temperature difference between the inlet and outlet water of the first heat exchanger and the flow temperature difference threshold. If the air source heat pump unit enters the defrosting operation when the water flow rate is low, the water in the first heat exchanger can easily cool down and freeze, causing the first heat exchanger to freeze and crack. When the water flow rate is low, the shutdown control of the air source heat pump unit is carried out to realize the antifreeze protection of the first heat exchanger. At the same time, the short-term low water flow may cause a large temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger, and setting the duration avoids frequent shutdowns caused by short-term low water flow. In this way, frequent shutdowns are reduced, and the operation of the air source heat pump unit is more stable. At the same time, the air source heat pump unit no longer needs to install a flow meter separately, which reduces the cost. After shutting down, in order to prevent the occasional low water flow in the first heat exchanger from affecting the normal operation of the air source heat pump unit, the air source heat pump unit will automatically restart after a certain period of time. Therefore, the control of the air source heat pump unit is more reliable.

During the actual operation of the air source heat pump unit, another method for antifreezing of the air source heat pump unit is shown in Figure 12, including:

S1201, the air source heat pump unit receives a defrosting operation instruction.

S1202. Detect the outlet water temperature T _wo of the first heat exchanger.

S1203, judging whether the first condition for entering the defrosting operation is satisfied. If yes, execute step S1206. Otherwise, execute step S1204. Assuming that T _wo is 19°C, the first condition is that T _wo ≥ 20°C. At this point, step S1204 is executed. Assuming that T _wo is 22°C, the first condition is that T _wo ≥ 20°C. At this point, step S1206 is executed.

S1204, turning on the auxiliary electric heating device.

S1205, judging whether the second condition for entering the defrosting operation is satisfied. If yes, execute step S1206. Otherwise, return to step S1205. Assume that the initial T _wo is 19°C, and the second condition is T _wo >22°C and lasts for 30s. After turning on the auxiliary electric heating device for a period of time, T _wo rises above 22° C. and lasts for 30 seconds, and executes step S1206 .

S1206. Control the air source heat pump unit to enter the defrosting operation.

S1207, judging whether T _wo <T _wo2 is satisfied. If yes, execute step S1209. Otherwise, execute step S1208. Assume that T _wo2 is 20°C. At this time, T _wo is 19° C., and step S1209 is executed.

S1208, judging whether T _wo >T _wo3 is satisfied. If yes, execute step S1210. Otherwise, return to step S1207. T _wo3 is 23°C. At this time, T _wo is 24° C., and step S1210 is executed.

S1209, turning on the auxiliary electric heating device. Return to step S1208.

S1210, turning off the auxiliary electric heating device. Return to step S1207.

S1211. After the air source heat pump unit enters the defrosting operation, it is judged whether T _wo <max(T _wo4 -T _wo8 , T _wo9 ) is satisfied. If yes, execute step S1212. Otherwise, return to step S1211. Assume that T _wo4 is 25°C, T _wo8 is 12°C, and T _wo9 is 10°C. Then T _wo7 =max(25°C-12°C, 10°C)=13°C. Assuming that T _wo is 12°C at this time, step S1212 is executed.

S1212, controlling the air source heat pump unit to exit the defrosting operation.

S1213, after the air source heat pump unit enters the defrosting operation, detect the inlet water temperature T _wi of the first heat exchanger.

S1214, calculate ΔT _w =T _wi -T _wo . The temperature difference ΔT _w between the inlet water temperature and the outlet water temperature of the first heat exchanger is obtained.

S1215, judging whether ΔT _w > _ΔTcold is satisfied and the duration reaches the fourth duration T _C4 . If yes, execute step S1216. Otherwise, return to step S1215. Assume that the calculated ΔT _cold is 2°C and T _C4 is 1 min when the compressor is running. If ΔT _w >2°C and the duration reaches 1 min, step S1216 is executed.

S1216, shutting down the air source heat pump unit.

Wherein, steps S1207 to S1210, steps S1211 to S1212 and steps S1213 to S1216 are executed synchronously.

As shown in FIG. 13 , an embodiment of the present disclosure provides a device for preventing freezing of an air source heat pump unit, including a processor (processor) 1300 and a memory (memory) 1301 storing program instructions. Optionally, the device may further include a communication interface (Communication Interface) 1302 and a bus 1303 . Wherein, the processor 1300 , the communication interface 1302 , and the memory 1301 can communicate with each other through the bus 1303 . Communication interface 1302 may be used for information transfer. The processor 1300 can call the logic instructions in the memory 1301 to execute the method for preventing freezing of an air source heat pump unit in the above embodiment.

In addition, the above logic instructions in the memory 1301 may be implemented in the form of software function units and when sold or used as an independent product, may be stored in a computer-readable storage medium.

As a storage medium, the memory 1301 can be used to store software programs and computer executable programs, such as program instructions/modules corresponding to the methods in the embodiments of the present disclosure. The processor 1300 executes the program instructions/modules stored in the memory 1301 to execute functional applications and data processing, that is, to implement the method for antifreezing of the air source heat pump unit in the above-mentioned embodiments.

The memory 1301 may include a program storage area and a data storage area, wherein the program storage area may store an operating system and an application program required by at least one function; the data storage area may store data created according to the use of the terminal device, and the like. In addition, the memory 1301 may include a high-speed random access memory, and may also include a non-volatile memory.

An embodiment of the present disclosure provides an air source heat pump unit, including a refrigerant circulation loop 1 , a water circulation loop 2 and the above-mentioned anti-freezing device for the air source heat pump unit. The refrigerant circulation circuit 1 includes a compressor 4 and a first heat exchanger 5 . The air inlet of the compressor 4 is provided with a pressure sensor 7 for detecting the air inlet pressure of the compressor 4 . The water circulation circuit 2 includes a circulating water pump 3 and an auxiliary electric heating device 6 . The circulating water pump 3 is used to start the water circulation of the air source heat pump unit. The auxiliary electric heating device 6 is used for heating the water flowing into the first heat exchanger 5 . Wherein, the first heat exchanger 5 exchanges heat with the water circulation loop 2 . The first heat exchanger 5 includes a water inlet and a water outlet, and the water inlet and the water outlet communicate with the water circulation circuit 2 . The water circulation circuit 2 corresponding to the water inlet is provided with a first temperature sensor 8 for detecting the water inlet temperature of the first heat exchanger 5 . The water circulation circuit 2 corresponding to the water outlet is provided with a second temperature sensor 9 for detecting the outlet water temperature of the first heat exchanger 5 . The processor in the above-mentioned device for antifreezing of the air source heat pump unit is at least electrically connected to the auxiliary electric heating device 6 , the pressure sensor 7 , the first temperature sensor 8 and the second temperature sensor 9 .

An embodiment of the present disclosure provides a storage medium, which stores program instructions, and the program instructions are configured to execute the above method for antifreezing of an air source heat pump unit.

The above-mentioned storage medium may be a transitory computer-readable storage medium, or a non-transitory computer-readable storage medium. Non-transitory storage media, including: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disk, etc., which can store program codes media, which may also be transitory storage media.

The above description and drawings sufficiently illustrate the embodiments of the present disclosure to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, procedural, and other changes. The examples merely represent possible variations. Individual components and functions are optional unless explicitly required, and the order of operations may vary. Portions and features of some embodiments may be included in or substituted for those of other embodiments. Also, the terms used in the present application are used to describe the embodiments only and are not used to limit the claims. As used in the examples and description of the claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well unless the context clearly indicates otherwise . Similarly, the term "and/or" as used in this application is meant to include any and all possible combinations of one or more of the associated listed ones. Additionally, when used in this application, the term "comprise" and its variants "comprises" and/or comprising (comprising) etc. refer to stated features, integers, steps, operations, elements, and/or The presence of a component does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groupings of these. Without further limitations, an element defined by the statement "comprising a ..." does not exclude the presence of additional identical elements in the process, method or apparatus comprising said element. Herein, what each embodiment focuses on may be the difference from other embodiments, and the same and similar parts of the various embodiments may refer to each other. For the method, product, etc. disclosed in the embodiment, if it corresponds to the method part disclosed in the embodiment, then the relevant part can refer to the description of the method part.

Those skilled in the art can appreciate that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software may depend on the specific application and design constraints of the technical solution. Said artisans may implement the described functions using different methods for each particular application, but such implementation should not be regarded as exceeding the scope of the disclosed embodiments. The skilled person can clearly understand that for the convenience and brevity of the description, the specific working process of the above-described system, device and unit can refer to the corresponding process in the above-mentioned method embodiment, which will not be repeated here.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to embodiments of the disclosure. In this regard, each block in a flowchart or block diagram may represent a module, program segment, or part of code that includes one or more Executable instructions. In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks in succession may, in fact, be executed substantially concurrently, or they may sometimes be executed in the reverse order, depending upon the functionality involved. In the descriptions corresponding to the flowcharts and block diagrams in the accompanying drawings, the operations or steps corresponding to different blocks may also occur in a different order than that disclosed in the description, and sometimes there is no specific agreement between different operations or steps. order. For example, two consecutive operations or steps may, in fact, be performed substantially concurrently, or they may sometimes be performed in the reverse order, depending upon the functionality involved. Each block in the block diagrams and/or flowcharts, and combinations of blocks in the block diagrams and/or flowcharts, can be implemented by a dedicated hardware-based system that performs the specified function or action, or can be implemented by dedicated hardware implemented in combination with computer instructions.

Claims (10)

1. A method for antifreezing an air source heat pump unit, the air source heat pump unit comprising: a water circulation loop; and, a refrigerant circulation loop including a first heat exchanger; wherein, the first heat exchanger exchanges heat with the water circulation loop; its It is characterized in that the method comprises: In the case of cooling operation of the air source heat pump unit, detecting the inlet water temperature T _wi and the outlet water temperature T _wo of the first heat exchanger; Calculate △T _w =T _wi -T _wo to obtain the temperature difference △T _w between the inlet water temperature and the outlet water temperature of the first heat exchanger; When △ _Tw >△ _Tcold and the duration reaches the fourth duration T _C4 , shut down the air source heat pump unit; Wherein, ΔT _cold is the first flow temperature difference threshold. 2 . The method according to claim 1 , wherein the refrigerant circulation circuit further includes a compressor, and ΔT _cold is determined according to the operating frequency of the compressor. 3. The method according to claim 2, wherein determining ΔT _cold according to the operating frequency of the compressor includes: Obtain the operating frequency f of the current compressor; According to the corresponding relationship between ΔT _cold and the operating frequency f of the compressor, the ΔT _cold corresponding to the current operating frequency f of the compressor is determined. 4. The method according to claim 1, wherein the refrigerant circulation circuit also includes a compressor, and the method further includes: In the case of cooling operation of the air source heat pump unit, detect the air inlet pressure P _s of the compressor; Determine the low pressure saturation temperature P _st corresponding to P _s ; In the case of P _st <P _s-t1 , control the operation of the compressor to adjust the water temperature of the first heat exchanger; Wherein, P _s-t1 is the first low pressure saturation temperature threshold. 5. The method according to claim 4, characterized in that, in the case of P _st <P _s-t1 , controlling the operation of the compressor comprises: In the case of P _s-t1 >P _st ≥P _s-t2 , the operating frequency of the compressor is prohibited from increasing; In the case of P _s-t2 >P _st ≥P _s-t3 , reduce the operating frequency of the compressor; When P _st < P _s-t3 and the duration reaches the first duration T _C1 , stop the compressor; Wherein, P _s-t2 is the second low pressure saturation temperature threshold, and P _s-t3 is the third low pressure saturation temperature threshold. 6. The method according to any one of claims 1 to 5, wherein the water circulation loop comprises: an auxiliary electric heating device for heating the water flowing into the first heat exchanger; the method further comprises: When the air source heat pump unit enters the defrosting operation, detect the outlet water temperature T _wo of the first heat exchanger; The operation of the auxiliary electric heating device is controlled according to the outlet water temperature T _wo to adjust the water temperature of the first heat exchanger. 7. The method according to any one of claims 1 to 5, further comprising: In the case of the heating operation of the air source heat pump unit, detect the inlet water temperature T _wi and the outlet water temperature T _wo of the first heat exchanger; Calculate △T _w =T _wo -T _wi to obtain the temperature difference △T _w between the inlet water temperature and the outlet water temperature of the first heat exchanger; When △ _Tw >△Thot and the duration reaches the seventh duration T _C7 , shut down the air source _heat pump unit; Wherein, ΔT _heat is the second flow temperature difference threshold. 8. A device for antifreezing of an air source heat pump unit, comprising a processor and a memory storing program instructions, characterized in that the processor is configured to execute any one of claims 1 to 7 when running the program instructions The method for preventing freezing of an air source heat pump unit. 9. An air source heat pump unit, comprising: The refrigerant circulation circuit includes a compressor and a first heat exchanger, and a pressure sensor is arranged at the air inlet of the compressor for detecting the air inlet pressure of the compressor; and, The water circulation loop includes a circulating water pump and an auxiliary electric heating device; the circulating water pump is used to start the water circulation of the air source heat pump unit; the auxiliary electric heating device is used to heat the water flowing into the first heat exchanger; Wherein, the first heat exchanger exchanges heat with the water circulation loop, the first heat exchanger includes a water inlet and a water outlet, and the water inlet and the water outlet are connected to the water circulation loop; the water circulation loop corresponding to the water inlet is provided with a first temperature sensor, used For detecting the water inlet temperature of the first heat exchanger; the water circulation loop corresponding to the water outlet is provided with a second temperature sensor for detecting the water outlet temperature of the first heat exchanger; It is characterized in that the air source heat pump unit also includes: The device for antifreezing of an air source heat pump unit according to claim 8, wherein the processor is at least electrically connected to the auxiliary electric heating device, the pressure sensor, the first temperature sensor and the second temperature sensor. 10. A storage medium storing program instructions, characterized in that, when the program instructions are running, the method for antifreezing of an air source heat pump unit according to any one of claims 1 to 7 is executed.

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