A method for inhibiting frost formation in a hot water unit

Abstract

The present invention discloses a method for inhibiting frost formation in a hot water unit. In the method, after the unit is in heating operation, the current outdoor ambient temperature T1 is detected, and the air guide device extracts air in the working chamber; the air guide device changes the direction and temperature of its exhaust air according to the outdoor ambient temperature T1; wherein, when the outdoor ambient temperature T1≤x, the air guide device sends the extracted air to the outside of the hot water unit; when the outdoor ambient temperature T1 is in the interval (y, x), the air guide device blows part of the extracted air to the outer wall of the evaporator; when the outdoor ambient temperature T1 is in the interval [z, y], the air guide device heats the extracted air and blows all of it to the rear wall of the evaporator. Thus, the growth of frost crystals can be inhibited and prolonged without affecting the operation of the hot water unit or increasing the power consumption of the unit, so as to ensure the energy consumption of the unit and the efficiency of the unit in producing hot water.

Description

Technical Field

[0001] The invention relates to the field of heat pump water heaters, and in particular to a method for inhibiting frost formation in a water heater unit. Background Art

[0002] When the outer ring temperature of the unit is below 12℃, the evaporator will gradually frost. The frosting process and the post-frosting process will affect the heat exchange effect of the heat pump water heater. When a certain time and temperature are reached, the system cuts the valve through the four-way valve to increase the evaporator temperature to achieve the purpose of defrosting. The normal defrosting time is generally about 3 to 5 minutes. Chilled water will be produced in this process. The above process will lead to a decrease in the energy efficiency of the unit and an increase in the time required to produce hot water.

[0003] The patent document with publication number CN110360775B discloses a method for inhibiting frosting of a heat pump and a device for inhibiting frosting of a heat pump, including the following contents: judging the frosting state of the heat pump unit and when judging that the heat pump unit is in the frost crystal growth period, opening the control valve connected in parallel with the throttling device of the heat pump unit. The heat pump unit of the air source heat pump water heater (the heat pump unit of the outdoor part) is prone to frost in a low temperature and high humidity environment. As the frost crystals grow on the evaporator, the contact area with the surrounding air continues to increase, and the heat dissipation through the frost crystal surface continues to increase. Then, the cooling capacity used for water vapor condensation and frosting in the cooling capacity continues to decrease, and the growth of the frost layer is inhibited to a certain extent during this period. Therefore, the prior art is intended to extend the frost crystal growth (condensation) period, which can inhibit the growth of the frost layer to a certain extent. Referring to the attached drawings of the prior art, a control valve is connected in parallel to the throttling device, and the control valve may be a solenoid valve. When the high-temperature and high-pressure liquid refrigerant passes through the throttling device, it becomes a low-temperature and low-pressure liquid refrigerant. If the control valve is in an open state, part of the high-temperature and high-pressure refrigerant will flow to the evaporator through the control valve; at this time, the refrigerant passing through the throttling device is mixed with the refrigerant that has not passed through the throttling device. Compared with all the refrigerants passing through the throttling device, the former situation can increase the temperature of the refrigerant, and then, the temperature of the refrigerant entering the evaporator is relatively increased, which has a certain inhibitory effect on the frosting on the evaporator, and can slow down the frost crystal growth (condensation) period to a certain extent. In other words, it can also be said that the growth of the frost layer can be inhibited to a certain extent.

[0004] In the prior art, in order to inhibit the growth of frost crystals, part of the high-temperature and high-pressure refrigerant is controlled to flow to the evaporator. The temperature of the refrigerant in the evaporator is relatively increased, which has a certain inhibitory effect on the frosting on the evaporator. However, although such means have achieved the effect of inhibiting the growth of frost crystals, it reduces the heat exchange efficiency of the unit during the period of inhibiting the growth of frost crystals, and also increases the power consumption and load of the unit. Summary of the invention

[0005] In order to solve the problems in the prior art, the purpose of the present invention is to provide a method for inhibiting frosting of a hot water unit, which can inhibit and prolong the growth of frost crystals without affecting the operation of the hot water unit and increasing the power consumption of the unit, so as to ensure the energy consumption of the unit and the efficiency of the unit in producing hot water.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0007] A method for inhibiting frost formation of a hot water unit, the hot water unit comprising a casing, a compressor, an evaporator, a flash tank, a heat exchanger and a water tank, the compressor, the heat exchanger, the flash tank and the evaporator being connected to form a circulating loop through a main pipeline, a working chamber and a heat exchange chamber being arranged in the casing, the compressor, the flash tank and an electric control element for controlling the operation of the unit being installed in the working chamber, the evaporator being installed in the heat exchange chamber and the rear wall of the evaporator being able to directly contact the external environment, the heat exchanger being arranged in the water tank, and the hot water unit further comprising an air guide device;

[0008] The specific steps of inhibiting frost formation of the hot water unit are as follows: Step 1) After the unit is in heating operation, the current outdoor ambient temperature T1 is detected, and the air guide device extracts air from the working chamber; Step 2) The air guide device changes the direction and temperature of its exhaust air according to the outdoor ambient temperature T1;

[0009] Among them, when the outdoor ambient temperature T1≤x, the air guide device sends the extracted air to the outside of the hot water unit; when the outdoor ambient temperature T1 is in the interval (y, x), the air guide device blows part of the extracted air to the outer wall of the evaporator; when the outdoor ambient temperature T1 is in the interval [z, y], the air guide device heats the extracted air and blows all of it to the back wall of the evaporator.

[0010] Preferably, when the outdoor ambient temperature T1 is within the interval (y, x), the higher the outdoor ambient temperature T1 is, the less air is blown toward the evaporator.

[0011] Preferably, the air guiding device comprises an auxiliary heat pipeline for heating air, and the auxiliary heat pipeline is connected to a part of the main pipeline between the heat exchanger and the evaporator.

[0012] Preferably, an electronic expansion valve is installed on the auxiliary heating pipeline.

[0013] Preferably, when the outdoor ambient temperature T1 is in the interval (y, x), if the compressor exhaust temperature T2>q, the auxiliary heating pipeline is connected to the main pipeline, the auxiliary heating pipeline heats the air drawn by the air guide device, and then the air guide device blows the heated air to the rear wall of the evaporator.

[0014] Preferably, after the air is heated, if any one of T2<T2max-h, H1<H1max-i, and T1>x is satisfied, the heating of the air is stopped; wherein T2 is the compressor exhaust temperature, T2max is the upper limit of the exhaust temperature, H1 is the compressor high pressure, H1max is the upper limit of the compressor high pressure pressure, and T1 is the ambient temperature.

[0015] Preferably, when the outdoor ambient temperature T1 is in the interval [z, y], if T2>T2min and T3>j are satisfied at the same time, the auxiliary heating pipeline is connected to the main pipeline, and the air drawn from the working chamber by the air guide device is heated by the auxiliary heating pipeline and then blown to the rear wall of the evaporator; wherein T2 is the compressor exhaust temperature, T2min is the lower limit of the exhaust temperature, and T3 is the auxiliary heating pipeline temperature.

[0016] Preferably, after the air is heated, if T3<j, the air guiding device stops operating.

[0017] Preferably, after the air guide device stops, the evaporator fin temperature T4≤l, and the compressor running time is greater than m, the unit enters the defrost stage, otherwise the compressor exhaust temperature T2 and the auxiliary heating pipeline temperature T3 are re-detected to determine whether the air guide device is turned on.

[0018] Preferably, the air guiding device includes an air duct, a cross-flow fan is installed in the air duct, and an auxiliary heat pipeline is installed in the air duct. After the auxiliary heat pipeline is connected to the main pipeline, the auxiliary heat pipeline first heats the space in the air duct, and then the cross-flow fan draws air in the working chamber and blows it toward the rear wall of the evaporator.

[0019] The invention can recycle the heat generated by the compressor, evaporator, flash tank, electronic control elements and other components, and send the above heat to the surface of the evaporator to inhibit frosting of the evaporator. It not only saves the heat required to inhibit frosting, but the remaining heat can also be absorbed by the evaporator for reuse. At the same time, it also discharges the heat in the working chamber of the unit, avoids excessive temperature and pressure in the working chamber, and ensures stable operation of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the principle diagram of the hot water unit in the present invention;

[0021] Figure 2 A flow chart of the present invention for inhibiting frost formation in a water heater;

[0022] Figure 3 It is a structural schematic diagram of a hot water unit;

[0023] Figure 4 It is a structural schematic diagram of the air guide device.

[0024] Figure numerals: 1. compressor; 11. working chamber; 12. heat exchange chamber; 14. bottom plate; 15. rear side plate; 16. first partition; 17. grid portion; 2. four-way valve; 3. heat exchanger; 4. flash tank; 5. evaporator; 6. water tank; 7. auxiliary heat pipeline; 71. electronic expansion valve; 72. one-way valve; 73. pipe temperature sensor; 8. air guide device; 81. air duct; 811. air inlet; 812. air outlet; 82. cross-flow fan assembly; 83. motor; 84. wind shield; 86. second partition; 88. first mounting plate; 89. second mounting plate; 9. main pipeline. DETAILED DESCRIPTION

[0025] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0026] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more, unless otherwise clearly specified.

[0028] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0030] Example 1

[0031] like Figure 1 A method for inhibiting frost formation in a hot water unit is shown, wherein the hot water unit includes a casing, a compressor 1, an evaporator 5, a flash tank 4, a heat exchanger 3 and a water tank 6. The compressor 1, the heat exchanger 3, the flash tank 4 and the evaporator 5 are connected to form a circulating loop through a main pipeline 9. A working chamber 11 and a heat exchange chamber 12 are arranged in the casing. The compressor 1, the flash tank 4 and the electric control element for controlling the operation of the unit are all installed in the working chamber 11. The evaporator 5 is installed in the heat exchange chamber 12 and the rear wall of the evaporator 5 can directly contact the external environment. The heat exchanger 3 is arranged in the water tank 6. The hot water unit also includes an air guide device 8;

[0032] The specific steps to inhibit frost formation in hot water units are as follows:

[0033] Step 1) After the unit is in heating operation, the current outdoor ambient temperature T1 is detected, and the air guide device 8 extracts air from the working chamber 11;

[0034] Step 2) the air guide device 8 changes the direction and temperature of its exhaust air according to the outdoor ambient temperature T1;

[0035] When the outdoor ambient temperature T1 ≥ x, the air guide device 8 delivers the extracted air to the outside of the hot water unit;

[0036] When the outdoor ambient temperature T1 is within the interval (y, x), the air guide device 8 blows part of the air it extracts toward the outer wall of the evaporator 5;

[0037] When the outdoor ambient temperature T1 is within the interval [z, y], the air guide device 8 heats the air it extracts and blows all of it toward the rear wall of the evaporator 5 .

[0038] By using the above method, when the unit is running, the heat generated by the compressor 1, the compressor 1, the evaporator 5, the flash tank 4, the electronic control element and other components is recovered, and the above heat is sent to the surface of the evaporator 5 to inhibit frosting of the evaporator 5, which not only saves the heat required for inhibiting frosting, but the remaining heat can also be absorbed by the evaporator 5 for the purpose of reuse, and at the same time, the heat in the working chamber 11 of the unit is discharged to avoid excessive temperature and pressure in the working chamber 11, thereby ensuring stable operation of the unit.

[0039] In this embodiment, the air guide device 8 includes an air duct 81, an air inlet 811 of the air duct 81 is connected to the working chamber 11, an air outlet 812 of the air duct 811 is connected to the heat exchange chamber 12, and the air outlet of the air duct 81 is located at the rear side of the evaporator 5. A crossflow fan assembly 82 for exhausting air is installed in the air duct 81, and the auxiliary heat pipeline 7 is arranged in the air duct 81; a windshield 84 is installed at the air outlet 812 of the air duct 81, and a motor 83 connected to the windshield 84 is also installed on the air duct 81. In this way, the opening of the windshield 84 and the air outlet direction of the air duct are controlled by the motor, and the air blowing to the evaporator 5 can be more flexibly controlled. The air duct 81 is also equipped with an auxiliary heat pipe 7 for heating the air, which is connected to a part of the main pipe 9 between the heat exchanger 3 and the evaporator 5. In this way, the refrigerant after the heat exchange in the water tank 6 flows through the auxiliary pipe 7 in the air duct, so that the residual heat after the heat exchange of the refrigerant is used to suppress the frost on the surface of the evaporator 5, thereby improving the utilization of the heat of the unit without reducing the efficiency of hot water production, and suppressing the frost while increasing the load of the unit; the auxiliary heat pipe 7 is equipped with an electronic expansion valve 71, and the opening of the electronic expansion valve 71 is controlled to adjust the air temperature in the air duct. Furthermore, the electronic expansion valve can also be a solenoid valve, which makes the unit easier to control.

[0040] In this embodiment, when the outdoor ambient temperature T1 ≥ x, the opening of the wind shield 84 is first opened to the maximum, the electronic expansion valve is closed, and after n seconds, the crossflow fan is turned on to extract the hot air in the working chamber 11 and send it to the outside of the water heater;

[0041] In this embodiment, when the outdoor ambient temperature T1 is within the interval (y, x), the motor 83 adjusts the opening of the wind shield 84 to e% according to the current outdoor ambient temperature T1, and turns on the cross-flow fan after f seconds; wherein, the higher the outdoor ambient temperature T1, the less air is blown toward the evaporator 5, thereby avoiding overheating of the working chamber 11 of the unit, and avoiding overheating inside the working chamber 11, so that the unit can operate stably.

[0042] In this embodiment, the outdoor environment temperature T1 is within the interval (y, x), and the exhaust temperature T2 of the compressor 1 in the current state is detected g seconds after the crossflow fan assembly 84 is turned on. If the exhaust temperature T2 of the compressor 1 is greater than the lower limit of the exhaust temperature T2min, the electronic expansion valve 71 is turned on, the auxiliary heat pipe 7 is connected to the main pipe 9, the auxiliary heat pipe 7 heats the air extracted by the air guide device 8, and then the air guide device 8 blows the heated air to the rear wall of the evaporator 5. In this way, the residual heat after heat exchange is used to further suppress the frost of the evaporator 5. Further, after the air is heated, if T2<T2max-h, H1<H1max-i, and T1>x are satisfied at the same time, indicating that the unit has been running stably or the ambient temperature has risen, the electronic expansion valve 71 is closed and the heating of the air in the air duct 81 is stopped, otherwise the electronic expansion valve 71 continues to open; wherein, T2 is the exhaust temperature of compressor 1, T2max is the upper limit of the exhaust temperature, H1 is the high pressure of compressor 1, H1max is the upper limit of the high pressure of compressor 1, T1 is the ambient temperature, h is a constant, and i is a constant. Ensure stable operation of the unit and avoid overheating of the unit. Further, by controlling the opening of the electronic expansion valve 71, the temperature of the air in the air duct is controlled, and by controlling the opening of the windshield 84, the air volume and heat blown to the evaporator 5 are controlled.

[0043] In this embodiment, when the outdoor ambient temperature T1 is in the interval [z, y], it indicates that the external ambient temperature is relatively low. If T2>T2min and T3>j are satisfied at the same time, it indicates that the exhaust temperature of the compressor 1 is relatively high, the load of the unit is relatively large, and the temperature in the current water tank 6 is relatively high. Then the electronic expansion valve 71 is opened, and the auxiliary heat pipe 7 is connected to the main pipe 9. The auxiliary heat pipe 7 first heats up the temperature in the air duct 81, and the wind shield 84 is opened to the minimum opening. Then the cross-flow fan assembly 84 is opened to blow all the heated air to the rear wall of the evaporator 5; wherein T2 is the exhaust temperature of the compressor 1, T2min is the lower limit of the exhaust temperature, and T3 is the temperature of the auxiliary heat pipe; thus, it indicates that the ambient temperature is relatively low and frost is very likely to occur, so more heat is needed to position the surface temperature of the rear wall of the evaporator 5. Further, after the air is heated, if T3<j, it indicates that more heat is needed in the water tank 6 to produce hot water, and the air guide device 8 needs to be stopped, the electronic expansion valve is closed, and the wind shield 84 is closed. Furthermore, after the air guide device 8 stops, the fin temperature T4 of the evaporator 5 is ≤1, and the running time of the compressor 1 is greater than m, indicating that the evaporator 5 has been frosted, and the unit enters the defrosting stage, otherwise the exhaust temperature T2 of the compressor 1 and the temperature T3 of the auxiliary heat pipe are re-detected to determine whether the air guide device 8 is turned on. In this way, the heat generation efficiency and heat exchange efficiency of the unit can be guaranteed, the low temperature can be avoided from affecting the unit, and the unit can be operated stably.

[0044] In this embodiment, the compressor 1 is connected to the heat exchanger 3 or the evaporator 5 through the four-way valve 2, an exhaust temperature sensor is installed on the main pipeline 9, a fin sensor for detecting the fin temperature is installed on the evaporator 5, a pipe temperature sensor 73 for detecting the temperature of the auxiliary heating pipeline 7 is installed on the auxiliary heating pipeline 7, and a one-way valve 72 is also installed on the auxiliary heating pipeline 7. The one-way valve 72 is installed at the outlet of the auxiliary heating pipeline 7, and the pipe temperature sensor 73 is located between the electronic expansion valve 71 and the one-way valve 72.

[0045] In this embodiment, the casing includes a bottom plate 14, a top plate, a front side plate, a rear side plate 15, a left side plate and a right side plate, and the front side plate, the left side plate, the rear side plate 15 and the right side plate enclose a hollow structure, and the top plate and the bottom plate 14 close the upper and lower ends of the hollow structure; a first partition plate 16 is fixedly installed in the casing, and the first partition plate 16 is respectively connected to the top plate, the bottom plate 14, the rear side plate 15 and the front side plate, so as to divide the internal space of the casing into a working chamber 11 and a heat exchange chamber 12, and a cross-flow fan is arranged on the front side of the evaporator 5, and the cross-flow fan is installed on the front side plate. The evaporator 5 is an L-shaped structure, and the right side plate is a grid structure. The part of the rear side plate 15 located on the rear side of the evaporator 5 is a grid-shaped grid portion 17 structure, which enables the rear side wall of the evaporator 5 to be directly in contact with the external environment, and the evaporator 5 needs to exchange heat with the external environment, so the position where frost is most likely to occur is the rear wall of the evaporator 5.

[0046] In this embodiment, the air guide device 8 includes a second partition 86, which is located in the working chamber 11. The second partition 86 is connected to the top plate, the bottom plate 14, the first partition 16 and the rear side plate 15 respectively, so that part of the top plate, part of the bottom plate 14, part of the first partition 16, part of the rear side plate 15 and the second partition 86 enclose the air duct 81, the air inlet 811 of the air duct 81 is a second opening opened on the second partition 86 to connect the working chamber 11 and the air duct 81, the air outlet 8112 of the air duct 81 is a first opening opened on the first partition 16 to connect the air duct 81 and the heat exchange chamber 12, the first opening is located between the evaporator 5 and the rear side plate 15, and because the part of the rear side plate 15 located behind the evaporator 5 is a grid-like structure, the first opening can also be between the rear side plate 15 and the evaporator 5, and the auxiliary heat pipe 7 is located in the air duct 81 and installed on the second partition 86. In this way, the structure of the unit can be made more compact. Furthermore, a first mounting plate 88 and a second mounting plate 89 are fixed in the air duct 81, the first mounting plate 88 is located above the second mounting plate 89, the upper and lower ends of the wind shield 84 are respectively hinged to the first mounting plate 88 and the second mounting plate 89, the motor 83 is mounted on the first mounting plate 88, and the air inlet 811 and the air outlet 8112 are both located between the first mounting plate 88 and the second mounting plate 89. In this way, the first partition 16, the second partition 86, the first mounting plate 88 and the second mounting plate 89 enclose the air duct 81, so that the motor 83 in the crossflow fan assembly and the motor 83 connected to the wind shield 84 can be installed on the first mounting plate 88 or the second mounting plate 89, so that the volume of the unit will not be increased, and the structure of the unit is more compact.

[0047] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0048] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A method for inhibiting frost formation in a hot water unit, The hot water unit comprises a casing, a compressor (1), an evaporator (5), a flash tank (4), a heat exchanger (3) and a water tank (6); the compressor (1), the heat exchanger (3), the flash tank (4) and the evaporator (5) are connected to form a circulation loop via a main pipeline (9); a working chamber (11) and a heat exchange chamber (12) are arranged in the casing; the compressor (1), the flash tank (4) and an electric control element for controlling the operation of the unit are all installed in the working chamber (11); the evaporator (5) is installed in the heat exchange chamber (12) and the rear wall of the evaporator (5) can directly contact the external environment; the heat exchanger (3) is arranged in the water tank (6); Features: The hot water unit also includes an air guide device (8); The specific steps to inhibit frost formation in hot water units are as follows: Step 1) After the unit starts heating operation, the current outdoor ambient temperature T1 is detected, and the air guide device (8) extracts air from the working chamber (11); Step 2) the air guide device (8) changes the direction and temperature of its exhaust air according to the outdoor ambient temperature T1; When the outdoor ambient temperature T1 ≥ x, the air guide device (8) sends the extracted air to the outside of the hot water unit; When the outdoor ambient temperature T1 is within the interval (y, x), the air guide device (8) blows part of the extracted air toward the outer wall of the evaporator (5); When the outdoor ambient temperature T1 is within the interval [z, y], the air guide device (8) heats the air it extracts and blows all of it toward the rear wall of the evaporator (5); The air guide device (8) comprises an auxiliary heat pipe (7) for heating air, wherein the auxiliary heat pipe (7) is connected to a portion of the main pipe (9) located between the heat exchanger (3) and the evaporator (5); an electronic expansion valve (71) is installed on the auxiliary heat pipe (7); The air guide device (8) comprises an air duct (81), a cross-flow fan (82) for driving air flow is installed in the air duct (81), an auxiliary heat pipe (7) is installed in the air duct (81), after the auxiliary heat pipe (7) and the main pipe (9) are connected, the auxiliary heat pipe (7) first heats the space in the air duct (81), and then the cross-flow fan (82) extracts air from the working chamber (11) and blows it toward the rear wall of the evaporator (5), the air inlet of the air duct (81) is connected to the working chamber (11), the air outlet of the air duct (81) is located at the rear side of the evaporator (5), and the air outlet of the air duct (81) is installed with a windshield (74), and the air guide device (8) also comprises a motor (83) for controlling the opening of the windshield.

2. A method for inhibiting frost formation in a water heater according to claim 1, Features: When the outdoor ambient temperature T1 is within the interval (y, x), the higher the outdoor ambient temperature T1 is, the less air is blown toward the evaporator (5).

3. A method for inhibiting frost formation in a water heater according to claim 1, Features: When the outdoor ambient temperature T1 is within the interval (y, x), if the exhaust temperature T2 of the compressor (1) is greater than the lower limit of the exhaust temperature T2min, the auxiliary heating pipeline (7) is connected to the main pipeline (9), the auxiliary heating pipeline (7) heats the air extracted by the air guide device (8), and then the air guide device (8) blows part of the heated air toward the rear wall of the evaporator (5).

4. A method for inhibiting frost formation in a water heater according to claim 3, Features: After the air is heated, if T2<T2max-h, H1<H1max-i, and T1>x are satisfied at the same time, the air heating is stopped, otherwise the auxiliary heating pipeline (7) continues to heat the air; wherein T2 is the exhaust temperature of the compressor, T2max is the upper limit of the exhaust temperature, H1 is the high pressure of the compressor, H1max is the upper limit of the high pressure of the compressor, and T1 is the ambient temperature.

5. A method for inhibiting frost formation in a water heater according to claim 1, Features: When the outdoor ambient temperature T1 is within the interval [z, y], if T2>T2min and T3>j are satisfied at the same time, the auxiliary heating pipeline (7) is connected to the main pipeline (9), and the air drawn from the working chamber (11) by the air guide device (8) is heated by the auxiliary heating pipeline (7) and then blown toward the rear wall of the evaporator (5); wherein T2 is the exhaust temperature of the compressor (1), T2min is the lower limit of the exhaust temperature, and T3 is the temperature of the auxiliary heating pipeline (7).

6. A method for inhibiting frost formation in a water heater according to claim 5, Features: After the air is heated, if T3 < j, the air guide device (8) stops operating.

7. A method for inhibiting frost formation in a water heater according to claim 6, Features: After the air guide device (8) stops, the fin temperature T4 of the evaporator (5) is less than or equal to l, and the operation time of the compressor (1) is greater than m, then the unit enters the defrosting stage; otherwise, the exhaust temperature T2 of the compressor (1) and the temperature T3 of the auxiliary heat pipe (7) are re-detected to determine whether the air guide device (8) is turned on.

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