CN115183403A

CN115183403A - Method and device for preventing air source heat pump unit from freezing, air source heat pump unit and storage medium

Info

Publication number: CN115183403A
Application number: CN202210799128.3A
Authority: CN
Inventors: 刘涛; 韩伟涛; 刘国清; 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: 2022-10-14

Abstract

The application relates to the technical field of intelligent household appliances and discloses a method for preventing an air source heat pump unit from freezing, wherein the air source heat pump unit comprises: a water circulation loop comprising an auxiliary electrical heating device; and, a refrigerant circulation loop comprising a first heat exchanger; wherein, the first heat exchanger exchanges heat with the water circulation loop; the auxiliary electric heating device is used for heating the water flowing into the first heat exchanger; the method comprises the following steps: detecting the outlet water temperature T of the first heat exchanger under the condition that the air source heat pump unit enters defrosting operation _wo (ii) a According to the temperature T of the outlet water _wo And controlling the operation of the auxiliary electric heating device to adjust the water temperature of the first heat exchanger. The method can reduce the probability of frost cracking of the first heat exchanger in the defrosting operation process of the air source heat pump unit and reduce the occurrence of the frost cracking phenomenon. The application also discloses a device for preventing the air source heat pump unit from freezing, the 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, for example, to a method and a device for preventing an air source heat pump unit from freezing, 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, if the water flow passing through the inside of the plate heat exchanger is insufficient or the water temperature is too low, or the water side heat exchanger is frozen and cracked due to factors such as too low evaporation temperature in the refrigeration process. Most of the existing air source heat pump units adopt a reverse defrosting mode, however, based on the defrosting mode, when the air source heat pump units are switched to a defrosting working condition, 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 easy to freeze.

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 the air source heat pump unit. The method comprises the following steps: the operation of the refrigerant circulation loop is controlled by comparing the water flow in the water circulation loop with a preset water flow; when the air source heat pump unit is in a defrosting condition, the high-low pressure balance valve is controlled to be opened for a preset protection duration; the running states of a compressor and an electronic expansion valve are controlled by acquiring the low-pressure of a refrigerant circulation loop when an air source heat pump unit is under a refrigeration working condition; and then effectively guarantee that the water side heat exchanger can not receive the influence of factors such as the water flow is too little, the temperature of water is low excessively and leads to its problem of being cracked by the frost under any operating mode to effectively guarantee its reliability.

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 this technique can play certain effect to preventing frostbite of air supply heat pump set water side heat exchanger, nevertheless get into under the condition of defrosting operating mode at air supply heat pump set, it is long when presetting the protection through controlling high-low pressure balance valve and opening, along with the temperature of the water in the water side heat exchanger constantly descends, still can often appear the phenomenon that water side heat exchanger frost crack.

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 nor is intended to identify key/critical elements or to delineate the scope of such embodiments but rather as a prelude to the more detailed description that is presented later.

The embodiment of the disclosure provides a method and a device for preventing an air source heat pump unit from freezing, the air source heat pump unit and a storage medium, and the method and the device can reduce the probability of frost cracking of a water side heat exchanger in the defrosting operation process of the air source heat pump unit and reduce the occurrence of the frost cracking phenomenon.

In some embodiments, an air source heat pump unit comprises: a water circulation loop comprising an auxiliary electrical heating device; and, a refrigerant circulation loop comprising a first heat exchanger; wherein the first heat exchangerExchanging heat with a water circulation loop; the auxiliary electric heating device is used for heating the water flowing into the first heat exchanger; the method comprises the following steps: detecting the outlet water temperature T of the first heat exchanger under the condition that the air source heat pump unit enters defrosting operation _wo (ii) a According to the temperature T of the outlet water _wo And controlling the operation of the auxiliary electric heating device to adjust the water temperature of the first heat exchanger.

In some embodiments, the device for preventing freezing of an air source heat pump unit comprises a processor and a memory storing program instructions, wherein the processor is configured to execute the method for preventing freezing of an air source heat pump unit when the program instructions are executed.

In some embodiments, an air source heat pump unit comprises: 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 pressure of the air inlet 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 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, the first heat exchanger comprises a water inlet and a water outlet, and the water inlet and the water outlet are communicated with the water circulation loop; a first temperature sensor is arranged on the water circulation loop corresponding to the water inlet and used for detecting the water inlet temperature of the first heat exchanger; the water circulation loop corresponding to the water outlet is provided with a second temperature sensor for detecting the water outlet temperature of the first heat exchanger; and the processor is at least electrically connected with 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 above-described method for air source heat pump unit freeze protection.

In the embodiment of the disclosure, since the defrosting operation is basically equal to the cooling operation, the temperature of the first heat exchanger is reduced after the air source heat pump unit is switched 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 degrees), then if the temperature of the water in the first heat exchanger is also relatively low, the probability of freezing of the water in the first heat exchanger increases. 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 water outlet temperature, so that the water in the first heat exchanger can be kept at a higher water temperature during defrosting operation. In this way, in the case of defrosting operation, the rate of decrease in the water temperature 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 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 in the accompanying drawings, which correspond to the accompanying drawings and not in limitation thereof, in which elements having the same reference numeral designations are shown as like elements and not in limitation thereof, and wherein:

FIG. 1 is a schematic view 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 preventing freezing of an air source heat pump unit according to an embodiment of the present disclosure;

FIG. 3 is a schematic diagram of another method for preventing freezing of an air source heat pump unit according to an embodiment of the present disclosure;

FIG. 4 is a schematic diagram of another method for preventing freezing of an air source heat pump unit according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of another method for preventing freezing of an air source heat pump unit according to an embodiment of the present disclosure;

FIG. 6 is a schematic diagram of another method for preventing freezing of an air-source heat pump unit according to an embodiment of the disclosure;

FIG. 7 is a schematic diagram of another method for preventing freezing of an air source heat pump unit according to an embodiment of the present disclosure;

FIG. 8 is a schematic diagram of another method for preventing freezing of an air-source heat pump unit according to an embodiment of the disclosure;

FIG. 9 is a schematic diagram of another method for preventing freezing of an air source heat pump unit according to an embodiment of the present disclosure;

FIG. 10 is a schematic view of another method for preventing freezing of an air-source heat pump unit according to an embodiment of the present disclosure;

FIG. 11 is a schematic diagram of another method for preventing freezing of an air-source heat pump unit according to an embodiment of the disclosure;

FIG. 12 is a schematic diagram of another method for preventing freezing of an air source heat pump unit according to an embodiment of the present disclosure;

FIG. 13 is a schematic view of an anti-freezing device for an air source heat pump unit according to an embodiment of the disclosure.

Reference numerals are as follows:

1: a refrigerant circulation circuit; 2: a water circulation loop; 3: a water circulating 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 elements of the disclosed embodiments can be understood in detail, a more particular description of the disclosed embodiments, briefly summarized above, may be had by reference to the embodiments, some of which are illustrated in the appended drawings. 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 be practiced without these details. In other instances, well-known structures and devices may be shown in simplified form in order to simplify the drawing.

The terms "first," "second," and the like in the description and in the claims, and the above-described drawings of embodiments of the present disclosure, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the data so used may be interchanged as appropriate for the embodiments of the disclosure described herein. Furthermore, the terms "include" 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 orientations or positional relationships based on the orientations or positional relationships shown in the drawings. These terms are used primarily to better describe the disclosed embodiments and their examples and are not intended to limit the indicated devices, elements or components to a particular orientation or to be constructed and operated in a particular orientation. Moreover, some of the above terms may be used to indicate other meanings besides the orientation or positional relationship, for example, the term "on" may also be used to indicate some kind of attachment or connection relationship in some cases. The specific meanings of these terms in the embodiments of the present disclosure can be understood by those of ordinary skill in the art as appropriate.

The term "plurality" means two or more unless otherwise specified.

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

The term "and/or" is an associative relationship that describes objects, meaning that three relationships may exist. E.g., a and/or B, represents: a or B, or A and B.

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

In addition, the term "set" should be interpreted broadly.

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

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

The water circulation circuit 2 comprises a circulating water pump 3 and an auxiliary electric heating device 6. And the circulating water pump 3 is used for starting water circulation of the air source heat pump unit. The auxiliary electric heating device 6 is communicated with the first heat exchanger 5, and is used for heating the water flowing into the first heat exchanger 5. The first heat exchanger 5 exchanges heat with the water circulation 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 first heat exchanger 5 is provided with first temperature sensor 8, and first temperature sensor 8 is used for detecting the temperature of intaking of first heat exchanger 5. A 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.

Under the condition of the air conditioner refrigeration 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 reversed, and at this time, the refrigeration state is communicated) 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 high-pressure liquid refrigerant exchanges heat (absorbs heat) with water in the water circulation loop 2 in the first heat exchanger 5 to be converted into a low-temperature low-pressure gaseous refrigerant. The low-temperature and low-pressure gaseous refrigerant returns to the compressor 4 through the four-way valve 11, the gas-liquid separator 13 and the pressure sensor 7. Under the condition of heating operation of the air conditioner, 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 reversed, and at the moment, the communicated heating state) to exchange heat (release heat) with water in the water circulation loop 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, is throttled and depressurized, enters the second heat exchanger 10, and is subjected to heat exchange in the second heat exchanger 10 to be converted into a low-temperature low-pressure gaseous refrigerant. The low-temperature and low-pressure gaseous refrigerant returns to the compressor 4 through the four-way valve 11, the gas-liquid separator 13 and the pressure sensor 7.

The processor can control the operation of the auxiliary electric heating device of the air source heat pump unit according to the outlet water temperature of the first heat exchanger, so that the frost crack probability of the first heat exchanger is reduced, and the occurrence of the frost crack phenomenon is reduced.

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

s801, detecting the outlet water temperature T of the first heat exchanger by the processor under the condition that the air source heat pump unit enters defrosting operation _wo 。

S802, the processor is used for processing according to the water outlet temperature T _wo And controlling the operation of the auxiliary electric heating device 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 refrigerating operation, the temperature of the first heat exchanger is reduced after the air source heat pump unit is switched from the heating operation to the defrosting operation. In the case of a relatively low (below zero) refrigerant temperature in the first heat exchanger, the probability of the water in the first heat exchanger freezing 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 water outlet temperature, so that the water in the first heat exchanger can be kept at a higher water temperature under the defrosting operation condition. In this way, in the case of defrosting operation, the rate of decrease in the water temperature 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.

Optionally, the processor is based on the outlet water temperature T _wo Controlling operation of the auxiliary electric heating device, comprising: at T _wo <T _wo2 In this case, the processor turns on the auxiliary electric heating device. At T _wo >T _wo3 In case of (2), the processor turns off the auxiliary electric heating device. Wherein, T _wo2 Is the second outlet water temperature threshold, T _wo3 Is a third outlet water temperature threshold, T _wo3 >T _wo2 。T _wo2 The value range of (C) is [15 ℃,20 DEG C]. Alternatively, T _wo2 At 15 ℃, 17 ℃ or 20 ℃. T is _wo3 The value range of (20 ℃,25℃)]. Alternatively, T _wo3 At 21 ℃, 23 ℃ or 25 ℃. In this way, the temperature of the water in the first heat exchanger can be kept oneThe higher temperature reduces the probability of frost crack of the first heat exchanger. Thus, the occurrence of the first heat exchanger frost crack phenomenon is reduced. Meanwhile, the auxiliary electric heating device is turned off under the condition that the temperature of the outlet water is higher than a certain value, so that the energy consumption can be saved.

Optionally, before the air source heat pump unit enters the defrosting operation, the method further comprises: processor judges T _wo Whether a first condition for entering a defrosting operation is satisfied. 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 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 the defrosting operation or not is controlled by judging the outlet water temperature, and the water temperature in the first heat exchanger can 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. And a plurality of methods are adopted to carry out anti-freezing protection on the first heat exchanger together, so that the frost cracking probability of the first heat exchanger is greatly reduced, and the occurrence of the frost cracking phenomenon is reduced.

Referring to fig. 3, another method for preventing freezing of an air source heat pump unit is provided in an embodiment of the present disclosure, including:

s901, the air source heat pump unit receives an instruction of defrosting operation.

S902, the processor detects the outlet water temperature T of the first heat exchanger _wo 。

S903, the processor determines whether a first condition for entering a defrosting operation is satisfied. If yes, go to step S906. Otherwise, step S904 is executed.

S904, the processor starts the auxiliary electric heating device.

And S905, judging whether a second condition for entering the defrosting operation is met by the processor. If yes, go to step S906. Otherwise, the process returns to step S905.

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

S907, the processor judges whether T is satisfied _wo <T _wo2 . If so, thenStep S909 is executed. Otherwise, step S908 is performed.

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

S909, the processor turns on the auxiliary electric heating device. The execution returns to step S908.

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

In the embodiment of the disclosure, whether the air source heat pump unit enters the defrosting operation or not is controlled by judging the outlet water temperature, so that the water temperature in the first heat exchanger can be kept at a higher temperature under the condition of entering the defrosting operation. Therefore, the frost crack probability of the first heat exchanger is reduced, and the occurrence of the frost crack phenomenon is reduced. After the defrosting operation is carried out, the temperature of water in the first heat exchanger can be kept at a higher temperature by controlling the switch of the auxiliary electric heating equipment according to the temperature of the outlet water, and meanwhile, the energy consumption can be saved by turning off the auxiliary electric heating device under the condition that the temperature of the outlet water is higher than a certain value.

Optionally, the first condition comprises: t is _wo ≥T _wo4 . Wherein, T _wo4 Is the fourth effluent temperature threshold. T is a unit of _wo4 The value range of (C) is [20 ℃,45 DEG C]. Alternatively, T _wo4 At 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 probability of frost cracking of the first heat exchanger is reduced. Thus, the occurrence of the frost crack phenomenon of the first heat exchanger is reduced.

Optionally, the second condition comprises: t is _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 a fifth effluent temperature threshold, T _wo6 Is the sixth outlet water temperature threshold, T _C5 >T _C6 。T _wo5 The value range of (C) is [20 ℃,22 DEG C]. Alternatively, T _wo5 At 20 ℃, 21 ℃ or 22 ℃. T is _wo6 The value range of (A) is [15 ℃,22 DEG C]. Alternatively, T _wo6 Is 15 ℃, 18 ℃ or 22 ℃. T is _C5 The value range of (1) is [10min,1h]. Alternatively, T _C5 Is 10min, 30min or 1h. T is _C6 The value range of (0s, 60s)]. Alternatively, T _C6 10s, 30s or 60s. Therefore, the water temperature in the first heat exchanger can be kept at a higher temperature under the defrosting operation condition, and the frost crack probability of the first heat exchanger is reduced. Thus, the occurrence of the frost crack phenomenon of the first heat exchanger is reduced.

Optionally, during the defrosting operation of the air source heat pump unit, the method further comprises: at T _wo <T _wo7 Under the condition, the processor controls the air source heat pump unit to exit the defrosting operation. Wherein, T _wo7 According to T _wo4 、T _wo8 And T _wo9 Determination of T _wo7 Is a seventh effluent temperature threshold, T _wo8 Is the eighth outlet water temperature threshold value, T _wo9 Is the ninth effluent temperature threshold. Under the condition that the water outlet temperature of the first heat exchanger is lower than a certain temperature, the probability of icing of water in the first heat exchanger is increased, and the air source heat pump unit is controlled to quit 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. And a plurality of methods are adopted to carry out anti-freezing protection on the first heat exchanger together, so that the frost cracking probability of the first heat exchanger is greatly reduced, and the occurrence of the frost cracking phenomenon is reduced.

Optionally, according to T _wo4 、T _wo8 And T _wo9 Determination of T _wo7 The method comprises the following steps: t is _wo7 ＝max(T _wo4 -T _wo8 ，T _wo9 ). Wherein, T _wo4 -T _wo8 Is an expression mode of the drop amplitude of the outlet water temperature of the first heat exchanger, T _wo9 Is the lower limit value of the outlet water temperature of the first heat exchanger. T is _wo8 The value range of (A) is [10 ℃,15℃ ]]. Alternatively, T _wo8 At 10 ℃, 12 ℃ or 15 ℃. T is _wo9 The value range of (C) is [5 ℃,10℃ ]]. Alternatively, T _wo9 At 5 deg.C, 8 deg.C or 10 deg.C. Wherein, T _wo4 -T _wo8 Mainly aiming at the condition of quitting the defrosting operation set when the air source heat pump unit enters the defrosting operation according to the first condition, if the defrosting operation is carried out due to insufficient water flow or low-pressure saturationThe temperature of the outlet water of the first heat exchanger caused by factors such as too low temperature is reduced too fast, and the risk of frost cracking of the first heat exchanger is large. T is _wo9 Mainly aiming at the condition that the air source heat pump unit enters defrosting operation according to the second condition and is set to exit the defrosting operation, 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 frost crack probability of the first heat exchanger is reduced by taking the falling amplitude of the outlet water temperature and the lower limit value of the outlet water temperature as the condition for quitting the defrosting operation. Thus, the occurrence of the frost crack phenomenon of the first heat exchanger is reduced. E.g. at T _wo4 At 25 ℃ and T _wo8 At 12 ℃ and T _wo9 At 10 ℃ when T is _wo7 = max (25 ℃ -12 ℃,10 ℃) =13 ℃. At T _wo4 At 21 ℃ and T _wo8 At 15 ℃ and T _wo9 At 8 ℃ when T is _wo7 ＝max(21℃-15℃，8℃)＝8℃。

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 of the compressor _s . Processor determination and P _s Corresponding low pressure saturation temperature P _s-t . At P _s-t <P _s-t1 In this case, the processor controls the operation of the compressor to adjust the water temperature of the first heat exchanger. Wherein, P _s-t1 Is a first low pressure saturation temperature threshold. P _s-t1 The value range of (C) is (-5 ℃ and (-3 ℃). Alternatively, P _s-t1 At-4.5 deg.C, -4 deg.C or-3.5 deg.C. Under the condition of defrosting operation of the air source heat pump unit, the pressure of an air inlet of a 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 lower 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 a 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 protected from freezing by adopting a plurality of methods, thereby greatly reducing the probability of freezing crack of the first heat exchanger and reducing the occurrence of freezing crack。

Optionally, at P _s-t <P _s-t1 The processor controls operation of the compressor, including: at P _s-t1 >P _s-t ≥P _s-t2 The processor prohibits the operating frequency of the compressor from increasing. At P _s-t2 >P _s-t ≥P _s-t3 The processor reduces the operating frequency of the compressor. At 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, P _s-t3 Is a third low pressure saturation temperature threshold. P _s-t1 >P _s-t2 >P _s-t3 。T _C1 The value range of (0 s, 60s). Alternatively, T _C1 Is 5s, 20s, 35s or 50s. The setting duration can avoid the short-time low-pressure saturation temperature from being too low to cause frequent shutdown, so that the air source heat pump unit is more stable in operation. P is _s-t1 The value range of (C) is (-5 ℃ and (-3 ℃), P _s-t2 The value range of (C) is (-7 deg.C, -5 deg.C), P _s-t3 The value range of (C) is (-10 deg.C, -6 deg.C). Alternatively, P _s-t1 At-4.5 ℃ and P _s-t2 At-6 ℃ P _s-t3 Is-8 ℃. Or, P _s-t1 At-3.5 ℃ P _s-t2 At-5 ℃ P _s-t3 Is-7 ℃. Or, P _s-t1 At-4.5 ℃ and P _s-t2 At-6.5 ℃ P _s-t3 Is-9 ℃. Since the higher the compressor operating frequency, the lower the inlet pressure of the compressor, the lower the corresponding low pressure saturation temperature. In the case where the low pressure saturation temperature is in a different temperature zone, the inlet pressure of the compressor may be controlled by prohibiting the operating 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 defrosting operation of the air source heat pump unit, the processor detects the water inlet temperature T of the first heat exchanger _wi . Processor calculating Δ T _w ＝T _wi -T _wo Obtaining the temperature difference delta T between the inlet water temperature and the outlet water temperature of the first heat exchanger _w . At Δ T _w >△T _{Cooling by cooling} And the duration reaches a fourth duration T _C4 And under the condition of (4), the processor shuts down the air source heat pump unit. Wherein, delta T _Cold Is a first flow rate delta t threshold. T is a unit of _C4 The value range of (0min, 5min)]. Alternatively, T _C4 Is 1min, 3min or 5min. The air source heat pump unit operates in a refrigerating mode, and under the condition that the refrigerating capacity is certain, the temperature difference between the inlet water temperature and the outlet water temperature of water with different flow rates flowing through the first heat exchanger is different. The smaller the water flow, the greater the temperature difference between the inlet water temperature and the outlet water temperature. The water flow can be judged by judging the actual temperature difference between the inlet water and the outlet water and the corresponding first flow 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 temperature difference threshold value and lasts for a certain time, the water flow at the moment can be determined to be low. And the air source heat pump unit is shut down under the condition of low water flow, so that the anti-freezing protection of the first heat exchanger is realized. Meanwhile, the temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger is large due to short-term low water flow, and frequent shutdown caused by short-term low water flow is avoided due to the set duration. Therefore, frequent shutdown is reduced, and the operation of the air source heat pump unit is more stable. Meanwhile, the air source heat pump unit does not need to be provided with a flowmeter independently, and the cost is reduced. The first heat exchanger is protected from freezing by adopting a plurality of methods, so that the probability of freezing crack of the first heat exchanger is greatly reduced, and the occurrence of the freezing crack phenomenon is reduced.

Alternatively, Δ T _Cold According to the operating frequency of the compressor. According to experimental verification, under the condition that the air source heat pump unit is in defrosting operation, the temperature difference of inlet and outlet water of the first heat exchanger is related to the operation frequency of the compressor. Thus, under the condition that the running frequency of the compressor is constant, the temperature difference between the water temperature after passing through the first heat exchanger and the water temperature after passing through the first heat exchanger is different. Thus, Δ T may be determined by the operating frequency of the compressor _Cold . By real-time compressor operationFrequency determination Δ T _Cold And the water flow can be judged more accurately. Therefore, the control on the air source heat pump unit is more accurate, and the anti-freezing effect is better.

Optionally, Δ T is determined from the operating frequency of the compressor _{Cooling by cooling} The method comprises the following steps: the processor obtains the current operating frequency f of the compressor. Processor according to DeltaT _Cold Determining the corresponding delta T of the current operating frequency f of the compressor according to the corresponding relation of the operating frequency f of the compressor _Cold . Under the condition that the water flow 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 to stop the unit and restart the unit after the water temperature is reduced, so that the unit is frequently switched on and off. Under the condition that the water flow in the first heat exchanger of the air source heat pump unit is overlarge, the water temperature in the water circulation cannot reach the set temperature for a long time, and the user experience is poor. Therefore, the air source heat pump unit can set a normal running water flow range according to the refrigerating capacity. Delta T _Cold The corresponding relation with the running frequency f of the compressor is that the temperature difference delta T between the corresponding inlet water temperature and the outlet water temperature is measured according to the running frequencies of a plurality of different compressors on the basis of ensuring the lower limit of the normal running water flow range of the air source heat pump unit _Cold And then, obtaining a corresponding fitting formula according to the multiple groups of data. Delta T _Cold ＝12.5×(f/Q ₃ ). Wherein Q is ₃ Are the correction values of the fitting formula. Q ₃ Has a value range of [75, 85 ]]. Alternatively, Q ₃ 75, 80 or 85. Different series of products have different fitting formulas due to the influence of the performance of the compressor or the structure of the product and the like. Thus, passing Q ₃ The formula is corrected, 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 condition of defrosting operation of the air source heat pump unit includes: the refrigerant circulation loop performs refrigeration operation, and the operation time of the circulating water pump reaches a first operation time T _Y1 The case (1). T is _Y1 The value range of (0min, 3min)]. Alternatively, T _Y1 Is 1min, 2min or 3min. When the running time of the circulating water pump reaches the first running timeT _Y1 And then, 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. Therefore, the shutdown caused by unstable water flow in the first heat exchanger when the air source heat pump unit is started is effectively avoided, and the operation of the air source heat pump unit is more stable.

Optionally, after the processor shuts down the air source heat pump unit, the method further comprises: at m<In the case of M, a second waiting period T is spaced _D2 And the post-processor starts the air source heat pump unit again to operate. Under the condition that M is larger than or equal to M, the processor performs processing according to a second constraint duration T _S2 Number of internal stops m ₁ And controlling the start and stop of the air source heat pump unit. Wherein M is the accumulated low water flow shutdown times of the air source heat pump unit, and M is a second constraint duration T _S2 The maximum number of shutdowns allowed. T is a unit of _D2 The value range of (0min, 10min)]. Alternatively, T _D2 Is 2min, 5min, 8min or 10min. T is a unit of _S2 The value range of (0h, 2h)]. Alternatively, T _S2 Is 0.5h, 1h or 2h. The value range of M is [1,5 ]]And M is a positive integer. Alternatively, M is 1, 3 or 5. After the machine is shut down, in order to prevent the accidental phenomenon that the water flow in the first heat exchanger is low from influencing 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 more reliably controlled.

Optionally, the processor is arranged to restrict the duration T according to a second constraint _S2 Number of internal stops m ₁ Control air source heat pump set's opening and stopping includes: at m ₁ And under the condition of being more than or equal to M, the processor keeps the shutdown state of the air source heat pump unit. At m ₁ <In the case of M, a second waiting period T is spaced _D2 And the post processor starts the air source heat pump unit again to operate. If the air source heat pump unit is frequently stopped within the constraint duration, faults or other conditions may exist at present, and the air source heat pump unit needs to be protected by keeping the stopped state and not restarting any more. For example, in the case that the water flow 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 frost-cracked. By adopting the control mode of stopping the machine, the machine can be effectively usedThe frost crack probability of the first heat exchanger is reduced, and the occurrence of the frost crack phenomenon is reduced.

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

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

s201, in the condition of air source heat pump unit refrigerating operation, a processor detects air inlet pressure P of a compressor _s 。

S202, the processor determines and P _s Corresponding low pressure saturation temperature P _s-t 。

S203 at P _s-t <P _s-t1 In this case, the processor controls the operation of the compressor to adjust the water temperature of the first heat exchanger. Wherein, P _s-t1 Is a first low pressure saturation temperature threshold. P is _s-t1 The value range of (C) is (-5 ℃ and (-3 ℃). Alternatively, P _s-t1 At-4.5 deg.C, -4 deg.C or-3.5 deg.C.

In the embodiment of the disclosure, under the condition of refrigeration operation of the air source heat pump unit, the pressure of an air inlet 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 lower low pressure saturation temperature. If the low pressure saturation temperature is below a certain value, the chance of the water in the first heat exchanger freezing 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 a condition of too low temperature for a long time, and the anti-freezing protection of the first heat exchanger is realized. Compared with the prior art, the embodiment of the disclosure does not need to adjust the electronic expansion valve, thereby reducing the complexity of the control process and improving the reliability of the scheme.

Optionally, at P _s-t <P _s-t1 The processor controls operation of the compressor, including: at P _s-t1 >P _s-t ≥P _s-t2 In case of (2), the processor inhibits the pressingThe operating frequency of the compressor increases. At P _s-t2 >P _s-t ≥P _s-t3 In case of (2), the processor reduces the operating frequency of the compressor. At 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, P _s-t3 Is a third low pressure saturation temperature threshold. P _s-t1 >P _s-t2 >P _s-t3 。T _C1 The value range of (0 s, 60s). Alternatively, T _C1 Is 5s, 20s, 35s or 50s. The duration is set, so that frequent shutdown caused by too low short low-pressure saturation temperature can be avoided, and the air source heat pump unit is more stable in operation. P _s-t1 The value range of (C) is (-5 ℃ and (-3 ℃), P _s-t2 The value range of (1) is (-7 deg.C, -5 deg.C), P _s-t3 The value range of (C) is (-10 deg.C, -6 deg.C). Alternatively, P _s-t1 At-4.5 ℃ and P _s-t2 At a temperature of-6 ℃ P _s-t3 Is-8 ℃. Or, P _s-t1 At-3.5 ℃ P _s-t2 At a temperature of-5 ℃ P _s-t3 Is-7 ℃. Or, P _s-t1 At-4.5 ℃ and P _s-t2 At-6.5 ℃ and P _s-t3 Is-9 ℃. 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 a different temperature zone, the inlet pressure of the compressor may be controlled by prohibiting the operating frequency of the compressor from increasing or decreasing the operating frequency of the compressor 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 that the air source heat pump unit is in heating operation, the processor detects the water inlet temperature T of the first heat exchanger _wi And the temperature T of the outlet water _wo . Processor calculating Δ T _w ＝T _wo -T _wi Obtaining the temperature difference delta T between the inlet water temperature and the outlet water temperature of the first heat exchanger _w . At Δ T _w >△T _{Heat generation} And the duration reaches a seventh duration T _C7 And under the condition of (4), the processor shuts down the air source heat pump unit. Wherein, delta T _{Heat generation} Is a second flow rate temperature difference threshold. T is _C7 The value range of (0min, 5min)]. Alternatively, T _C7 Is 1min, 3min or 5min. The air source heat pump unit heats operation and under the certain circumstances of the heating capacity, the temperature difference of temperature of the water that flows through behind the first heat exchanger and leaving water temperature of different flow is different. The smaller the water flow, the greater the temperature difference between the inlet water temperature and the outlet water temperature. The water flow can be judged by judging the actual temperature difference between the inlet water and the outlet water and the corresponding second flow temperature difference threshold value. If the temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger is larger than the second flow temperature difference threshold value and lasts for a certain time, the water flow 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, the temperature of water in the first heat exchanger is easily reduced and the water is frozen to cause frost cracking of the first heat exchanger. And the air source heat pump unit is shut down under the condition of low water flow, so that the anti-freezing protection of the first heat exchanger is realized. Meanwhile, the temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger is large due to short-term low water flow, and frequent shutdown caused by short-term low water flow is avoided due to the set duration. Therefore, frequent shutdown is reduced, and the operation of the air source heat pump unit is more stable. Meanwhile, the air source heat pump unit does not need to be provided with a flowmeter independently, and the cost is reduced. And a plurality of methods are adopted to carry out anti-freezing protection on the first heat exchanger together, so that the frost cracking probability of the first heat exchanger is greatly reduced, and the occurrence of the frost cracking phenomenon is reduced.

Alternatively, Δ T _{Heat generation} According to the operating frequency of the compressor and the outdoor ambient temperature. According to experimental verification, under the condition that the air source heat pump unit is in heating operation, the temperature difference of inlet and outlet water 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 running frequency of the compressor and the outdoor environment temperature are constant, the temperature difference between the water temperature after the water passes through the first heat exchanger and the water temperature after the water passes through the first heat exchanger is different. Thus, Δ T may be determined by the operating frequency of the compressor and the outdoor ambient temperature _{Heat generation} . Determining DeltaT by real-time compressor operating frequency and outdoor ambient temperature _{Heat generation} And the water flow can be judged more accurately. Therefore, the control on the air source heat pump unit is more accurate, and the anti-freezing effect is better.

Optionally, Δ T is determined according to the operating frequency of the compressor and the outdoor ambient temperature _{Heat generation} The method comprises the following steps: the processor obtains the current running frequency f of the compressor and the outdoor environment temperature T _ao . Processor according to DeltaT _{Heat generation} Determining the current running frequency f and the outdoor environment temperature T of the compressor according to the corresponding relation between the running frequency and the outdoor environment temperature of the compressor _ao Corresponding delta T _{Heat generation} . Under the condition that the water flow 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 to stop the unit and restart the unit after the water temperature is reduced, so that the unit is frequently switched on and off. Under the condition that the water flow in the first heat exchanger of the air source heat pump unit is overlarge, the water temperature in the water circulation cannot reach the set temperature for a long time, and the user experience is poor. Therefore, the air source heat pump unit can set a normal operation water flow range according to the heating capacity. Delta T _{Heat generation} The corresponding relation between the running frequency of the compressor and the outdoor environment temperature is that on the basis of ensuring the lower limit of the normal running water flow range of the air source heat pump unit, the temperature difference delta T between the corresponding inlet water temperature and outlet water temperature is measured according to the running frequency and the outdoor environment temperature of a plurality of different compressors _{Heat generation} And then, obtaining a corresponding fitting formula according to the multiple groups of data. At T _ao At a temperature of not less than 21 DEG C _{Heat generation} ＝20×(f/Q ₁ ). At T _ao <At 21 ℃ and. DELTA.T _{Heat generation} ＝2×(0.25×(T _ao +12)+5)×(f/Q ₂ ). Wherein Q is ₁ 、Q ₂ Are the correction values of the fitting formula. Q ₁ Has a value range of [40, 60 ]]，Q ₂ Has a value range of [75, 85 ]]. Alternatively, Q ₁ 40, 50 or 60. Alternatively, Q ₂ 75, 80 or 85. Different series of products have different fitting formulas due to the influence of the performance of the compressor or the structure of the product and the like. Thus, passing Q ₁ 、Q ₂ By correcting the formula, calibration can be obtainedA threshold for a determined flow temperature difference. Therefore, the control of the air source heat pump unit can be more accurate, and the anti-freezing effect is better.

Optionally, the condition of the air source heat pump unit heating operation includes: the refrigerant circulation loop heats and operates, and the operation time of the circulating water pump reaches a second operation time T _Y2 The case (1). T is _Y2 The value range of (0min, 3min)]. Alternatively, T _Y2 Is 1min, 2min or 3min. When the running time of the circulating water pump reaches the second running time T _Y2 And then, 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. Therefore, the shutdown caused by unstable water flow in the first heat exchanger when the air source heat pump unit is started is effectively avoided, and the operation of the air source heat pump unit is more stable.

Optionally, after the processor shuts down the air source heat pump unit, the method further comprises: at i<In the case of I, at interval of third waiting time T _D3 And the post-processor starts the air source heat pump unit again to operate. Under the condition that I is larger than or equal to I, the processor is used for limiting the time length T according to the third constraint _S3 Number of internal shutdowns i ₁ And controlling the start and stop of the air source heat pump unit. Wherein I is the accumulated low water flow shutdown frequency of the air source heat pump unit, and I is the third constraint duration T _S3 Maximum number of shutdowns allowed in. T is a unit of _D3 The value range of (0min, 10min)]. Alternatively, T _D3 Is 2min, 5min, 8min or 10min. T is _S3 The value range of (0h, 2h)]. Alternatively, T _S3 Is 0.5h, 1h or 2h. The value range of I is [1,5 ]]And I is a positive integer. Alternatively, I is 1, 3 or 5. After the machine is shut down, in order to prevent the accidental phenomenon that the water flow in the first heat exchanger is low from influencing 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 more reliably controlled.

Optionally, the processor is arranged to determine the duration T according to a third constraint _S3 Number of internal shutdowns i ₁ Control air source heat pump set's opening and stopping includes: at i ₁ And the processor keeps the shutdown state of the air source heat pump unit under the condition that the temperature is more than or equal to I. At i ₁ <In the case of I, at interval of a third waiting time T _D3 And the post processor starts the air source heat pump unit again to operate. If the air source heat pump unit is frequently stopped during the constraint duration, faults or other situations may exist at present, and the air source heat pump unit needs to be protected by keeping the stopped state and not restarting. Therefore, the air source heat pump unit can operate more reliably.

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 of the first heat exchanger _wo And inlet water temperature T _wi . At T _wi ≤T _wi1 And the duration reaches the second duration T _C2 And (4) under the condition that the processor shuts down the air source heat pump unit. Or, at T _wo ≤T _wo1 And the duration reaches a third duration T _C3 And under the condition of (4), the processor shuts down the air source heat pump unit. Wherein, T _wi1 Is a first inlet water temperature threshold, T _wo1 Is the first effluent temperature threshold. T is _wi1 The value range of (A) is [3 ℃,5 DEG C]. Alternatively, T _wi1 At 3 ℃,4 ℃ or 5 ℃. T is a unit of _wo1 The value range of (A) is [3 ℃,5 DEG C]. Alternatively, T _wo1 At 3 ℃,4 ℃ or 5 ℃. T is a unit of _C2 The value range of (A) is [0min,2min]. Alternatively, T _C2 Is 0min, 1min or 2min. T is _C3 The value range of [0min,2min]. Alternatively, T _C3 Is 0min, 1min or 2min. In the case of air source heat pump unit cooling operation, the first heat exchanger temperature may decrease. In the case where the temperature of the refrigerant in the first heat exchanger is relatively low (below zero degrees), then if the temperature of the water in the first heat exchanger is also relatively low, the probability of freezing of the water in the first heat exchanger increases. Under the condition that the water inlet temperature or the water outlet temperature of the first heat exchanger is lower than a certain temperature and lasts for a period of time, the air source heat pump unit is shut down, and icing caused by over-low water temperature of the first heat exchanger is avoided. Thus, the first heat exchanger is protected from freezing. Meanwhile, the setting of the duration avoids the frequent shutdown of the air source heat pump unit caused by the short-time low temperature of the inlet and outlet water. Therefore, frequent shutdown is reduced, and the operation of the air source heat pump unit is more stable. By a plurality of methodsThe first heat exchanger is protected from freezing jointly, 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.

Referring to fig. 5, another method for preventing freezing of an air source heat pump unit is provided in an embodiment of the present disclosure, including:

s301, starting the air source heat pump unit to perform refrigeration operation.

S302, the processor detects the air inlet pressure P of the compressor _s 。

S303, the processor determines and P _s Corresponding low pressure saturation temperature P _s-t 。

S304, the processor judges whether P is satisfied _s-t <P _s-t1 . If yes, go to step S305. Otherwise, the step S304 is executed back. Wherein, P _s-t1 Is a first low pressure saturation temperature threshold.

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

S306, the processor detects the outlet water temperature T of the first heat exchanger _wo And inlet water temperature T _wi 。

S307, the processor judges whether T is satisfied _wi ≤T _wi1 And the duration reaches the second duration T _C2 . If yes, go to step S309. Otherwise, the process returns to step S307.

S308, the processor judges whether T is satisfied _wo ≤T _wo1 And the duration reaches a 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 is prevented from being in a condition of too low temperature for a long time, and the anti-freezing protection of the first heat exchanger is realized. Compared with the prior art, the embodiment of the disclosure does not need to adjust the electronic expansion valve, thereby reducing the complexity of the control process and improving the reliability of the scheme. Meanwhile, the air source heat pump unit is controlled to be shut down by judging the water inlet and outlet temperature of the first heat exchanger, so that icing caused by too low water temperature of the first heat exchanger is avoided. Thereby, the freeze protection of the first heat exchanger is realized. The setting of the duration avoids the frequent shutdown of the air source heat pump unit caused by the short-time low temperature of inlet and outlet water. Therefore, frequent shutdown is reduced, and the operation of the air source heat pump unit is more stable. The first heat exchanger is protected from freezing by adopting a plurality of methods, so that the probability of freezing crack of the first heat exchanger is greatly reduced, and the occurrence of the freezing crack phenomenon is reduced.

Optionally, after the processor shuts down the air source heat pump unit, the method further comprises: at n<N, at a first waiting time T _D1 And the post-processor starts the air source heat pump unit again to operate. Under the condition that N is larger than or equal to N, the processor is used for limiting the time length T according to the first constraint time length _S1 Number of internal stops n ₁ And controlling the start and stop of the air source heat pump unit. Wherein N is the accumulated low-temperature shutdown frequency of the air source heat pump unit, and N is the first constraint duration T _S1 The maximum number of shutdowns allowed. T is _D1 The value range of (1) is [8min,15min]. Alternatively, T _D1 Is 8min, 10min, 12min or 15min. T is a unit of _S1 Has a value 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. Optionally, N is 1, 3 or 5. After the machine is shut down, in order to prevent the accidental phenomenon that the water temperature in the first heat exchanger is low from influencing 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 more reliably controlled.

Optionally according to a first constraint duration T _S1 Number of internal stops n ₁ Control air source heat pump set's start-stop includes: at n ₁ And under the condition that the temperature is more than or equal to N, the processor keeps the shutdown state of the air source heat pump unit. At n ₁ <N, at a first waiting time T _D1 And the post-processor starts the air source heat pump unit again to operate. If the air source heat pump unit is frequently stopped in the constraint duration, faults or others may exist at presentIn some cases, the air source heat pump unit needs to be protected by keeping the shutdown state and not restarting. For example, in the case where the heating operation is required in winter, the user misoperates as the cooling operation. Because the water temperature is lower in winter, if refrigeration is carried out again at the moment, water in the first heat exchanger is easy to freeze to cause frost crack of the first heat exchanger. By adopting the shutdown control mode, the frost crack probability of the first heat exchanger can be effectively reduced, and the occurrence of the frost crack phenomenon is reduced.

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

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

s401, under the condition of air source heat pump unit refrigerating operation, the processor detects the outlet water temperature T of the first heat exchanger _wo And inlet water temperature T _wi 。

S402, at T _wi ≤T _wi1 And the duration reaches the second duration T _C2 And under the condition of (4), the processor shuts down the air source heat pump unit.

S403, at T _wo ≤T _wo1 And the duration reaches a third duration T _C3 And under the condition of (4), the processor shuts down the air source heat pump unit.

Wherein, T _wi1 Is a first inlet water temperature threshold, T _wo1 Is the first outlet water temperature threshold. T is _wi1 The value range of (A) is [3 ℃,5 DEG C]. Alternatively, T _wi1 At 3 ℃,4 ℃ or 5 ℃. T is _wo1 The value range of (A) is [3 ℃,5℃ ]]. Alternatively, T _wo1 At 3 ℃,4 ℃ or 5 ℃. T is _C2 The value range of (A) is [0min,2min]. Alternatively, T _C2 Is 0min, 1min or 2min. T is a unit of _C3 The value range of (A) is [0min,2min]. Alternatively, T _C3 Is 0min, 1min or 2min.

In the embodiment of the disclosure, in the case of the air source heat pump unit performing cooling operation, the temperature of the first heat exchanger may decrease. In the case where the temperature of the refrigerant in the first heat exchanger is relatively low (below zero degrees), then if the temperature of the water in the first heat exchanger is also relatively low, the probability of freezing of the water in the first heat exchanger increases. Under the condition that the water inlet temperature or the water outlet temperature of the first heat exchanger is lower than a certain temperature and continues for a period of time, the air source heat pump unit is shut down, and icing caused by too low water temperature of the first heat exchanger is avoided. Thus, the first heat exchanger is protected from freezing. Meanwhile, the setting of the duration avoids the frequent shutdown of the air source heat pump unit caused by the short-time low temperature of the inlet and outlet water. Therefore, frequent shutdown is reduced, and the operation of the air source heat pump unit is more stable.

Referring to fig. 7, another method for preventing freezing of an air source heat pump unit is provided in the embodiments of the present disclosure, including:

s501, starting refrigeration operation by the air source heat pump unit.

S502, the processor detects the outlet water temperature T of the first heat exchanger _wo And inlet water temperature T _wi 。

S503, the processor judges whether T is satisfied _wi ≤T _wi1 And the duration reaches the second duration T _C2 . If yes, go to step S505. Otherwise, the process returns to step S503.

S504, the processor judges whether T is satisfied _wo ≤T _wo1 And the duration reaches a third duration T _C3 . If yes, go to step S505. Otherwise, the step S504 is executed back.

And 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, spacing a first waiting time length T _D1 And the post-processor starts the air source heat pump unit again to operate.

S508, the processor is used for limiting the duration T according to the first constraint duration _S1 Number of internal stops n ₁ And controlling the start and stop of the air source heat pump unit.

In the embodiment of the disclosure, under the condition of the air source heat pump unit in the cooling operation, the temperature of the first heat exchanger is reduced. In the case of a relatively low (below zero) refrigerant temperature in the first heat exchanger, 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 and continues for a period of time, the air source heat pump unit is shut down, and icing caused by too low water temperature of the first heat exchanger is avoided. Thus, the first heat exchanger is protected from freezing. Meanwhile, the setting of the duration avoids frequent shutdown of the air source heat pump unit caused by short-time low water inlet and outlet temperature. Therefore, frequent shutdown is reduced, and the operation of the air source heat pump unit is more stable. After the machine is shut down, in order to prevent the accidental phenomenon that the water temperature in the first heat exchanger is low from influencing 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 more reliably controlled.

Optionally, the method further comprises: processor calculating Δ T _w ＝T _wi -T _wo Obtaining the temperature difference delta T between the inlet water temperature and the outlet water temperature of the first heat exchanger _w . At Δ T _w >△T _{Cooling by cooling} And the duration reaches a fourth duration T _C4 And (4) under the condition that the processor shuts down the air source heat pump unit. Wherein, Δ T _{Cooling by cooling} Is a first flow rate differential temperature threshold. T is a unit of _C4 The value range of (0min, 5min)]. Alternatively, T _C4 Is 1min, 3min or 5min. The air source heat pump unit operates in a refrigerating mode, and under the condition that the refrigerating capacity is certain, the temperature difference between the inlet water temperature and the outlet water temperature of water with different flow rates flowing through the first heat exchanger is different. The smaller the water flow is, the larger the temperature difference between the inlet water temperature and the outlet water temperature is. The water flow can be judged by judging the actual temperature difference between the inlet water and the outlet water and the corresponding first flow temperature difference threshold value. If the temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger is larger than the first flow temperature difference threshold value and lasts for a certain time, the water flow at the moment can be determined to be low. The air source heat pump unit is shut down and controlled under the condition of low water flow, so that the first heat exchange is realizedAnd 4, anti-freezing protection of the device. Meanwhile, the temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger is large due to the short-term low water flow, and frequent shutdown caused by the short-term low water flow is avoided due to the set duration. Therefore, frequent shutdown is reduced, and the operation of the air source heat pump unit is more stable. Meanwhile, the air source heat pump unit does not need to be provided with a flowmeter independently, and the cost is reduced. And a plurality of methods are adopted to carry out anti-freezing protection on the first heat exchanger together, so that the frost cracking probability of the first heat exchanger is greatly reduced, and the occurrence of the frost cracking phenomenon is reduced.

Alternatively, Δ T _{Cooling by cooling} According to the operating frequency of the compressor. According to experimental verification, under the condition of refrigerating operation of the air source heat pump unit, the temperature difference of inlet and outlet water of the first heat exchanger is related to the operation frequency of the compressor. Thus, under the condition that the running frequency of the compressor is constant, the temperature difference between the water temperature after passing through the first heat exchanger and the water temperature after passing through the first heat exchanger is different. Thus, Δ T may be determined by the operating frequency of the compressor _{Cooling by cooling} . Determining DeltaT by real-time compressor operating frequency _Cold And the water flow can be judged more accurately. Therefore, the control on the air source heat pump unit is more accurate, and the anti-freezing effect is better.

Optionally, Δ T is determined from the operating frequency of the compressor _Cold The method comprises the following steps: the processor obtains the current operating frequency f of the compressor. Processor based on Δ T _Cold Corresponding relation with the operation frequency f of the compressor, and determining the delta T corresponding to the operation frequency f of the current compressor _Cold . Under the condition that the water flow 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 to stop the unit and restart the unit after the water temperature is reduced, so that the unit is frequently switched on and off. Under the condition that the water flow in the first heat exchanger of the air source heat pump unit is overlarge, the water temperature in the water circulation cannot reach the set temperature for a long time, and the user experience is poor. Therefore, the air source heat pump unit can set a normal operation water flow range according to the refrigerating capacity. Delta T _{Cooling by cooling} The corresponding relation with the running frequency f of the compressor is the basis for ensuring the lower limit of the normal running water flow range of the air source heat pump unitAccording to the operation frequencies of a plurality of different compressors, the temperature difference Delta T between the corresponding inlet water temperature and the outlet water temperature is measured _{Cooling by cooling} And then obtaining a corresponding fitting formula according to the multiple groups of data. Delta T _{Cooling by cooling} ＝12.5×(f/Q ₃ ). Wherein Q ₃ Are the correction values of the fitting formula. Q ₃ Has a value range of [75, 85 ]]. Alternatively, Q ₃ 75, 80 or 85. Different series of products have different fitting formulas due to the influence of the performance of the compressor or the structure of the product and the like. Thus, passing Q ₃ The formula is corrected, so that 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 case of air source heat pump unit cooling operation includes: the refrigerant circulation loop performs refrigeration operation, and the operation time of the circulating water pump reaches a first operation time T _Y1 In the case of (c). T is _Y1 The value range of (0min, 3min)]. Alternatively, T _Y1 Is 1min, 2min or 3min. When the running time of the circulating water pump reaches the first running time T _Y1 And then, 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. Therefore, the shutdown of the air source heat pump unit caused by unstable water flow in the first heat exchanger when the air source heat pump unit is started is effectively avoided, and the air source heat pump unit is more stable in operation.

Optionally, after the processor shuts down the air source heat pump unit, the method further comprises: at m<In the case of M, a second waiting period T is spaced _D2 And the post-processor starts the air source heat pump unit again to operate. Under the condition that M is larger than or equal to M, the processor performs processing according to a second constraint duration T _S2 Number of internal stops m ₁ And controlling the start and stop of the air source heat pump unit. Wherein M is the accumulated low water flow shutdown times of the air source heat pump unit, and M is a second constraint duration T _S2 Maximum number of shutdowns allowed in. T is _D2 The value range of (0min, 10min)]. Alternatively, T _D2 Is 2min, 5min, 8min or 10min. T is _S2 The value range of (0h, 2h)]. Alternatively, T _S2 Is 0.5h, 1h or 2h. The value range of M is [1,5 ]]M isA positive integer. Alternatively, M is 1, 3 or 5. After the machine is shut down, in order to prevent the accidental phenomenon that the water flow in the first heat exchanger is low from influencing 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 more reliably controlled.

Optionally, the processor is arranged to restrict the duration T according to a second constraint _S2 Number of internal stops m ₁ Control air source heat pump set's start-stop includes: at m ₁ And under the condition of being more than or equal to M, the processor keeps the shutdown state of the air source heat pump unit. At m ₁ <In the case of M, a second waiting period T is spaced _D2 And the post-processor starts the air source heat pump unit again to operate. If the air source heat pump unit is frequently stopped within the constraint duration, faults or other conditions may exist at present, and the air source heat pump unit needs to be protected by keeping the stopped state and not restarting any more. 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, which causes frost crack of the first heat exchanger. By adopting the shutdown control mode, the frost crack probability of the first heat exchanger can be effectively reduced, and the occurrence of the frost crack phenomenon is reduced.

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

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

s601, under the condition of air source heat pump unit refrigerating operation, detecting the water inlet temperature T of a first heat exchanger by a processor _wi And the temperature T of the outlet water _wo 。

S602, the processor calculates Delta T _w ＝T _wi -T _wo Obtaining the temperature difference delta T between the inlet water temperature and the outlet water temperature of the first heat exchanger _w 。

S603, at Δ T _w >△T _{Cooling by cooling} And the duration reaches the fourth durationDuration T _C4 And (4) under the condition that the processor shuts down the air source heat pump unit. Wherein, Δ T _Cold Is a first flow rate differential temperature threshold. T is _C4 The value range of (0min, 5min)]. 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 the refrigeration capacity is certain, the temperature difference between the water temperature after water flows through the first heat exchanger and the water temperature after water flows through the first heat exchanger is different. The smaller the water flow, the greater the temperature difference between the inlet water temperature and the outlet water temperature. The water flow can be judged by judging the actual temperature difference between the inlet water and the outlet water and the corresponding first flow temperature difference threshold value. If the temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger is larger than the first flow temperature difference threshold value and lasts for a certain time, the water flow at the moment can be determined to be low. And the air source heat pump unit is shut down under the condition of low water flow, so that the anti-freezing protection of the first heat exchanger is realized. Meanwhile, the temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger is large due to the short-term low water flow, and frequent shutdown caused by the short-term low water flow is avoided due to the set duration. Therefore, frequent shutdown is reduced, and the operation of the air source heat pump unit is more stable. Meanwhile, the air source heat pump unit does not need to be provided with a flowmeter independently, and 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:

and S701, starting refrigeration operation by the air source heat pump unit.

S702, the processor detects the outlet water temperature T of the first heat exchanger _wo And inlet water temperature T _wi 。

S703, the processor calculates Delta T _w ＝T _wi -T _wo Obtaining the temperature difference delta T between the inlet water temperature and the outlet water temperature of the first heat exchanger _w 。

S704, the processor judges whether the delta T is satisfied _w >△T _Cold And the duration reaches a fourth duration T _C4 . If yes, go to step S705. Otherwise, the step S704 is executed back.

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

S706, the processor judges whether M < M is satisfied. If yes, go to step S707. Otherwise, step S708 is executed.

S707, spacing a second waiting time T _D2 And the post processor starts the air source heat pump unit again to operate.

S708, the processor is used for limiting the duration T according to the second constraint duration _S2 Number of internal stops m ₁ And controlling the start and stop of the air source heat pump unit.

In the embodiment of the disclosure, the water flow in the first heat exchanger is judged by comparing the temperature difference of the inlet water and the outlet water of the first heat exchanger with the flow temperature difference threshold, and the air source heat pump unit is controlled to be turned off under the condition of low water flow. Thereby, the freeze protection of the first heat exchanger is achieved. Meanwhile, the temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger is large due to short-term low water flow, and frequent shutdown caused by short-term low water flow is avoided due to the set duration. Therefore, frequent shutdown is reduced, and the air source heat pump unit is more stable in operation. After the machine is shut down, in order to prevent the accidental phenomenon that the water flow in the first heat exchanger is low from influencing 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 more reliably controlled.

Optionally, the processor is arranged to determine the duration T according to a second constraint _S2 Number of internal stops m ₁ Control air source heat pump set's start-stop includes: at m ₁ And under the condition of being more than or equal to M, the processor keeps the shutdown state of the air source heat pump unit. At m ₁ <In the case of M, a second waiting period T is spaced _D2 And the post-processor starts the air source heat pump unit again to operate. If the air source heat pump unit is frequently stopped within the constraint duration, faults or other conditions may exist at present, and the air source heat pump unit needs to be protected by keeping the stopped state and not restarting any more. For example, in the case that the water flow 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 frost-cracked. By adopting the control mode of stopping the machine, the machine canThe frost crack probability of the first heat exchanger is effectively reduced, and the occurrence of the frost crack phenomenon is reduced.

Optionally, the method further comprises: in the case of the air source heat pump unit cooling operation, the processor detects the air inlet pressure P of the compressor _s . Processor determination and P _s Corresponding low pressure saturation temperature P _s-t . At P _s-t <P _s-t1 In this case, the processor controls the operation of the compressor to adjust the water temperature of the first heat exchanger. Wherein, P _s-t1 Is a first low pressure saturation temperature threshold. P _s-t1 The value range of (C) is (-5 ℃ and (-3 ℃). Alternatively, P _s-t1 At-4.5 deg.C, -4 deg.C or-3.5 deg.C. Under the condition of refrigeration operation of the air source heat pump unit, the pressure of an air inlet 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 lower 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 a condition of too low temperature for a long time, and the anti-freezing protection of the first heat exchanger is realized. Compared with the prior art, the embodiment of the disclosure does not need to adjust the electronic expansion valve, thereby reducing the complexity of the control process and improving the reliability of the scheme. The first heat exchanger is protected from freezing by adopting a plurality of methods, so that the probability of freezing crack of the first heat exchanger is greatly reduced, and the occurrence of the freezing crack phenomenon is reduced.

The start and stop of the air source heat pump unit can be controlled according to the temperature difference between the inlet water and the outlet water of the first heat exchanger through the processor, so that the anti-freezing protection of the first heat exchanger is realized. And frequent shutdown of the air source heat pump unit can be reduced, so that the air source heat pump unit is more stable in operation.

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

s1001, under the condition that the air source heat pump unit is in heating operation, the processor detects the water inlet temperature T of the first heat exchanger _wi And the temperature T of the outlet water _wo 。

S1002, the processor calculates Delta T _w ＝T _wo -T _wi Obtaining the temperature difference delta T between the inlet water temperature and the outlet water temperature of the first heat exchanger _w 。

S1003 at DeltaT _w >△T _{Heat generation} And the duration reaches a seventh duration T _C7 And under the condition of (4), the processor shuts down the air source heat pump unit. Wherein, delta T _{Heat generation} Is a second flow rate temperature difference threshold. T is _C7 The value range of (0min, 5min)]. Alternatively, T _C7 Is 1min, 3min or 5min.

In the embodiment of the disclosure, the air source heat pump unit performs heating operation, and under the condition that the heating quantity is certain, the temperature difference between the water inlet temperature and the water outlet temperature of water with different flows after flowing through the first heat exchanger is different. The smaller the water flow, the greater the temperature difference between the inlet water temperature and the outlet water temperature. The water flow can be judged by judging the actual temperature difference between the inlet water and the outlet water and the corresponding second flow temperature difference threshold value. If the temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger is larger than the second flow temperature difference threshold value and lasts for a certain time, the water flow 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, the temperature of water in the first heat exchanger is easily reduced and the water is frozen to cause frost cracking of the first heat exchanger. And the air source heat pump unit is shut down under the condition of low water flow, so that the anti-freezing protection of the first heat exchanger is realized. Meanwhile, the temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger is large due to short-term low water flow, and frequent shutdown caused by short-term low water flow is avoided due to the set duration. Therefore, frequent shutdown is reduced, and the operation of the air source heat pump unit is more stable. The air source heat pump unit does not need to be separately provided with a flowmeter, so that the cost is reduced.

Referring to fig. 11, another method for preventing freezing of an air source heat pump unit is provided in the embodiments of the present disclosure, including:

s1101, starting heating operation by the air source heat pump unit.

S1102, processor detectionOutlet water temperature T of the first heat exchanger _wo And inlet water temperature T _wi 。

S1103, the processor calculates Δ T _w ＝T _wo -T _wi Obtaining the temperature difference delta T between the inlet water temperature and the outlet water temperature of the first heat exchanger _w 。

S1104, the processor judges whether or not Δ T is satisfied _w >△T _{Heat generation} And the duration reaches a seventh duration T _C7 . If yes, go to step S1105. Otherwise, the process returns to step S1104.

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

S1106, the processor judges whether I < I is satisfied. If yes, go to step S1107. Otherwise, step S1108 is performed.

S1107, with a third waiting period T _D3 And the post-processor starts the air source heat pump unit again to operate.

S1108, the processor according to the third constraint duration T _S3 Number of internal stops i ₁ And controlling the start and stop of the air source heat pump unit.

In the embodiment of the disclosure, under the condition that the air source heat pump unit is in heating operation, the water flow in the first heat exchanger is judged by comparing the temperature difference of the inlet water and the outlet water of 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, the temperature of water in the first heat exchanger is easily reduced and the water is frozen to cause frost cracking of the first heat exchanger. And the air source heat pump unit is shut down under the condition of low water flow, so that the anti-freezing protection of the first heat exchanger is realized. Meanwhile, the temperature difference between the inlet water temperature and the outlet water temperature of the first heat exchanger is large due to short-term low water flow, and frequent shutdown caused by short-term low water flow is avoided due to the set duration. Therefore, frequent shutdown is reduced, and the operation of the air source heat pump unit is more stable. Meanwhile, the air source heat pump unit does not need to be provided with a flowmeter independently, and the cost is reduced. After the machine is shut down, in order to prevent the accidental phenomenon that the water flow in the first heat exchanger is low from influencing 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 more reliably controlled.

In the actual operation process of the air source heat pump unit, another method for preventing the air source heat pump unit from being frozen is shown in fig. 12, and comprises the following steps:

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

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

S1203, it is determined whether a first condition for entering the defrosting operation is satisfied. If yes, go to step S1206. Otherwise, step S1204 is executed. Let T be _wo At 19 ℃ under the first condition of T _wo Not less than 20 ℃. At this time, step S1204 is executed. Let T be _wo At 22 ℃ under the first condition of T _wo More than or equal to 20 ℃. At this time, step S1206 is performed.

And S1204, starting the auxiliary electric heating device.

And S1205, judging whether a second condition for entering the defrosting operation is met. If yes, go to step S1206. Otherwise, return to execute step S1205. Suppose, an initial T _wo At 19 ℃ and the second condition is T _wo >22 ℃ and for 30s. After the auxiliary electric heating device is started for a period of time, T _wo And increasing the temperature to be above 22 ℃ for 30S, and executing step S1206.

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

S1207, judging whether T is satisfied _wo <T _wo2 . If yes, go to step S1209. Otherwise, step S1208 is performed. Let it be assumed that T _wo2 The temperature was 20 ℃. At this time, T _wo At 19 deg.c, step S1209 is performed.

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

S1209, the auxiliary electric heating device is started. Return to execute step S1208.

And S1210, closing the auxiliary electric heating device. Return is made to step S1207.

S1211, after the air source heat pump unit enters into defrosting operation, judging whether T is met _wo <max(T _wo4 -T _wo8 ，T _wo9 ). If yes, go to step S1212. Otherwise, the process returns to step S1211. Let T be _wo4 At 25 ℃ and T _wo8 At a temperature of 12 ℃ and T _wo9 Is 10 ℃. Then T _wo7 = max (25 ℃ -12 ℃,10 ℃) =13 ℃. Suppose T at this time _wo At 12 deg.c, step S1212 is executed.

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

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

S1214, calculating Delta T _w ＝T _wi -T _wo . Obtaining the temperature difference delta T between the inlet water temperature and the outlet water temperature of the first heat exchanger _w 。

S1215, judging whether delta T is satisfied _w >△T _Cold And the duration reaches a fourth duration T _C4 . If yes, go to step S1216. Otherwise, return to execute step S1215. Suppose that, at this time, Δ T calculated in the compressor operating state _Cold At 2 ℃ T _C4 Is 1min. Delta T _w >2 ℃ and the duration reaches 1min, step S1216 is executed.

And S1216, shutting down the air source heat pump unit.

Wherein, steps S1207 to S1210, steps S1211 to S1212, and steps S1213 to S1216 are performed in synchronization.

Referring to fig. 13, an apparatus for preventing freezing of an air source heat pump unit according to an embodiment of the present disclosure includes a processor (processor) 1300 and a memory (memory) 1301 storing program instructions. Optionally, the apparatus may also include a 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. Communication interface 1302 may be used for the transfer of information. The processor 1300 may invoke logic instructions in the memory 1301 to perform the method for air source heat pump unit freeze protection of the above embodiments.

In addition, the logic instructions in the memory 1301 may be implemented in the form of software functional units and stored in a computer readable storage medium when the logic instructions are sold or used as a separate product.

The memory 1301 is used as a storage medium to store software programs, computer executable programs, and program instructions/modules corresponding to the methods in the embodiments of the disclosure. The processor 1300 executes the program instructions/modules stored in the memory 1301 so as to execute functional applications and data processing, i.e., to implement the method for preventing freeze of the air source heat pump unit in the above embodiment.

The memory 1301 may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created according to the use of the terminal device, and the like. In addition, the memory 1301 can include high speed random access memory, as well as non-volatile 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 the air source heat pump unit from freezing. 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 used for detecting the pressure of the air inlet of the compressor 4. The water circulation circuit 2 includes a circulation water pump 3 and an auxiliary electric heating device 6. And the circulating water pump 3 is used for starting water circulation of the air source heat pump unit. The auxiliary electric heating device 6 is used to heat 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 outlet water temperature of the first heat exchanger 5. The processor in the device for preventing the air source heat pump unit from freezing is at least electrically connected with 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, and the program instructions are set to execute the method for preventing the air source heat pump unit from freezing.

The storage medium described above may be a transitory computer-readable storage medium or a non-transitory computer-readable storage medium. A non-transitory storage medium comprising: a U-disk, a portable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other media capable of storing program codes, and may also be a transient storage medium.

The above description and the drawings sufficiently illustrate embodiments of the disclosure to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. The examples merely typify 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. Furthermore, the words used in the specification are words of description only and are not intended to limit the claims. As used in the description of the embodiments and the claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Similarly, the term "and/or" as used in this application is meant to encompass any and all possible combinations of one or more of the associated listed. Furthermore, the terms "comprises" and/or "comprising," when used in this application, specify the presence of stated features, integers, steps, operations, elements, and/or components, 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 a" \8230; "does not exclude the presence of additional like elements in a process, method or apparatus comprising the element. In this document, each embodiment may be described with emphasis on differences from other embodiments, and the same and similar parts between the respective embodiments may be referred to each other. For methods, products, etc. of the embodiment disclosures, reference may be made to the description of the method section for relevance if it corresponds to the method section of the embodiment disclosure.

Those of skill in the art would 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 may depend upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the disclosed embodiments. It can be clearly understood by the skilled person that, for convenience and simplicity of description, the specific working processes of the system, the apparatus, and the unit described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to embodiments of the 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 disclosed in the description, and sometimes there is no specific order between the different operations or steps. For example, two sequential operations or steps may in fact be executed substantially concurrently, or they may sometimes be executed in the reverse order, depending upon the functionality involved. Each block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

Claims

1. A method for preventing an air source heat pump unit from freezing comprises the following steps: a water circulation loop comprising an auxiliary electrical heating device; and, a refrigerant circulation loop comprising a first heat exchanger; wherein, the first heat exchanger exchanges heat with the water circulation loop; the auxiliary electric heating device is used for heating the water flowing into the first heat exchanger; characterized in that the method comprises:

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

According to the temperature T of the outlet water _wo And controlling the operation of the auxiliary electric heating device to adjust the water temperature of the first heat exchanger.

2. The method of claim 1, wherein the temperature T is determined according to the leaving water temperature _wo Controlling operation of an auxiliary electric heating device, comprising:

at T _wo <T _wo2 In case of (2), turning on the auxiliary electric heating device;

at T _wo >T _wo3 In case (2), the auxiliary electric heating device is turned off;

wherein, T _wo2 Is the second outlet water temperature threshold, T _wo3 Is a third outlet water temperature threshold, T _wo3 >T _wo2 。

3. The method of claim 1 or 2, wherein the refrigerant circulation circuit further comprises a compressor, the method further comprising:

detecting the air inlet pressure P of the compressor under the condition that the air source heat pump unit enters the defrosting operation _s ；

Determining and P _s Corresponding low pressure saturation temperature P _s-t ；

At P _s-t <P _s-t1 In case of (2), controlling the operation of the compressor to adjust the water temperature of the first heat exchanger;

wherein, P _s-t1 Is a first low pressure saturation temperature threshold.

4. The method of claim 3, wherein P is the number of bits in the sequence _s-t <P _s-t1 Controlling the operation of the compressor, including:

at P _s-t1 >P _s-t ≥P _s-t2 Prohibiting the operating frequency of the compressor from increasing;

at P _s-t2 >P _s-t ≥P _s-t3 In the case of (2), reducing the operating frequency of the compressor;

at P _s-t <P _s-t3 And the duration reaches the first duration T _C1 Shutting down the compressor;

wherein, P _s-t2 Is the second low-pressure saturation temperature threshold, P _s-t3 Is a third low pressure saturation temperature threshold.

5. The method of claim 1 or 2, further comprising:

detecting the water inlet temperature T of the first heat exchanger under the condition that the air source heat pump unit enters into defrosting operation _wi ；

Calculating Δ T _w ＝T _wi -T _wo Obtaining the temperature difference delta T between the inlet water temperature and the outlet water temperature of the first heat exchanger _w ；

At Δ T _w >△T _Cold And the duration reaches a fourth duration T _C4 Under the condition of (1), the air source heat pump unit is shut down;

wherein, Δ T _Cold Is a first flow rate delta t threshold.

6. The method as claimed in claim 5, wherein the refrigerant circulation circuit further comprises a compressor, Δ T _Cold According to the operating frequency of the compressor.

7. Method according to claim 6, characterized in that Δ T is determined as a function of the operating frequency of the compressor _Cold The method comprises the following steps:

acquiring the operating frequency f of the current compressor;

according to Δ T _Cold Determining the corresponding delta T of the current operating frequency f of the compressor according to the corresponding relation of the operating frequency f of the compressor _Cold 。

8. An apparatus for air source heat pump unit freeze protection, comprising a processor and a memory having stored thereon program instructions, characterized in that the processor is configured, upon execution of the program instructions, to carry out the method for air source heat pump unit freeze protection as claimed in any one of claims 1 to 7.

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 pressure of the air inlet of the compressor; and the combination of (a) and (b),

the water circulation loop comprises a circulating water pump and an auxiliary electric heating device; the circulating water pump is used for starting 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, the first heat exchanger comprises a water inlet and a water outlet, and the water inlet and the water outlet are communicated with the water circulation loop; a first temperature sensor is arranged on the water circulation loop corresponding to the water inlet and used for detecting the water inlet temperature of the first heat exchanger; the water circulation loop corresponding to the water outlet is provided with a second temperature sensor used for detecting the outlet water temperature of the first heat exchanger;

its characterized in that, air source heat pump set still includes:

the device for preventing freezing of an air source heat pump unit as claimed in claim 8, wherein 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.

10. A storage medium storing program instructions, wherein the program instructions, when executed, perform the method for preventing freeze of an air source heat pump unit according to any one of claims 1 to 7.