Defrosting control method and refrigeration equipment

Abstract

The invention provides a defrosting control method and refrigeration equipment, and the method comprises the steps that a defrosting condition is preset, if the defrosting condition is met, a first air return pipe temperature difference is calculated, and the first air return pipe temperature difference is the difference value between the air return pipe average temperature before the defrosting condition is met and the air return temperature; if the first air return pipe temperature difference is smaller than a first temperature difference threshold value and larger than or equal to a second temperature difference threshold value, a first defrosting instruction is executed; if the first air return pipe temperature difference is smaller than a second temperature difference threshold value and larger than or equal to a third temperature difference threshold value, a second defrosting instruction is executed; and if the first air return pipe temperature difference is smaller than a third temperature difference threshold value, a third defrosting instruction is executed. According to the method, by calculating the temperature difference of the air return pipe and dynamically adjusting the defrosting instruction according to the change of the temperature difference of the air return pipe, the frosting condition of the fin evaporator can be judged more accurately, the unnecessary defrosting frequency is reduced, and energy consumption is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of defrost control, and in particular to a defrost control method and a refrigeration device. Background Art

[0002] During the operation of the refrigeration equipment, when the cold air passes through the fin evaporator, the water vapor in it will condense on the low-temperature surface and gradually form a frost or ice layer. The frost layer will hinder the heat exchange between the refrigerant and the outside air, resulting in a decrease in heat transfer efficiency. When the fin evaporator is covered with frost, the ability to absorb heat is weakened, resulting in the refrigeration equipment being unable to effectively reduce the temperature.

[0003] To improve refrigeration efficiency, defrost can be performed through defrost control methods. For example, the frosting condition of the refrigerator fin evaporator can be judged through temperature environment, cumulative compressor operating time, number of door openings and closings, etc., so as to adjust the defrost control strategy for effective defrosting.

[0004] However, based on the above jump, only the frosting condition of the fin evaporator can be sensed. When the preset conditions are reached, the fin evaporator will be only partially frosted. At this time, defrosting is started, resulting in energy waste. Summary of the invention

[0005] The present application provides a defrost control method and a refrigeration device to solve the problem of energy waste during the defrost process.

[0006] In a first aspect, the present application provides a defrost control method, comprising:

[0007] Preset defrost conditions;

[0008] If the defrosting condition is met, the first return air pipe temperature difference is calculated, where the first return air pipe temperature difference is the difference between the return air pipe average temperature and the return air temperature before the defrosting condition is met;

[0009] If the temperature difference of the first air return pipe is less than the first temperature difference threshold and greater than or equal to the second temperature difference threshold, execute the first defrost instruction;

[0010] If the temperature difference of the first air return pipe is less than the second temperature difference threshold and greater than or equal to the third temperature difference threshold, execute the second defrost instruction;

[0011] If the temperature difference of the first return air pipe is less than the third temperature difference threshold, the third defrost instruction is executed.

[0012] In some feasible embodiments, the defrosting conditions at least include ambient temperature, cumulative compressor operation time, and door opening and closing times;

[0013] If the defrosting condition is met, the temperature difference of the first return air pipe is calculated, including:

[0014] Obtain the ambient temperature, cumulative compressor operation time, and door opening and closing times;

[0015] If the ambient temperature is lower than the ambient temperature threshold, or the accumulated running time of the compressor is higher than the time threshold, or the number of door openings and closings is higher than the number threshold, the average temperature of the return air pipe is obtained;

[0016] Calculating an average value of the ambient temperature and matching the return air temperature based on the average value;

[0017] The first return air pipe temperature difference is calculated by the return air pipe average temperature and the return air temperature.

[0018] In some feasible embodiments, matching the return air temperature based on the average value includes:

[0019] If the average value is less than or equal to the first temperature, a first return air temperature is matched, where the first return air temperature is the difference between the average temperature of the return air pipe and a first preset value;

[0020] If the average value is greater than the first temperature and less than or equal to the second temperature, match the second return air temperature, the second return air temperature is the difference between the average temperature of the return air pipe and a second preset value, and the second preset value is greater than the first preset value;

[0021] If the average value is greater than the second temperature, the third return air temperature is matched, and the third return air temperature is the difference between the average temperature of the return air pipe and a third preset value, and the third preset value is greater than the second preset value.

[0022] In some feasible embodiments, if the first return air pipe temperature difference is less than a first temperature difference threshold and greater than or equal to a second temperature difference threshold, executing a first defrost instruction includes:

[0023] If the first return air duct temperature difference is less than the first temperature difference threshold and greater than or equal to the second temperature difference threshold, obtain a first preset number of second return air duct temperature differences, where the second return air duct temperature difference is the return air duct temperature difference obtained after obtaining the first return air duct temperature difference;

[0024] If there is a preset proportion of the second return air pipe temperature difference in the first preset number that is less than the first temperature difference threshold and greater than or equal to the second temperature difference threshold, set the first defrost instruction to perform defrosting after the defrost interval is increased by the first time;

[0025] If there is a preset proportion of the second return air pipe temperature difference in the first preset number that is less than the second temperature difference threshold and greater than or equal to the third temperature difference threshold, execute the second defrost instruction;

[0026] If there is a preset proportion of the second return air pipe temperature difference in the first preset number that is less than the third temperature difference threshold, the third defrost instruction is executed.

[0027] In some feasible embodiments, if the first return air pipe temperature difference is less than the second temperature difference threshold and greater than or equal to the third temperature difference threshold, executing the second defrost instruction includes:

[0028] If the first return air duct temperature difference is less than the second temperature difference threshold and greater than or equal to the third temperature difference threshold, obtain a second preset number of third return air duct temperature differences, where the third return air duct temperature difference is the return air duct temperature difference before obtaining the first return air duct temperature difference;

[0029] Obtaining a second preset number of accumulated time durations during which the temperature difference of the third air return pipe is less than the second temperature difference threshold;

[0030] If the accumulated time is less than the first time, the second defrost instruction is set to add a second time to the defrost interval, and the second time is less than the first time.

[0031] In some feasible embodiments, if the first return air pipe temperature difference is less than the second temperature difference threshold and greater than or equal to the third temperature difference threshold, executing the second defrost instruction further includes:

[0032] If the accumulated time is greater than or equal to the first time and less than the second time, obtain a first preset number of accumulated time periods during which the temperature difference of the third return air pipe is less than the second temperature difference threshold;

[0033] If the accumulated time is greater than or equal to the second time, the defrosting time is calculated, where the defrosting time is the time from the last defrosting completion;

[0034] If the defrost time is greater than or equal to the first time, the second defrost instruction is set to execute defrost.

[0035] In some feasible embodiments, if the temperature difference of the first return air pipe is less than a third temperature difference threshold, executing a third defrost instruction includes:

[0036] If the first return air pipe temperature difference is less than the third temperature difference threshold, obtaining a fourth return air pipe temperature difference, where the fourth return air pipe temperature difference is the return air pipe temperature difference before obtaining the first return air pipe temperature difference;

[0037] If there is a preset proportion of the temperature difference of the fourth return air pipe in the first preset number that is less than the third temperature difference threshold, the defrost time is calculated, and the defrost time is the time from the last defrost completion;

[0038] If the defrost time is greater than or equal to the first time, the third defrost instruction is set to execute defrost.

[0039] In some feasible embodiments, the method further includes:

[0040] If there is a preset proportion of the temperature difference of the fourth return air pipe in the first preset number that is greater than or equal to the third temperature difference threshold and less than the second temperature difference threshold, execute the second defrost instruction;

[0041] If there is no preset proportion of the fourth return air duct temperature difference less than the third temperature difference threshold value in the first preset number, or there is no preset proportion of the fourth return air duct temperature difference greater than or equal to the third temperature difference threshold value and less than the second temperature difference threshold value in the first preset number, obtain the fifth return air duct temperature difference of the third preset number, and the fifth return air duct temperature difference is the return air duct temperature difference obtained after obtaining the first return air duct temperature difference;

[0042] Based on the third preset number of fifth return air duct temperature differences, the first preset number of sixth return air duct temperature differences are obtained, so as to obtain a defrost instruction through the sixth return air duct temperature difference, the sixth return air duct temperature difference is the return air duct temperature difference obtained after obtaining the fifth return air duct temperature difference, and the defrost instruction includes a first defrost instruction, a second defrost instruction and a third defrost instruction.

[0043] In some feasible embodiments, the method further includes:

[0044] If the temperature difference of the first air return pipe is greater than or equal to the first temperature difference threshold, the defrost instruction is not executed.

[0045] In a second aspect, the present application provides a refrigeration device, comprising:

[0046] A control unit configured to preset defrost conditions;

[0047] The temperature acquisition module is configured to calculate a first return air pipe temperature difference if the defrosting condition is met, wherein the first return air pipe temperature difference is a difference between an average return air pipe temperature before the defrosting condition is met and the return air temperature;

[0048] The control unit is further configured to:

[0049] If the temperature difference of the first air return pipe is less than the first temperature difference threshold and greater than or equal to the second temperature difference threshold, execute the first defrost instruction;

[0050] If the temperature difference of the first air return pipe is less than the second temperature difference threshold and greater than or equal to the third temperature difference threshold, execute the second defrost instruction;

[0051] If the temperature difference of the first return air pipe is less than the third temperature difference threshold, the third defrost instruction is executed.

[0052] It can be seen from the above technical scheme that the present application provides a defrost control method and refrigeration equipment, the method comprising: presetting defrost conditions, if the defrost conditions are met, calculating the first return air pipe temperature difference, the first return air pipe temperature difference being the difference between the average temperature of the return air pipe before the defrost conditions are met and the return air temperature; if the first return air pipe temperature difference is less than the first temperature difference threshold, and greater than or equal to the second temperature difference threshold, executing the first defrost instruction; if the first return air pipe temperature difference is less than the second temperature difference threshold, and greater than or equal to the third temperature difference threshold, executing the second defrost instruction; if the first return air pipe temperature difference is less than the third temperature difference threshold, executing the third defrost instruction. The method calculates the return air pipe temperature difference, and then dynamically adjusts the defrost instruction according to the change of the return air pipe temperature difference, so as to more accurately judge the frosting condition of the fin evaporator, reduce the number of unnecessary defrosting times, and reduce energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0054] Figure 1 A schematic diagram of a process for controlling defrosting by preset conditions provided in an embodiment of the present application;

[0055] Figure 2 A schematic diagram of a defrost control method provided in an embodiment of the present application;

[0056] Figure 3 A schematic diagram of the temperature difference treatment of the second air return pipe provided in an embodiment of the present application;

[0057] Figure 4 Schematic diagram of the temperature difference processing of the third return air pipe provided in an embodiment of the present application. DETAILED DESCRIPTION

[0058] The following embodiments are described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following embodiments do not represent all implementations consistent with the present application. They are only examples of systems and methods consistent with some aspects of the present application as detailed in the claims.

[0059] Defrosting is a maintenance operation during the operation of refrigeration equipment, such as refrigerators and air conditioners, to remove frost or ice formed on the surface of the fin evaporator.

[0060] As the cold air passes through the finned evaporator, the water vapor in it will condense on the low-temperature surface and gradually form a frost or ice layer. These frost layers will hinder the heat exchange between the refrigerant and the outside air, resulting in a decrease in heat transfer efficiency. If these frost layers are not removed in time, the effective heat exchange area of ​​the finned evaporator will be reduced, which will affect the cooling effect of the entire refrigeration equipment.

[0061] When the fin evaporator is covered with frost, the ability to absorb heat is reduced, which will cause the refrigerator or air conditioner to not be able to effectively reduce the temperature. For refrigerators, food may not be fully cooled or frozen; for air conditioners, the room temperature will be reduced more slowly or even fail to reach the set temperature. Defrosting can restore the working efficiency of the fin evaporator, ensuring that the refrigeration system can work normally as required and maintain the required temperature level.

[0062] The fin evaporator is a component in a refrigeration system that improves heat exchange efficiency by increasing the surface area. In some embodiments, the fin evaporator includes tubes, fins, a frame, and connectors.

[0063] Low-temperature and low-pressure refrigerant circulates inside the tubes. The finned evaporator is composed of a series of slender metal tubes arranged in parallel. Each tube is attached to the outside with thin and dense metal sheets, namely fins. The fins can increase the effective surface area in contact with the surrounding air, thereby improving the heat exchange efficiency.

[0064] To support the finned evaporator and ensure smooth airflow, the finned evaporator is mounted in a sturdy frame, and connectors are used to connect the refrigerant input and output ends to other parts of the system, such as the compressor, condenser, etc.

[0065] When the refrigerant flows through the finned evaporator, it changes from liquid to gas and absorbs a lot of heat. This process occurs inside the tube, and the heat comes from the outside air or liquid medium. The function of the fin is to increase the heat exchange area so that more heat can be transferred from the surrounding air to the refrigerant. As the temperature of the refrigerant rises, it begins to evaporate, taking away a lot of heat in the process, causing the air or liquid passing through the finned evaporator to be cooled.

[0066] To ensure optimal heat exchange, the finned evaporator can also be used in conjunction with a fan or other device to direct the airflow through the gaps between the fins to maximize heat transfer efficiency.

[0067] The fin evaporator in the refrigerator is located inside or near the freezer. Since the internal environment of the refrigerator is relatively closed and the temperature is low, frost is easily formed. Therefore, the fin evaporator of the refrigerator needs to be specially designed to delay frosting and cooperate with timed defrost or frost-free technology.

[0068] The finned evaporator in the air conditioner needs to be able to cope with a wider range of temperature and humidity changes, especially in the high temperature and high humidity conditions in summer. The air conditioner will also produce frost under certain circumstances, but its defrosting mechanism is automatic and can be completed without affecting the user's comfort. In order to achieve rapid cooling and energy-saving operation, the design of the finned evaporator of the air conditioner pays more attention to air duct optimization, corrosion resistance and easy cleaning and maintenance.

[0069] The presence of frost not only reduces refrigeration efficiency, but also forces the compressor and other components to increase power or work in other ways to compensate for the lost energy, thereby increasing energy consumption. Regular defrosting helps to maintain the system in optimal operating condition, avoid unnecessary waste of electricity, and reduce operating costs.

[0070] Excessive frost accumulation can cause physical damage to the components inside the refrigeration equipment, such as increasing mechanical stress, causing fan blades to become unbalanced, or causing electrical connections to short out due to moisture. Proper defrosting procedures can help protect these sensitive components from damage and extend the overall life of the equipment.

[0071] In air conditioners, heavy frost can block air ducts, restrict air flow, and affect indoor air quality and cooling / heating effects. Removing frost ensures proper air circulation, allowing the air conditioner to regulate the room temperature more evenly and helping to maintain good indoor environmental quality.

[0072] In summary, defrosting ensures that refrigeration equipment can operate efficiently and reliably while saving energy and protecting the equipment from damage.

[0073] The defrost mechanism may include various methods, such as periodic defrosting, cumulative running time defrosting, temperature and humidity condition defrosting, door opening and closing times defrosting, comprehensive defrost control, etc.

[0074] In some embodiments, the defrost procedure is automatically triggered according to a fixed time interval. For example, a refrigerator or air conditioner may be programmed to defrost once every 6 hours, 12 hours, or 24 hours. No additional sensors are required, which is suitable for daily use scenarios. However, it cannot adapt to the actual changes in frosting conditions, which may lead to unnecessary defrosting operations and waste energy.

[0075] Cumulative running time defrost records the cumulative running time of the compressor. When the preset threshold is reached, the defrost procedure will be started. This method assumes that as the compressor running time increases, the frost layer on the evaporator will gradually thicken. Taking into account the actual workload of the equipment, but lacking direct measurement of the specific frosting situation, it may lead to premature or late defrosting during low-load operation.

[0076] Temperature and humidity conditional defrosting combines ambient temperature and humidity levels to predict the possibility of frost. For example, under low temperature and high humidity conditions, frost is more likely to form, so the defrosting frequency can be adjusted. It can better reflect the impact of the external environment on frost and improve the accuracy of defrosting decisions. However, it requires additional sensor support, which increases complexity and cost.

[0077] For refrigerators, frequent door openings will cause more moisture to enter the interior, accelerating the frosting process. Therefore, the speed of frosting can be estimated by counting the number of door openings and closings, and the defrosting cycle can be adjusted accordingly. It can directly link user behavior with the frosting rate, making defrosting closer to actual needs. However, it is only applicable to equipment with a clear door opening mechanism, such as refrigerators, and cannot be used alone as a basis for judgment. It needs to be used in combination with other conditions.

[0078] Comprehensive defrost control can combine the above factors to form an algorithm to determine the optimal defrost time. For example, some refrigerators will consider factors such as compressor running time, ambient temperature, humidity, and door opening and closing times at the same time, using built-in logic or artificial intelligence algorithms to make intelligent decisions.

[0079] like Figure 1 As shown, in some embodiments, when the refrigeration equipment is in a refrigeration state, the number of door openings and closings and the cumulative working time of the compressor are recorded, and the ambient temperature is detected by an ambient temperature sensor, and preset conditions are set. The preset conditions may be an ambient temperature threshold, a door opening and closing number threshold, a compressor cumulative working time threshold, etc. If the threshold is exceeded, refrigeration is stopped, and the heater is controlled to start and continue heating. If the temperature detected by the defrost sensor reaches the preset temperature, the heater is controlled to stop running and wait for defrosting. If the threshold is not exceeded, the number of door openings and closings and the cumulative working time of the compressor are obtained again.

[0080] In summary, relying on preset conditions, such as ambient temperature, cumulative compressor operating time, door opening and closing times, etc. to estimate the degree of frosting on the evaporator and arranging the defrost cycle accordingly has certain limitations, because it is impossible to accurately judge the actual frosting situation.

[0081] When the refrigerator's fin evaporator is only partially frosted, if the defrost process is started according to the above-mentioned fixed defrost strategy, the defrost heater requires energy to melt the frost layer, even when it is not necessary. Unnecessary defrosting consumes extra electricity; and after each defrost, the set cooling temperature needs to be reached again, which prolongs the freezing and refrigeration time; excessive use of the defrost heater and other components may cause these parts to wear out faster, thereby shortening their service life and increasing energy consumption.

[0082] To solve the above problems, some embodiments of the present application provide a defrost control method, which calculates the temperature difference of the return air pipe and dynamically adjusts the defrost instruction according to the change of the temperature difference of the return air pipe. This method can more accurately judge the frosting condition of the fin evaporator, reduce the number of unnecessary defrosting times, and reduce energy consumption.

[0083] like Figure 2 As shown, the method comprises the following steps:

[0084] S100: Preset defrost conditions.

[0085] In this embodiment, the defrost conditions are preset first, and then the judgment is continued based on the defrost conditions. The defrost conditions refer to a set of parameters or logic rules preset in the control system of the refrigeration equipment. When these conditions are met, the control system can start the defrost program. However, in this embodiment, if the defrost conditions are met, other parameters are continued to be judged without directly starting the defrost program. Among them, the defrost conditions at least include the ambient temperature, the cumulative running time of the compressor, and the number of door openings and closings.

[0086] Ambient temperature refers to the temperature of the air in the environment where the refrigeration equipment is located. It can be measured by a temperature sensor installed inside or outside the equipment. The ambient temperature affects the workload of the refrigeration equipment and the frost formation speed on the evaporator. Lower ambient temperatures will lead to faster frost formation, while higher temperatures may slow down the frosting process.

[0087] As part of the defrost condition, the defrost frequency can be adjusted based on the current ambient temperature. For example, in cold seasons, more frequent defrost may be required even if the compressor runs for a shorter time.

[0088] The cumulative running time of the compressor is the total time the compressor has been working continuously since the last defrost, which can be recorded by the built-in timer and stored in the equipment control system. The running time of the compressor is related to the accumulation of cold on the surface of the evaporator. A longer running time means that more cold is transferred to the evaporator, which increases the possibility of frost.

[0089] The thickness of the frost layer that may form on the evaporator can be predicted based on the accumulated running time of the compressor, and the defrost cycle can be set based on the frost thickness. If the compressor has been running for a long time, defrost may be triggered even if other conditions have not been met.

[0090] In refrigeration equipment, for refrigerators, the number of door openings and closings is the number of times the refrigerator door is opened and closed within a certain period of time, which can be calculated by the switch sensor or infrared sensing device installed on the door. Every time the user opens the door, external moisture will enter the refrigerator, increasing the risk of frost on the evaporator. Frequent door opening and closing actions can easily accelerate the formation of frost.

[0091] The defrost strategy can be dynamically adjusted according to the number of door opening and closing times. If a large number of door opening and closing events are detected in a short period of time, defrost can be started in advance to prevent excessive frost accumulation even if the compressor operating time and ambient temperature have not reached the preset thresholds.

[0092] S200: If the defrosting condition is met, the temperature difference of the first return air pipe is calculated.

[0093] In this embodiment, the defrost conditions can be achieved by the ambient temperature, the cumulative running time of the compressor and the number of door openings and closings simultaneously satisfying the defrost conditions, or a certain condition can satisfy the defrost conditions. For example, when the ambient temperature is greater than the ambient temperature threshold, the temperature difference of the first return air pipe is calculated; for example, when the ambient temperature is greater than the ambient temperature threshold, the cumulative running time of the compressor is greater than the time threshold, and the number of door openings and closings is greater than the number threshold, and all of these conditions are met, then the temperature difference of the first return air pipe is calculated, and no limitation is made here.

[0094] In some embodiments, the ambient temperature, the cumulative running time of the compressor, and the number of door openings and closings are obtained;

[0095] If the ambient temperature is greater than the ambient temperature threshold, or the cumulative running time of the compressor is greater than the time threshold, or the number of door openings and closings is greater than the number threshold, the average temperature of the return air pipe is obtained;

[0096] Calculating an average value of the ambient temperature and matching the return air temperature based on the average value;

[0097] The first return air pipe temperature difference is calculated by the return air pipe average temperature and the return air temperature.

[0098] The ambient temperature threshold is a preset temperature threshold used to determine whether the current ambient temperature is low enough to cause evaporator frosting. The ambient temperature threshold is used as a trigger to obtain the average temperature of the return air pipe. Only when the ambient temperature is low, the frosting condition is further confirmed. For example, when the ambient temperature is lower than the ambient temperature threshold, by setting the ambient temperature threshold, the risk of frosting in a low temperature environment can be responded to more accurately to avoid unnecessary defrosting operations.

[0099] The time threshold is a preset time limit, which indicates that the continuous operation of the compressor may cause sufficient frost to form on the evaporator after reaching this time. The time threshold is used as a condition to trigger the acquisition of the average temperature of the return air pipe. Further evaluation of the frosting situation is only considered after the compressor has been running for a long time. For example, the cumulative running time of the compressor is greater than the time threshold. By clarifying the limit of the compressor running time, it is helpful to accurately predict the frosting caused by long-term refrigeration, so as to start the defrost program in time.

[0100] The number threshold is a preset limit on the number of door openings, which characterizes the extent to which frequent opening of the refrigerator door may cause rapid frosting of the evaporator. The number threshold serves as a trigger for obtaining the average temperature of the return air pipe. Further evaluation of the frosting situation is only considered after the door is frequently opened and closed in a short period of time. For example, if the number of door openings is greater than the number threshold, setting the door opening number limit can adapt to user usage habits and promptly respond to frosting problems caused by frequent door openings.

[0101] The return air pipe is a pipe connecting the fin evaporator and the compressor, which is used to bring the refrigerant that has absorbed heat and evaporated into gas in the fin evaporator back to the compressor.

[0102] When the evaporating pipe and fins are covered with frost or ice, the heat exchange will be reduced, the evaporation amount of liquid refrigerant, that is, the refrigerant will be reduced, and the liquid refrigerant returning to the compressor will increase, resulting in a decrease in the return air pipe temperature. The proportion of frost on the fin evaporator is different, and the return air temperature will also change accordingly.

[0103] During the refrigeration process, the average temperature of the return air pipe is obtained after the compressor is turned on for a preset time. The preset time can be 10 minutes, that is, the average temperature Tc of the return air pipe is obtained every 10 minutes, and then the average value Th of the ambient temperature is calculated.

[0104] Matching the return air temperature according to the average value of the ambient temperature, the return air temperature is the return air temperature when the refrigeration equipment is under light load, the return air temperature includes a first return air temperature, a second return air temperature and a third return air temperature. In some embodiments, if the average value is less than or equal to the first temperature, matching the first return air temperature, the first return air temperature is the difference between the average temperature of the return air pipe and the first preset value;

[0105] If the average value is greater than the first temperature and less than or equal to the second temperature, match the second return air temperature, the second return air temperature is the difference between the average temperature of the return air pipe and a second preset value, and the second preset value is greater than the first preset value;

[0106] If the average value is greater than the second temperature, the third return air temperature is matched, and the third return air temperature is the difference between the average temperature of the return air pipe and a third preset value, and the third preset value is greater than the second preset value.

[0107] Among them, the first temperature is 28°C, the first preset value is 1.5, the second temperature is 35°C, the second preset value is 2, and the third preset value is 2.5.

[0108] The average value of the ambient temperature can also be further differentiated to further match the return air temperature, see the table below:

[0109]

[0110] For example, if the average value is 25°C, the second return air temperature is 23°C.

[0111] After matching the return air temperature, calculate the first return air pipe temperature difference ΔT. The first return air pipe temperature difference is the difference between the average return air pipe temperature before the defrosting condition is reached and the return air temperature. During the refrigeration process of the refrigeration equipment, after the compressor is turned on for 10 minutes, the average return air pipe temperature is obtained every 10 minutes. By matching the return air temperature, the first return air pipe temperature difference can be calculated.

[0112] The first return air pipe temperature difference refers to the difference between the average return air pipe temperature and the current return air temperature. The refrigerant in the return air pipe has just flowed out after absorbing heat from the evaporator. Therefore, its temperature directly reflects the working status of the evaporator. Since the return air pipe temperature difference is closely related to the actual performance of the evaporator, it can provide the most direct and accurate information about the degree of frost on the evaporator.

[0113] When the evaporator begins to frost, the heat exchange efficiency decreases, causing the return air temperature to drop, and this change can be captured by the return air pipe temperature difference. Other temperature differences, such as the difference between the ambient temperature and the set temperature, may be affected by more external factors.

[0114] In addition, the return air duct is located inside the refrigeration system and is relatively closed, which is less affected by the external environment. This means that the measurement results are more stable and reliable, and are not easily affected by factors such as room temperature fluctuations and door opening times. For example, if the ambient temperature is used as a reference point, the temperature reading may fluctuate due to user behavior or seasonal changes, thus affecting the accuracy of the judgment.

[0115] As the thickness of the frost layer increases, the heat exchange efficiency of the evaporator gradually decreases, and the return air temperature will also decrease accordingly. By monitoring the changing trend of the return air pipe temperature difference, the degree of frost can be more accurately assessed. Other types of temperature differences may not be able to reflect this change process so carefully, especially when the frost layer just begins to form, the change may not be obvious enough.

[0116] S300: If the temperature difference of the first return air pipe is less than the first temperature difference threshold and is greater than or equal to the second temperature difference threshold, execute the first defrost instruction.

[0117] The first temperature difference threshold is 0°C and the second temperature difference threshold is -0.5°C. In some embodiments, if the temperature difference of the first return air pipe is greater than or equal to the first temperature difference threshold, the defrost instruction is not executed. When the temperature difference of the first return air pipe is large, the heat exchange efficiency of the evaporator is still high, and there may not be enough frost layer to significantly affect the refrigeration effect. By setting a higher first temperature difference threshold, it can be ensured that the defrost program is started only when it is really needed, avoiding frequent defrosting due to slight frost, thereby reducing energy waste.

[0118] Frequent defrosting operations may cause additional burden on the compressor and other components, increasing the risk of mechanical stress or electrical failure. By setting reasonable defrosting trigger conditions, that is, defrosting is performed only when the return air pipe temperature difference is less than a certain threshold, the equipment can be effectively protected and its service life can be extended.

[0119] like Figure 3 As shown, in some embodiments, if the first return air duct temperature difference is less than the first temperature difference threshold value and greater than or equal to the second temperature difference threshold value, a first preset number of second return air duct temperature differences are obtained, and the second return air duct temperature difference is the return air duct temperature difference obtained after obtaining the first return air duct temperature difference;

[0120] If there is a preset proportion of the second return air pipe temperature difference in the first preset number that is less than the first temperature difference threshold and greater than or equal to the second temperature difference threshold, set the first defrost instruction to perform defrosting after the defrost interval is increased by the first time;

[0121] If there is a preset proportion of the second return air pipe temperature difference in the first preset number that is less than the second temperature difference threshold and greater than or equal to the third temperature difference threshold, execute the second defrost instruction;

[0122] If there is a preset proportion of the second return air pipe temperature difference in the first preset number that is less than the third temperature difference threshold, the third defrost instruction is executed.

[0123] For the second return air pipe temperature difference, the decision on whether to perform the defrosting operation immediately is made by observing the changing trend in the future. When the first return air pipe temperature difference is in a relatively mild range (less than the first temperature difference threshold and greater than or equal to the second temperature difference threshold), it is necessary to further confirm whether the frosting situation will continue to deteriorate. Therefore, new temperature difference data, i.e., the second return air pipe temperature difference, is continuously collected in the next period of time to determine whether there is sufficient evidence to support immediate defrosting.

[0124] Without affecting the refrigeration effect, unnecessary defrost operations can be delayed to save energy. By dynamically monitoring subsequent changes, the defrost strategy can be adjusted more flexibly to ensure that the defrost program is started only when needed.

[0125] In this embodiment, the first temperature difference threshold is 0°C, the second temperature difference threshold is -0.5°C, the third temperature difference threshold is -1°C, the first preset number is the number of return air pipe temperature differences obtained continuously, the first preset number can be 3, the preset ratio is two-thirds, and the first time is 6h.

[0126] It is understandable that the first preset number of second return air pipe temperature differences ΔT2 can be multiple values, and the three ΔT2 can be ΔT 21 , ΔT 22 , ΔT 23For the preset ratio of the second return air pipe temperature difference being less than the first temperature difference threshold and greater than or equal to the second temperature difference threshold, there can be multiple cases, for example, -0.5℃<ΔT 21 ≤0℃ and -0.5℃<ΔT 22 ≤0℃; for example, -0.5℃<ΔT 21 ≤0℃ and -0.5℃<ΔT 23 ≤0℃; for example, -0.5℃<ΔT 22 ≤0℃ and -0.5℃<ΔT 23 ≤0°C. For other contents with preset ratios in this embodiment, this example can be referred to, and the same is true for this example.

[0127] The first temperature difference threshold is the upper limit threshold of the return air pipe temperature difference. When the return air pipe temperature difference is greater than or equal to the first temperature difference threshold, the defrost instruction is not executed, ensuring that the defrost program is started only when defrosting is really needed to avoid unnecessary energy waste.

[0128] The second temperature difference threshold is an intermediate threshold between the first temperature difference threshold and the third temperature difference threshold, and is used to distinguish different degrees of frosting conditions and guide the system to select an appropriate defrosting strategy.

[0129] The third temperature difference threshold is the lower limit threshold of the return air pipe temperature difference. When the return air pipe temperature difference is less than this value, it indicates that a thicker frost layer has formed on the evaporator, triggering a more urgent defrost operation to prevent a significant decrease in refrigeration efficiency.

[0130] If the temperature difference of the first return air pipe is less than 0℃ and greater than or equal to -0.5℃, obtain the temperature difference of the second return air pipe, and continuously obtain the temperature difference of the return air pipe at the next three time points, i.e., the temperature difference of the second return air pipe, to form a set of data. If two or more of the temperature differences of the second return air pipe are less than 0℃ and greater than or equal to -0.5℃ at these three time points, set the first defrost instruction to perform defrosting after the defrost interval is increased by 6 hours, which indicates that although there is slight frost, it is not enough to defrost immediately, so the defrost time is postponed to save energy.

[0131] If the temperature difference of the second return air pipe is less than -0.5℃ and greater than or equal to -1℃ at two or more of the three time points, the second defrost instruction is executed, which means that there is a certain amount of frost layer and it is necessary to defrost in time to maintain the refrigeration effect. If the temperature difference of the second return air pipe is less than -1℃ at two or more of the three time points, the third defrost instruction is executed, which indicates that a thick frost layer has formed on the evaporator and it is necessary to defrost immediately to restore the refrigeration performance.

[0132] The second defrost command and the third defrost command are described in detail in S400 and S500 .

[0133] By setting the temperature difference threshold and preset ratio, the accuracy and reliability of defrost decisions can be improved. It can not only reduce unnecessary full-cycle defrost caused by partial frosting, thereby reducing energy waste, but also better adapt to different usage scenarios and maintain the best refrigeration effect.

[0134] S400: If the temperature difference of the first return air pipe is less than the second temperature difference threshold and is greater than or equal to the third temperature difference threshold, execute the second defrost instruction.

[0135] like Figure 4 As shown, in some embodiments, if the first return air duct temperature difference is less than the second temperature difference threshold value and greater than or equal to the third temperature difference threshold value, a second preset number of third return air duct temperature differences are obtained, and the third return air duct temperature difference is the return air duct temperature difference before the first return air duct temperature difference is obtained;

[0136] Obtaining a second preset number of accumulated time durations during which the temperature difference of the third air return pipe is less than the second temperature difference threshold;

[0137] If the accumulated time is less than the first time, the second defrost instruction is set to add a second time to the defrost interval, and the second time is less than the first time.

[0138] The second preset number of third return air duct temperature differences ΔT3 can be 15 different values, similar to the second return air duct temperature difference, which will not be described in detail herein.

[0139] Among them, the second preset number is 15, the first duration is 90 minutes, and the second time is 3 hours.

[0140] Exemplarily, the first return air duct temperature difference is -0.7°C, which satisfies the conditions of being less than the second temperature difference threshold (-0.5°C) and greater than or equal to the third temperature difference threshold (-1°C), and 15 third return air duct temperature differences are obtained, that is, the return air duct temperature difference before obtaining the first return air duct temperature difference. Ten of the 15 temperature differences are less than -0.5°C, and the cumulative duration is 80 minutes (less than the first duration of 90 minutes). The second defrost instruction is set to perform defrost after the defrost interval is increased by 3 hours to adapt to the current lighter frosting conditions, which saves energy and ensures the refrigeration effect.

[0141] For the third return air pipe temperature difference, the trend is verified by reviewing historical data to see if the current frosting situation continues. When the first return air pipe temperature difference has shown a lower value (less than the second temperature difference threshold and greater than or equal to the third temperature difference threshold), it is necessary to confirm whether this is a one-time fluctuation or a long-term trend. Therefore, by obtaining the temperature difference data for a period of time before this, that is, the third return air pipe temperature difference, to ensure that the current low temperature difference is not an accidental phenomenon, it helps to avoid making wrong defrosting decisions due to short-term fluctuations and improve the reliability of defrosting instructions. At the same time, by analyzing historical data, the future frosting development trend can be predicted more accurately, thereby optimizing the defrosting interval.

[0142] In this embodiment, the second defrost instruction can be to increase the defrost interval time or to perform defrost immediately. If there is a preset proportion of the second return air pipe temperature difference in the first preset number that is less than the second temperature difference threshold and greater than or equal to the third temperature difference threshold, the accumulated time can be further determined to determine the specific content of the second defrost instruction.

[0143] In some embodiments, if the accumulated time is greater than or equal to the first time and less than the second time, a first preset number of accumulated time periods during which the temperature difference of the third return air pipe is less than the second temperature difference threshold is obtained;

[0144] If the accumulated time is greater than or equal to the second time, the defrosting time is calculated, where the defrosting time is the time from the last defrosting completion;

[0145] If the defrost time is greater than or equal to the first time, the second defrost instruction is set to execute defrost.

[0146] Among them, the second duration is 120 minutes. For example, the temperature difference of the first return air pipe is -0.7°C, which meets the conditions of less than -0.5°C and greater than or equal to -1°C. Review the 15 third return air pipe temperature differences, that is, the return air pipe temperature difference before obtaining the first return air pipe temperature difference. Twelve of these 15 temperature differences are less than -0.5°C, and the cumulative duration is 110 minutes (greater than the first duration of 90 minutes and less than the second duration of 120 minutes). Continue to obtain the cumulative duration of the 15 third return air pipe temperature differences. If it reaches or exceeds 120 minutes, calculate the defrost time. If the defrost time exceeds 6 hours, set the second defrost instruction to perform defrost immediately to ensure that the frost layer is removed in time and the refrigeration performance is restored.

[0147] S500: If the temperature difference of the first air return pipe is less than the third temperature difference threshold, execute the third defrost instruction.

[0148] The third instruction is to perform defrosting immediately. If a preset proportion of the temperature difference of the second return air pipe in the first preset number is less than the third temperature difference threshold, defrosting is performed immediately.

[0149] In some embodiments, if the first return air duct temperature difference is less than the third temperature difference threshold, a fourth return air duct temperature difference is obtained, where the fourth return air duct temperature difference is the return air duct temperature difference before the first return air duct temperature difference is obtained;

[0150] If there is a preset proportion of the temperature difference of the fourth return air pipe in the first preset number that is less than the third temperature difference threshold, the defrost time is calculated, and the defrost time is the time from the last defrost completion;

[0151] If the defrost time is greater than or equal to the first time, the third defrost instruction is set to execute defrost.

[0152] For example, the temperature difference of the first return air pipe is -1.2℃, which meets the condition of less than -1℃. Looking back at the first three temperature differences of the fourth return air pipe, two of the three temperature differences are less than -1℃, which meets the preset ratio. The defrost time is calculated, that is, the time since the last defrost was completed, and the result is 7 hours. Based on the above results, the third defrost instruction is set to execute defrost immediately to ensure timely removal of the frost layer and restore refrigeration performance.

[0153] When the first return air pipe temperature difference is significantly lower than the third temperature difference threshold, it indicates that the frost layer on the evaporator is already thick, affecting the heat exchange efficiency. In this case, it may not be necessary to continue to collect a large amount of historical data, for example, 15 times, because the current low temperature difference already shows a serious frosting problem. By only obtaining the fourth return air pipe temperature difference for the first three times, it is possible to confirm whether the frosting trend continues, so as to make defrosting decisions faster and avoid affecting the refrigeration effect due to delays.

[0154] In some embodiments, the method further comprises:

[0155] If there is a preset proportion of the temperature difference of the fourth return air pipe in the first preset number that is greater than or equal to the third temperature difference threshold and less than the second temperature difference threshold, execute the second defrost instruction;

[0156] If there is no preset proportion of the fourth return air duct temperature difference less than the third temperature difference threshold value in the first preset number, or there is no preset proportion of the fourth return air duct temperature difference greater than or equal to the third temperature difference threshold value and less than the second temperature difference threshold value in the first preset number, obtain the fifth return air duct temperature difference of the third preset number, and the fifth return air duct temperature difference is the return air duct temperature difference obtained after obtaining the first return air duct temperature difference;

[0157] Based on the third preset number of fifth return air duct temperature differences, the first preset number of sixth return air duct temperature differences are obtained, so as to obtain a defrost instruction through the sixth return air duct temperature difference, the sixth return air duct temperature difference is the return air duct temperature difference obtained after obtaining the fifth return air duct temperature difference, and the defrost instruction includes a first defrost instruction, a second defrost instruction and a third defrost instruction.

[0158] If two-thirds of the temperature difference of the fourth return air pipe in the first preset number is less than -1°C, calculate the defrost time. If the defrost time is greater than or equal to 6 hours, set the third defrost instruction to execute defrost immediately, which indicates that the frosting situation is more serious and needs to be defrosted immediately to restore the refrigeration performance.

[0159] If, for example, two-thirds of the fourth return air pipe temperature differences in the first preset number are greater than or equal to -1°C and less than -0.5°C, the second defrost instruction is executed, indicating that the frosting situation is relatively mild and lighter defrost measures need to be taken to avoid starting defrost too early and save energy.

[0160] The third preset number is 2. For the fourth return air pipe temperature difference ΔT4, there are three situations. The first situation is that any two times ΔT4 is less than -1°C, and the defrost instruction is executed immediately after the time from the last defrost is ≥6h. The second situation is that any two times -1°C ≤ △T < -0.5°C, and S400 continues to judge. If the first and second situations are not met, the third situation is met, and the return air pipe temperature difference continues to be monitored twice, that is, the fifth return air pipe temperature difference.

[0161] Combined with these two return air pipe temperature differences, the last three return air pipe temperature differences, i.e., the sixth return air pipe temperature difference, are obtained, and the defrost instruction is obtained through the last three return air pipe temperature differences. For example, if any two times 1°C ≤ the sixth return air pipe temperature difference <-0.5°C, the judgment is continued through S400. This ensures that the defrost control can be based on the latest data, improves the flexibility and accuracy of decision-making, and avoids making wrong defrost decisions due to short-term fluctuations.

[0162] Based on the above-mentioned defrost control method, some embodiments of the present application further provide a refrigeration device, including:

[0163] A control unit configured to preset defrost conditions;

[0164] The temperature acquisition module is configured to calculate a first return air pipe temperature difference if the defrosting condition is met, wherein the first return air pipe temperature difference is a difference between an average return air pipe temperature before the defrosting condition is met and the return air temperature;

[0165] The control unit is further configured to:

[0166] If the temperature difference of the first air return pipe is less than the first temperature difference threshold and greater than or equal to the second temperature difference threshold, execute the first defrost instruction;

[0167] If the temperature difference of the first air return pipe is less than the second temperature difference threshold and greater than or equal to the third temperature difference threshold, execute the second defrost instruction;

[0168] If the temperature difference of the first return air pipe is less than the third temperature difference threshold, the third defrost instruction is executed.

[0169] The refrigeration equipment provided in the embodiments of the present application may be a refrigerator, an air conditioner, etc. Taking a refrigerator as an example, in order to achieve refrigeration and operation, it at least includes a refrigeration system, a cooling system, a control system, and a box. Among them, the refrigeration system is used to produce a refrigeration effect, the cooling system is used to maintain a low temperature environment, the control system is used to control the temperature and humidity in the refrigerator, etc., and the box is used to provide storage space. It is understandable that the refrigeration system, the cooling system, and the control system include specific components that can achieve the above functions.

[0170] In some embodiments, the refrigeration system includes a compressor, a condenser, an evaporator, and a throttling device. Among them, the compressor is used to compress the refrigerant gas, increase the pressure and temperature, and thus promote the flow of the refrigerant in the system. During the compression process, the refrigerant changes from a low-pressure and high-temperature gas to a high-pressure and high-temperature gas, thereby producing a refrigeration effect. The condenser is used to cool the high-temperature and high-pressure gas discharged from the compressor into a liquid state. The heat is released through the heat sink, and the refrigerant gas is converted into a liquid state, ready to enter the next step of the refrigeration cycle. The evaporator is used to absorb heat in the refrigeration system. The refrigerant evaporates from a liquid state to a gas state in the evaporator, absorbing heat from the surrounding environment, thereby achieving the purpose of lowering the temperature inside the refrigerator. The throttling device may include an expansion valve and a capillary tube, which are used to adjust the flow rate of the refrigerant, reduce its pressure, and make it become a low-temperature and low-pressure gas-liquid mixed state, ready to enter the evaporator.

[0171] In some embodiments, the cooling system includes a fan connected to the evaporator. The fan circulates air in the compartments, such as the freezer and refrigerator, to transfer heat to the evaporator, helping to maintain a low temperature environment inside the refrigerator.

[0172] It should be noted that the above example is merely a simple division of the functions of the refrigerator and does not constitute a limitation on the specific structure of the refrigerator in the embodiment of the present application.

[0173] Similar parts between the embodiments provided in this application can be referenced to each other. The specific implementation methods provided above are only a few examples under the general concept of this application and do not constitute a limitation on the protection scope of this application. For those skilled in the art, any other implementation methods expanded based on the scheme of this application without creative work belong to the protection scope of this application.

Claims

1. A defrost control method, characterized in that: include: Preset defrost conditions; If the defrosting condition is met, the first return air pipe temperature difference is calculated, where the first return air pipe temperature difference is the difference between the return air pipe average temperature and the return air temperature before the defrosting condition is met; If the temperature difference of the first air return pipe is less than the first temperature difference threshold and greater than or equal to the second temperature difference threshold, execute the first defrost instruction; If the temperature difference of the first air return pipe is less than the second temperature difference threshold and greater than or equal to the third temperature difference threshold, execute the second defrost instruction; If the temperature difference of the first return air pipe is less than the third temperature difference threshold, the third defrost instruction is executed.

2. The defrost control method according to claim 1, characterized in that: The defrosting conditions at least include the ambient temperature, the cumulative running time of the compressor and the number of door openings and closings; If the defrosting condition is met, the temperature difference of the first return air pipe is calculated, including: Obtain the ambient temperature, cumulative compressor operation time, and door opening and closing times; If the ambient temperature is lower than the ambient temperature threshold, or the accumulated running time of the compressor is higher than the time threshold, or the number of door openings and closings is higher than the number threshold, the average temperature of the return air pipe is obtained; Calculating an average value of the ambient temperature and matching the return air temperature based on the average value; The first return air pipe temperature difference is calculated by the return air pipe average temperature and the return air temperature.

3. The defrost control method according to claim 2, characterized in that: The matching of the return air temperature based on the average value comprises: If the average value is less than or equal to the first temperature, a first return air temperature is matched, where the first return air temperature is the difference between the average temperature of the return air pipe and a first preset value; If the average value is greater than the first temperature and less than or equal to the second temperature, match the second return air temperature, the second return air temperature is the difference between the average temperature of the return air pipe and a second preset value, and the second preset value is greater than the first preset value; If the average value is greater than the second temperature, a third return air temperature is matched, where the third return air temperature is the difference between the average temperature of the return air pipe and a third preset value, and the third preset value is greater than the second preset value.

4. The defrost control method according to claim 1, characterized in that: If the temperature difference of the first return air pipe is less than a first temperature difference threshold and greater than or equal to a second temperature difference threshold, executing a first defrost instruction includes: If the first return air duct temperature difference is less than the first temperature difference threshold and greater than or equal to the second temperature difference threshold, obtain a first preset number of second return air duct temperature differences, where the second return air duct temperature difference is the return air duct temperature difference obtained after obtaining the first return air duct temperature difference; If there is a preset proportion of the second return air pipe temperature difference in the first preset number that is less than the first temperature difference threshold and greater than or equal to the second temperature difference threshold, set the first defrost instruction to perform defrosting after the defrost interval is increased by the first time; If there is a preset proportion of the second return air pipe temperature difference in the first preset number that is less than the second temperature difference threshold and greater than or equal to the third temperature difference threshold, execute the second defrost instruction; If there is a preset proportion of the second return air pipe temperature difference in the first preset number that is less than the third temperature difference threshold, the third defrost instruction is executed.

5. The defrost control method according to claim 1, characterized in that: If the temperature difference of the first return air pipe is less than the second temperature difference threshold and greater than or equal to the third temperature difference threshold, executing the second defrost instruction includes: If the first return air duct temperature difference is less than the second temperature difference threshold and greater than or equal to the third temperature difference threshold, obtain a second preset number of third return air duct temperature differences, where the third return air duct temperature difference is the return air duct temperature difference before obtaining the first return air duct temperature difference; Obtaining a second preset number of accumulated time durations during which the temperature difference of the third air return pipe is less than the second temperature difference threshold; If the accumulated time is less than the first time, the second defrost instruction is set to add a second time to the defrost interval, and the second time is less than the first time.

6. The defrost control method according to claim 5, characterized in that: If the temperature difference of the first return air pipe is less than the second temperature difference threshold and greater than or equal to the third temperature difference threshold, executing the second defrost instruction also includes: If the accumulated time is greater than or equal to the first time and less than the second time, obtain a first preset number of accumulated time periods during which the temperature difference of the third return air pipe is less than the second temperature difference threshold; If the accumulated time is greater than or equal to the second time, the defrosting time is calculated, where the defrosting time is the time from the last defrosting completion; If the defrost time is greater than or equal to the first time, the second defrost instruction is set to execute defrost.

7. The defrost control method according to claim 1, characterized in that: If the temperature difference of the first air return pipe is less than a third temperature difference threshold, executing a third defrost instruction includes: If the first return air pipe temperature difference is less than the third temperature difference threshold, obtaining a fourth return air pipe temperature difference, wherein the fourth return air pipe temperature difference is the return air pipe temperature difference before obtaining the first return air pipe temperature difference; If there is a preset proportion of the temperature difference of the fourth return air pipe in the first preset number that is less than the third temperature difference threshold, the defrost time is calculated, and the defrost time is the time from the last defrost completion; If the defrost time is greater than or equal to the first time, the third defrost instruction is set to execute defrost.

8. The defrost control method according to claim 7, characterized in that: The method further comprises: If there is a preset proportion of the temperature difference of the fourth return air pipe in the first preset number that is greater than or equal to the third temperature difference threshold and less than the second temperature difference threshold, execute the second defrost instruction; If there is no preset proportion of the fourth return air duct temperature difference less than the third temperature difference threshold value in the first preset number, or there is no preset proportion of the fourth return air duct temperature difference greater than or equal to the third temperature difference threshold value and less than the second temperature difference threshold value in the first preset number, obtain the fifth return air duct temperature difference of the third preset number, and the fifth return air duct temperature difference is the return air duct temperature difference obtained after obtaining the first return air duct temperature difference; Based on the third preset number of fifth return air duct temperature differences, the first preset number of sixth return air duct temperature differences are obtained, so as to obtain a defrost instruction through the sixth return air duct temperature difference, the sixth return air duct temperature difference is the return air duct temperature difference obtained after obtaining the fifth return air duct temperature difference, and the defrost instruction includes a first defrost instruction, a second defrost instruction and a third defrost instruction.

9. The defrost control method according to claim 1, characterized in that: The method further comprises: If the temperature difference of the first air return pipe is greater than or equal to the first temperature difference threshold, the defrost instruction is not executed.

10. A refrigeration device, characterized in that: include: A control unit configured to preset defrost conditions; The temperature acquisition module is configured to calculate a first return air pipe temperature difference if the defrosting condition is met, wherein the first return air pipe temperature difference is a difference between an average return air pipe temperature before the defrosting condition is met and the return air temperature; The control unit is further configured to: If the temperature difference of the first air return pipe is less than the first temperature difference threshold and greater than or equal to the second temperature difference threshold, execute the first defrost instruction; If the temperature difference of the first air return pipe is less than the second temperature difference threshold and greater than or equal to the third temperature difference threshold, execute the second defrost instruction; If the temperature difference of the first return air pipe is less than the third temperature difference threshold, the third defrost instruction is executed.

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