Defrosting control method, air conditioning unit and computer readable storage medium

Abstract

The application discloses a defrosting control method, an air conditioning unit and a computer readable storage medium, and comprises the following steps: the unit enters a defrosting mode; the exhaust temperature of a compressor is detected, the suction pressure of the compressor is detected, and the suction temperature is calculated to obtain the suction superheat; when the exhaust temperature is greater than or equal to a second preset temperature T2 and the suction superheat is less than a first preset temperature T1, the unit is temporarily switched to a refrigeration mode for operation. The application detects the pressure and the suction temperature, calculates the suction superheat, judges whether the compressor is liquid-carrying, simultaneously detects the exhaust temperature, judges whether the exhaust temperature is reduced, and when the two conditions occur, the compressor heating belt can be started and switched to refrigeration, the refrigeration operation is performed during the defrosting interval, and the defrosting is switched again when the exhaust temperature is increased and the system operation is stable. Through the control method, the defrosting effect can be improved, and the compressor liquid-carrying during defrosting can be avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of air-conditioning defrosting, and in particular to a defrosting control method, an air-conditioning unit and a computer-readable storage medium. Background Art

[0002] After a refrigeration system has been running for a long time, frost will form on the evaporator. This frost reduces cooling efficiency and increases energy consumption, necessitating defrosting. Currently, the most commonly used defrosting methods in refrigeration systems are electric heating and thermal fluorine defrosting. Thermal fluorine defrosting consumes less energy, has a lower exhaust temperature than electric heating, and does not cause significant fluctuations in vehicle cabin temperature, making it increasingly popular.

[0003] Flooded operation of a compressor occurs when liquid enters the compressor, causing the liquid and gas to mix, forming a two-phase flow. This increases the load on the compressor and reduces its efficiency. Furthermore, the presence of liquid increases friction and wear, shortening its service life. Furthermore, liquid in the compressor may cause liquid hammer. Liquid hammer is the shock wave generated by the liquid within the compressor, which can impact and damage internal components and piping. This can lead to compressor failure and shutdown. Furthermore, liquid in the compressor can dilute the lubricant and reduce cooling effectiveness. This dilution reduces lubrication, increases friction and wear, and reduces cooling effectiveness, causing compressor temperatures to rise, potentially leading to overheating and damage. Overall, flooded operation negatively impacts compressor performance, lifespan, and reliability. Therefore, if flooded operation is detected, prompt inspection and maintenance should be performed to ensure proper operation.

[0004] However, the current logic of the unit's hot fluorine bypass defrost is not perfect and intelligent enough. When the ambient temperature is below 18°C, a thicker layer of frost will form on the evaporator, and the defrosting time is long. During defrosting, the compressor is likely to be liquid-carrying, which will affect the life of the compressor and reduce the reliability of the unit. At the same time, it is also likely to cause the exhaust temperature of the compressor to drop, resulting in a low temperature of the gaseous refrigerant entering the evaporator, which will make it impossible to melt the frost layer on the evaporator normally, thereby affecting the refrigeration effect and resulting in poor defrosting effect. Summary of the Invention

[0005] In order to solve the technical problem of poor hot fluorine bypass defrosting effect in the above-mentioned prior art, the present invention provides a defrost control method, an air conditioning unit and a computer-readable storage medium.

[0006] The technical solution adopted in the present invention is:

[0007] The present invention proposes a defrost control method, comprising the steps of:

[0008] The unit enters defrost mode;

[0009] Detect the exhaust temperature of the compressor, detect the suction pressure and suction temperature of the compressor to calculate the suction superheat;

[0010] When the exhaust gas temperature is greater than or equal to the second preset temperature T2 and the suction gas superheat is less than the first preset temperature T1, the control unit is temporarily switched to the cooling mode.

[0011] When the exhaust temperature is lower than the second preset temperature T2, the compressor heating belt is turned on to increase the exhaust temperature of the compressor.

[0012] After the air-conditioning unit is temporarily switched to the cooling mode, the unit is controlled to switch from the cooling mode to the defrosting mode to continue defrosting until the exhaust temperature is greater than the third preset temperature T3.

[0013] When the exhaust temperature is greater than or equal to the second preset temperature T2, and the suction superheat is greater than or equal to the first preset temperature T1, detect whether the defrost exit condition is met. If so, end the defrost and control the unit to switch from defrost mode to refrigeration mode. If not, continue to run in defrost mode.

[0014] Specifically, before the unit is switched from the defrost mode to the refrigeration mode, the defrost water accumulated during the defrost process is discharged.

[0015] Specifically, the control unit temporarily switches to the cooling mode to increase the opening of the electronic expansion valve.

[0016] The defrost exit conditions specifically include: the cumulative defrost operation time reaches a preset time, or the temperature detected by the defrost temperature sensor is greater than the preset defrost exit temperature.

[0017] The conditions for the unit to enter the defrost mode include: the temperature detected by the defrost temperature sensor is lower than the preset defrost temperature and lasts for a second preset time.

[0018] The present invention also provides an air-conditioning unit that controls defrosting using the above-mentioned defrost control method.

[0019] The present invention also provides a computer-readable storage medium for storing a computer program, wherein the computer program executes the above-mentioned defrost control method when running.

[0020] Compared with the existing technology, the defrost control method proposed in the present invention can improve the reliability of the unit and make defrosting more intelligent. By detecting the pressure and suction temperature, calculating the suction superheat, and judging whether the compressor is entrained with liquid, and detecting the exhaust temperature at the same time, judging whether the exhaust temperature has dropped, when these two situations occur, the compressor heating belt can be turned on and switched to refrigeration. Refrigeration operation can be carried out during the defrosting interval. When the exhaust temperature rises and the system operation stabilizes, the defrost can be switched back to defrosting. This control method can not only improve the defrosting effect, but also avoid compressor entrainment during defrosting, improve the reliability of compressor operation, and make defrosting more intelligent. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 is a flow chart in an embodiment of the present invention;

[0023] Figure 2 It is a flow chart in a specific embodiment of the present invention;

[0024] Figure 3 This is a flow chart of entering defrost in an embodiment of the present invention;

[0025] Figure 4 This is a flow chart of exiting defrost in an embodiment of the present invention;

[0026] Figure 5 A simplified structural diagram of an embodiment of the present invention;

[0027] 1. Compressor; 11. Exhaust temperature sensor; 12. Intake temperature sensor; 13. Pressure sensor;

[0028] 2. Four-way valve;

[0029] 3. Condenser;

[0030] 4. Evaporator;

[0031] 5. Electronic expansion valve. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0033] The principle and structure of the present invention are described in detail below with reference to the accompanying drawings and embodiments.

[0034] Flooded operation of a compressor occurs when liquid enters the compressor, causing the liquid and gas to mix, forming a two-phase flow. This increases the load on the compressor and reduces its efficiency. Furthermore, the presence of liquid increases friction and wear, shortening its service life. Furthermore, liquid in the compressor may cause liquid hammer. Liquid hammer is the shock wave generated by the liquid within the compressor, which can impact and damage internal components and piping. This can lead to compressor failure and shutdown. Furthermore, liquid in the compressor can dilute the lubricant and reduce cooling effectiveness. This dilution reduces lubrication, increases friction and wear, and reduces cooling effectiveness, causing compressor temperatures to rise, potentially leading to overheating and damage. Overall, flooded operation negatively impacts compressor performance, lifespan, and reliability. Therefore, if flooded operation is detected, prompt inspection and maintenance should be performed to ensure proper operation.

[0035] The current defrosting logic for hot fluorine bypass in chillers is not fully developed or intelligent enough. When the ambient temperature is below 18°C, a thick layer of frost forms on the evaporator, requiring a long defrost time. This can easily lead to compressor carryover, shortening compressor life and reducing unit reliability. Furthermore, it can easily lower the compressor's exhaust temperature, resulting in a low temperature for the gaseous refrigerant entering the evaporator. This prevents the frost from being properly melted, further impacting the cooling effect and resulting in poor defrosting. To address this issue, the present invention proposes a defrost control method that, while operating in defrost mode, temporarily switches to cooling mode based on the exhaust temperature and suction superheat to prevent compressor carryover, which can affect compressor life. This method increases the exhaust temperature and the temperature of the gaseous refrigerant entering the evaporator, thereby improving the defrosting effect.

[0036] like Figure 1 、 2 As shown, the present invention proposes a defrost control method for an air-conditioning unit with thermal fluorine defrosting, which specifically includes the following steps:

[0037] After the unit meets the defrost conditions, it enters the defrost mode, that is, it runs in the defrost mode;

[0038] Real-time detection of the compressor's exhaust temperature, suction pressure and temperature, and calculation of the compressor's suction superheat;

[0039] Determine whether the exhaust temperature of the compressor is less than the second preset temperature T2, and determine whether the suction superheat of the compressor is less than the first preset temperature T1;

[0040] When the exhaust temperature is greater than or equal to the second preset temperature T2, and the suction superheat is less than the first preset temperature T1, the control unit temporarily switches from the defrost mode to the refrigeration mode. This is because the hot fluorine refrigeration system has only one electronic expansion valve. During defrosting, the electronic expansion valve is fully open and cannot adjust the pressure of the compressor suction port. The electronic expansion valve cannot play a regulating role. When the frost layer is very thick and cannot evaporate, liquid will appear. During normal refrigeration, the suction pressure can be adjusted by the electronic expansion valve. When the suction superheat is too low, it will switch back to the refrigeration mode to ensure that the compressor runs without liquid. After the system runs stably and the exhaust temperature rises, it will switch to the defrost mode to continue defrosting. This can ensure defrost efficiency and avoid the compressor running with liquid, thereby avoiding increasing the load on the compressor.

[0041] In a specific embodiment, it is determined whether the exhaust temperature of the compressor is less than the second preset temperature T2. When the exhaust temperature is less than the second preset temperature T2, the compressor heating belt is turned on to increase the exhaust temperature of the compressor until the exhaust temperature is greater than or equal to the second preset temperature T2. That is, the compressor or the exhaust section of the compressor is directly heated by the heating belt installed on the compressor to slowly increase the exhaust temperature of the compressor. A compressor exhaust temperature that is too low may mean that the workload of the compressor is too light and its design capacity cannot be fully utilized. This will lead to a decrease in system efficiency and an increase in energy consumption. A compressor exhaust temperature that is too low may cause the temperature of the lubricating oil to be too low, causing its viscosity to increase, affecting the lubrication effect. This may lead to problems such as poor lubrication and lubricating oil leakage, thereby affecting the life and performance of the compressor. Therefore, maintaining an appropriate compressor exhaust temperature in defrost mode is very important for the normal operation and performance of the system.

[0042] The defrost control method proposed in the present invention can improve the reliability of the unit and make defrosting more intelligent. By detecting the pressure and suction temperature, calculating the suction superheat, and judging whether the compressor is entrained with liquid, and detecting the exhaust temperature at the same time, judging whether the exhaust temperature has dropped, when these two situations occur, the compressor heating belt can be turned on and switched to refrigeration. Refrigeration operation can be carried out during the defrosting interval. When the exhaust temperature rises and the system operation stabilizes, the defrost can be switched back to defrosting. This control method can not only improve the defrosting effect, but also avoid the compressor from entraining with liquid during defrosting, improve the reliability of the compressor operation, and make defrosting more intelligent.

[0043] Specifically, after the control unit temporarily switches to the cooling mode, it switches from the cooling mode to the defrost mode to continue defrosting until the exhaust temperature exceeds the third preset temperature T3. This ensures that the compressor maintains an appropriate exhaust temperature and the compressor is in normal operation, and then switches back to the defrost mode to continue defrosting.

[0044] When the exhaust temperature is greater than or equal to the second preset temperature T2, and the suction superheat is greater than or equal to the first preset temperature T1, detect whether the defrost exit condition is met. If so, end the defrost and control the unit to switch from defrost mode to refrigeration mode. If not, continue to run in defrost mode.

[0045] When the exhaust temperature is greater than or equal to the second preset temperature T2 and the suction superheat is greater than or equal to the first preset temperature T1, the compressor is in normal working condition. In this state, the defrosting efficiency is the highest if the defrosting is continued. If the air-conditioning unit reaches the conditions for exiting defrosting, the defrosting is terminated and the air-conditioning unit is controlled to switch from the defrosting mode to the cooling mode.

[0046] Before temporarily switching the unit to cooling mode, drain the defrost water accumulated during the defrosting process (specifically, drain the defrost from the evaporator's water receiving tray) and then switch back to cooling mode. This prevents the water from re-condensing and forming frost in cooling mode, which can affect the defrosting effect. In addition, when temporarily switching the unit to cooling mode, increase the opening of the electronic expansion valve (the opening of the electronic expansion valve can be increased to the previous opening before returning to defrost mode). This increases the refrigerant flow rate and reduces the suction superheat. While ensuring that there is no liquid, try to increase the evaporation temperature as much as possible. Frost will not form if the evaporation temperature is controlled above 0°C. These two control conditions ensure that repeated frosting will not occur after temporarily switching to cooling mode.

[0047] like Figure 3 As shown, the condition for the air conditioner to enter the defrost mode includes: the temperature detected by the defrost temperature sensor is lower than the preset defrost temperature and lasts for a second preset time. In addition, there are other commonly used conditions for air conditioners to enter the defrost mode in the prior art, such as when the humidity is too high.

[0048] like Figure 4 As shown, the defrost exit conditions of the air-conditioning unit specifically include: the cumulative defrost operation time reaches a preset time, or the temperature detected by the defrost temperature sensor is greater than the preset defrost exit temperature.

[0049] The present invention also provides an air-conditioning unit that controls defrosting using the above-mentioned defrost control method.

[0050] like Figure 5As shown, the air conditioner is a conventional heat-compression defrosting air conditioner, specifically one with a four-way valve that switches between cooling and heating modes. The air conditioning unit specifically comprises a compressor 1, a condenser 3, a four-way valve 2, an electronic expansion valve 5, and an evaporator 4, interconnected by a pipeline. The intake side of compressor 1 is equipped with an intake temperature sensor 12 for detecting intake air temperature and a pressure sensor 13 for detecting intake air pressure. The exhaust side of compressor 1 is equipped with an exhaust temperature sensor 11 for detecting exhaust air temperature. The compressor draws in low-temperature, low-pressure refrigerant gas, which is then compressed to increase its temperature and pressure. The condenser transfers heat from the high-temperature, high-pressure refrigerant gas to the surrounding environment, cooling it and converting it into a high-temperature, high-pressure refrigerant liquid. The electronic expansion valve controls the flow of the refrigerant liquid, directing it into the evaporator. The evaporator absorbs heat from the surrounding environment through evaporation, converting it into a low-temperature, low-pressure refrigerant gas. The low-temperature, low-pressure refrigerant gas is then drawn back into the compressor, repeating the cycle. Throughout this process, through the refrigerant's continuous phase change, the air conditioner transfers heat from the indoor environment to the outdoors, achieving a cooling effect. The four-way valve can switch the refrigerant flow direction, so that the refrigerant from the compressor exhaust side changes from flowing directly to the condenser to flowing directly to the evaporator, that is, switching from refrigeration mode to defrost mode, and defrosting through thermal fluorine, that is, defrosting the evaporator through the heat of the refrigerant.

[0051] The present invention mainly detects the exhaust temperature, suction pressure and suction temperature, and judges whether the exhaust temperature is reduced and whether the compressor is liquid-carrying based on the two key parameters of exhaust temperature and superheat. The unit controls the compressor heating belt to turn on to increase the exhaust temperature and improve the defrosting effect, and turns on the defrost interval refrigeration operation to prevent the compressor from being liquid-carrying, thereby improving the operating reliability of the compressor. Through this complete set of defrost control logic, the effect of intelligent defrosting is achieved, and the operating reliability of the unit is improved at the same time.

[0052] The present invention also provides a computer-readable storage medium for storing a computer program, wherein the computer program executes the above-mentioned defrost control method when running.

[0053] In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software as a computer program product, the functions may be stored on or transmitted via a computer-readable medium as one or more instructions or code. Computer-readable media includes both computer storage media and communication media, including any medium that facilitates the transfer of a computer program from one location to another. A storage medium may be any available medium that can be accessed by a computer. By way of example and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Any connection is also properly referred to as a computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. As used herein, disk and disc include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, where disks typically reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0054] It should be noted that the terms used above are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0055] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments can have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0056] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention; the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0057] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0058] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0059] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A defrost control method, characterized in that: Including steps: The air conditioning unit enters defrost mode; Detect the exhaust temperature of the compressor, detect the suction pressure and suction temperature of the compressor and calculate the suction superheat; When the exhaust temperature is greater than or equal to the second preset temperature T2 and the suction air superheat is less than the first preset temperature T1, the air conditioning unit is controlled to temporarily switch to the cooling mode.

2. The defrost control method according to claim 1, wherein: When the exhaust temperature is lower than the second preset temperature T2, the compressor heating belt is turned on to increase the exhaust temperature of the compressor.

3. The defrost control method according to claim 1, wherein: After the air conditioning unit is controlled to temporarily switch to the cooling mode, until the exhaust temperature is greater than the third preset temperature T3, the air conditioning unit is controlled to switch from the cooling mode to the defrosting mode to continue defrosting.

4. The defrost control method according to claim 1, wherein: When the exhaust temperature is greater than or equal to the second preset temperature T2, and the suction superheat is greater than or equal to the first preset temperature T1, it is detected whether the defrost exit condition is met; if so, defrost is terminated; if not, the defrost mode is continued.

5. The defrost control method according to claim 1, wherein: Before controlling the air-conditioning unit to temporarily switch from defrost mode to cooling mode, discharge the defrost water accumulated during the defrost process.

6. The defrost control method according to claim 1, wherein: The air conditioning unit temporarily switches to the cooling mode and increases the opening of the electronic expansion valve.

7. The defrost control method according to claim 4, wherein: The defrost exit condition specifically includes: the accumulated defrost operation time reaches a preset time, or the temperature detected by the defrost temperature sensor is greater than a preset defrost exit temperature.

8. The defrost control method according to claim 1, wherein: The condition for the air-conditioning unit to enter the defrost mode includes: the temperature detected by the defrost temperature sensor is lower than the preset defrost entry temperature and lasts for a second preset time period.

9. An air conditioning unit, characterized in that: Defrosting is controlled using the defrost control method according to any one of claims 1 to 8.

10. A computer-readable storage medium for storing a computer program, characterized in that: When the computer program is running, the defrost control method according to any one of claims 1 to 8 is executed.

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