Defrosting control method, cold storage and computer readable storage medium

Abstract

The application discloses a defrosting control method, a cold storage and a computer readable storage medium, and the defrosting control method comprises the following steps: collecting the operation parameters of the cold storage, and performing defrosting trigger determination based on the operation parameters; when it is determined that the defrosting trigger condition is met, a defrosting strategy is dynamically selected according to the real-time relative humidity in the cold storage during the defrosting process; if the real-time relative humidity in the cold storage is higher than a first humidity threshold, a high-humidity environment defrosting strategy is executed, the compressor is controlled to stop, the evaporator fan is controlled to reverse, and the working time of the defrosting heater is controlled to be reduced in proportion to the frost thickness d; if the real-time relative humidity in the cold storage is not higher than the first humidity threshold, a low-humidity environment defrosting strategy is executed, the compressor is controlled to rotate in the positive direction at a reduced speed, the evaporator fan is controlled to rotate in the positive direction, and the power of the defrosting heater is reduced. The application realizes accurate adaptation of the defrosting process to the actual working condition of the cold storage, ensures the defrosting effect, significantly reduces energy consumption, and belongs to an energy-saving refrigeration equipment.

Description

Technical Field

[0001] This invention relates to the field of refrigeration technology, and in particular to defrosting control methods, cold storage facilities, and computer-readable storage media. Background Technology

[0002] During long-term operation, refrigeration units such as cold storage rooms and refrigerated containers will experience frost buildup on the evaporator surface due to heat exchange. Thick frost significantly reduces heat exchange efficiency, increases energy consumption, and can even prevent the storage temperature from reaching the required level. Therefore, defrosting control is a crucial aspect of maintaining the efficient operation of refrigeration units.

[0003] Current defrosting strategies typically focus only on the defrosting of the evaporator coils, lacking differentiated treatment based on the humidity of the cold storage environment. In high humidity environments, the frost layer is loose and has poor thermal conductivity, while in low humidity environments, the frost layer is dense and easily forms stubborn ice at the bottom. Existing solutions often use a uniform heating power and duration, which not only causes overheating in high humidity environments but also fails to address the problems of evaporator fin warping and obstructed return air caused by residual ice at the bottom in low humidity environments.

[0004] Furthermore, in existing technologies, defrosting triggering methods often rely on a single parameter such as a fixed time period, a fixed coil temperature, or the cumulative operating time of the compressor. However, the actual operating conditions of cold storage are greatly affected by ambient humidity, cargo heat load, and door opening and closing frequency. The aforementioned rigid control logic cannot match the actual frost formation rate, which can easily lead to problems such as "frost melting before it becomes thick enough" (energy waste) or "frost becoming too thick and not melting enough" (refrigeration failure).

[0005] Therefore, how to select an appropriate defrosting strategy based on changes in ambient humidity and frost thickness, and how to optimize energy consumption and protect equipment while ensuring defrosting effectiveness, are technical problems that urgently need to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing cold storage defrosting control systems, which offer only a single strategy and fail to balance energy optimization in high-humidity environments with anti-icing protection in low-humidity environments, this invention proposes a defrosting control method, a cold storage facility, and a computer-readable storage medium. By collecting cold storage operating parameters to determine defrosting triggers, and dynamically selecting between a high-humidity or low-humidity defrosting strategy based on whether the real-time relative humidity inside the cold storage is above or below a first humidity threshold, this method eliminates the need for fixed time periods or single temperature thresholds. It achieves precise adaptation of the defrosting process to the actual operating conditions of the cold storage, significantly reducing energy consumption while ensuring effective defrosting, thus classifying it as an energy-efficient refrigeration device.

[0007] The technical solution adopted in this invention is to design a defrosting control method, including the following steps:

[0008] Collect the operating parameters of the cold storage, and determine the defrosting trigger based on the operating parameters;

[0009] When the defrosting trigger condition is met, the real-time relative humidity inside the warehouse during the defrosting process is used as a reference. Dynamically select defrosting strategy:

[0010] If the relative humidity inside the warehouse is real time If the humidity exceeds the first humidity threshold, a high humidity defrosting strategy is implemented. The high humidity defrosting strategy includes controlling the compressor to stop, starting the evaporator fan to reverse at a speed lower than normal, and reducing the working time of the defrosting heater proportionally based on the frost thickness d.

[0011] If the relative humidity inside the warehouse is real time If the humidity is not higher than the first humidity threshold, a low-humidity defrosting strategy is implemented. The low-humidity defrosting strategy includes controlling the compressor to reduce its speed and rotate in the forward direction, starting the evaporator fan to rotate in the forward direction at a speed lower than the normal value, and reducing the power of the defrosting heater.

[0012] The defrosting process ends based on the termination condition corresponding to the selected strategy.

[0013] This design addresses the limitations of existing technologies that rely on a single defrosting strategy and cannot adapt to environmental changes by dynamically selecting either a high-humidity or low-humidity defrosting strategy through real-time monitoring of relative humidity within the storage facility. Under the high-humidity strategy, the compressor is stopped to prevent the risk of liquid slugging caused by heat backflow during defrosting. Simultaneously, the fan reverses to accelerate defrosting and shorten heating time, reducing energy consumption in high-humidity environments. Under the low-humidity strategy, the compressor operates at low speed and heating power is reduced, minimizing thermal shock and energy waste in low-humidity environments. Overall, the defrosting process is matched to the operating conditions, improving unit energy efficiency and defrosting efficiency.

[0014] Furthermore, the low-humidity defrosting strategy also includes: activating the chassis heating device of the evaporator.

[0015] This design incorporates a chassis heating device to specifically melt ice buildup at the bottom of the evaporator during defrosting in low-humidity environments. This solves the problem of dense, difficult-to-melt frost layers at the bottom in low-humidity conditions, preventing evaporator fin warping and return air obstruction caused by bottom ice buildup, and ensuring the long-term operational reliability of the equipment.

[0016] Furthermore, the reduction in the defrosting heater's operating time proportional to the frost thickness d includes:

[0017] Multiple sets of frost layer thicknesses d and reference heating times are pre-stored. The correspondence;

[0018] Will Multiply by the first proportionality coefficient to obtain the target working time for defrosting in high humidity environments;

[0019] Control the defrosting heater to operate within the target operating time.

[0020] This design reduces the heating time proportionally to the frost thickness, matching the heating time with the actual frost load. This avoids excessive energy consumption or incomplete defrosting caused by heating for a fixed duration, further improving energy efficiency in high humidity environments.

[0021] Furthermore, in the low-humidity defrosting strategy, the compressor rotates forward at a second ratio of its rated frequency, and the defrosting heater operates at a third ratio of its rated power.

[0022] This design, by limiting the specific proportion of low-speed forward rotation of the compressor and the reduction in heater power, enables more precise and controllable energy input in low-humidity environments. This maintains the necessary defrosting heat while preventing temperature fluctuations and energy waste caused by excessively high temperatures, thus achieving stable operation of the defrosting process in low humidity.

[0023] Furthermore, the termination condition corresponding to the low-humidity defrosting strategy is: monitoring the temperature T of the evaporator's water tray, and determining that defrosting ends when the water tray temperature T reaches the first temperature threshold.

[0024] This design uses the temperature of the drip tray as the termination condition for low-humidity defrosting, directly reflecting the actual defrosting status at the bottom of the evaporator. Compared to traditional timed termination or coil temperature termination, this method can more accurately determine whether the ice at the bottom has completely melted, ensuring the defrosting effect while avoiding ineffective heating.

[0025] Furthermore, defrosting control methods also include:

[0026] After executing the low-humidity defrosting strategy, if the water tray temperature T fails to reach the first temperature threshold and the duration of the low-humidity defrosting strategy exceeds the preset maximum defrosting time threshold, then the defrosting process is forcibly terminated and the refrigeration operation is resumed.

[0027] This design uses a maximum defrost time threshold as a fallback protection mechanism. When the drip tray temperature is abnormal or the heating efficiency is too low, defrosting is forcibly terminated and cooling is resumed. This prevents the defrosting process from being prolonged indefinitely due to sensor failure or extreme operating conditions, ensuring the reliability of the core refrigeration function of the cold storage and avoiding large fluctuations in the storage temperature.

[0028] Furthermore, the termination condition corresponding to the high humidity environment defrosting strategy is: when the working time of the defrosting heater reaches the target working time, the defrosting is determined to end.

[0029] This design uses the target operating time as the termination condition for high-humidity defrosting, which corresponds to the heating time calculated based on frost thickness in weight 3. This timing termination method is logically simple and reliable, ensuring that heating stops promptly after the frost layer has completely melted in high-humidity environments, effectively preventing over-defrosting.

[0030] Furthermore, based on the real-time relative humidity inside the warehouse during the defrosting process... Dynamic selection of defrosting strategies also includes:

[0031] If the cold storage refrigeration unit enters the high humidity environment defrosting strategy, and the real-time relative humidity inside the storage is... If the humidity drops to less than or equal to the first humidity threshold, the system automatically switches to the low-humidity defrosting strategy until the current defrosting cycle ends, and then stops based on the humidity level. The change is to switch back to a high-humidity environment defrosting strategy.

[0032] This design solves the unit oscillation problem caused by frequent switching near the humidity threshold by allowing unidirectional switching and locking from a high-humidity strategy to a low-humidity strategy. This ensures that the latter half of the defrosting process can enter a more energy-efficient and safer low-humidity mode as the humidity decreases, improving the stability and safety of the defrosting process.

[0033] Furthermore, the operating parameters include real-time relative humidity inside the storage area. The thickness of the frost layer on the evaporator surface (d) and the real-time cooling capacity (Q) of the cold storage refrigeration unit;

[0034] Determining defrost trigger based on the aforementioned operating parameters includes:

[0035] Calculate the cooling capacity decay rate η based on the real-time cooling capacity Q and the initial rated cooling capacity Q0 of the cold storage refrigeration unit;

[0036] When the cooling capacity decay rate η is greater than the first decay threshold and the real-time relative humidity H in the storage room is simultaneously satisfied... in When the humidity is greater than the second humidity threshold and the frost thickness d is greater than the first thickness threshold, the defrosting trigger condition is determined to be met.

[0037] Wherein, the second humidity threshold is less than the first humidity threshold.

[0038] This design utilizes the cooling capacity decay rate η and the real-time relative humidity inside the warehouse H. in The combined determination of defrosting trigger conditions using three parameters—including the frost thickness (d)—is more accurate than that using a single parameter. This effectively avoids false defrosting caused by misjudgment from a single sensor or occasional environmental fluctuations, ensuring consistency between the defrosting trigger timing and the actual frost condition.

[0039] Furthermore, the operating parameters include real-time relative humidity inside the storage area. The thickness of the frost layer on the evaporator surface (d) and the real-time cooling capacity (Q) of the cold storage refrigeration unit;

[0040] Determining defrost trigger based on the aforementioned operating parameters includes:

[0041] When any emergency defrosting condition is met, the defrosting trigger condition is determined to be met;

[0042] The first emergency defrosting condition is that the frost layer thickness d is greater than or equal to the second thickness threshold, and the second thickness threshold is greater than the first thickness threshold.

[0043] The second emergency defrosting condition is that the cooling capacity decay rate η is greater than the second decay threshold and the duration exceeds the first duration threshold, and the second decay threshold is greater than the first decay threshold.

[0044] The third emergency defrosting condition is the real-time relative humidity inside the warehouse. The humidity is greater than a third humidity threshold and the duration exceeds a second duration threshold, and the third humidity threshold is greater than the first humidity threshold.

[0045] This design, by setting independent emergency defrosting conditions, can bypass the conventional judgment logic and directly initiate defrosting when the frost layer is too thick, the decay rate is too high, or the humidity is too high. This improves the unit's response speed under extreme operating conditions, prevents refrigeration failure or equipment damage caused by severe frost buildup, and enhances the unit's reliability.

[0046] Furthermore, the calculation of the cooling capacity attenuation rate η includes:

[0047] Collect the temperature difference ΔT1 at the evaporator inlet and ΔT2 at the evaporator outlet, and calculate the logarithmic mean temperature difference between the evaporator inlet and outlet. ;

[0048] Collect compressor operating frequency f and compressor discharge temperature and evaporator inlet dry bulb temperature ;

[0049] According to the formula Calculate the real-time cooling capacity Q, where , , These are calibration coefficients;

[0050] According to the formula Calculate the cooling capacity decay rate η;

[0051] Where Q0 is the initial rated cooling capacity.

[0052] This design calculates real-time cooling capacity and attenuation rate using a specific formula, comprehensively considering multi-dimensional parameters such as compressor frequency, temperature difference, and exhaust temperature. This method is more accurate than simple current or temperature estimation, providing a reliable data foundation for defrosting trigger determination and cooling capacity monitoring.

[0053] Furthermore, the operating parameters also include the continuous operating time of the cold storage refrigeration unit. ;

[0054] Determining defrost trigger based on the aforementioned operating parameters includes:

[0055] When the operating parameters do not meet the defrosting trigger conditions, but the continuous operating time of the cold storage refrigeration unit is... If the set time threshold is exceeded, the defrosting trigger condition is determined to be met.

[0056] This design, by setting a fallback defrosting trigger condition based on continuous operating time, ensures that the unit can still force defrosting according to the longest cycle even if the sensor fails or the parameter fluctuation does not reach the threshold. This constitutes the safety baseline for defrosting triggering, preventing severe frost buildup caused by prolonged operation without defrosting and ensuring the basic operational safety of the unit.

[0057] The present invention also proposes a cold storage unit, comprising: a cold storage refrigeration unit and a controller, wherein the evaporator of the cold storage refrigeration unit provides cooling capacity to the storage unit, the evaporator is provided with an evaporator fan and a defrost heater, and the controller is electrically connected to the cold storage refrigeration unit, the evaporator fan and the defrost heater respectively, and the controller is configured to execute the above-described defrost control method.

[0058] This design integrates the aforementioned defrosting control method into the cold storage's controller, enabling the cold storage to intelligently adjust its defrosting strategy based on ambient humidity and frost thickness. This directly improves the overall energy efficiency and intelligence level of the cold storage unit, reduces manual intervention, and lowers operating costs.

[0059] Furthermore, a chassis is provided at the bottom of the evaporator, and a chassis heating device is provided below or inside the chassis, and the chassis heating device is electrically connected to the controller.

[0060] This design provides the necessary hardware support for bottom defrosting in low-humidity environments by installing a chassis and heating device at the bottom of the evaporator. The rational structural layout effectively conducts heat to the ice accumulation area, solving the physical problem of defrosting in low humidity and improving the cold storage's adaptability to complex environments.

[0061] The present invention also proposes a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-described defrosting control method.

[0062] This design provides a carrier for the deployment, upgrading and maintenance of the control algorithm by storing the computer program that implements the above-mentioned defrosting control method. This allows the defrosting control method to exist and spread independently in software form, making it easy to port and apply in different models of equipment.

[0063] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0064] 1. In the defrosting stage, this invention abandons the uniform heating mode and instead dynamically selects a high-humidity or low-humidity defrosting strategy based on the real-time relative humidity inside the cold storage. This solution can accurately match the corresponding defrosting logic according to the differences in humidity in the cold storage environment. In high-humidity environments, efficiency is improved by reversing the fan and shortening the heating time. In low-humidity environments, energy consumption is reduced by running the compressor at low speed and reducing the heating power. This achieves precise adaptation between the defrosting process and operating conditions, effectively avoiding energy waste and temperature fluctuations in the cold storage, and significantly improving the overall energy efficiency and defrosting thoroughness of the unit under different humidity environments.

[0065] 2. In the defrosting strategy for low-humidity environments, this invention adds a chassis heating device and uses the temperature of the water tray as the criterion for determining the termination of defrosting. This targeted heating and closed-loop control logic solves the technical problems of dense frost layer, easy ice formation at the bottom and difficulty in melting in low-humidity environments. It avoids damage to evaporator fins and obstruction of return air caused by ice accumulation at the bottom. While ensuring the defrosting effect, it extends the service life of the equipment and enhances the operational reliability of the unit.

[0066] 3. This invention introduces a unidirectional dynamic switching mechanism based on a humidity threshold during the defrosting process, supplemented by proportional heating time control based on frost thickness. When the humidity changes from high to low, the unit automatically switches from a high-humidity strategy to a low-humidity strategy and locks it. This prevents frequent oscillations near the humidity threshold and ensures that the heating energy matches the actual defrosting load. This refined process control maximizes the unit's energy-saving potential while ensuring defrosting efficiency, avoiding over-defrosting or incomplete defrosting.

[0067] 4. This invention constructs a multi-level defrosting judgment system that combines conventional triggering, emergency triggering, and forced triggering. It accurately monitors the heat exchange efficiency decay through a real-time cooling capacity calculation model and initiates emergency defrosting when the frost layer is too thick or the humidity is abnormal. At the same time, it forces defrosting based on the longest running time when the parameters do not meet the standards. This enables the unit to maintain a stable safe operating boundary when dealing with complex and ever-changing actual operating conditions and occasional sensor failures, thereby reducing the equipment failure rate and the risk of temperature runaway. Attached Figure Description

[0068] The present invention will now be described in detail with reference to the embodiments and accompanying drawings, wherein:

[0069] Figure 1 This is a logical schematic diagram of the defrosting control method of the present invention;

[0070] Figure 2 This is a schematic flowchart of the defrosting control method of the present invention;

[0071] Figure 3 This is a schematic diagram of the execution flow of the dynamic defrosting strategy of the present invention;

[0072] Figure 4 This is a schematic diagram illustrating the application process of the dynamic defrosting strategy of this invention;

[0073] Figure 5 This is a schematic diagram of the hierarchical triggering logic of the defrosting control method of the present invention;

[0074] Figure 6 This is a schematic diagram of the conventional defrosting trigger of the defrosting control method of the present invention;

[0075] Figure 7 This is a schematic diagram of the emergency defrosting trigger of the defrosting control method of the present invention;

[0076] Figure 8 This is a schematic diagram of the execution flow of the hierarchical triggering logic of the present invention;

[0077] Figure 9 This is a schematic diagram of the application process of the hierarchical triggering logic of the present invention. Detailed Implementation

[0078] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be 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.

[0079] This invention proposes a defrosting control method based on dynamic adjustment of humidity and frost thickness, suitable for commercial or industrial cold storage facilities operating continuously for extended periods. The cold storage unit includes a refrigeration unit, a defrosting heater, a humidity sensor, a frost thickness detection module, a temperature sensor, and a controller. The compressor, condenser, evaporator, and expansion valve in the refrigeration unit form a refrigeration cycle. The evaporator provides cooling to the storage area, and the evaporator fan drives the air circulation and heat exchange within the storage. The defrosting heater heats and melts the frost layer on the evaporator surface. The humidity sensor is located in the middle of the cold storage return air duct or at the geometric center height of the storage room to detect the real-time relative humidity inside the storage. The frost thickness detection module uses an ultrasonic non-contact ranging module, installed parallel to the air outlet grille of the evaporator, to detect the frost thickness d on the evaporator surface. The controller is electrically connected to the compressor, evaporator fan, defrost heater, humidity sensor, and frost thickness detection module, and is configured to execute the following defrosting control method.

[0080] See Figure 1 and Figure 2 As shown, the defrosting control method based on dynamic adjustment of humidity and frost thickness includes the following steps:

[0081] Collect the operating parameters of the cold storage, and determine the defrosting trigger based on the operating parameters;

[0082] When the defrosting trigger conditions are met, it means that a layer of frost has accumulated on the surface of the cold storage evaporator, sufficient to affect heat exchange efficiency, and the current operating conditions meet the entry requirements for defrosting execution. At this time, based on the real-time relative humidity inside the cold storage during the defrosting process... The reason for dynamically selecting the defrosting strategy is that the relative humidity inside the warehouse directly determines the physical form and melting characteristics of the frost layer. In a high humidity environment, the frost layer has a high water content and poor thermal conductivity, while in a low humidity environment, the frost layer is loose but the bottom is prone to forming ice that is difficult to melt. A single control logic cannot take into account both energy efficiency and thorough defrosting.

[0083] If the relative humidity inside the warehouse is real time If the humidity level exceeds the first humidity threshold, it indicates a high moisture content in the air inside the refrigeration unit, resulting in a dense frost layer with low thermal conductivity and strong adhesion. In this case, a high-humidity defrosting strategy is implemented. This strategy includes shutting down the compressor to interrupt the refrigeration cycle and prevent defrosting heat from flowing back to the compressor via the return air line, which could cause liquid slugging or oil dilution. When executing this strategy, the controller first issues a shutdown command to the compressor, isolating it from the refrigeration queue. Then, the evaporator fan is started at a speed lower than normal and reversed to introduce dry air from outside the refrigeration unit with a lower relative humidity than inside, which flows across the evaporator surface to accelerate the sublimation and shedding of the frost layer. Based on this, the operating time of the defrosting heater is reduced proportionally to the frost layer thickness (d), utilizing the heat exchange enhancement characteristics of the fan disturbance in a high-humidity environment to ensure effective defrosting while avoiding overheating.

[0084] If the relative humidity inside the warehouse is real time If the humidity is not higher than the first humidity threshold, it indicates that the relative humidity of the air inside the warehouse is low, the frost layer is relatively loose, but ice shells are easily formed at the bottom. It is difficult to quickly melt the ice at the bottom by simply relying on heating. At this time, a low humidity environment defrosting strategy is implemented. The low humidity environment defrosting strategy includes controlling the compressor to reduce the speed and rotate forward, starting the evaporator fan to rotate forward at a speed lower than the normal value to maintain the low pressure side pressure of the unit and prevent a large amount of cold air backflow. At the same time, the power of the defrosting heater is reduced. With gentle heat input and subsequent bottom heating, the bottom anti-icing problem is mainly solved in a low humidity environment.

[0085] The defrosting process ends and the system resets based on the termination conditions corresponding to the selected strategy, thereby ensuring that the defrosting process accurately matches the actual operating conditions and minimizing disturbance to the storage temperature and energy waste while ensuring the cleanliness of the evaporator.

[0086] See Figure 2 As shown, specifically in some application examples of the present invention, after the unit is powered on and running, the controller periodically collects the operating parameters of the cold storage. These operating parameters include the real-time relative humidity inside the cold storage. The frost thickness d on the evaporator surface and the real-time cooling capacity Q of the cold storage refrigeration unit, as well as the compressor operating frequency f, evaporator inlet temperature ΔT1, evaporator outlet temperature difference ΔT2, and compressor discharge temperature. Evaporator inlet dry bulb temperature and continuous running time Humidity sensors should be placed in the middle of the cold storage return air duct or at the geometric center of the warehouse (1.2 to 1.5 meters from the ground), and at least 0.5 meters away from the side walls and air outlets, avoiding areas obstructed by goods and areas directly exposed to condensate, to ensure... It can accurately reflect the water vapor content of the air inside the warehouse. The frost thickness detection module uses an ultrasonic non-contact ranging module, which is installed parallel to the air outlet grille of the evaporator. By measuring the time difference between the transmission and reception of the ultrasonic wave, the distance from the frost surface to the sensor is calculated, thereby obtaining the frost thickness d. This parameter serves as a direct indicator of the physical accumulation of frost and is used to assist in trigger judgment and provide safety fallback protection. The controller is set with a basic monitoring cycle (e.g., 5 to 10 seconds), and performs a comprehensive logic evaluation at the end of each monitoring cycle. If a significant change in the state is detected (such as a sudden change in frost thickness or a sudden drop in humidity), an immediate evaluation is triggered.

[0087] After collecting the above parameters, the controller determines whether to trigger defrost based on the operating parameters. A standard defrost trigger determination requires the following three conditions to be met simultaneously: the cooling capacity decay rate η is greater than the first decay threshold; and the real-time relative humidity inside the cold storage is [value missing]. The humidity threshold is greater than the second humidity threshold; and the frost thickness d is greater than the first thickness threshold; wherein the second humidity threshold is less than the first humidity threshold. The above three parameters are used to determine the false triggering caused by single sensor drift or local micro-frost, because even if η is high alone, the unit will not trigger defrosting as long as the humidity or frost thickness conditions are not met.

[0088] When the defrosting trigger condition is met, the controller determines that the defrosting process is in accordance with the real-time relative humidity inside the warehouse. Dynamically select the defrosting strategy. If... If the humidity exceeds the first humidity threshold, the controller executes a high-humidity defrosting strategy. Under this strategy, the controller first stops the compressor to prevent backflow of defrosting heat from causing liquid slugging in the compressor; simultaneously, it reverses the evaporator fan at a speed lower than normal to introduce dry air from outside the evaporator with a lower relative humidity than inside, accelerating the melting of the frost layer. If the humidity is not higher than the first humidity threshold, the controller executes a low-humidity defrosting strategy. Under this strategy, the controller controls the compressor to reduce its speed and rotate forward (the compressor rotates forward at the second ratio of the rated frequency), starts the evaporator fan to rotate forward at a speed lower than the normal value to maintain the unit pressure balance and prevent cold air backflow. At the same time, the power of the defrosting heater is reduced to the third ratio of the rated power to reduce the overall heat input.

[0089] This design dynamically selects between high and low humidity defrosting strategies by monitoring the relative humidity inside the unit in real time, solving the problem of existing technologies having a single defrosting strategy and being unable to adapt to environmental changes. Under the high humidity strategy, the fan reverses to accelerate defrosting and shorten heating time, reducing energy consumption in high humidity environments. Under the low humidity strategy, the compressor operates at low speed and heating power is reduced, while the chassis heating device is activated to prevent ice buildup at the bottom, reducing thermal shock and energy waste in low humidity environments. Overall, the defrosting process is matched with operating conditions, improving unit energy efficiency and defrosting efficiency.

[0090] In this invention, the normal operating speed of the evaporator fan refers to the reference operating speed of the evaporator fan in order to maintain the set temperature and heat exchange efficiency inside the cold storage unit when the refrigeration unit is in normal refrigeration operation mode and defrosting is not performed. In practical applications, this normal value is usually dynamically adjusted according to the heat load demand inside the cold storage unit or preset by the unit at the factory.

[0091] See Figure 3 and Figure 4 As shown, in some feasible embodiments of the present invention, the low-humidity defrosting strategy also includes activating the chassis heating device of the evaporator.

[0092] The chassis heating element is an electric heating element attached to or embedded in the bottom of the evaporator chassis. It transfers heat to the chassis surface and drip tray area via heat conduction. In low-humidity defrosting strategies, the controller simultaneously activates the chassis heating element when switching to or initially determining a low-humidity strategy. In low-humidity environments, the frost layer is relatively loose. The top frost melts first under the action of the heater, but the melted water droplets easily refreeze when they fall to the cooler bottom of the evaporator, forming a difficult-to-handle ice shell that can cause drain blockage or secondary frosting. The chassis heating element is designed to specifically melt the ice buildup at the bottom, preventing damage to the evaporator fins and obstruction of return air.

[0093] This design, by adding a chassis heating device, specifically melts the ice buildup at the bottom of the evaporator in a low-humidity defrosting strategy. This solves the problem of dense and difficult-to-melt frost layers at the bottom in low-humidity environments, avoids evaporator fin warping damage and return air obstruction caused by bottom ice buildup, and ensures the long-term operational reliability of the equipment.

[0094] See Figure 3 and Figure 4 As shown, in some feasible embodiments of the present invention, reducing the operating time of the defrosting heater proportionally to the frost thickness d includes: pre-storing multiple sets of frost thickness d and reference heating time. The correspondence; Multiply by the first proportionality coefficient to obtain the target working time for defrosting in a high humidity environment; control the defrosting heater to operate within the target working time.

[0095] for The method for determining the evaporator thickness involves calibrating the unit under multiple stepped operating conditions before it leaves the factory: the evaporator surface is uniformly frosted to multiple preset thicknesses (such as 3mm, 6mm, 9mm, 12mm, etc.), and the measured heating time required to completely melt the frost layer at each thickness is recorded. Then, the least squares method was used to compare the frost thickness d with... A linear fit was performed to obtain the baseline heating time. The correspondence between the frost thickness d and the frost layer thickness d is stored internally in the controller. In actual operation, the controller obtains the corresponding frost thickness d based on the real-time frost thickness d measured by the ultrasonic ranging module through table lookup or linear interpolation. The first proportionality coefficient is a value less than 1, determined based on engineering experiments: In high humidity environments, the fan reverses to introduce dry air, significantly improving the convective mass transfer and heat exchange efficiency on the frost surface. Therefore, the heating time can be safely shortened from the baseline time, ensuring complete defrosting while reducing energy consumption. For example, when the measured frost thickness d is 6mm, the controller queries... The time is 8 minutes. Multiplying this by the first proportionality factor (e.g., 0.85) gives the target working time of 6.8 minutes. The defrosting heater is only powered on and operates during this 6.8 minutes.

[0096] This design reduces the heating time proportionally to the frost thickness, matching the heating time with the actual frost load. This avoids excessive energy consumption or incomplete defrosting caused by heating for a fixed duration, further improving energy efficiency in high humidity environments.

[0097] See Figure 3 and Figure 4 As shown, in some feasible embodiments of the present invention, in the low-humidity defrosting strategy, the compressor rotates forward at a second ratio of the rated frequency, the evaporator fan can also rotate forward at a second ratio of the normal value, and the defrosting heater operates at a third ratio of the rated power.

[0098] The specific values ​​of the second and third ratios can be determined according to the specifications and operating conditions of the cold storage. The core constraints are: when the compressor is running at low speed, its discharge volume is sufficient to maintain the basic pressure balance of the unit and prevent refrigerant backflow caused by excessively low pressure on the low-pressure side after shutdown; the evaporator fan runs at the normal value of the second ratio to prevent cold air backflow; when the defrost heater is running at derating power, its heat generation is sufficient to slowly melt the frost layer, while avoiding drastic temperature fluctuations in the cold storage due to excessive power.

[0099] For example, a cold storage compressor has a rated frequency of 60Hz and a second proportional calibration range of 20% to 30%, meaning the compressor's operating frequency is maintained between 12 and 18Hz during defrosting. The defrost heater has a rated power of 4kW and a third proportional calibration range of 80%, meaning the actual operating power is 3.2kW. This combination of "frequency reduction for pressure maintenance + derated heating" ensures that the unit can maintain the necessary defrosting heat input in low-humidity environments without causing temperature control issues due to excessively high temperatures or pressure imbalances.

[0100] This design, by limiting the specific ratio of low-speed forward rotation of the compressor and the reduction ratio of heater power, makes the energy input in low-humidity environments more precise and controllable. It maintains the necessary defrosting heat while preventing temperature fluctuations and energy waste caused by excessively high temperatures, thus achieving stable operation of the low-humidity defrosting process.

[0101] See Figure 3 and Figure 4 As shown, in some feasible embodiments of the present invention, the termination condition corresponding to the low humidity environment defrosting strategy is: monitoring the water tray temperature T of the evaporator, and determining that defrosting ends when the water tray temperature T reaches the first temperature threshold.

[0102] The temperature T of the drip tray is collected in real time by a temperature sensor installed at the drip tray at the bottom of the evaporator. The first temperature threshold is determined based on engineering experimental calibration. Its core principle is that when the drip tray temperature reaches this threshold, it indicates that the ice accumulated at the bottom of the evaporator and in the drip tray area has completely melted into liquid water, which can be smoothly discharged through the drain pipe without any residual ice shell. Using the drip tray temperature as the termination criterion, rather than the traditional timed termination or coil temperature termination, has the advantage of directly reflecting the physical state of the most difficult-to-melt area at the bottom of the evaporator.

[0103] For example, the first temperature threshold can be set to 5°C. During the defrosting process in a low-humidity environment, the chassis heating device and the defrosting heater work together to heat the water tray. The temperature T gradually rises from below zero. Once T reaches 5°C, the controller determines that the ice at the bottom has completely melted, and then stops defrosting and resumes cooling.

[0104] This design uses the temperature of the drip tray as the termination condition for low-humidity defrosting, which directly reflects the actual defrosting status at the bottom of the evaporator. Compared with traditional timed termination or coil temperature termination, it can more accurately determine whether the ice at the bottom has melted completely, ensuring the defrosting effect and avoiding ineffective heating.

[0105] Based on this, the preferred solution is that the defrosting control method further includes: after implementing the low humidity environment defrosting strategy, if the water tray temperature T does not reach the first temperature threshold and the duration of the low humidity environment defrosting strategy exceeds the preset maximum defrosting time threshold, then the defrosting is forcibly exited and the refrigeration operation is restored.

[0106] The value of the maximum defrosting time threshold is determined based on the unit's thermal inertia tuning. Its core consideration is to prevent the water tray temperature T from failing to reach the first temperature threshold under extreme low temperature conditions (such as a thick ice shell at the bottom of the evaporator or sensor malfunction), which would lead to an indefinitely prolonged defrosting process and a serious exceedance of the storage temperature.

[0107] For example, the maximum defrost time threshold can be calibrated to 10 to 15 minutes. During defrosting, the controller continuously accumulates the duration of the low humidity strategy and compares the relationship between T and the first temperature threshold in real time. If the duration exceeds the maximum defrost time threshold but T still does not meet the standard, the controller determines that the current defrost process is abnormal and immediately forces the defrost exit procedure: shutting down the defrost heater and chassis heating device, restoring the compressor's normal operating frequency and the fan's forward rotation, and recording the bottom defrost timeout fault code in the unit log for subsequent troubleshooting by maintenance personnel.

[0108] This design uses a maximum defrost time threshold as a fallback protection. When the water tray temperature is abnormal or the heating efficiency is too low, it forces the defrosting process to stop and resumes refrigeration. This prevents the defrosting process from being prolonged indefinitely due to sensor failure or extreme operating conditions, ensuring the reliability of the core refrigeration function of the cold storage and avoiding large fluctuations in the storage temperature.

[0109] See Figure 3 and Figure 4 As shown, in some feasible embodiments of the present invention, the termination condition corresponding to the high humidity environment defrosting strategy is: when the working time of the defrosting heater reaches the target working time, the defrosting is determined to end.

[0110] This termination condition corresponds to the aforementioned step of calculating the target operating time based on frost thickness d. When the controller enters the high-humidity defrosting strategy, a dedicated timer is activated. The termination condition terminates when the accumulated timer reaches the target operating time (i.e.,...). When the product of the first proportional coefficient is reached, the controller determines that high-humidity defrosting is complete, and then shuts off the defrosting heater, stops the fan reversal, and resumes compressor operation and fan forward rotation. This timed termination method has a simple and reliable logic. In high-humidity environments, the fan reversal significantly improves defrosting efficiency, allowing the frost layer to fully melt within the target working time, ensuring timely cessation of heating and effectively preventing over-defrosting.

[0111] This design uses the target working time as the termination condition for high-humidity defrosting, which corresponds to the heating time calculated based on the frost thickness. The timing termination method has a simple and reliable logic, which can ensure that heating stops in time after the frost layer has completely melted in a high-humidity environment, effectively preventing excessive defrosting.

[0112] See Figure 3 and Figure 4 As shown, in some feasible embodiments of the present invention, the relative humidity inside the warehouse during the defrosting process is used as a reference. Dynamic defrosting strategy selection also includes: defrosting strategy if the cold storage refrigeration unit enters a high humidity environment, and real-time relative humidity inside the storage room. If the humidity drops to below or equal to the first humidity threshold, the system will automatically switch to a low-humidity defrosting strategy until the current defrosting cycle is complete, and will no longer adjust based on humidity levels. The change is to switch back to a high-humidity environment defrosting strategy.

[0113] The first humidity threshold is the dividing point between high and low humidity strategies, and its value is based on engineering experimental calibration (e.g., 80%). When the unit initially enters the high humidity defrosting strategy, dry air from outside the evaporator is continuously introduced due to the evaporator fan reversing its direction. It may gradually decrease during the defrosting process. Once... Once the humidity drops to below or equal to the first humidity threshold, the controller detects this change and executes a strategy switch: immediately stopping the fan in reverse, activating the chassis heating device, and changing the termination condition from "timer reaching the target operating time" to "drain pan temperature T reaching the first temperature threshold." The key locking mechanism is that once switched to the low humidity strategy, it remains in effect until the current defrosting cycle ends, even if subsequent cycles... As the operating conditions change and increase again, the controller no longer switches back to the high humidity strategy, fundamentally eliminating problems such as frequent start-stop of the fan in forward and reverse directions and frequent on / off switching of the bottom heater caused by frequent switching near the threshold.

[0114] For example, at the beginning of a certain defrosting When the humidity reaches 82% (above the first humidity threshold of 80%), the unit enters high humidity mode, and the evaporator fan reverses at 40% of its normal speed; when defrosting reaches the 3rd minute... When the humidity drops to 78% (below 80%), the controller immediately switches to a low-humidity strategy, stops the evaporator fan from reversing, and starts the chassis heating device. Even after this... The humidity level rose to 85%, but the unit maintained a low humidity strategy until the water tray temperature T reached the first temperature threshold.

[0115] This design solves the problem of unit oscillation caused by frequent switching near the humidity threshold by allowing unidirectional switching and locking from a high humidity strategy to a low humidity strategy. It ensures that the latter half of the defrosting process can enter a more energy-efficient and safer low humidity processing mode as the humidity decreases, thus improving the stability and safety of the defrosting process.

[0116] See Figure 5 and Figure 6 As shown above, the conventional defrosting triggering requirements have been illustrated with an example. Specifically, the refrigeration capacity decay rate η is calculated based on the real-time refrigeration capacity Q of the cold storage refrigeration unit and the initial rated refrigeration capacity Q0. The defrosting triggering condition is determined when the refrigeration capacity decay rate η is greater than the first decay threshold and the real-time relative humidity inside the cold storage is [value missing]. When the humidity is greater than the second humidity threshold and the frost thickness d is greater than the first thickness threshold, the defrosting trigger condition is determined to be met; wherein, the second humidity threshold is less than the first humidity threshold.

[0117] The calculation of the cooling capacity attenuation rate η employs a triple-parameter joint judgment architecture. The real-time cooling capacity Q is calculated by collecting data from the evaporator inlet temperature difference ΔT1, outlet temperature difference ΔT2, compressor operating frequency f, and exhaust temperature. and inlet dry bulb temperature Substitution Therefore, the initial rated cooling capacity Q0 is the baseline value stored by the unit under standard operating conditions with no frost. Cooling capacity decay rate. This reflects the extent to which frosting affects the unit's heat exchange efficiency.

[0118] The specific values ​​of the first attenuation threshold, the second humidity threshold, and the first thickness threshold are based on engineering experimental calibration: the first attenuation threshold is calibrated at 15%, reflecting the critical point of heat exchange efficiency decline; the second humidity threshold is calibrated at 75%, because when the humidity inside the storage exceeds this value, the deposition rate of water vapor in the air increases significantly, and the frost layer changes from loose to dense; the first thickness threshold is calibrated at 5mm, representing that the amount of physical frost has reached the level that needs to be removed. These three thresholds have a clear hierarchical relationship: the second humidity threshold (75%) is less than the first humidity threshold (80%, i.e., the boundary between high and low humidity), and the first thickness threshold (5mm) is less than the second thickness threshold (10mm, i.e., absolute frost thickness protection). All three conditions must be met simultaneously to trigger regular defrosting, which effectively avoids misjudgment based on a single parameter: for example, even without frost in a low-temperature, high-humidity environment, η may be higher due to the influence of ambient temperature, but as long as... If the diameter is ≤75% or d≤5mm, the unit will not trigger erroneously.

[0119] This design utilizes the cooling capacity decay rate η and the real-time relative humidity inside the warehouse. The three parameters of the defrost layer thickness d are used to determine the defrost trigger condition. This method is more accurate than the single parameter method and effectively avoids false defrosting caused by misjudgment by a single sensor or occasional environmental fluctuations. It ensures that the defrost trigger time is consistent with the actual frost state.

[0120] See Figure 7 As shown, in addition, when any emergency defrosting condition is met, the unit immediately starts defrosting without waiting for the normal defrosting conditions to be met simultaneously.

[0121] The first emergency defrosting condition is that the frost layer thickness d is greater than or equal to the second thickness threshold, and the second thickness threshold is greater than the first thickness threshold (the second thickness threshold is greater than the first thickness threshold, which serves as an absolute frost thickness protection to prevent mechanical blockage).

[0122] The second emergency defrosting condition is that the cooling capacity decay rate η is greater than the second decay threshold and the duration exceeds the first duration threshold, and the second decay threshold is greater than the first decay threshold (the second decay threshold is greater than the first decay threshold to prevent the compressor from being damaged due to severe energy efficiency decay).

[0123] The third emergency defrosting condition is the real-time relative humidity inside the warehouse. The humidity level is greater than the third humidity threshold and the duration exceeds the second duration threshold, and the third humidity threshold is greater than the first humidity threshold (the third humidity threshold being greater than the first humidity threshold serves as a high humidity warning to prevent moisture accumulation).

[0124] Emergency defrosting conditions constitute a highest-priority triggering path independent of conventional judgments. Its design aims to bypass the "triple simultaneous fulfillment" logic of conventional judgments, directly initiating defrosting under extreme conditions. For example, the second thickness threshold is calibrated to 10mm as absolute frost thickness protection to prevent excessive frost buildup from causing mechanical blockage or air duct obstruction; the first thickness threshold is 5mm, with the second thickness threshold being greater than the first. The second decay threshold is calibrated to 25%, and the first duration threshold is calibrated to 30 minutes, meaning it triggers when η > 25% and lasts for more than 30 minutes, preventing compressor damage due to severe energy efficiency degradation; the second decay threshold is greater than the first decay threshold (15%). The third humidity threshold is calibrated to 90%, and the second duration threshold is calibrated to 10 minutes, meaning it triggers when η > 25% and lasts for more than 30 minutes, preventing compressor damage due to severe energy efficiency degradation; the second decay threshold is greater than the first decay threshold (15%). Triggered when humidity is >90% and lasts for more than 10 minutes; the third humidity threshold is greater than the first humidity threshold (80%), based on the fact that when humidity is greater than 90%, a liquid water film is easily formed locally, which freezes instantly on the cold wall surface and blocks the fins, requiring early intervention to prevent moisture accumulation.

[0125] The three emergency conditions are related by an "OR" condition; any one of them being met will trigger the defrost. For example, in a cold storage facility, although the normal defrosting conditions have not been met (η is only 12%), the frost thickness d has reached 10mm (meeting the first emergency condition). The controller immediately initiates defrosting without waiting for η, d, or d. All three conditions, d, must simultaneously meet the standard defrosting requirements.

[0126] This design, by setting independent emergency defrosting conditions, can bypass the conventional judgment logic and directly start defrosting when the frost layer is too thick, the decay rate is too high, or the humidity is too high. This improves the unit's response speed under extreme operating conditions, prevents refrigeration failure or equipment damage caused by severe frost, and enhances the unit's reliability.

[0127] In some feasible embodiments of the present invention, the calculation process of the cooling capacity attenuation rate η is as follows:

[0128] First, calculate the logarithmic mean temperature difference ΔT between the evaporator inlet and outlet. The formula is as follows: This formula is derived from the logarithmic mean of the temperature difference between the two ends of a heat exchanger in heat transfer, which can more accurately characterize the overall heat transfer driving force of the evaporator. When the values ​​of ΔT1 and ΔT2 are close (such as when the difference between the two is less than the preset tolerance), in order to avoid the instability of the logarithmic calculation, the controller directly takes the arithmetic mean of the two as ΔT.

[0129] Then substitute the calibration coefficients. , , Using the formula Calculate the real-time cooling capacity Q. The formula for calculating the real-time cooling capacity Q includes... The term reflects the linear contribution of compressor frequency and heat exchange temperature difference to the cooling capacity. This item reflects the correction of exhaust superheat to the unit's cooling efficiency. This represents the offset of the unit's inherent constants. Three calibration coefficients. , , Regression fitting under multiple sets of stepped operating conditions determined that: a large number of actual measured values ​​of Q and corresponding f and ΔT were collected under different compressor frequencies and different ambient temperatures. , The data was fitted using the least squares method to obtain the optimal coefficient combination. This cooling capacity estimation method based on a multi-parameter model is more accurate than simple current estimation or single temperature estimation, providing a reliable data foundation for defrost trigger determination.

[0130] Finally, according to the formula Calculate the cooling capacity decay rate η, where Q0 is the initial rated cooling capacity stored in the controller.

[0131] This design calculates real-time cooling capacity and attenuation rate using a specific formula, taking into account multiple parameters such as compressor frequency, temperature difference, and exhaust temperature. Compared to simple current or temperature estimation, it is more accurate and provides a reliable data foundation for defrosting trigger determination and cooling capacity monitoring.

[0132] See Figure 8 As shown, as a further safety net, a forced defrosting condition is also designed, that is, when the operating parameters do not meet the above-mentioned normal and emergency defrosting conditions, but the continuous operating time is... When the set time threshold is exceeded, the controller also determines that the defrosting trigger condition is met and forcibly starts defrosting, thus forming the ultimate safety bottom line to prevent long-term under-defrosting caused by sensor failure.

[0133] Continuous running time The settings constitute the bottom layer for defrosting triggering. For example, the set time threshold can be calibrated to 72 hours, based on the fact that even under light load conditions where no parameters trigger normal or emergency conditions, long-term continuous operation will inevitably be accompanied by slow frost formation. If defrosting is not performed, the frost layer will accumulate to a level that is difficult to handle. The controller continuously accumulates the continuous operating time during unit operation. Once the set time threshold is exceeded, regardless of η, Whether sensor 'd' or 'd' meets its respective trigger condition, the defrosting procedure is forcibly initiated to prevent prolonged operation without defrosting due to sensor failure or parameter fluctuations below the threshold. After defrosting is complete, the controller will... Reset to zero and restart the timer.

[0134] This design, by setting a fallback defrosting trigger condition based on continuous operating time, ensures that the unit can still force defrosting according to the longest cycle even when the sensor fails or the parameter fluctuation does not reach the threshold. This constitutes a safety bottom line for defrosting triggering, prevents severe frost buildup caused by long-term operation without defrosting, and ensures the basic operational safety of the unit.

[0135] See Figure 4 and Figure 9 As shown, the following is a detailed description of the defrosting control method based on dynamic adjustment of humidity and frost thickness according to an application example of the present invention:

[0136] Assume a large logistics cold storage facility with a set internal temperature of -18℃, equipped with a single cold storage refrigeration unit. The unit includes a cold storage refrigeration unit (compressor, condenser, evaporator, and expansion valve), an evaporator fan, a defrost heater, a chassis heating device, a humidity sensor, an ultrasonic frost thickness detection module, a drip tray temperature sensor, and a controller. The humidity sensor is located in the middle of the return air duct (1.3 meters from the ground and 0.6 meters from the side wall). The ultrasonic ranging module is installed behind the air outlet grille of the evaporator fan. The chassis heating device is attached to the bottom of the evaporator chassis, and the drip tray temperature sensor is installed on the wall of the evaporator drip tray. The controller is connected to all actuators and sensors via a communication bus to execute the following defrost control process.

[0137] Step S1: Collect cold storage operating parameters.

[0138] The controller periodically collects various operating parameters: real-time relative humidity inside the warehouse is measured by a humidity sensor. The thickness d of the frost layer on the evaporator surface was measured using an ultrasonic ranging module; the temperature difference ΔT1 at the evaporator inlet, the temperature difference ΔT2 at the evaporator outlet, and the compressor exhaust temperature were collected using temperature sensors. Evaporator inlet dry bulb temperature The current operating frequency f is read through the compressor driver; the continuous running time is continuously accumulated. The sampling interval can be set to 5 to 10 seconds to provide a data basis for subsequent calculations.

[0139] Step S2: Calculate the real-time cooling capacity Q and the cooling capacity decay rate η.

[0140] The controller first calculates the logarithmic mean temperature difference between the evaporator inlet and outlet. When ΔT1 and ΔT2 are close, take the arithmetic mean. , , Using the formula Calculate the real-time cooling capacity Q, and finally use the formula Calculate the cooling capacity decay rate η.

[0141] Step S3: Determine the defrosting trigger based on the running parameters.

[0142] The controller performs a routine trigger determination to check whether the following three conditions are met: η is greater than the first attenuation threshold (15%). The humidity is greater than the second humidity threshold (75%), and d is greater than the first thickness threshold (5mm). If all three conditions are met simultaneously, the normal defrosting trigger condition is met, and the process proceeds to step S4. If the normal conditions are not met, the controller further determines whether any of the emergency defrosting conditions are met: the first emergency condition (d ≥ the second thickness threshold of 10mm), the second emergency condition (η > the second attenuation threshold of 25% and lasts for more than the first duration threshold of 30 minutes), and the third emergency condition ( >The third humidity threshold is 90% and remains above the second duration threshold for 10 minutes. If any emergency condition is met, proceed immediately to step S4. If neither the normal nor the emergency condition is met, the controller determines the continuous running time. Check if the set time threshold (72 hours) has been exceeded. If it has, proceed to step S4.

[0143] Step S4: Dynamically select and execute the defrosting strategy.

[0144] When the defrosting trigger condition is met, the controller determines based on real-time data... The strategy is selected based on the comparison results with the first humidity threshold (80%).

[0145] like >At the first humidity threshold (80%), a high-humidity defrosting strategy is implemented. The controller first stops the compressor; then it reverses the evaporator fan at a speed lower than normal (e.g., 40% of normal) to accelerate the melting of frost using dry air; simultaneously, it queries the pre-stored frost thickness-baseline duration correspondence based on the current frost thickness d to obtain... ,Will Multiply by a first proportionality factor (e.g., 0.85) to obtain the target operating time; control the defrosting heater to operate within the target operating time. The termination condition is when the timer reaches the target operating time;

[0146] like When the humidity level is ≤1 humidity threshold (80%), a low-humidity defrosting strategy is implemented. The controller controls the compressor to rotate forward at a second percentage of its rated frequency (e.g., 20% to 30%), while the evaporator fan rotates in reverse at a speed lower than normal (e.g., 20% to 30% of normal) to prevent cold air backflow. The defrosting heater power is reduced to a third percentage of its rated power (e.g., 80%). The chassis heating device is simultaneously activated to melt the ice accumulated at the bottom. The termination condition is when the water tray temperature T reaches the first temperature threshold (e.g., 5°C). If T fails to reach the threshold and the duration exceeds the maximum defrosting time threshold (e.g., 15 minutes), defrosting is forcibly terminated and cooling is resumed, and a fault code is recorded.

[0147] Among them, if the initial defrosting strategy is a high humidity strategy and it is real-time When the humidity drops to ≤80%, the controller automatically switches to the low humidity strategy (stops fan reversal, starts chassis heating device, changes termination condition to T≥first temperature threshold), and locks it until the defrosting ends, without switching back to the high humidity strategy.

[0148] Step S5: Defrosting complete and resetting.

[0149] Once all units participating in defrosting have met the termination conditions of their respective strategies (the high humidity strategy timer ends or the low humidity strategy temperature reaches the target), the controller determines that defrosting is complete. The controller then restores the compressor to its normal operating frequency, resumes forward rotation of the fan, shuts down the defrosting heater and chassis heating device, resets the timer and status flag, and reintegrates the unit into the regular monitoring cycle, awaiting the next round of frost level assessment.

[0150] Let's take a specific defrosting process as an example to illustrate:

[0151] Measurements taken during unit operation , , Since η > 15%, If all three conditions—>75%, d>5mm—are met simultaneously, the standard defrosting trigger condition is satisfied. When humidity exceeds 80% (the first humidity threshold), the unit enters a high-humidity defrosting strategy. The controller shuts down the compressor and starts the evaporator fan in reverse rotation at 40% of its normal speed; according to... Query results Multiply the time by 0.85 to get the target working time of 6.8 minutes, and start the defrosting heater. When defrosting reaches the 4-minute mark, due to the fan reversing and introducing a large amount of dry air, the defrosting process begins. It rapidly dropped to 78%. The controller detected this. If the temperature is ≤80%, immediately switch to a different strategy: stop the fan reversal, start the chassis heating device, and change the termination condition to monitoring the water tray temperature T. As defrosting continues, the water tray temperature T gradually rises. When it reaches 5℃, the controller determines that defrosting is complete, shuts off all heating devices, the compressor resumes normal operating frequency, the fan resumes forward rotation, and the unit re-enters refrigeration mode. If, due to extreme circumstances, T fails to reach 5℃ for more than 15 minutes, the controller will also forcibly exit defrosting, resume refrigeration operation, and record the fault code to ensure the safety of the storage temperature.

[0152] As can be seen from the above embodiments, the present invention can dynamically adjust the defrosting strategy according to real-time operating conditions, significantly reduce energy consumption while ensuring defrosting effect, and effectively solve the problem of bottom icing in low humidity environments.

[0153] The present invention also proposes a cold storage unit, including a cold storage refrigeration unit and a controller. The evaporator of the cold storage refrigeration unit provides cooling capacity to the storage unit. The evaporator is equipped with an evaporator fan and a defrost heater. The controller is electrically connected to the cold storage refrigeration unit, the evaporator fan and the defrost heater respectively. The controller is configured to execute the defrost control method as described in any of the foregoing embodiments.

[0154] The specific structure of the cold storage unit is as follows: The refrigeration unit includes a compressor, condenser, expansion valve, and evaporator, which form a refrigeration cycle through parallel or series connections to provide cooling capacity to the storage area. The evaporator is located inside the storage room or in the cold air circulation duct, and its surface gradually frosts up during the refrigeration process. The evaporator fan is configured to supply or exhaust air to the evaporator, and its forward or reverse rotation can be controlled according to a strategy during defrosting. The defrost heater is installed near the evaporator coil to provide the heat required to melt the frost layer during defrosting. The controller, as the core computing and decision-making unit of the cold storage, is electrically connected to the compressor, evaporator fan, defrost heater, chassis heating device, humidity sensor, and frost thickness detection module. It is configured to execute all steps of the aforementioned defrosting control method, including data acquisition, trigger determination, strategy selection, dynamic switching, and termination reset. By integrating the aforementioned methods into the cold storage controller, the cold storage unit gains the ability to intelligently adjust the defrosting strategy based on ambient humidity and frost thickness, directly improving the overall energy efficiency and intelligence level of the unit.

[0155] This design integrates the aforementioned defrosting control method into the cold storage's controller, enabling the cold storage to intelligently adjust its defrosting strategy based on ambient humidity and frost thickness. This directly improves the overall energy efficiency and intelligence level of the cold storage unit, reduces manual intervention, and lowers operating costs.

[0156] In some feasible embodiments of the present invention, a chassis is provided at the bottom of the evaporator, and a chassis heating device is provided below or inside the chassis, the chassis heating device being electrically connected to the controller. The chassis, located at the bottom of the evaporator, is disc-shaped or trough-shaped, used to collect defrost water generated during the defrosting process and guide it to the drain pipe. The chassis heating device is an electric heating wire or heating film, attached to the bottom of the chassis or embedded in the chassis wall, uniformly transferring heat to the chassis surface through heat conduction. The chassis heating device is electrically connected to the controller and receives power-on / off commands from the controller. In a low-humidity defrosting strategy, the controller activates the chassis heating device, causing it to continuously heat until the water tray temperature T reaches a first temperature threshold. This structural design provides the necessary hardware support for bottom defrosting in low-humidity environments, effectively conducting heat to the ice accumulation area and solving the physical implementation problem of low-humidity defrosting.

[0157] This design provides the necessary hardware support for bottom defrosting in low-humidity environments by setting a chassis and heating device at the bottom of the evaporator. The reasonable structural layout can effectively conduct heat to the ice accumulation area, solve the physical problem of low-humidity defrosting, and improve the adaptability of cold storage in complex environments.

[0158] The present invention also proposes a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the defrosting control method as described in any of the foregoing embodiments.

[0159] The computer-readable storage medium can be flash memory, hard disk, solid-state drive, optical disk, or any other medium capable of storing computer programs. The computer program contains all the instructions for implementing the defrosting control method described above, including code logic for steps such as data acquisition, trigger determination, strategy selection, dynamic switching, and termination / reset. When the storage medium is mounted on the processor of the cold storage controller, the processor reads and executes the program to achieve intelligent defrosting control. This provides a convenient platform for the deployment, upgrading, and maintenance of the control algorithm, enabling the defrosting control method to exist and spread independently in software form, facilitating its portability and application in different equipment models.

[0160] This design provides a carrier for the deployment, upgrading and maintenance of the control algorithm by storing the computer program that implements the above-mentioned defrosting control method. This allows the defrosting control method to exist and spread independently in software form, making it easy to port and apply in different models of equipment.

[0161] It should be noted that the terminology used above is for describing specific embodiments only and is not intended to limit the exemplary embodiments of the present invention. When the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. The order of execution of actions, steps, etc., in the apparatus and methods shown in the specification and drawings may be implemented in any order unless a specific express order is specified, and as long as the output of a previous process is not used in a subsequent process. Similar sequential terms used for ease of description do not imply that such an order must be followed.

[0162] Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as constraints. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0163] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A defrosting control method, characterized in that, Includes the following steps: Collect the operating parameters of the cold storage, and determine the defrosting trigger based on the operating parameters; When the defrosting trigger condition is met, the real-time relative humidity inside the warehouse during the defrosting process is used as a reference. Dynamically select defrosting strategy: If the relative humidity inside the warehouse is real time If the humidity exceeds the first humidity threshold, a high humidity defrosting strategy is implemented. The high humidity defrosting strategy includes controlling the compressor to stop, starting the evaporator fan to reverse at a speed lower than normal, and reducing the working time of the defrosting heater proportionally based on the frost thickness d. If the relative humidity inside the warehouse is real time If the humidity is not higher than the first humidity threshold, a low-humidity defrosting strategy is implemented. The low-humidity defrosting strategy includes controlling the compressor to reduce its speed and rotate in the forward direction, starting the evaporator fan to rotate in the forward direction at a speed lower than the normal value, and reducing the power of the defrosting heater. The defrosting process ends based on the termination condition corresponding to the selected strategy.

2. The defrosting control method according to claim 1, characterized in that, The defrosting strategy for low-humidity environments also includes: activating the chassis heating device of the evaporator.

3. The defrosting control method according to claim 1, characterized in that, The reduction in defrosting heater operating time proportional to the frost thickness d includes: Multiple sets of frost layer thicknesses d and reference heating times are pre-stored. The correspondence; Will Multiply by the first proportionality coefficient to obtain the target working time for defrosting in high humidity environments; Control the defrosting heater to operate within the target operating time.

4. The defrosting control method according to claim 1, characterized in that, In the low-humidity defrosting strategy, the compressor rotates forward at a second ratio of its rated frequency, and the defrosting heater operates at a third ratio of its rated power.

5. The defrosting control method according to claim 2, characterized in that, The termination condition for the low-humidity defrosting strategy is: monitor the temperature T of the evaporator's water tray, and determine that defrosting ends when the water tray temperature T reaches the first temperature threshold.

6. The defrosting control method according to claim 5, characterized in that, Also includes: After executing the low-humidity defrosting strategy, if the water tray temperature T fails to reach the first temperature threshold and the duration of the low-humidity defrosting strategy exceeds the preset maximum defrosting time threshold, then the defrosting process is forcibly terminated and the refrigeration operation is resumed.

7. The defrosting control method according to claim 3, characterized in that, The termination condition for the high-humidity environment defrosting strategy is: when the working time of the defrosting heater reaches the target working time, the defrosting is determined to end.

8. The defrosting control method according to claim 1, characterized in that, Based on the real-time relative humidity inside the warehouse during the defrosting process Dynamic selection of defrosting strategies also includes: If the cold storage refrigeration unit enters the high humidity environment defrosting strategy, and the real-time relative humidity inside the storage is... If the humidity drops to less than or equal to the first humidity threshold, the system automatically switches to the low-humidity defrosting strategy until the current defrosting cycle ends, and then stops based on the humidity level. The change is to switch back to a high-humidity environment defrosting strategy.

9. The defrosting control method according to claim 1, characterized in that, The operating parameters include the real-time relative humidity inside the warehouse. The thickness of the frost layer on the evaporator surface (d) and the real-time cooling capacity (Q) of the cold storage refrigeration unit; Determining defrost trigger based on the aforementioned operating parameters includes: Calculate the cooling capacity decay rate η based on the real-time cooling capacity Q and the initial rated cooling capacity Q0 of the cold storage refrigeration unit; When the cooling capacity decay rate η is greater than the first decay threshold and the real-time relative humidity H in the storage room is simultaneously satisfied... in When the humidity is greater than the second humidity threshold and the frost thickness d is greater than the first thickness threshold, the defrosting trigger condition is determined to be met. Wherein, the second humidity threshold is less than the first humidity threshold.

10. The defrosting control method according to claim 9, characterized in that, The operating parameters include the real-time relative humidity inside the warehouse. The thickness of the frost layer on the evaporator surface (d) and the real-time cooling capacity (Q) of the cold storage refrigeration unit; Determining defrost trigger based on the aforementioned operating parameters includes: When any emergency defrosting condition is met, the defrosting trigger condition is determined to be met; The first emergency defrosting condition is that the frost layer thickness d is greater than or equal to the second thickness threshold, and the second thickness threshold is greater than the first thickness threshold. The second emergency defrosting condition is that the cooling capacity decay rate η is greater than the second decay threshold and the duration exceeds the first duration threshold, and the second decay threshold is greater than the first decay threshold. The third emergency defrosting condition is the real-time relative humidity inside the warehouse. The humidity is greater than a third humidity threshold and the duration exceeds a second duration threshold, and the third humidity threshold is greater than the first humidity threshold.

11. The defrosting control method according to claim 9 or 10, characterized in that, The calculation of the cooling capacity attenuation rate η includes: Collect the temperature difference ΔT1 at the evaporator inlet and ΔT2 at the evaporator outlet, and calculate the logarithmic mean temperature difference between the evaporator inlet and outlet. ; Collect compressor operating frequency f and compressor discharge temperature and evaporator inlet dry bulb temperature ; According to the formula Calculate the real-time cooling capacity Q, where , , These are calibration coefficients; According to the formula Calculate the cooling capacity decay rate η; Where Q0 is the initial rated cooling capacity.

12. The defrosting control method according to claim 9 or 10, characterized in that, The operating parameters also include the continuous operating time of the cold storage refrigeration unit. ; Determining defrost trigger based on the aforementioned operating parameters includes: When the operating parameters do not meet the defrosting trigger conditions, but the continuous operating time of the cold storage refrigeration unit is... If the set time threshold is exceeded, the defrosting trigger condition is determined to be met.

13. Cold storage, including: A cold storage refrigeration unit and a controller, wherein the evaporator of the cold storage refrigeration unit provides cooling capacity to the storage room, the evaporator is equipped with an evaporator fan and a defrost heater, and the controller is electrically connected to the cold storage refrigeration unit, the evaporator fan and the defrost heater respectively, characterized in that the controller is configured to perform the defrost control method as described in any one of claims 1 to 12.

14. The cold storage facility according to claim 13, characterized in that, The evaporator is provided with a chassis at the bottom, and a chassis heating device is provided below or inside the chassis, and the chassis heating device is electrically connected to the controller.

15. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the defrosting control method as described in any one of claims 1 to 12.

Images