A defrost control method and a combined power generation unit

Abstract

The present invention discloses a defrost control method and a combined heat and power supply (CHP) unit. The CHP unit includes a hot water generator, an indoor heat exchanger, and an outdoor heat exchanger. The hot water generator leads to a bypass hot water pipe, at least a portion of which is disposed adjacent to the outdoor heat exchanger. The outdoor heat exchanger includes a condensing coil and a defrosting coil. The method comprises: determining a user's hot water demand when defrosting is required; controlling the bypass hot water pipe or the defrosting coil to be conductive based on the hot water demand to defrost the outdoor heat exchanger; and maintaining heating operation during the defrosting process. The present invention enables uninterrupted heating during defrosting, thereby satisfying both the user's hot water and heating needs and improving the user experience.

Description

Technical Field

[0001] The present invention relates to the technical field of units, and in particular to a defrost control method and a combined power generation unit. Background Art

[0002] In recent years, combined heat and water systems (CHPs) have become increasingly popular among consumers in northern China. The principle behind a CHP unit's ability to simultaneously heat and supply hot water is that a compressor compresses high-temperature, high-pressure refrigerant, which then passes through a hot water generator and indoor heat exchanger for heat exchange, liquefies and releases heat. The refrigerant then enters the outdoor heat exchanger for vaporization, absorbs heat from the air, and re-enters the compressor, completing a cycle. During the cycle, condensation forms on the surface of the outdoor heat exchanger. When the ambient temperature of the outdoor heat exchanger is low or the heat exchange demand of the indoor heat exchanger is high, the condensed water forms frost, reducing the heat exchange efficiency between the outdoor and indoor heat exchangers. Without stopping the unit for defrosting, liquid refrigerant may enter the compressor directly, leading to compressor liquid shock. Several existing approaches exist to address this issue: First, shutting down the unit for defrosting, then controlling the unit to heat normally after defrosting is complete. This approach results in heating interruptions, impacting user experience. Second, using electric heating for defrosting. This approach results in a surge in electricity consumption and increases the unit's energy consumption.

[0003] With regard to the problem in the prior art that the combined heat generation unit cannot achieve uninterrupted heating during the defrosting process, no effective solution has been proposed yet. Summary of the Invention

[0004] The embodiments of the present invention provide a defrost control method and a CHP unit to solve the problem in the prior art that the CHP unit cannot achieve uninterrupted heating during the defrost process.

[0005] To solve the above technical problems, the present invention provides a defrost control method, which is applied to a combined heat and power supply unit, wherein the combined heat and power supply unit includes a hot water generator, an indoor heat exchanger, and an outdoor heat exchanger, wherein a bypass hot water pipe is led out from the hot water generator, and at least a portion of the bypass hot water pipe is arranged adjacent to the outdoor heat exchanger, and the outdoor heat exchanger includes a condensing coil and a defrost coil. The method comprises:

[0006] When defrosting is required, determine the user's hot water demand;

[0007] The bypass hot water pipe or the defrost coil is controlled to be turned on according to the hot water demand to defrost the outdoor heat exchanger; wherein, during the defrosting process, the indoor heat exchanger and the outdoor heat exchanger maintain heating operation.

[0008] Furthermore, controlling the bypass hot water pipe or the defrost coil to be turned on according to the hot water demand to defrost the outdoor heat exchanger includes:

[0009] Determining whether the hot water demand is less than a preset threshold;

[0010] If yes, the bypass hot water pipe is controlled to be open to defrost the outdoor heat exchanger;

[0011] If not, the defrost coil is controlled to be turned on to defrost the outdoor heat exchanger.

[0012] Furthermore, determining whether the hot water demand is less than a preset threshold includes:

[0013] Determine whether the current period is a low water consumption period;

[0014] If yes, determining that the hot water demand is less than a preset threshold;

[0015] If not, it is determined that the hot water demand is greater than or equal to the preset threshold.

[0016] Furthermore, a first valve is provided at the inlet end of the bypass hot water pipe to control the conduction of the bypass hot water pipe. The method further comprises:

[0017] detecting the temperature of the frosted surface of the outdoor heat exchanger;

[0018] The opening of the first valve is adjusted according to the temperature of the frosted surface; wherein, the lower the temperature of the frosted surface, the larger the opening of the first valve.

[0019] Furthermore, a second valve is provided at the inlet end of the defrost coil, and after controlling the defrost coil to be turned on, the method further includes:

[0020] detecting the temperature of the frosted surface of the outdoor heat exchanger;

[0021] The opening of the second valve is adjusted according to the temperature of the frosted surface; wherein, the lower the temperature of the frosted surface, the larger the opening of the second valve.

[0022] Furthermore, after controlling the bypass hot water pipe or the defrost coil to be turned on according to the hot water demand and defrosting the outdoor heat exchanger, the method further includes:

[0023] Determining whether the temperature parameter of the outdoor heat exchanger meets the defrost stopping condition;

[0024] If yes, the hot water demand is controlled to control the bypass hot water pipe or the defrost coil to be turned off, and defrosting of the outdoor heat exchanger is stopped.

[0025] The present invention further provides a combined heat and power supply unit, comprising a hot water generator, an indoor heat exchanger, and an outdoor heat exchanger, wherein a bypass hot water pipe is led out from the hot water generator, at least a portion of the bypass hot water pipe is arranged adjacent to the outdoor heat exchanger, the outdoor heat exchanger comprises a condensing coil and a defrosting coil, and the combined heat and power supply unit further comprises:

[0026] The controller is used to determine the user's hot water demand when defrosting is required, and control the bypass hot water pipe or the defrost coil to be turned on according to the hot water demand to defrost the outdoor heat exchanger; wherein, during the defrosting process, the indoor heat exchanger and the outdoor heat exchanger maintain heating operation.

[0027] Furthermore, the dual heat supply unit further includes a compressor, and the hot water generator is arranged adjacent to the compressor.

[0028] Furthermore, the combined power generation unit further comprises:

[0029] a first valve, disposed at the inlet end of the bypass hot water pipe;

[0030] The second valve is arranged at the inlet end of the defrost coil.

[0031] The present invention also provides a computer-readable storage medium having a computer program stored thereon, and the program implements the above-mentioned defrost control method when executed by a processor.

[0032] By applying the technical solution of the present invention, when defrosting is required, the user's hot water demand is determined, and the bypass hot water pipe or the defrost coil is controlled to be turned on according to the hot water demand to defrost the outdoor heat exchanger. Uninterrupted heating can be achieved during defrosting, thereby meeting the user's hot water and heating needs and improving the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a system structure diagram of a combined heat and power generation unit according to an embodiment of the present invention;

[0034] Figure 2 4 is a flow chart of a defrost control method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions, and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings. It is apparent that the embodiments described are only some, not all, of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0036] The terms used in the embodiments of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The singular forms "a," "an," "the," and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, and unless the context clearly indicates otherwise, "a plurality" generally includes at least two.

[0037] It should be understood that the term "and / or" as used herein is merely a description of the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0038] It should be understood that although the terms "first," "second," etc. may be used to describe valves in embodiments of the present invention, these valves should not be limited to these terms. These terms are merely used to distinguish valves located in different positions. For example, a first valve could also be referred to as a second valve, and similarly, a second valve could also be referred to as a first valve without departing from the scope of the present invention.

[0039] As used herein, the words "if" and "if" may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0040] It should also be noted that the terms "include," "comprises," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a product or device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such product or device. In the absence of further limitations, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the product or device comprising the element.

[0041] The optional embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0042] Example 1

[0043] This embodiment provides a defrost control method, which is applied to a dual-energy-supply unit. Figure 1 is a system structure diagram of a dual-energy-generating unit according to an embodiment of the present invention, as shown in FIG. Figure 1As shown, the combined heat supply unit includes a hot water generator 3, an indoor heat exchanger (not shown in the figure), and an outdoor heat exchanger 4. The hot water generator 3 is a shell-and-tube heat exchanger, which includes a refrigerant pipeline 31 and a hot water pipeline 32. The hot water pipeline 32 of the hot water generator 3 leads to a bypass hot water pipe 33 near the water outlet. At least part of the bypass hot water pipe 33 is arranged adjacent to the outdoor heat exchanger 4. The outdoor heat exchanger 4 includes a condensing coil 41 and a defrosting coil 42. The defrosting coil is preferably a copper tube with good heat dissipation performance. A water pump 7 is provided at the water inlet of the hot water pipeline 32 to drive the water flow in the hot water pipeline 32. Similarly, a water pump can also be provided on the bypass hot water pipe 33 to drive the hot water flow.

[0044] In other embodiments of the present invention, a separate defrost heat exchanger may also be provided. The defrost heat exchanger is provided adjacent to the outdoor heat exchanger 4 and includes a defrost coil.

[0045] In the heating mode, on the one hand, the high-temperature and high-pressure refrigerant is discharged from the compressor 1, passes through the oil separator 2, port D of the four-way valve 5, and port E of the four-way valve 5, enters the indoor heat exchanger, condenses and dissipates heat in the outdoor heat exchanger, and provides heat for the indoor room, then passes through the first expansion valve EXV1 to enter the outdoor heat exchanger 4, evaporates and absorbs heat in the outdoor heat exchanger 4, then passes through ports C and port S of the four-way valve 5, and then passes through the gas-liquid separator 6 to return to the suction end of the compressor 1, completing the heating cycle and providing heat for the indoor room; on the other hand, the high-temperature and high-pressure refrigerant discharged from the compressor 1 passes through the oil separator 2 and enters the refrigerant pipeline 31 of the hot water generator 3, and in the refrigerant pipeline 31, exchanges heat with the cold water in the hot water pipeline of the hot water generator 3, heating the cold water into hot water, and the hot water flows to the user or bypasses the hot water pipe 33. After heat exchange, the refrigerant in the refrigerant pipeline 31 flows through the second electronic expansion valve to EXV2 and then to the gas-liquid separator 6, and finally returns to the suction end of the compressor 1, completing the hot water cycle. The hot water is circulated by the water pump 7 .

[0046] During defrosting, the hot water in the bypass hot water pipe 33 can be used to defrost the outdoor heat exchanger 4. The specific principle is: the hot water in the bypass hot water pipe 33 flows to the outdoor heat exchanger 4, exchanges heat with the surface of the outdoor heat exchanger 4, and defrosts the outdoor heat exchanger 4. The hot water after heat exchange flows back to the water inlet of the hot water pipe. During this defrosting process, the indoor and outdoor heat exchangers maintain heating operation.

[0047] The outdoor heat exchanger 4 can also be defrosted through the defrost coil 42 in the outdoor heat exchanger 4. The specific principle is: the high-temperature and high-pressure refrigerant discharged from the compressor 1 passes through the oil separator 2 and enters the defrost coil 42. The defrost coil 42 exchanges heat with the frosted surface of the outdoor heat exchanger 4, and the heat emitted is used to defrost the outdoor heat exchanger 4. The refrigerant after heat exchange returns to the suction end of the compressor 1. The medium-temperature and medium-pressure refrigerant after defrosting returns to the compressor for further compression, which is equivalent to replenishing air and increasing enthalpy. The heating capacity of the entire machine can be increased, and there is no need to set up an expansion tank in the unit to replenish air and increase enthalpy. During the above-mentioned defrosting process, the indoor heat exchanger and the outdoor heat exchanger maintain heating operation.

[0048] A first temperature sensor T1 is set at the inlet end of the outdoor heat exchanger 4, a second temperature sensor T2 is set at the outlet end, a third sensor T3 is also set on the outdoor heat exchanger 4 for detecting the outdoor ambient temperature, and a fourth sensor T4 is set on the frosted surface of the outdoor heat exchanger 4 for detecting the temperature of the frosted surface.

[0049] Figure 2 FIG. 1 is a flow chart of a defrost control method according to an embodiment of the present invention. Figure 2 As shown, the method includes:

[0050] S101, when defrosting is required, determining the user's hot water demand.

[0051] Since this embodiment is applied to a dual-energy supply unit including a hot water generator 3, an indoor heat exchanger and an outdoor heat exchanger 4, the hot water generator 3 is used to produce hot water. When the user's hot water demand is large, hot water is supplied to the user first. However, when the hot water demand is small and there is no hot water demand, the hot water generated by the hot water generator 3 can be used to defrost the outdoor heat exchanger 4. Therefore, it is necessary to first determine the user's hot water demand.

[0052] In specific implementation, a first temperature sensor T1 can be set at the inlet end of the outdoor heat exchanger 4 to detect the inlet temperature of the outdoor heat exchanger 4, and a second temperature sensor T2 can be set at the outlet end of the outdoor heat exchanger 4 to detect the outlet temperature of the outdoor heat exchanger 4. Whether defrosting is required is determined based on the temperature difference between the outlet temperature and the inlet temperature of the outdoor heat exchanger 4. If the above temperature difference is lower than or equal to the set threshold, it means that defrosting is required; if the above temperature difference is higher than the set threshold, it means that defrosting is not required; or, the outdoor ambient temperature is detected by a third sensor T3 also set on the outdoor heat exchanger 4. If the outdoor ambient temperature is lower than or equal to the set temperature threshold, it means that defrosting is required; if the outdoor ambient temperature is higher than the set temperature threshold, it means that defrosting is not required.

[0053] S102, controlling the bypass hot water pipe or the defrost coil to be turned on according to the hot water demand, to defrost the outdoor heat exchanger; wherein, during the defrosting process, the indoor heat exchanger and the outdoor heat exchanger maintain heating operation.

[0054] The defrost control method of this embodiment determines the user's hot water demand when defrosting is required, controls the bypass hot water pipe or the defrost coil to be turned on according to the hot water demand, and defrosts the outdoor heat exchanger. It can achieve uninterrupted heating during defrosting, and simultaneously meet the user's hot water demand and heating demand, thereby improving the user experience.

[0055] As described above, when the user's demand for hot water is large, hot water is supplied to the user first. However, when the demand for hot water is small and there is no hot water demand, the hot water generated by the hot water generator 3 can be used to defrost the outdoor heat exchanger 4. Therefore, the bypass hot water pipe 33 or the defrost coil is controlled to be turned on according to the hot water demand to defrost the outdoor heat exchanger 4, including: judging whether the hot water demand is less than a preset threshold; if so, controlling the bypass hot water pipe 33 to be turned on to defrost the outdoor heat exchanger 4; if not, controlling the defrost coil to be turned on to defrost the outdoor heat exchanger 4.

[0056] Hot water usage in typical households typically has peak and off-peak hours. During off-peak hours, such as during the day when no one is home, water usage decreases dramatically. During peak hours, such as between get off work and bedtime, water usage increases dramatically. Determining whether hot water demand is less than a preset threshold involves determining whether the current time period is a low-use period; if so, determining that the hot water demand is less than the preset threshold; if not, determining that the hot water demand is greater than or equal to the preset threshold. In specific implementations, historical hot water usage data can be analyzed to categorize off peak and off-peak periods.

[0057] Since the degree of frost on the outdoor heat exchanger 4 is different under different ambient temperatures or heat exchange requirements, in order to accurately adjust the hot water flow in the bypass hot water pipe 33 according to the degree of frost on the outdoor heat exchanger 4, and thus control the defrosting speed, a first valve V1 is set at the inlet end of the bypass hot water pipe. After controlling the conduction of the bypass hot water pipe, the above method also includes: detecting the temperature of the frosted surface of the outdoor heat exchanger 4; adjusting the opening of the first valve V1 according to the temperature of the frosted surface; wherein, the lower the temperature of the frosted surface, the greater the opening of the first valve V1.

[0058] Similarly, a second valve V2 is set at the inlet end of the defrost coil 42. After controlling the conduction of the defrost coil, the above method also includes: detecting the temperature of the frosted surface of the outdoor heat exchanger 4; adjusting the opening of the second valve V2 according to the temperature of the frosted surface; wherein, the lower the temperature of the frosted surface, the greater the opening of the second valve V2.

[0059] Since the defrosting process consumes a certain amount of refrigerant or hot water, it is necessary to stop defrosting in time after the defrosting is completed to avoid affecting the heat exchange efficiency of the unit or affecting the user's water use. The bypass hot water pipe or the defrost coil is controlled to be turned on according to the hot water demand. After the outdoor heat exchanger 4 is defrosted, the above method also includes: judging whether the temperature parameters of the outdoor heat exchanger 4 meet the conditions for stopping defrosting; if so, controlling the hot water demand to control the bypass hot water pipe or the defrost coil to be turned off, and stopping defrosting the outdoor heat exchanger 4. The above-mentioned temperature parameters include judging whether it is necessary to stop defrosting based on the temperature difference between the outlet and inlet ends of the outdoor heat exchanger 4 or the temperature of the frosted surface of the outdoor heat exchanger 4. If the above-mentioned temperature difference is lower than or equal to the set threshold, it means that defrosting is required; if the above-mentioned temperature difference is higher than the set threshold, it means that defrosting needs to be stopped; or, the temperature of the frosted surface is detected by the fourth sensor T4 also provided on the outdoor heat exchanger 4. If the temperature of the frosted surface is lower than or equal to the set temperature threshold, it means that defrosting is required; if the outdoor ambient temperature is higher than the set temperature threshold, it means that defrosting needs to be stopped to reduce heat waste.

[0060] In this embodiment, air is introduced through the defrost coil 42 or hot water is introduced through the bypass hot water pipe 33 to heat the outdoor heat exchanger 4, so that defrosting can be achieved without stopping the machine, thereby improving user experience.

[0061] Example 2

[0062] This embodiment provides a dual-energy-generation unit. The system structure diagram of the dual-energy-generation unit in this embodiment is as mentioned above. Figure 1 As shown in FIG, it includes a hot water generator 3, an indoor heat exchanger (not shown), and an outdoor heat exchanger 4. The hot water generator 3 is a double-tube heat exchanger, which includes a refrigerant pipeline 31 and a hot water pipeline 32. The hot water pipeline 32 of the hot water generator 3 leads to a bypass hot water pipe 33 near the water outlet. At least part of the bypass hot water pipe 33 is arranged adjacent to the outdoor heat exchanger 4. The outdoor heat exchanger 4 includes a condensing coil 41 and a defrosting coil 42. The defrosting coil is preferably a copper tube with good heat dissipation performance. A water pump 7 is provided at the water inlet of the hot water pipeline 32 to drive the water flow in the hot water pipeline 32. Similarly, a water pump can also be provided on the bypass hot water pipe 33 to drive the hot water flow.

[0063] In this embodiment, air is introduced through the defrost coil 42 or hot water is introduced through the bypass hot water pipe 33 to heat the outdoor heat exchanger 4, so that defrosting can be achieved without stopping the machine, thereby improving user experience.

[0064] In other embodiments of the present invention, a separate defrost heat exchanger may also be provided. The defrost heat exchanger is provided adjacent to the outdoor heat exchanger 4 and includes a defrost coil.

[0065] In the heating mode, on the one hand, the high-temperature and high-pressure refrigerant is discharged from the compressor 1, passes through the oil separator 2, port D of the four-way valve 5, and port E of the four-way valve 5, enters the indoor heat exchanger, condenses and dissipates heat in the outdoor heat exchanger, and provides heat for the indoor room, then passes through the first expansion valve EXV1 to enter the outdoor heat exchanger 4, evaporates and absorbs heat in the outdoor heat exchanger 4, then passes through ports C and port S of the four-way valve 5, and then passes through the gas-liquid separator 6 to return to the suction end of the compressor 1, completing the heating cycle and providing heat for the indoor room; on the other hand, the high-temperature and high-pressure refrigerant discharged from the compressor 1 passes through the oil separator 2 and enters the refrigerant pipeline 31 of the hot water generator 3, and in the refrigerant pipeline 31, exchanges heat with the cold water in the hot water pipeline of the hot water generator 3, heating the cold water into hot water, and the hot water flows to the user or bypasses the hot water pipe 33. After heat exchange, the refrigerant in the refrigerant pipeline 31 flows through the second electronic expansion valve to EXV2 and then to the gas-liquid separator 6, and finally returns to the suction end of the compressor 1, completing the hot water cycle. The hot water is circulated by the water pump 7 .

[0066] During defrosting, the outdoor heat exchanger 4 can be defrosted by the hot water in the bypass hot water pipe 33. The specific principle is: the hot water in the bypass hot water pipe 33 flows to the outdoor heat exchanger 4, exchanges heat with the surface of the outdoor heat exchanger 4, and defrosts the outdoor heat exchanger 4. The hot water after heat exchange flows back to the water inlet of the hot water pipeline.

[0067] The outdoor heat exchanger 4 can also be defrosted through the defrost coil 42 in the outdoor heat exchanger 4. The specific principle is: the high-temperature and high-pressure refrigerant discharged from the compressor 1 passes through the oil separator 2 and enters the defrost coil 42. The defrost coil 42 exchanges heat with the frosted surface of the outdoor heat exchanger 4, and the heat emitted is used to defrost the outdoor heat exchanger 4. The refrigerant after heat exchange returns to the suction end of the compressor 1. The medium-temperature and medium-pressure refrigerant after defrosting returns to the compressor for further compression, which is equivalent to replenishing air and increasing enthalpy. The heating capacity of the entire machine can be increased, and there is no need to set up an expansion tank in the unit to replenish air and increase enthalpy.

[0068] A first temperature sensor T1 is set at the inlet end of the outdoor heat exchanger 4, a second temperature sensor T2 is set at the outlet end, a third sensor T3 is also set on the outdoor heat exchanger 4 for detecting the outdoor ambient temperature, and a fourth sensor T4 is set on the frosted surface of the outdoor heat exchanger 4 for detecting the temperature of the frosted surface.

[0069] In order to control the defrost coil 42 to draw air or the bypass hot water pipe 33 to draw hot water to heat the outdoor heat exchanger 4, the dual-energy supply unit also includes: a controller (not shown in the figure), which is used to determine the user's hot water demand when defrosting is required, and control the bypass hot water pipe or defrost coil to be connected according to the hot water demand to defrost the outdoor heat exchanger 4; wherein, during the defrost process, the indoor heat exchanger and the outdoor heat exchanger 4 maintain heating operation.

[0070] Since the refrigerant in the hot water generator eventually needs to return to the compressor 1 , in order to shorten the refrigerant pipeline of the hot water generator as much as possible, the hot water generator 3 is disposed adjacent to the compressor 1 .

[0071] In order to control the on-off and flow rate of the bypass hot water pipe 33 and avoid heat waste, the above-mentioned two-energy supply unit also includes: a first valve V1, which is arranged at the inlet end of the bypass hot water pipe 33; similarly, in order to control the on-off and flow rate of the defrost coil 42 and avoid heat waste, the above-mentioned two-energy supply unit also includes: a defrost coil second valve V2, which is arranged at the inlet end of the defrost coil.

[0072] Example 3

[0073] This embodiment provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the defrost control method of the above embodiment is implemented.

[0074] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, or of course, by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the existing technology can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or certain parts of the embodiments.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A defrost control method, applied to a combined heat and power generation unit, characterized in that: The combined heat and power generation unit includes a hot water generator, an indoor heat exchanger, and an outdoor heat exchanger, wherein a bypass hot water pipe is led out from the hot water generator, at least a portion of the bypass hot water pipe is arranged adjacent to the outdoor heat exchanger, and the outdoor heat exchanger includes a condensing coil and a defrosting coil. The method includes: When defrosting is required, determine the user's hot water demand; According to the hot water demand, the bypass hot water pipe or the defrost coil is controlled to be turned on to defrost the outdoor heat exchanger; wherein, during the defrosting process, the indoor heat exchanger and the outdoor heat exchanger maintain heating operation; The defrosting process of the defrost coil includes: the high-temperature and high-pressure refrigerant discharged from the compressor passes through the oil separator and enters the defrost coil, heat is exchanged between the defrost coil and the frosted surface of the outdoor heat exchanger, the outdoor heat exchanger is defrosted by using the emitted heat, and the refrigerant after heat exchange returns to the suction end of the compressor.

2. The method according to claim 1, characterized in that Controlling the bypass hot water pipe or the defrost coil to be turned on according to the hot water demand to defrost the outdoor heat exchanger includes: Determining whether the hot water demand is less than a preset threshold; If yes, the bypass hot water pipe is controlled to be open to defrost the outdoor heat exchanger; If not, the defrost coil is controlled to be turned on to defrost the outdoor heat exchanger.

3. The method according to claim 2, characterized in that Determining whether the hot water demand is less than a preset threshold includes: Determine whether the current period is a low water consumption period; If yes, determining that the hot water demand is less than a preset threshold; If not, it is determined that the hot water demand is greater than or equal to the preset threshold.

4. The method according to claim 2, characterized in that A first valve is provided at the inlet end of the bypass hot water pipe to control the conduction of the bypass hot water pipe, and the method further includes: detecting the temperature of the frosted surface of the outdoor heat exchanger; The opening of the first valve is adjusted according to the temperature of the frosted surface; wherein, the lower the temperature of the frosted surface, the larger the opening of the first valve.

5. The method according to claim 2, characterized in that A second valve is provided at the inlet end of the defrost coil to control the defrost coil to be turned on, and the method further comprises: detecting the temperature of the frosted surface of the outdoor heat exchanger; The opening of the second valve is adjusted according to the temperature of the frosted surface; wherein, the lower the temperature of the frosted surface, the larger the opening of the second valve.

6. The method according to claim 1, wherein After controlling the bypass hot water pipe or the defrost coil to be turned on according to the hot water demand to defrost the outdoor heat exchanger, the method further includes: Determining whether the temperature parameter of the outdoor heat exchanger meets the defrost stopping condition; If yes, the hot water demand is controlled to control the bypass hot water pipe or the defrost coil to be turned off, and defrosting of the outdoor heat exchanger is stopped.

7. A combined power generation unit, characterized in that: The combined heat and power supply unit includes a hot water generator, an indoor heat exchanger, and an outdoor heat exchanger. The hot water generator leads to a bypass hot water pipe, at least part of which is arranged adjacent to the outdoor heat exchanger. The outdoor heat exchanger includes a condensing coil and a defrosting coil. The combined heat and power supply unit also includes: a controller configured to determine a user's hot water demand when defrosting is required, and control the bypass hot water pipe or the defrost coil to be turned on according to the hot water demand, so as to defrost the outdoor heat exchanger; wherein, during the defrosting process, the indoor heat exchanger and the outdoor heat exchanger maintain heating operation; The defrosting process of the defrost coil includes: the high-temperature and high-pressure refrigerant discharged from the compressor passes through the oil separator and enters the defrost coil, heat is exchanged between the defrost coil and the frosted surface of the outdoor heat exchanger, the outdoor heat exchanger is defrosted by using the emitted heat, and the refrigerant after heat exchange returns to the suction end of the compressor.

8. The combined heat and power generation unit according to claim 7, characterized in that: The dual heat supply unit further includes a compressor, and the hot water generator is arranged adjacent to the compressor.

9. The combined heat and power generation unit according to claim 7, characterized in that: The combined power generation unit further includes: a first valve, disposed at the inlet end of the bypass hot water pipe; The second valve is arranged at the inlet end of the defrost coil.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 1 to 6 is implemented.

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