CN115289611B

CN115289611B - Method and device for antifreezing air source heat pump unit, air source heat pump unit, and storage medium

Info

Publication number: CN115289611B
Application number: CN202210799801.3A
Authority: CN
Inventors: 刘涛; 刘国清; 温钧霞; 韩业飞; 张宝库
Original assignee: Qingdao Haier Air Conditioner Gen Corp Ltd; Qingdao Haier Air Conditioning Electric Co Ltd; Haier Smart Home Co Ltd
Current assignee: Qingdao Haier Air Conditioner Gen Corp Ltd; Qingdao Haier Air Conditioning Electric Co Ltd; Haier Smart Home Co Ltd
Priority date: 2022-07-08
Filing date: 2022-07-08
Publication date: 2024-10-18
Anticipated expiration: 2042-07-08
Also published as: CN115289611A

Abstract

The present application relates to the technical field of smart home appliances, and discloses a method for antifreezing an air source heat pump unit, wherein the air source heat pump unit comprises: a water circulation loop; and a refrigerant circulation loop, comprising a first heat exchanger; wherein the first heat exchanger exchanges heat with the water circulation loop; the method comprises: when the air source heat pump unit is in heating operation, detecting the inlet water temperature T _wi and the outlet water temperature T _wo of the first heat exchanger; calculating △T _w =T _wo ‑T _wi , obtaining the temperature difference △T _w between the inlet water temperature and the outlet water temperature of the first heat exchanger; when △T _w >△T _heat and the duration reaches the seventh duration T _C7 , shutting down the air source heat pump unit; wherein △T _heat is the second flow temperature difference threshold. The method can not only realize the antifreeze protection of the first heat exchanger, but also reduce the frequent shutdown of the unit, making the unit run more stably. The present application also discloses a device for antifreezing an air source heat pump unit, an air source heat pump unit and a storage medium.

Description

Method and device for preventing air source heat pump unit from freezing, air source heat pump unit and storage medium

Technical Field

The application relates to the technical field of intelligent household appliances, in particular to a method and a device for preventing freezing of an air source heat pump unit, the air source heat pump unit and a storage medium.

Background

At present, the plate heat exchanger is widely applied to the water side heat exchanger of the air source heat pump unit, and if the water flow passing through the inside of the plate heat exchanger is insufficient or the water temperature is too low, or the evaporation temperature is too low in the refrigeration process, and other factors can cause the problem that the water side heat exchanger is frosted. Most of the existing air source heat pump units adopt a reverse defrosting mode, but based on the defrosting mode, when the air source heat pump units are switched to defrosting working conditions, the refrigerant in the loop reversely passes through the water side heat exchanger, so that the temperature of the water side heat exchanger is reduced, and the water side heat exchanger is easily frozen and cracked.

In order to solve the problem that a water side heat exchanger in an air source heat pump unit is easy to frost crack, the related technology discloses a control method for water flow abnormality of a heat pump hot water unit. Through detecting water temperature of the water inlet and outlet of the water side heat exchanger, whether water flow is abnormal or not is judged according to the range of the temperature difference value, and the shutdown of the unit is controlled. And further effectively ensures that the water side heat exchanger is not frosted due to the influence of too little water flow.

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

Although the technology can have a certain effect on the freezing prevention of the water side heat exchanger of the air source heat pump unit, the air source heat pump unit can be stopped immediately under the condition that the temperature difference of the inlet water and the outlet water of the water side heat exchanger is detected to be larger than a specified threshold value, and the unit can be stopped frequently due to short water flow, so that the running is unstable.

Disclosure of Invention

The following presents a simplified summary in order to provide a basic understanding of some aspects of the disclosed embodiments. This summary is not an extensive overview, and is intended to neither identify key/critical elements nor delineate the scope of such embodiments, but is intended as a prelude to the more detailed description that follows.

The embodiment of the disclosure provides a method and a device for preventing freezing of an air source heat pump unit, the air source heat pump unit and a storage medium, which can realize the anti-freezing protection of a water side heat exchanger, reduce frequent shutdown of the air source heat pump unit and enable the air source heat pump unit to operate more stably.

In some embodiments, an air source heat pump unit includes: a water circulation circuit; and, a refrigerant circulation circuit including a first heat exchanger; the first heat exchanger exchanges heat with the water circulation loop; the method comprises the following steps: under the condition of heating 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; calculating DeltaT _w＝T_wo-T_wi to obtain a temperature difference DeltaT _w between the inlet water temperature and the outlet water temperature of the first heat exchanger; shutting down the air source heat pump unit when the delta T _w>△T_{Heat of the body} is reached and the duration reaches a seventh duration T _C7; wherein Δt _{Heat of the body} is the second flow temperature difference threshold.

In some embodiments, an apparatus for air source heat pump unit freeze protection includes a processor and a memory storing program instructions, the processor configured to perform the method for air source heat pump unit freeze protection described above when executing the program instructions.

In some embodiments, an air source heat pump unit includes: the refrigerant circulation loop comprises a compressor and a first heat exchanger, wherein a pressure sensor is arranged at an air inlet of the compressor and used for detecting the air inlet pressure of the compressor; the water circulation loop comprises a circulating water pump and an auxiliary electric heating device; the circulating water pump is used for starting the water circulation of the air source heat pump unit; the auxiliary electric heating device is used for heating the water flowing into the first heat exchanger; the first heat exchanger exchanges heat with the water circulation loop, and comprises a water inlet and a water outlet which are communicated with the water circulation loop; the water circulation loop corresponding to the water inlet is provided with a first temperature sensor 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; and the processor is electrically connected with at least the auxiliary electric heating device, the pressure sensor, the first temperature sensor and the second temperature sensor.

In some embodiments, a storage medium stores program instructions that, when executed, perform the method for air source heat pump unit antifreeze described above.

In the embodiment of the disclosure, under the condition of heating operation of the air source heat pump unit, the water flow in the first heat exchanger is judged by comparing the temperature difference of water entering and exiting the first heat exchanger with the flow temperature difference threshold value. If the air source heat pump unit enters defrosting operation under the condition of low water flow, water in the first heat exchanger is easy to cool and freeze, so that the first heat exchanger is frozen. And under the condition of low water flow, the air source heat pump unit is shut down and controlled, so that the anti-freezing protection of the first heat exchanger is realized. Meanwhile, the short water flow is low, so that the temperature difference between the water inlet temperature and the water outlet temperature of the first heat exchanger is large, and the frequent shutdown caused by the short water flow is avoided by setting the duration. Therefore, frequent shutdown of the air source heat pump unit is reduced, and the air source heat pump unit operates more stably.

The foregoing general description and the following description are exemplary and explanatory only and are not restrictive of the application.

Drawings

One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which like reference numerals refer to similar elements, and in which:

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

FIG. 2 is a schematic diagram of a method for air source heat pump unit freeze protection provided in an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of another method for air source heat pump unit freeze protection provided by an embodiment of the present disclosure;

FIG. 4 is a schematic diagram of another method for air source heat pump unit freeze protection provided by an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of another method for air source heat pump unit freeze protection provided by an embodiment of the present disclosure;

FIG. 6 is a schematic diagram of another method for air source heat pump unit freeze protection provided by an embodiment of the present disclosure;

FIG. 7 is a schematic diagram of another method for air source heat pump unit freeze protection provided by an embodiment of the present disclosure;

FIG. 8 is a schematic diagram of another method for air source heat pump unit freeze protection provided by an embodiment of the present disclosure;

FIG. 9 is a schematic diagram of another method for air source heat pump unit freeze protection provided by an embodiment of the present disclosure;

FIG. 10 is a schematic diagram of another method for air source heat pump unit freeze protection provided by an embodiment of the present disclosure;

FIG. 11 is a schematic diagram of another method for air source heat pump unit freeze protection provided by an embodiment of the present disclosure;

FIG. 12 is a schematic diagram of another method for air source heat pump unit freeze protection provided by an embodiment of the present disclosure;

Fig. 13 is a schematic view of an apparatus for freezing protection of an air source heat pump unit according to an embodiment of the present disclosure.

Reference numerals:

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

Detailed Description

So that the manner in which the features and techniques of the disclosed embodiments can be understood in more detail, a more particular description of the embodiments of the disclosure, briefly summarized below, may be had by reference to the appended drawings, which are not intended to be limiting of the embodiments of the disclosure. In the following description of the technology, 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 still be practiced without these details. In other instances, well-known structures and devices may be shown simplified in order to simplify the drawing.

The terms first, second and the like in the description and in the claims of the embodiments of the disclosure and in the above-described figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate in order to describe embodiments of the present disclosure. Furthermore, the terms "comprise" and "have," as well as any variations thereof, are intended to cover a non-exclusive inclusion.

In the embodiments of the present disclosure, the terms "upper", "lower", "inner", "middle", "outer", "front", "rear", and the like indicate an azimuth or a positional relationship based on that shown in the drawings. These terms are used primarily to better describe embodiments of the present disclosure and embodiments thereof and are not intended to limit the indicated device, element, or component to a particular orientation or to be constructed and operated in a particular orientation. Also, some of the terms described above may be used to indicate other meanings in addition to orientation or positional relationships, for example, the term "upper" may also be used to indicate some sort of attachment or connection in some cases. The specific meaning of these terms in the embodiments of the present disclosure will be understood by those of ordinary skill in the art in view of the specific circumstances.

The term "plurality" means two or more, unless otherwise indicated.

In the embodiment of the present disclosure, the character "/" indicates that the front and rear objects are an or relationship. For example, A/B represents: a or B.

The term "and/or" is an associative relationship that describes an object, meaning that there may be three relationships. For example, a and/or B, represent: a or B, or, A and B.

The term "corresponding" may refer to an association or binding relationship, and the correspondence between a and B refers to an association or binding relationship between a and B.

In addition, the term "disposed" should be construed broadly.

It should be noted that, without conflict, the embodiments of the present disclosure and features of the embodiments may be combined with each other.

Referring to fig. 1, an embodiment of the present disclosure provides an air source heat pump unit, which includes a refrigerant circulation loop 1, a water circulation loop 2, and a processor (not shown). The refrigerant circulation loop 1 comprises 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 which are sequentially connected. The inlet of the compressor 4 is provided with a pressure sensor 7, the pressure sensor 7 being arranged to detect the pressure at the inlet of the compressor 4.

The water circulation circuit 2 comprises a circulation water pump 3 and an auxiliary electric heating device 6. The circulating water pump 3 is used for starting the water circulation of the air source heat pump unit. The auxiliary electric heating means 6 is in communication with the first heat exchanger 5 for heating the water flowing into the first heat exchanger 5. The first heat exchanger 5 exchanges heat with the water circulation loop 2. The first heat exchanger 5 comprises a water inlet and a water outlet which are communicated with the water circulation loop 2. The water inlet of the first heat exchanger 5 is provided with a first temperature sensor 8, and the first temperature sensor 8 is used 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, and the second temperature sensor 9 is used for detecting the water outlet temperature of the first heat exchanger 5.

In the air conditioning cooling operation or the defrosting operation, the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 4 flows to the second heat exchanger 10 through the four-way valve 11 (which can be switched, and the refrigerating state is communicated at this time) to exchange heat, and the high-pressure gaseous refrigerant is converted into a high-pressure liquid refrigerant. Then, the high-pressure liquid refrigerant flows through the electronic expansion valve 12 to be throttled and depressurized, and then enters the first heat exchanger 5, and the first heat exchanger 5 exchanges heat (absorbs heat) with water in the water circulation loop 2 to be converted into a low-temperature low-pressure gaseous refrigerant. The low-temperature 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 the air conditioning heating operation, the high-temperature and high-pressure gaseous refrigerant discharged from the compressor 4 flows to the first heat exchanger 5 through the four-way valve 11 (which can be switched and the heating state is communicated at this time) to exchange heat (release heat) with the water in the water circulation circuit 2, and the high-pressure gaseous refrigerant is converted into a high-pressure liquid refrigerant. Then, the high-pressure liquid refrigerant flows through the electronic expansion valve 12 to be throttled and depressurized, and then enters the second heat exchanger 10, and the second heat exchanger 10 exchanges heat to be converted into a low-temperature low-pressure gaseous refrigerant. The low-temperature 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 water inlet and outlet temperature difference of the first heat exchanger, so that the anti-freezing protection of the first heat exchanger is realized. And the frequent shutdown of the air source heat pump unit can be reduced, so that the air source heat pump unit can operate more stably.

In connection with the air source heat pump unit shown in fig. 1, an embodiment of the present disclosure provides a method for freezing prevention of the air source heat pump unit, as shown in fig. 2. The method comprises the following steps:

s1001, under the condition of heating 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.

S1002, the processor calculates DeltaT _w＝T_wo-T_wi to obtain a temperature difference DeltaT _w between the inlet water temperature and the outlet water temperature of the first heat exchanger.

S1003, in the case of Δt _w>△T_{Heat of the body} and the duration reaching the seventh duration T _C7, the processor turns off the air source heat pump unit. Wherein Δt _{Heat of the body} is the second flow temperature difference threshold. T _C7 is (0 min,5 min) alternatively T _C7 is 1min, 3min or 5min.

In the embodiment of the disclosure, the air source heat pump unit heats and runs, and under the condition that the heating quantity is certain, 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 water flow rate can be judged by judging the actual water inlet and outlet temperature difference and the corresponding second flow rate temperature difference threshold value. 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 rate temperature difference threshold value for a certain time, then the water flow rate at the moment can be determined to be low. If the air source heat pump unit enters defrosting operation under the condition of low water flow, water in the first heat exchanger is easy to cool and freeze, so that the first heat exchanger is frozen. And under the condition of low water flow, the air source heat pump unit is shut down and controlled, so that the anti-freezing protection of the first heat exchanger is realized. Meanwhile, the short water flow is low, so that the temperature difference between the water inlet temperature and the water outlet temperature of the first heat exchanger is large, and the frequent shutdown caused by the short water flow is avoided by setting the duration. Therefore, frequent shutdown is reduced, and the air source heat pump unit operates more stably. The air source heat pump unit does not need to be provided with a flowmeter independently, so that the cost is reduced.

Alternatively, deltaT _{Heat of the body} is determined based on the operating frequency of the compressor and the outdoor ambient temperature. According to experimental verification, under the condition of heating operation of the air source heat pump unit, the water inlet and outlet temperature difference of the first heat exchanger is related to the operation frequency of the compressor and the outdoor environment temperature. Thus, under the condition that the operating frequency of the compressor and the outdoor environment temperature are fixed, the temperature difference between the inlet water temperature and the outlet water temperature after the water flows through the first heat exchanger is different. Accordingly, Δt _{Heat of the body} can be determined by the operating frequency of the compressor and the outdoor ambient temperature. The DeltaT _{Heat of the body} is determined through the real-time running frequency of the compressor and the outdoor environment temperature, so that the water flow judgment can be more accurate. Therefore, the air source heat pump unit is controlled more accurately, and the anti-freezing effect is better.

Optionally, determining Δt _{Heat of the body} from the operating frequency of the compressor and the outdoor ambient temperature includes: the processor acquires the current compressor operating frequency f and the outdoor ambient temperature T _ao. The processor determines the operating frequency f of the current compressor and the DeltaT _{Heat of the body} corresponding to the outdoor environment temperature T _ao according to the corresponding relation between DeltaT _{Heat of the body} and the operating frequency of the compressor and the outdoor environment temperature. Under the condition that the water flow rate in the first heat exchanger of the air source heat pump unit is insufficient, the water temperature in the water circulation quickly reaches the set temperature, so that the unit is stopped and restarted after the water temperature is reduced, and the unit is frequently started and stopped. Under the condition that the water flow rate in the first heat exchanger of the air source heat pump unit is too large, the water temperature in the water circulation cannot reach the set temperature for a long time, and therefore user experience is poor. Therefore, the air source heat pump unit can set a normal running water flow range according to the heating quantity. The corresponding relation between DeltaT _{Heat of the body} and the operating frequency of the compressor and the outdoor environment temperature is that on the basis of guaranteeing the lower limit of the normal operating water flow range of the air source heat pump unit, the temperature difference DeltaT _{Heat of the body} between the corresponding water inlet temperature and the corresponding water outlet temperature is measured according to the operating frequencies of a plurality of different compressors and the outdoor environment temperature, and then a corresponding fitting formula is obtained according to a plurality of groups of data. At T _ao. Gtoreq.21℃,. DELTA.T _{Heat of the body}＝20×(f/Q₁). In the case of T _ao <21 ℃, Δt _{Heat of the body}＝2×(0.25×(T_ao+12)+5)×(f/Q₂). Wherein Q ₁、Q₂ is the correction value of the fitting formula. Q ₁ is in the range of [40, 60], and Q ₂ is in the range of [75, 85]. Optionally, Q ₁ is 40, 50, or 60. Alternatively, Q ₂ is 75, 80, or 85. Different series of products can have different fitting formulas due to the influence of the performance of the compressor or the structure of the products. Therefore, the formula is corrected through Q ₁、Q₂, and a more accurate flow temperature difference threshold value can be obtained. Therefore, the control of the air source heat pump unit can be more accurate, and the anti-freezing effect is better.

Optionally, the heating operation of the air source heat pump unit includes: and (3) under the condition that the refrigerant circulation loop heats and runs and the running time of the circulating water pump reaches the second running time T _Y2. The value range of T _Y2 is (0 min,3 min) alternatively, T _Y2 is 1min, 2min or 3min, after the running time of the circulating water pump reaches the second running time T _Y2, the water flow in the water circulation loop is judged, so that the water flow in the first heat exchanger can be effectively ensured to be stable.

Optionally, after the processor shuts down the air source heat pump unit, the method further comprises: and under the condition of I < I, the air source heat pump unit is started to operate again by the processor after the third waiting time length T _D3 is reserved. And under the condition that I is more than or equal to I, the processor controls the start and stop of the air source heat pump unit according to the stop times I ₁ in the third constraint time T _S3. Wherein I is the accumulated low water flow shutdown times of the air source heat pump unit, and I is the maximum shutdown times allowed in the third constraint time T _S3. The range of T _D3 is (0 min,10 min) optionally, T _D3 is 2min, 5min, 8min or 10min T _S3 is (0 h,2 h) optionally, T _S3 is 0.5h, 1h or 2h I is [1,5], I is a positive integer optionally, I is 1,3 or 5. After stopping, the air source heat pump unit is automatically restarted after a certain time interval to prevent the low water flow in the occasional first heat exchanger from affecting the normal operation of the air source heat pump unit.

As shown in conjunction with fig. 3, an embodiment of the present disclosure provides another method for freezing protection 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 DeltaT _w＝T_wo-T_wi to obtain the temperature difference DeltaT _w between the inlet water temperature and the outlet water temperature of the first heat exchanger.

S1104, the processor determines whether Δt _w>△T_{Heat of the body} is satisfied and the duration reaches a seventh duration T _C7. If yes, step S1105 is executed. Otherwise, the process returns to step S1104.

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

S1106, the processor determines whether I < I is satisfied. If yes, step S1107 is executed. Otherwise, step S1108 is performed.

S1107, the air source heat pump unit is started to operate again by the processor after the third waiting time length T _D3.

S1108, the processor controls the start and stop of the air source heat pump unit according to the stop times i ₁ in the third constraint time period T _S3.

In the embodiment of the disclosure, under the condition of heating operation of the air source heat pump unit, the water flow in the first heat exchanger is judged by comparing the temperature difference of water entering and exiting the first heat exchanger with the flow temperature difference threshold value. If the air source heat pump unit enters defrosting operation under the condition of low water flow, water in the first heat exchanger is easy to cool and freeze, so that the first heat exchanger is frozen. And under the condition of low water flow, the air source heat pump unit is shut down and controlled, so that the anti-freezing protection of the first heat exchanger is realized. Meanwhile, the short water flow is low, so that the temperature difference between the water inlet temperature and the water outlet temperature of the first heat exchanger is large, and the frequent shutdown caused by the short water flow is avoided by setting the duration. Therefore, frequent shutdown is reduced, and the air source heat pump unit operates more stably. Meanwhile, the air source heat pump unit does not need to be provided with a flowmeter independently, so that the cost is reduced. After stopping, in order to prevent the phenomenon of low water flow in the occasional first heat exchanger from affecting the normal operation of the air source heat pump unit, the air source heat pump unit is automatically restarted after a certain time interval. Therefore, the air source heat pump unit is controlled more reliably.

Optionally, the processor controls the start-stop of the air source heat pump unit according to the stop times i ₁ in the third constraint time period T _S3, including: and under the condition that I ₁ is more than or equal to I, the processor keeps the shutdown state of the air source heat pump unit. In the case of I ₁ < I, the processor again starts the air source heat pump unit to operate after the interval of the third waiting time period T _D3. If the air source heat pump unit is frequently shut down within the constraint time period, a fault or other conditions may exist at present, and the shut down state needs to be kept and not restarted any more to protect the air source heat pump unit. For example, if the defrosting operation is entered under the condition that the water flow rate in the first heat exchanger is low, the water in the first heat exchanger is easily cooled and frozen to cause the frost cracking of the first heat exchanger. By adopting the control mode of stopping, the frost cracking probability of the first heat exchanger can be effectively reduced, and the occurrence of the frost cracking phenomenon is reduced.

Optionally, the method further comprises: under the condition that the air source heat pump unit enters 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 substantially equivalent to the cooling operation, the temperature of the first heat exchanger may be lowered after the air source heat pump unit is changed from the heating operation to the defrosting operation. In the case where the temperature of the refrigerant in the first heat exchanger is relatively low (below zero), then the probability of freezing of the water in the first heat exchanger increases if the temperature of the water in the first heat exchanger is also relatively low. Under the condition of defrosting operation of the air source heat pump unit, the operation of the auxiliary electric heating device is controlled by judging the temperature of the discharged water, so that the water in the first heat exchanger can be ensured to keep a higher water temperature under the condition of defrosting operation. In this way, in the case of defrosting operation, the speed of water temperature decrease in the first heat exchanger is slowed down. Therefore, the probability of frost cracking of the first heat exchanger is reduced, and the occurrence of the frost cracking phenomenon is reduced. The first heat exchanger is subjected to anti-freezing protection by adopting a plurality of methods, so that the probability of frost cracking of the first heat exchanger is greatly reduced, and the occurrence of the frost cracking phenomenon is reduced.

Optionally, the processor controls the operation of the auxiliary electric heating device according to the outlet water temperature T _wo, including: in the case of T _wo<T_wo2, the processor turns on the auxiliary electrical heating. In the case of T _wo>T_wo3, the processor turns off the auxiliary electrical heating. Wherein, T _wo2 is the second water outlet temperature threshold, T _wo3 is the third water outlet temperature threshold, and the value range of T _wo3>T_wo2.T_wo2 is [15 ℃,20 ℃). Alternatively, T _wo2 is 15 ℃, 17 ℃ or 20 ℃. The range of T _wo3 is (20 ℃,25 ℃) optionally, T _wo3 is 21 ℃, 23 ℃ or 25 ℃, so that the water temperature in the first heat exchanger can be kept at a higher temperature, and the probability of frost cracking of the first heat exchanger is reduced.

Optionally, before the air source heat pump unit enters the defrosting operation, the method further comprises: the processor determines whether T _wo satisfies a first condition to enter defrost operation. If yes, the processor controls the air source heat pump unit to enter defrosting operation. Otherwise, the processor starts the auxiliary electric heating device, and the processor controls the air source heat pump unit to enter the defrosting operation under the condition that the outlet water temperature meets the second condition of entering the defrosting operation. Therefore, whether the air source heat pump unit enters defrosting operation is controlled by judging the water temperature, and the water temperature in the first heat exchanger can be ensured to be kept at a higher temperature under the condition of entering the defrosting operation. Therefore, the probability of frost cracking of the first heat exchanger is reduced, and the occurrence of the frost cracking phenomenon is reduced. The first heat exchanger is subjected to anti-freezing protection by adopting a plurality of methods, so that the probability of frost cracking of the first heat exchanger is greatly reduced, and the occurrence of the frost cracking phenomenon is reduced.

Optionally, the first condition includes: t _wo≥T_wo4. Wherein T _wo4 is a fourth outlet water temperature threshold. T _wo4 has a value of [20 ℃,45 ℃). Alternatively, T _wo4 is 20 ℃, 30 ℃ or 45 ℃. Therefore, the water temperature in the first heat exchanger can be kept at a higher temperature under the condition of defrosting operation, and the frost cracking probability of the first heat exchanger is reduced. Therefore, the occurrence of the frost cracking phenomenon of the first heat exchanger is reduced.

Optionally, the second condition includes: t _wo6≤T_wo≤T_wo5 and the duration reaches a fifth duration T _C5. Or T _wo>T_wo5 and the duration reaches a sixth duration T _C6. Wherein, T _wo5 is the fifth water outlet temperature threshold, T _wo6 is the sixth water outlet temperature threshold, and the value range of T _C5>T_C6.T_wo5 is [20 ℃,22 ℃). Alternatively, T _wo5 is 20 ℃, 21 ℃ or 22 ℃. T _wo6 has a value of 15 deg.C and 22 deg.C. Alternatively, T _wo6 is 15 ℃, 18 ℃ or 22 ℃. T _C5 has a value of [10min,1h ]. Alternatively, T _C5 is 10min, 30min, or 1h. The range of the value of T _C6 is (0 s,60 s) alternatively, T _C6 is 10s, 30s or 60s, thus, the water temperature in the first heat exchanger can be ensured to keep a higher temperature under the condition of defrosting operation, and the probability of frost cracking of the first heat exchanger is reduced, thereby reducing the occurrence of the frost cracking phenomenon of the first heat exchanger.

Optionally, during defrosting operation of the air source heat pump unit, the method further comprises: under the condition of T _wo<T_wo7, the processor controls the air source heat pump unit to exit the defrosting operation. Wherein, T _wo7 is determined according to T _wo4、T_wo8 and T _wo9, T _wo7 is a seventh outlet water temperature threshold, T _wo8 is an eighth outlet water temperature threshold, and T _wo9 is a ninth outlet water temperature threshold. Under the condition that the outlet water temperature of the first heat exchanger is lower than a certain temperature, the probability of freezing water in the first heat exchanger is increased at the moment, and the air source heat pump unit is controlled to exit the defrosting operation. Therefore, the probability of frost cracking of the first heat exchanger can be reduced, and the occurrence of the frost cracking phenomenon is reduced. The first heat exchanger is subjected to anti-freezing protection by adopting a plurality of methods, so that the probability of frost cracking of the first heat exchanger is greatly reduced, and the occurrence of the frost cracking phenomenon is reduced.

Optionally, determining T _wo7 according to T _wo4、T_wo8 and T _wo9 includes: t _wo7＝max(T_wo4-T_wo8,T_wo9). Wherein, T _wo4-T_wo8 is the expression mode of the descending amplitude 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. T _wo8 has a value of [10 ℃,15 ℃). Alternatively, T _wo8 is 10 ℃, 12 ℃ or 15 ℃. T _wo9 is 5 deg.C, 10 deg.C. Alternatively, T _wo9 is 5, 8, or 10 ℃. the T _wo4-T_wo8 is mainly used for controlling the air source heat pump unit to enter the defrosting operation set condition according to the first condition and exit the defrosting operation, if the water outlet temperature of the first heat exchanger drops too fast due to factors such as insufficient water flow or too low-pressure saturation temperature in the defrosting operation, the frost crack risk of the first heat exchanger is larger. T _wo9 mainly aims at the condition that the air source heat pump unit enters the defrosting operation according to the second condition and exits the defrosting operation, and if the outlet water temperature of the first heat exchanger is too low in the defrosting operation, the frost crack risk of the first heat exchanger is larger. therefore, the probability of frost cracking of the first heat exchanger is reduced according to the water outlet temperature falling amplitude and the lower limit value of the water outlet temperature which are jointly used as the conditions for exiting defrosting operation. Therefore, the occurrence of the frost cracking phenomenon of the first heat exchanger is reduced. For example, in the case where T _wo4 is 25 ℃, T _wo8 is 12 ℃, and T _wo9 is 10 ℃, at which time T _wo7 =max (25 ℃ -12 ℃, 10 ℃) =13 ℃. in the case where T _wo4 is 21 ℃, T _wo8 is 15 ℃, and T _wo9 is 8 ℃, then T _wo7 = max (21 ℃ -15 ℃, 8 ℃) =8 ℃.

The operation of the compressor can be controlled according to the air inlet pressure of the compressor through the processor, the anti-freezing protection of the first heat exchanger is realized, the complexity of the control process can be reduced, and the reliability of the scheme is improved.

In connection with the air source heat pump unit shown in fig. 1, another method for freezing protection of the air source heat pump unit is provided in an embodiment of the present disclosure, as shown in fig. 4. The method comprises the following steps:

S201, under the condition that the air source heat pump unit operates in a refrigerating mode, the processor detects the air inlet pressure P _s of the compressor.

S202, the processor determines a low pressure saturation temperature P _s-t corresponding to P _s.

S203, in the case of P _s-t<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 range of P _s-t1 is (-5 ℃, -3 ℃). Alternatively, P _s-t1 is-4.5 ℃, -4℃or-3.5 ℃.

In the embodiment of the disclosure, under the condition of refrigerating operation of the air source heat pump unit, the air inlet pressure of the compressor fluctuates according to the operation frequency of the compressor. The higher the compressor operating frequency, the lower the compressor inlet pressure and the corresponding low pressure saturation temperature. If the low pressure saturation temperature is below a certain value, the probability of freezing of the water in the first heat exchanger increases. The operation of the compressor is controlled through the low-pressure saturation temperature of the compressor, so that the first heat exchanger can be prevented from being in the condition of too low temperature for a long time, and the anti-freezing protection of the first heat exchanger is realized. Compared with the related art, the embodiment of the disclosure does not need to adjust the electronic expansion valve, reduces the complexity of the control process, and improves the reliability of the scheme.

Optionally, in the case of P _s-t<P_s-t1, the processor controls operation of the compressor, including: in the case of P _s-t1>P_s-t≥P_s-t2, the processor prohibits the compressor from operating at an elevated frequency. In the case of P _s-t2>P_s-t≥P_s-t3, the processor reduces the operating frequency of the compressor. In the event that P _s-t<P_s-t3 and the duration reaches the first duration T _C1, the processor shuts down 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. The range of P _s-t1>P_s-t2>P_s-t3.T_C1 is (0 s,60 s). Alternatively, T _C1 is 5s, 20s, 35s, or 50s. The setting of the duration time can avoid frequent shutdown caused by too low short low-pressure saturation temperature, so that the air source heat pump unit can operate more stably. The range of P _s-t1 is (-5 ℃, -3 ℃), the range of P _s-t2 is (-7 ℃, -5 ℃), and the range of P _s-t3 is (-10 ℃, -6 ℃). Alternatively, P _s-t1 is-4.5 ℃, P _s-t2 is-6 ℃, and P _s-t3 is-8 ℃. Or P _s-t1 is-3.5deg.C, P _s-t2 is-5deg.C, and P _s-t3 is-7deg.C. Or P _s-t1 is-4.5deg.C, P _s-t2 is-6.5deg.C, and P _s-t3 is-9deg.C. Since the higher the compressor operating frequency, the lower the compressor inlet pressure, the lower the corresponding low pressure saturation temperature. In the case where the low pressure saturation temperature is in different temperature intervals, the intake port pressure of the compressor can be controlled by prohibiting the operation frequency of the compressor from increasing or decreasing or shutting down the compressor. Therefore, the cooling speed of water in the first heat exchanger can be reduced by controlling the operation of the compressor in time, the anti-freezing protection of the first heat exchanger is effectively realized, and the occurrence of the frost cracking phenomenon is reduced.

Optionally, the method further comprises: under the condition of heating 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. The processor calculates DeltaT _w＝T_wo-T_wi to obtain a temperature difference DeltaT _w between the inlet water temperature and the outlet water temperature of the first heat exchanger. In the event Δt _w>△T_{Heat of the body} and the duration reaches seventh duration T _C7, the processor shuts down the air-source heat pump unit. Wherein Δt _{Heat of the body} is the second flow temperature difference threshold. The value range of T _C7 is (0 min,5 min) optionally, T _C7 is 1min, 3min or 5min, under the condition that the air source heat pump unit heats and operates and the heating quantity is certain, the temperature difference of the water with different flow rates after flowing through the first heat exchanger is different, the smaller the water flow rate is, the larger the temperature difference of the water inlet temperature and the water outlet temperature is, the size of the water flow rate can be judged by judging the size of the actual water inlet temperature difference and the corresponding second flow rate temperature difference threshold value, if the temperature difference of the water inlet temperature and the water outlet temperature of the first heat exchanger is larger than the second flow rate temperature difference threshold value and lasts for a certain time, the water flow rate at the moment can be determined to be low, if the air source heat pump unit enters into defrosting operation under the condition that the water flow rate is lower, the water in the first heat exchanger is easy to cool down and freeze, so that the first heat exchanger is frozen, the air source heat pump unit is shut down and controlled under the condition of low water flow, at the same time, the short water flow rate can cause the large temperature difference between the water inlet temperature and the water outlet temperature of the first heat exchanger, the method has the advantages that the method can prevent the first heat exchanger from being frosted and protected by adopting a plurality of methods, thereby greatly reducing the probability of frost cracking of the first heat exchanger and reducing the occurrence of the frost cracking phenomenon.

Optionally, the method further comprises: under the condition of refrigerating 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. In the event T _wi≤T_wi1 and the duration reaches the second duration T _C2, the processor shuts down the air source heat pump unit. Or, in the case that T _wo≤T_wo1 and the duration reaches the third duration T _C3, the processor turns off the air-source heat pump unit. Wherein T _wi1 is a first inlet water temperature threshold, and T _wo1 is a first outlet water temperature threshold. T _wi1 is 3 deg.C, 5 deg.C. Alternatively, T _wi1 is 3 ℃,4 ℃ or 5 ℃. T _wo1 is 3 deg.C, 5 deg.C. Alternatively, T _wo1 is 3 ℃,4 ℃ or 5 ℃. T _C2 is within the range of [0min,2min ]. Alternatively, T _C2 is 0min, 1min, or 2min. T _C3 is within the range of [0min,2min ]. Alternatively, T _C3 is 0min, 1min, or 2min. under the condition of the refrigerating operation of the air source heat pump unit, the temperature of the first heat exchanger can be reduced. In the case where the temperature of the refrigerant in the first heat exchanger is relatively low (below zero), then the probability of freezing of the water in the first heat exchanger increases if the temperature of the water in the first heat exchanger is also relatively low. Under the condition that the water inlet temperature or the water outlet 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, and icing caused by the fact that the water temperature of the first heat exchanger is too low is avoided. Thereby, the anti-freezing protection of the first heat exchanger is realized. Meanwhile, the setting of the duration avoids frequent shutdown of the air source heat pump unit caused by short water inlet and outlet temperature. Therefore, frequent shutdown is reduced, and the air source heat pump unit operates more stably. The first heat exchanger is subjected to anti-freezing protection by adopting a plurality of methods, so that the probability of frost cracking of the first heat exchanger is greatly reduced, and the occurrence of the frost cracking phenomenon is reduced.

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

s301, the air source heat pump unit starts refrigerating operation.

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

S303, the processor determines a low pressure saturation temperature P _s-t corresponding to P _s.

S304, the processor judges whether P _s-t<P_s-t1 is met. If yes, step S305 is performed. Otherwise, the process returns 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 determines whether T _wi≤T_wi1 is satisfied and the duration reaches the second duration T _C2. If yes, go to step S309. Otherwise, step S307 is executed back.

S308, the processor determines whether T _wo≤T_wo1 is satisfied and the duration reaches the third duration T _C3. If yes, go to step S309. Otherwise, the process returns 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 performed synchronously, and step S307 and step S308 are performed synchronously.

In the embodiment of the disclosure, the operation of the compressor is controlled by the low-pressure saturation temperature of the compressor, so that the first heat exchanger can be prevented from being in the condition of too low temperature for a long time, and the anti-freezing protection of the first heat exchanger is realized. Compared with the related art, the embodiment of the disclosure does not need to adjust the electronic expansion valve, reduces the complexity of the control process, and improves the reliability of the scheme. Meanwhile, the air source heat pump unit is shut down and controlled by judging the water inlet and outlet temperature of the first heat exchanger, so that icing caused by the fact that the water temperature of the first heat exchanger is too low is avoided. Thereby, the anti-freezing protection of the first heat exchanger is realized. The setting of the duration avoids frequent shutdown of the air source heat pump unit caused by short water inlet and outlet temperature. Therefore, frequent shutdown is reduced, and the air source heat pump unit operates more stably. The first heat exchanger is subjected to anti-freezing protection by adopting a plurality of methods, so that the probability of frost cracking of the first heat exchanger is greatly reduced, and the occurrence of the frost cracking phenomenon is reduced.

Optionally, after the processor shuts down the air source heat pump unit, the method further comprises: and under the condition that N is less than N, the air source heat pump unit is started to operate again by the processor after the first waiting time is longer than T _D1. And under the condition that N is more than or equal to N, the processor controls the starting and stopping of the air source heat pump unit according to the stopping times N ₁ in the first constraint time T _S1. Wherein N is the accumulated low-temperature shutdown times of the air source heat pump unit, and N is the maximum shutdown times allowed in the first constraint duration T _S1. T _D1 has a value of 8min and 15min. Alternatively, T _D1 is 8min, 10min, 12min, or 15min. T _S1 is in the range of [1h,2h ]. Alternatively, T _S1 is 1h, 1.5h, or 2h. The value range of N is [1,5], and N is a positive integer. Alternatively, N is 1,3 or 5. After stopping, in order to prevent the phenomenon of 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 is automatically restarted after a certain time interval. Therefore, the air source heat pump unit is controlled more reliably.

Optionally, controlling the start-stop of the air source heat pump unit according to the stop times n ₁ in the first constraint time period T _S1 includes: and under the condition that N ₁ is more than or equal to N, the processor keeps the shutdown state of the air source heat pump unit. In the case of N ₁ < N, the processor again starts the air source heat pump unit operation after the interval first waiting period T _D1. If the air source heat pump unit is frequently shut down within the constraint time period, a fault or other conditions may exist at present, and the shut down state needs to be kept and not restarted any more to protect the air source heat pump unit. For example, in a case where a heating operation is required in winter, a user erroneously operates to a cooling operation. Because the water temperature in winter is lower, if the refrigeration is operated again at this time, the water in the first heat exchanger is easy to freeze, so that the first heat exchanger is frozen and cracked. By adopting the control mode of stopping, the frost cracking probability of the first heat exchanger can be effectively reduced, and the occurrence of the frost cracking phenomenon is reduced.

The processor can also control the start and stop of the air source heat pump unit according to the water inlet temperature or the water outlet temperature of the first heat exchanger, so that the anti-freezing protection of the first heat exchanger is realized. And the frequent shutdown of the air source heat pump unit can be reduced, so that the air source heat pump unit can operate more stably.

In connection with the air source heat pump unit shown in fig. 1, another method for freezing protection of the air source heat pump unit is provided in an embodiment of the present disclosure, as shown in fig. 6. The method comprises the following steps:

S401, under the condition of refrigerating 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.

And S402, under the condition that the duration reaches the second duration T _C2 and the duration T _wi≤T_wi1, the processor turns off the air source heat pump unit.

S403, if 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 a first inlet water temperature threshold, and T _wo1 is a first outlet water temperature threshold. T _wi1 is 3 deg.C, 5 deg.C. Alternatively, T _wi1 is 3 ℃,4 ℃ or 5 ℃. T _wo1 is 3 deg.C, 5 deg.C. Alternatively, T _wo1 is 3 ℃,4 ℃ or 5 ℃. T _C2 is within the range of [0min,2min ]. Alternatively, T _C2 is 0min, 1min, or 2min. T _C3 is within the range of [0min,2min ]. Alternatively, T _C3 is 0min, 1min, or 2min.

In the embodiment of the disclosure, under the condition of refrigerating operation of the air source heat pump unit, the temperature of the first heat exchanger is reduced. In the case where the temperature of the refrigerant in the first heat exchanger is relatively low (below zero), then the probability of freezing of the water in the first heat exchanger increases if the temperature of the water in the first heat exchanger is also relatively low. Under the condition that the water inlet temperature or the water outlet 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, and icing caused by the fact that the water temperature of the first heat exchanger is too low is avoided. Thereby, the anti-freezing protection of the first heat exchanger is realized. Meanwhile, the setting of the duration avoids frequent shutdown of the air source heat pump unit caused by short water inlet and outlet temperature. Therefore, frequent shutdown is reduced, and the air source heat pump unit operates more stably.

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

s501, the air source heat pump unit starts refrigeration 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 determines whether T _wi≤T_wi1 is satisfied and the duration reaches the second duration T _C2. If yes, step S505 is executed. Otherwise, step S503 is executed back.

S504, the processor determines whether T _wo≤T_wo1 is satisfied and the duration reaches the third duration T _C3. If yes, step S505 is executed. Otherwise, the process returns 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, go to step S507. Otherwise, step S508 is performed.

S507, starting the air source heat pump unit to operate again by the processor after the interval of the first waiting time length T _D1.

And S508, the processor controls the start and stop of the air source heat pump unit according to the stop times n ₁ in the first constraint time period T _S1.

In the embodiment of the disclosure, under the condition of refrigerating operation of the air source heat pump unit, the temperature of the first heat exchanger is reduced. In the case where the temperature of the refrigerant in the first heat exchanger is relatively low (below zero), then the probability of freezing of the water in the first heat exchanger increases if the temperature of the water in the first heat exchanger is also relatively low. Under the condition that the water inlet temperature or the water outlet 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, and icing caused by the fact that the water temperature of the first heat exchanger is too low is avoided. Thereby, the anti-freezing protection of the first heat exchanger is realized. Meanwhile, the setting of the duration avoids frequent shutdown of the air source heat pump unit caused by short water inlet and outlet temperature. Therefore, frequent shutdown is reduced, and the air source heat pump unit operates more stably. After stopping, in order to prevent the phenomenon of 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 is automatically restarted after a certain time interval. Therefore, the air source heat pump unit is controlled more reliably.

Optionally, the method further comprises: the processor calculates DeltaT _w＝T_wi-T_wo to obtain a temperature difference DeltaT _w between the inlet water temperature and the outlet water temperature of the first heat exchanger. In the event Δt _w>△T_{Cold water} and the duration reaches fourth duration T _C4, the processor shuts down the air-source heat pump unit. Wherein Δt _{Cold water} is the first flow temperature difference threshold. The value range of T _C4 is (0 min,5 min) alternatively, T _C4 is 1min, 3min or 5min, under the condition that the air source heat pump unit operates in a refrigerating mode and the refrigerating capacity is fixed, the temperature difference of the water inlet temperature and the water outlet temperature after the water flows through the first heat exchanger is different, the smaller the water flow is, the larger the temperature difference of the water inlet temperature and the water outlet temperature is, the size of the water flow can be judged by judging the size of the actual water inlet temperature difference and the corresponding first flow temperature difference threshold value, if the temperature difference of the water inlet temperature and the water outlet temperature of the first heat exchanger is larger than the first flow temperature difference threshold value and lasts for a certain period of time, the method can determine that the water flow is low at the moment, and under the condition of low water flow, the air source heat pump unit is shut down and controlled, thereby realizing the anti-freezing protection of the first heat exchanger, meanwhile, the short water flow can cause large temperature difference between the water inlet temperature and the water outlet temperature of the first heat exchanger, the setting duration time avoids frequent shutdown caused by short water flow, the method has the advantages that frequent shutdown is reduced, the air source heat pump unit is enabled to run more stably, meanwhile, the air source heat pump unit does not need to be provided with a flowmeter alone, and the cost is reduced.

Alternatively, deltaT _{Cold water} is determined based on the operating frequency of the compressor. According to experimental verification, under the condition of refrigerating operation of the air source heat pump unit, the water inlet and outlet temperature difference of the first heat exchanger is related to the operation frequency of the compressor. Thus, under the condition that the operation frequency of the compressor is fixed, the temperature difference between the inlet water temperature and the outlet water temperature after the water flows through the first heat exchanger is different. Thus, Δt _{Cold water} can be determined by the operating frequency of the compressor. The water flow judgment can be more accurate by determining DeltaT _{Cold water} through the running frequency of the compressor in real time. Therefore, the air source heat pump unit is controlled more accurately, and the anti-freezing effect is better.

Optionally, determining Δt _{Cold water} according to the operating frequency of the compressor includes: the processor obtains the current operating frequency f of the compressor. The processor determines the DeltaT _{Cold water} corresponding to the current operating frequency f of the compressor according to the corresponding relation between DeltaT _{Cold water} and the operating frequency f of the compressor. Under the condition that the water flow rate in the first heat exchanger of the air source heat pump unit is insufficient, the water temperature in the water circulation quickly reaches the set temperature, so that the unit is stopped and restarted after the water temperature is reduced, and the unit is frequently started and stopped. Under the condition that the water flow rate in the first heat exchanger of the air source heat pump unit is too large, the water temperature in the water circulation cannot reach the set temperature for a long time, and therefore user experience is poor. Therefore, the air source heat pump unit can set a normal running water flow range according to the refrigerating capacity. The corresponding relation between DeltaT _{Cold water} and the running frequency f of the compressors is that on the basis of guaranteeing the lower limit of the normal running water flow range of the air source heat pump unit, the temperature difference DeltaT _{Cold water} between the corresponding water inlet temperature and the corresponding water outlet temperature is measured according to the running frequencies of a plurality of different compressors, and then a corresponding fitting formula is obtained according to a plurality of groups of data. Δt _{Cold water}＝12.5×(f/Q₃). Wherein Q ₃ is the correction value of the fitting formula. Q ₃ has a value in the range of [75, 85]. Alternatively, Q ₃ is 75, 80, or 85. Different series of products can have different fitting formulas due to the influence of the performance of the compressor or the structure of the products. Therefore, the formula is corrected through Q ₃, and a more accurate flow temperature difference threshold value can be obtained. Therefore, the control of the air source heat pump unit can be more accurate, and the anti-freezing effect is better.

Optionally, the air source heat pump unit refrigeration operation condition includes: and (3) under the condition that the refrigerant circulation loop is in refrigeration operation and the operation time length of the circulating water pump reaches the first operation time length T _Y1. The value range of T _Y1 is (0 min,3 min) alternatively, T _Y1 is 1min, 2min or 3min, after the running time of the circulating water pump reaches the first running time T _Y1, the water flow in the water circulation loop is judged, so that the water flow in the first heat exchanger can be effectively ensured to be stable.

Optionally, after the processor shuts down the air source heat pump unit, the method further comprises: and under the condition that M < M, the air source heat pump unit is started to operate again by the processor after the interval of the second waiting time length T _D2. And under the condition that M is more than or equal to M, the processor controls the starting and stopping of the air source heat pump unit according to the stopping times M ₁ in the second constraint time T _S2. Wherein M is the accumulated low water flow shutdown times of the air source heat pump unit, and M is the maximum shutdown times allowed in the second constraint time T _S2. The range of T _D2 is (0 min,10 min) optionally, T _D2 is 2min, 5min, 8min or 10min T _S2 is (0 h,2 h) optionally, T _S2 is 0.5h, 1h or 2h.M is [1,5], and M is a positive integer optionally, M is 1,3 or 5. After stopping, in order to prevent the 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 is automatically restarted after a certain time interval, thereby enabling the air source heat pump unit to be controlled more reliably.

Optionally, the processor controls the start-stop of the air source heat pump unit according to the stop times m ₁ in the second constraint time period T _S2, including: and under the condition that M ₁ is more than or equal to M, the processor keeps the shutdown state of the air source heat pump unit. In the case of M ₁ < M, the processor again starts the air source heat pump unit to operate after a second waiting period T _D2. If the air source heat pump unit is frequently shut down within the constraint time period, a fault or other conditions may exist at present, and the shut down state needs to be kept and not restarted any more to protect the air source heat pump unit. For example, in the case that the water flow rate in the first heat exchanger is always low, the water in the first heat exchanger is easy to cool and freeze, so that the first heat exchanger is frozen and cracked. By adopting the control mode of stopping, the frost cracking probability of the first heat exchanger can be effectively reduced, and the occurrence of the frost cracking phenomenon is reduced.

The processor can also control the start and stop of the air source heat pump unit according to the water inlet and outlet temperature difference of the first heat exchanger, so that the anti-freezing protection of the first heat exchanger is realized. And the frequent shutdown of the air source heat pump unit can be reduced, so that the air source heat pump unit can operate more stably.

In connection with the air source heat pump unit shown in fig. 1, another method for freezing protection of the air source heat pump unit is provided in an embodiment of the present disclosure, as shown in fig. 8. The method comprises the following steps:

S601, under the condition of refrigerating 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 DeltaT _w＝T_wi-T_wo to obtain a temperature difference DeltaT _w between the inlet water temperature and the outlet water temperature of the first heat exchanger.

S603, in the case of Δt _w>△T_{Cold water} and the duration reaching the fourth duration T _C4, the processor shuts down the air source heat pump unit. Wherein Δt _{Cold water} is the first flow temperature difference threshold. T _C4 is (0 min,5 min) alternatively T _C4 is 1min, 3min or 5min.

In the embodiment of the disclosure, the air source heat pump unit performs refrigeration operation, and under the condition that refrigeration capacity is certain, 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 water flow rate can be judged by judging the actual water inlet and outlet temperature difference and the corresponding first flow rate temperature difference threshold value. 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 rate temperature difference threshold value for a certain period of time, then the water flow rate at the moment can be determined to be low. And under the condition of low water flow, the air source heat pump unit is shut down and controlled, so that the anti-freezing protection of the first heat exchanger is realized. Meanwhile, the short water flow is low, so that the temperature difference between the water inlet temperature and the water outlet temperature of the first heat exchanger is large, and the frequent shutdown caused by the short water flow is avoided by setting the duration. Therefore, frequent shutdown is reduced, and the air source heat pump unit operates more stably. Meanwhile, the air source heat pump unit does not need to be provided with a flowmeter independently, so that the cost is reduced.

As shown in connection with fig. 9. The embodiment of the disclosure provides another method for preventing freezing of an air source heat pump unit, which comprises the following steps:

s701, the air source heat pump unit starts refrigeration 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 DeltaT _w＝T_wi-T_wo to obtain a temperature difference DeltaT _w between the inlet water temperature and the outlet water temperature of the first heat exchanger.

S704, the processor determines whether Δt _w>△T_{Cold water} is satisfied and the duration reaches the fourth duration T _C4. If yes, step S705 is executed. Otherwise, the process returns to step S704.

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

S706, the processor determines whether M < M is satisfied. If yes, step S707 is executed. Otherwise, step S708 is performed.

And S707, starting the air source heat pump unit to operate again by the processor after the interval of the second waiting time length T _D2.

And S708, the processor controls the start and stop of the air source heat pump unit according to the stop times m ₁ in the second constraint time period T _S2.

In the embodiment of the disclosure, the water flow in the first heat exchanger is judged by comparing the temperature difference of water entering and exiting the first heat exchanger with the flow temperature difference threshold value, and the air source heat pump unit is shut down under the condition that the water flow is low. Thereby, the anti-freezing protection of the first heat exchanger is realized. Meanwhile, the short water flow is low, so that the temperature difference between the water inlet temperature and the water outlet temperature of the first heat exchanger is large, and the frequent shutdown caused by the short water flow is avoided by setting the duration. Therefore, frequent shutdown is reduced, and the air source heat pump unit operates more stably. After stopping, in order to prevent the phenomenon of low water flow in the occasional first heat exchanger from affecting the normal operation of the air source heat pump unit, the air source heat pump unit is automatically restarted after a certain time interval. Therefore, the air source heat pump unit is controlled more reliably.

Optionally, the method further comprises: under the condition of refrigerating operation of the air source heat pump unit, the processor detects the air inlet pressure P _s of the compressor. The processor determines a low pressure saturation temperature P _s-t corresponding to P _s. In the case of P _s-t<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 range of P _s-t1 is (-5 ℃, -3 ℃). Alternatively, P _s-t1 is-4.5 ℃, -4℃or-3.5 ℃. Under the refrigerating operation condition of the air source heat pump unit, the air inlet pressure of the compressor can fluctuate according to the operation frequency of the compressor. The higher the compressor operating frequency, the lower the compressor inlet pressure and the corresponding low pressure saturation temperature. If the low pressure saturation temperature is below a certain value, the probability of freezing of the water in the first heat exchanger increases. The operation of the compressor is controlled through the low-pressure saturation temperature of the compressor, so that the first heat exchanger can be prevented from being in the condition of too low temperature for a long time, and the anti-freezing protection of the first heat exchanger is realized. Compared with the related art, the embodiment of the disclosure does not need to adjust the electronic expansion valve, reduces the complexity of the control process, and improves the reliability of the scheme. The first heat exchanger is subjected to anti-freezing protection by adopting a plurality of methods, so that the probability of frost cracking of the first heat exchanger is greatly reduced, and the occurrence of the frost cracking phenomenon is reduced.

The operation of the auxiliary electric heating device of the air source heat pump unit can be controlled according to the water outlet temperature of the first heat exchanger through the processor, the frost cracking probability of the first heat exchanger is reduced, and the frost cracking phenomenon is reduced.

In connection with the air source heat pump unit shown in fig. 1, another method for freezing protection of the air source heat pump unit is provided in an embodiment of the present disclosure, as shown in fig. 10. The method comprises the following steps:

s801, under the condition that the air source heat pump unit enters 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 disclosure, since the defrosting operation is substantially equal to the cooling operation, the temperature of the first heat exchanger may be reduced after the air source heat pump unit is changed from the heating operation to the defrosting operation. In the case where the temperature of the refrigerant in the first heat exchanger is relatively low (below zero), then the probability of freezing of the water in the first heat exchanger increases if the temperature of the water in the first heat exchanger is also relatively low. Under the condition of defrosting operation of the air source heat pump unit, the operation of the auxiliary electric heating device is controlled by judging the temperature of the discharged water, so that the water in the first heat exchanger can be ensured to keep a higher water temperature under the condition of defrosting operation. In this way, in the case of defrosting operation, the speed of water temperature decrease in the first heat exchanger is slowed down. Therefore, the probability of frost cracking of the first heat exchanger is reduced, and the occurrence of the frost cracking phenomenon is reduced.

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

s901, an 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 determines whether a first condition for entering the defrosting operation is satisfied. If yes, go to step S906. Otherwise, step S904 is performed.

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

S905, the processor determines whether a second condition for entering the defrosting operation is satisfied. If yes, go to step S906. Otherwise, step S905 is executed back.

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

S907, the processor determines whether T _wo<T_wo2 is satisfied. If yes, step S909 is executed. Otherwise, step S908 is performed.

S908, the processor determines whether T _wo>T_wo3 is satisfied. If yes, go to step S910. Otherwise, step S907 is executed back.

S909, the processor turns on the auxiliary electric heating means. The process returns to step S908.

S910, the processor turns off the auxiliary electric heating. The process returns to step S907.

In the embodiment of the disclosure, whether the air source heat pump unit enters the defrosting operation is controlled by judging the water temperature, so that the water temperature in the first heat exchanger can be ensured to be kept at a higher temperature under the condition of entering the defrosting operation. Therefore, the probability of frost cracking of the first heat exchanger is reduced, and the occurrence of the frost cracking phenomenon is reduced. After defrosting operation, the auxiliary electric heating device is controlled according to the water outlet temperature, so that the water temperature in the first heat exchanger can be kept at a higher temperature, and meanwhile, the auxiliary electric heating device is turned off under the condition that the water outlet temperature is higher than a certain value, so that energy consumption can be saved.

Optionally, the method further comprises: under the condition of defrosting operation of the air source heat pump unit, the processor detects the air inlet pressure P _s of the compressor. The processor determines a low pressure saturation temperature P _s-t corresponding to P _s. In the case of P _s-t<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 range of P _s-t1 is (-5 ℃, -3 ℃). Alternatively, P _s-t1 is-4.5 ℃, -4℃or-3.5 ℃. Under the condition of defrosting operation of the air source heat pump unit, the air inlet pressure of the compressor can fluctuate according to the operation frequency of the compressor. The higher the compressor operating frequency, the lower the compressor inlet pressure and the corresponding low pressure saturation temperature. If the low pressure saturation temperature is below a certain value, the probability of freezing of the water in the first heat exchanger increases. The operation of the compressor is controlled through the low-pressure saturation temperature of the compressor, so that the first heat exchanger can be prevented from being in the condition of too low temperature for a long time, and the anti-freezing protection of the first heat exchanger is realized. The first heat exchanger is subjected to anti-freezing protection by adopting a plurality of methods, so that the probability of frost cracking of the first heat exchanger is greatly reduced, and the occurrence of the frost cracking phenomenon is reduced.

Optionally, the method further comprises: under the condition of defrosting operation of the air source heat pump unit, the processor detects the water inlet temperature T _wi of the first heat exchanger. The processor calculates DeltaT _w＝T_wi-T_wo to obtain a temperature difference DeltaT _w between the inlet water temperature and the outlet water temperature of the first heat exchanger. In the event Δt _w>△T_{Cold water} and the duration reaches fourth duration T _C4, the processor shuts down the air-source heat pump unit. Wherein Δt _{Cold water} is the first flow temperature difference threshold. The value range of T _C4 is (0 min,5 min) alternatively, T _C4 is 1min, 3min or 5min, under the condition that the air source heat pump unit operates in a refrigerating mode and the refrigerating capacity is fixed, the temperature difference of the water inlet temperature and the water outlet temperature after the water flows through the first heat exchanger is different, the smaller the water flow is, the larger the temperature difference of the water inlet temperature and the water outlet temperature is, the size of the water flow can be judged by judging the size of the actual water inlet temperature difference and the corresponding first flow temperature difference threshold value, if the temperature difference of the water inlet temperature and the water outlet temperature of the first heat exchanger is larger than the first flow temperature difference threshold value and lasts for a certain period of time, the method can determine that the water flow is low at the moment, and under the condition of low water flow, the air source heat pump unit is shut down and controlled, thereby realizing the anti-freezing protection of the first heat exchanger, meanwhile, the short water flow can cause large temperature difference between the water inlet temperature and the water outlet temperature of the first heat exchanger, the setting duration time avoids frequent shutdown caused by short water flow, the method has the advantages that frequent shutdown is reduced, the air source heat pump unit is enabled to run more stably, meanwhile, the air source heat pump unit does not need to be provided with a flowmeter alone, and the cost is reduced.

Alternatively, deltaT _{Cold water} is determined based on the operating frequency of the compressor. According to experimental verification, under the condition of defrosting operation of the air source heat pump unit, the water inlet and outlet temperature difference of the first heat exchanger is related to the operation frequency of the compressor. Thus, under the condition that the operation frequency of the compressor is fixed, the temperature difference between the inlet water temperature and the outlet water temperature after the water flows through the first heat exchanger is different. Thus, Δt _{Cold water} can be determined by the operating frequency of the compressor. The water flow judgment can be more accurate by determining DeltaT _{Cold water} through the running frequency of the compressor in real time. Therefore, the air source heat pump unit is controlled more accurately, and the anti-freezing effect is better.

Optionally, the defrosting operation of the air source heat pump unit includes: and (3) under the condition that the refrigerant circulation loop is in refrigeration operation and the operation time length of the circulating water pump reaches the first operation time length T _Y1. The value range of T _Y1 is (0 min,3 min) alternatively, T _Y1 is 1min, 2min or 3min, after the running time of the circulating water pump reaches the first running time T _Y1, the water flow in the water circulation loop is judged, so that the water flow in the first heat exchanger can be effectively ensured to be stable.

In the actual operation process of the air source heat pump unit, another method for preventing freezing of the air source heat pump unit is shown in fig. 12, and includes:

s1201, the air source heat pump unit receives a defrosting operation instruction.

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

S1203, it is determined whether the first condition for entering the defrosting operation is satisfied. If yes, go to step S1206. Otherwise, step S1204 is performed. Assuming that T _wo is 19 ℃, the first condition is T _wo. Gtoreq.20℃. At this time, step S1204 is performed. Assuming that T _wo is 22 ℃, the first condition is T _wo. Gtoreq.20℃. At this time, step S1206 is performed.

S1204, turning on the auxiliary electric heating device.

S1205, it is determined whether the second condition for entering the defrosting operation is satisfied. If yes, go to step S1206. Otherwise, the process returns to step S1205. Assuming an initial T _wo of 19 ℃, the second condition is T _wo >22 ℃ and for 30s. After turning on the auxiliary electric heating device for a period of time, T _wo rises to above 22 ℃ for 30S, and step S1206 is performed.

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

S1207, judging whether T _wo<T_wo2 is satisfied. If yes, step S1209 is performed. Otherwise, step S1208 is performed. Let T _wo2 be 20 ℃. At this time, when T _wo is 19 ℃, step S1209 is performed.

S1208, judging whether T _wo>T_wo3 is satisfied. If yes, go to step S1210. Otherwise, the process returns to step S1207.T _wo3 was 23 ℃. At this time, T _wo is 24 ℃, step S1210 is performed.

S1209, the auxiliary electric heating device is turned on. The process returns to step S1208.

S1210, turning off the auxiliary electric heating device. The process returns to step S1207.

S1211, after the air source heat pump unit enters defrosting operation, whether T _wo<max(T_wo4-T_wo8,T_wo9 is met or not is judged. If yes, go to step S1212. Otherwise, step S1211 is executed back. Let T _wo4 be 25 ℃, T _wo8 be 12 ℃, and T _wo9 be 10 ℃. Then T _wo7 = max (25 ℃ -12 ℃,10 ℃) = 13 ℃. Assuming that T _wo is 12 ℃, step S1212 is performed.

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

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

S1214, calculating DeltaT _w＝T_wi-T_wo. The temperature difference DeltaT _w between the inlet water temperature and the outlet water temperature of the first heat exchanger is obtained.

S1215, it is determined whether Δt _w>△T_{Cold water} is satisfied and the duration reaches the fourth duration T _C4. If yes, go to step S1216. Otherwise, step S1215 is executed back. Let it be assumed that at this time, Δt _{Cold water} calculated in the compressor operation state is 2 ℃, and T _C4 is 1min. The Δt _w >2 ℃ and the duration reaches 1min, then step S1216 is performed.

S1216, the air source heat pump unit is turned off.

Among them, steps S1207 to S1210, steps S1211 to S1212, and steps S1213 to S1216 are synchronously performed.

As shown in conjunction with fig. 13, an embodiment of the present disclosure provides an apparatus for freezing protection of an air source heat pump unit, including a processor 1300 and a memory 1301 storing program instructions. Optionally, the apparatus may further include a communication interface (Communication Interface) 1302 and a bus 1303. The processor 1300, the communication interface 1302, and the memory 1301 may communicate with each other through the bus 1303. The communication interface 1302 may be used for information transfer. Processor 1300 may invoke logic instructions in memory 1301 to perform the method for air source heat pump unit freeze protection of the above-described embodiments.

Further, the logic instructions in the memory 1301 described above may be implemented in the form of software functional units and may be stored in a computer readable storage medium when sold or used as a stand alone product.

The memory 1301 is used as a storage medium for storing a software program and a computer executable program, such as program instructions/modules corresponding to the methods in the embodiments of the present disclosure. The processor 1300 executes functional applications and data processing by running program instructions/modules stored in the memory 1301, i.e. implements the method for air source heat pump unit freeze protection in the above embodiments.

Memory 1301 may include a storage program area that may store an operating system, at least one application program required for functions, and a storage data area; the storage data area may store data created according to the use of the terminal device, etc. Further, the memory 1301 may include a high-speed random access memory, and may also include a nonvolatile memory.

The embodiment of the disclosure provides an air source heat pump unit, which comprises a refrigerant circulation loop 1, a water circulation loop 2 and the device for preventing freezing of the air source heat pump unit. The refrigerant circulation circuit 1 includes a compressor 4 and a first heat exchanger 5. A pressure sensor 7 is arranged at the air inlet of the compressor 4 and is used for detecting the air inlet pressure of the compressor 4. The water circulation circuit 2 comprises a circulation water pump 3 and an auxiliary electric heating device 6. The circulating water pump 3 is used for starting the water circulation of the air source heat pump unit. The auxiliary electric heating means 6 are 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 comprises a water inlet and a water outlet which are communicated with the water circulation loop 2. The water circulation loop 2 corresponding to the water inlet is provided with a first temperature sensor 8 for detecting the inlet water temperature of the first heat exchanger 5. The water circulation loop 2 corresponding to the water outlet is provided with a second temperature sensor 9 for detecting the water outlet temperature of the first heat exchanger 5. The processor in the device for preventing freezing of the air source heat pump unit is electrically connected with at least the auxiliary electric heating device 6, the pressure sensor 7, the first temperature sensor 8 and the second temperature sensor 9.

The embodiment of the disclosure provides a storage medium, which stores program instructions configured to execute the method for preventing freezing of an air source heat pump unit.

The storage medium may be a transitory computer readable storage medium or a non-transitory computer readable storage medium. A non-transitory storage medium comprising: a plurality of media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (RAM, random Access Memory), a magnetic disk, or an optical disk, or a transitory storage medium.

The above description and the drawings illustrate embodiments of the disclosure sufficiently to enable those skilled in the art to practice them. Other embodiments may involve structural, logical, electrical, process, and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the sequence of operations may vary. Portions and features of some embodiments may be included in, or substituted for, those of others. Moreover, the terminology used in the present application is for the purpose of describing embodiments only and is not intended to limit the claims. As used in the description of the embodiments and the claims, the singular forms "a," "an," and "the" (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 disclosure is meant to encompass any and all possible combinations of one or more of the associated listed. Furthermore, when used in the present disclosure, the terms "comprises," "comprising," and/or variations thereof, mean that the recited features, integers, steps, operations, elements, and/or components are present, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Without further limitation, an element defined by the phrase "comprising one …" does not exclude the presence of other like elements in a process, method or apparatus that includes the element. In this context, each embodiment may be described with emphasis on the differences from the other embodiments, and the same similar parts between the various embodiments may be referred to each other. For the methods, products, etc. disclosed in the embodiments, if they correspond to the method sections disclosed in the embodiments, the description of the method sections may be referred to for relevance.

Those of skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. The skilled artisan may use different methods for each particular application to achieve the described functionality, but such implementation should not be considered to be beyond the scope of the embodiments of the present disclosure. It will be clearly understood by those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the above-described method embodiments, and are not described herein again.

The flowcharts 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 present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. In the description corresponding to the flowcharts and block diagrams in the figures, operations or steps corresponding to different blocks may also occur in different orders than that disclosed in the description, and sometimes no specific order exists between different operations or steps. For example, two consecutive operations or steps may actually be performed substantially in parallel, they may sometimes be performed in reverse order, which may be dependent on the functions involved. Each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

Claims

1. An air source heat pump unit antifreeze method, the air source heat pump unit includes: a water circulation circuit; and, a refrigerant circulation circuit including a first heat exchanger; the first heat exchanger exchanges heat with the water circulation loop; characterized in that the method comprises:

Under the condition of heating 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;

Calculating DeltaT _w＝T_wo-T_wi to obtain a temperature difference DeltaT _w between the inlet water temperature and the outlet water temperature of the first heat exchanger;

Shutting down the air source heat pump unit when the delta T _w>△T_{Heat of the body} is reached and the duration reaches a seventh duration T _C7;

wherein Δt _{Heat of the body} is the second flow temperature difference threshold;

After detecting the water temperature T _wo, further comprising: judging whether T _wo meets a first condition for entering defrosting operation or not; under the condition that T _wo meets a first condition, controlling the air source heat pump unit to enter defrosting operation; under the condition that T _wo does not meet the first condition, starting an auxiliary electric heating device, and under the condition that the outlet water temperature meets the second condition of entering defrosting operation, controlling the air source heat pump unit to enter defrosting operation;

Wherein the first condition comprises: t _wo≥T_wo4,T_wo4 is a fourth outlet water temperature threshold; the second condition includes: t _wo6≤T_wo≤T_wo5 and the duration reaches a fifth duration T _C5; or T _wo>T_wo5 and the duration reaches a sixth duration T _C6,T_wo5 being a fifth outlet temperature threshold, T _wo6 being a sixth outlet temperature threshold and T _C5>T_C6.

2. The method of claim 1, wherein the refrigerant circuit further comprises a compressor, and Δt _{Heat of the body} is determined based on an operating frequency of the compressor and an outdoor ambient temperature.

3. The method of claim 2, wherein determining Δt _{Heat of the body} from the operating frequency of the compressor and the outdoor ambient temperature comprises:

Acquiring the running frequency f of the current compressor and the outdoor environment temperature T _ao;

And determining the operating frequency f of the current compressor and the DeltaT _{Heat of the body} corresponding to the outdoor environment temperature T _ao according to the corresponding relation between DeltaT _{Heat of the body} and the operating frequency of the compressor and the outdoor environment temperature.

4. The method according to claim 1, wherein the heating operation of the air source heat pump unit comprises:

And (3) under the condition that the refrigerant circulation loop heats and runs and the running time of the circulating water pump reaches the second running time T _Y2.

5. The method of claim 1, further comprising, after shutting down the air source heat pump unit:

under the condition of I < I, restarting the operation of the air source heat pump unit after a third waiting time length T _D3 is spaced;

When I is more than or equal to I, controlling the start and stop of the air source heat pump unit according to the stop times I ₁ in the third constraint time T _S3;

Wherein I is the accumulated low water flow shutdown times of the air source heat pump unit, and I is the maximum shutdown times allowed in the third constraint time T _S3.

6. The method according to any one of claims 1 to 5, wherein the water circulation circuit comprises: an auxiliary electric heating device for heating the water flowing into the first heat exchanger; the method further comprises the steps of:

Under the condition that the air source heat pump unit enters defrosting operation, detecting the outlet water temperature T _wo of the first heat exchanger;

And controlling 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.

7. The method of claim 6, wherein controlling operation of the auxiliary electric heating means in accordance with the outlet water temperature T _wo comprises:

in the case of T _wo<T_wo2, turning on the auxiliary electric heating means;

in the case of T _wo>T_wo3, the auxiliary electric heating is turned off;

Wherein, T _wo2 is a second outlet water temperature threshold, T _wo3 is a third outlet water temperature threshold, T _wo3>T_wo2.

8. An apparatus for air source heat pump unit freezing protection comprising a processor and a memory storing program instructions, characterized in that the processor is configured to execute the method for air source heat pump unit freezing protection as claimed in any one of claims 1 to 7 when running the program instructions.

9. An air source heat pump unit comprising:

The refrigerant circulation loop comprises a compressor and a first heat exchanger, wherein a pressure sensor is arranged at an air inlet of the compressor and used for detecting the air inlet pressure of the compressor; and, a step of, in the first embodiment,

The water circulation loop comprises a circulating water pump and an auxiliary electric heating device; the circulating water pump is used for starting the water circulation of the air source heat pump unit; the auxiliary electric heating device is used for heating the water flowing into the first heat exchanger;

The first heat exchanger exchanges heat with the water circulation loop, and comprises a water inlet and a water outlet which are communicated with the water circulation loop; the water circulation loop corresponding to the water inlet is provided with a first temperature sensor 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;

The air source heat pump unit is characterized by further comprising:

The apparatus for freeze protection of an air source heat pump unit of claim 8, the processor electrically connected to at least the auxiliary electrical heating device, the pressure sensor, the first temperature sensor, and the second temperature sensor.

10. A storage medium storing program instructions which, when executed, perform the method for air source heat pump unit antifreeze as claimed in any one of claims 1 to 7.