Vegetable refrigeration environment temperature and humidity decoupling control method

Abstract

The present application relates to a kind of vegetable refrigeration environment temperature and humidity decoupling control method, belong to vegetable refrigeration preservation environment control technical field, comprising: the return air of vegetable storage area is distributed to first return air path and second return air path before entering evaporator, make the return air in first return air path contact the first heat exchange zone of evaporator, the heat exchange surface temperature of first heat exchange zone is lower than the dew point temperature of return air, to precipitate the moisture in return air;Make the return air in second return air path bypass first heat exchange zone, and contact the second heat exchange zone of evaporator when needing to supplement cooling, the heat exchange surface temperature of second heat exchange zone is higher than or equal to the dew point temperature of return air;Two-way processed air is introduced into air supply mixing chamber after mixing and is sent into vegetable storage area, and according to return air dew point temperature, vegetable surface temperature and return air humidity parameter adjustment two-way air volume ratio, make cooling process and dehumidification process separate on air flow path, reduce temperature and humidity control interference and the drying effect of low dew point air to vegetable surface.

Description

Technical Field

[0001] This invention relates to the field of vegetable cold storage and preservation environment control technology, specifically a decoupled control method for temperature and humidity in vegetable cold storage environment. Background Technology

[0002] In existing technologies, vegetable cold storage and preservation typically rely on evaporator cooling, fan circulation, and humidification or dehumidification devices to uniformly regulate the storage space. This method can reduce the respiration intensity of vegetables and delay quality deterioration to some extent. However, temperature and humidity regulation are often coupled and completed within the same heat exchange airflow. When the temperature of the evaporator heat exchange surface is lower than the return air dew point temperature, the air condenses and dehumidifies while cooling. The cold air sent into the storage area is in a low-temperature, low-dew-point state, which can easily directly wash over the vegetable surface, exacerbating surface moisture evaporation. To maintain a higher relative humidity, additional humidification or a reduction in refrigeration intensity is required, resulting in a slower temperature response and greater fluctuations within the storage area. It is difficult to simultaneously meet the requirements of rapid cooling, humidity maintenance, and surface moisture prevention.

[0003] In recent years, Chinese patent documents, including publication number CN115930521A, have disclosed a fruit and vegetable pre-cooling system, fruit and vegetable storage equipment, and control method. This system uses an upper return air structure, a lower return air structure, and an air duct structure to create circulating air at different locations, which mixes with each other to promote heat exchange and circulation within the fruit and vegetable storage, improving cooling speed and temperature uniformity. While this solution focuses on the air circulation path and pre-cooling uniformity within the storage, the cooling and potential dehumidification of the return air after heat exchange are still primarily influenced by the heat exchange process. It does not address the relationship between the return air dew point temperature, vegetable surface temperature, and return air humidity, nor does it separate the dehumidifying airflow and the supplementary cooling airflow before they enter the evaporator. Therefore, in high-humidity vegetable storage scenarios, there is still a possibility that low-dew-point cold air may excessively dry the vegetable surface.

[0004] Another publication, CN115773624A, discloses a dual-circulation temperature and humidity control system and method for a constant temperature and humidity cold storage. This system achieves temperature and humidity regulation and intelligent management of the cold storage through an internal refrigeration and heating cycle, an external heat exchange cycle, an internal temperature and humidity alternation module, and a temperature and humidity monitoring system control module. While this type of solution can improve constant temperature and humidity control capabilities at the system level, its focus is on the comprehensive allocation of internal and external heat and cold resources and temperature and humidity monitoring and control. The controlled object is still mainly the overall temperature and humidity parameters within the cold storage, without further addressing the difficulty of independently adjusting sensible heat cooling and condensation dehumidification during the same evaporator heat exchange process. Especially for leafy vegetables and stem vegetables, which are sensitive to surface water loss, simply increasing the relative humidity inside the storage or using overall circulation control makes it difficult to accurately control the safety margin between the air supply dew point and the vegetable surface temperature, easily leading to localized condensation, wilting due to water loss, or delayed temperature recovery. Therefore, it is necessary to propose a decoupled control method for temperature and humidity in vegetable cold storage environment that can separate the cooling process and the dehumidification process in the air flow path and dynamically adjust the air volume ratio of different return air paths based on the return air dew point temperature, vegetable surface temperature and return air humidity parameters. Summary of the Invention

[0005] The purpose of this invention is to provide a decoupled control method for temperature and humidity in vegetable cold storage environments, thereby solving some of the drawbacks and shortcomings pointed out in the background art.

[0006] The present invention adopts the following technical solution to solve the above-mentioned technical problems: Before entering the evaporator, the return air from the vegetable storage area is distributed to the first return air path and the second return air path, so that the return air in the first return air path comes into contact with the first heat exchange zone of the evaporator. The temperature of the heat exchange surface of the first heat exchange zone is lower than the dew point temperature of the return air in the first return air path, so as to remove moisture from the return air. The return air in the second return air path bypasses the first heat exchange zone and comes into contact with the second heat exchange zone of the evaporator when additional cooling is needed. The heat exchange surface temperature of the second heat exchange zone is higher than or equal to the dew point temperature of the return air in the second return air path. The air processed by the first and second return air paths is introduced into the air mixing chamber, mixed, and then sent to the vegetable storage area. The air volume ratio of the first and second return air paths is adjusted according to the return air dew point temperature, vegetable surface temperature, and return air humidity parameters to separate the cooling process and the dehumidification process in the air flow path.

[0007] Furthermore, the air processed by the first return air path enters the upstream side of the air supply mixing chamber, and the air processed by the second return air path enters the downstream side of the air supply mixing chamber, so that the air near the air supply outlet is formed by the air processed by the second return air path, thereby reducing the degree of direct scouring of the vegetable surface by the low dew point air.

[0008] Furthermore, when the return air in the second return air path is configured to contact the second heat exchange zone, if the difference between the vegetable surface temperature and the return air dew point temperature is less than a first preset threshold and the vegetable storage zone temperature does not exceed the preset upper temperature limit, the return air in the second return air path is suspended from contacting the second heat exchange zone, so that the return air in the second return air path is used to mix with the air processed by the first return air path; after the dew point temperature of the mixed air is lower than the second preset threshold of the vegetable surface temperature, the contact between the second return air path and the second heat exchange zone is restored.

[0009] Furthermore, a buffer air layer consisting of return air from the second return air path is formed between the vegetable storage area and the entrance of the first return air path. By adjusting the air intake of the buffer air layer, the dehumidification intensity of the first return air path on the vegetable storage area is changed.

[0010] Furthermore, during the period when the return air in the second return air path is suspended from contacting the second heat exchange zone, the return air in the second return air path enters along the air outlet side of the air supply mixing chamber and surrounds the air processed by the first return air path along the outer periphery, so that a moisturizing air layer with a dew point temperature higher than that of the inner air is formed on the outside of the air supplied to the vegetable storage area.

[0011] Furthermore, after the dew point temperature of the mixed air is lower than the second preset threshold of the vegetable surface temperature, the preset proportion of return air in the second return air path is first made to contact the second heat exchange zone according to the preset start-stop cycle, and then the proportion of air volume in contact with the second heat exchange zone is increased according to the preset gradient, so that the rate of decrease of the vegetable surface temperature when the second heat exchange zone resumes heat exchange is within the preset rate range.

[0012] Furthermore, before restoring the contact between the second return air path and the second heat exchange zone, the return air in the second return air path is first mixed with the air processed by the first return air path in the air supply mixing chamber, and then the pre-mixed air of the preset ratio is introduced into the second heat exchange zone for secondary cooling.

[0013] Furthermore, the buffer air layer forms a decreasing wind speed along the first return air path toward the vegetable storage area, so that the air velocity on the side closer to the vegetable storage area is less than the air velocity on the side closer to the first return air path, thereby weakening the reverse diffusion of the low-temperature, low-dew-point air formed in the first heat exchange zone toward the vegetable storage area.

[0014] Furthermore, when the proportion of airflow entering the first return air path increases, the return airflow in the second return air path that forms the buffer air layer is increased simultaneously, so that the thickness of the buffer air layer increases with the increase of the dehumidification intensity of the first return air path.

[0015] Furthermore, when increasing the return air volume in the second return air path that forms the buffer air layer, the increase in the air intake volume on the side of the buffer air layer closer to the vegetable storage area is greater than the increase in the air intake volume on the side closer to the first return air path, so that the thickness increment of the buffer air layer on the side closer to the vegetable storage area is greater than the thickness increment on the side closer to the first return air path.

[0016] This invention distributes the return air to a first return air path and a second return air path before it enters the evaporator. In the first return air path, the return air contacts the first heat exchange zone where the surface temperature is lower than the dew point temperature of the return air to precipitate moisture. In the second return air path, the return air bypasses the first heat exchange zone and contacts the second heat exchange zone where the surface temperature is higher than or equal to its dew point temperature when supplemental cooling is needed. This allows the dehumidification process and the supplemental cooling process to be completed in different air paths, avoiding excessive dehumidification caused by all return air being treated by low-temperature heat exchange surfaces. This helps to reduce the mutual interference between temperature and humidity control in the vegetable cold storage environment.

[0017] Simultaneously, this invention introduces the processed air from both directions into the air mixing chamber, mixes them, and then delivers them to the vegetable storage area. The airflow ratio between the first and second return air paths is adjusted based on parameters such as the return air dew point temperature, vegetable surface temperature, and return air humidity. This allows for control of the dew point level of the mixed air supply while meeting the cooling requirements of the storage area, reducing the direct drying effect of low-dew-point air on the vegetable surface and minimizing the risk of wilting due to water loss. This method achieves the distribution and adjustment of dehumidification and cooling intensity without relying solely on external humidification compensation. It features clear control logic, applicability to high-humidity vegetable cold storage scenarios, and the ability to maintain vegetable surface moisture and improve storage quality stability. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the decoupled control of temperature and humidity in the vegetable cold storage environment according to the present invention.

[0019] Figure 2 This is a diagram showing the decoupling path of the two return air temperature and humidity in Embodiment 1 of the present invention.

[0020] Figure 3 This is a diagram showing the pause determination of the second return air path in Embodiment 1 of the present invention.

[0021] Figure 4 This is a progressive recovery control diagram for the second heat exchange zone in Embodiment 1 of the present invention.

[0022] Figure 5 This is a diagram illustrating the formation and isolation path of the buffer gas layer in Embodiment 2 of the present invention.

[0023] Figure 6 This is a diagram showing the decreasing wind speed determination of the buffer air layer in Embodiment 2 of the present invention.

[0024] Figure 7This is a diagram showing the adjustment of the buffer air layer thickness with the return air volume in Embodiment 2 of the present invention. Detailed Implementation

[0025] As attached Figure 1 As shown, in one embodiment, the refrigeration system includes a vegetable storage area, an evaporator, a return air duct, a supply air duct, and a supply air mixing chamber. The refrigeration system also includes a control system, a return air temperature and humidity sensor, a vegetable surface temperature sensor, and an airflow adjustment component. The airflow adjustment component is located at the designated positions of the return air duct and the first and second return air paths, or is respectively located within the first and second return air paths, to adjust the airflow ratio of the two return air paths. The control system is electrically connected to the return air temperature and humidity sensor, the vegetable surface temperature sensor, and the airflow adjustment component. The return air dew point temperature can be obtained by the control system based on the return air temperature and humidity parameters using a preset dew point conversion table or a preset control program. The vegetable surface temperature can be obtained by a non-contact temperature sensor located in the vegetable storage area, or by a temperature sensor in contact with the surface of a representative vegetable. The evaporator can be divided into a first heat exchange zone and a second heat exchange zone according to the airflow path. The first and second heat exchange zones can be separated by baffles, guide vanes, or independent air ducts, allowing the return air entering the first and second return air paths to exchange heat with their respective heat exchange zones. Air from the vegetable storage area, after returning through the return air duct, is divided into two airflows before entering the evaporator, entering the first and second return air paths respectively. The first return air path is responsible for the main dehumidification function. The return air entering the first return air path is guided to the first heat exchange zone of the evaporator and exchanges heat with its heat exchange surface. The temperature of the heat exchange surface in the first heat exchange zone is controlled to be lower than the dew point temperature of the return air in the first return air path, causing water vapor in the return air to precipitate on the heat exchange surface of the first heat exchange zone, thereby reducing the moisture content of the air after passing through the first return air path.

[0026] The second return air path serves as an auxiliary cooling and humidity buffer. The return air entering the second return air path bypasses the first heat exchange zone, preventing strong dehumidification within that zone. When the vegetable storage area still requires additional cooling, the return air in the second return air path is guided to the second heat exchange zone of the evaporator. The heat exchange surface temperature of the second heat exchange zone is controlled to reach or exceed the dew point temperature of the return air in the second return air path, ensuring that the return air in the second return air path does not produce significant water separation during heat exchange and cooling, or only produces a small amount of condensation that does not affect the humidity buffering target. The heat exchange surface temperature of the second heat exchange zone can be controlled by the control system by adjusting the refrigerant supply status, compressor operating status, throttling status, second return air path airflow, or the second heat exchange zone bypass ratio. The low dew point air processed by the first return air path and the air processed by the second return air path enter the air supply mixing chamber, mix there, and then are sent back to the vegetable storage area through the air supply duct. During the control process, the air volume ratio of the first return air path and the second return air path is adjusted according to the return air dew point temperature, vegetable surface temperature and return air humidity parameters, so that dehumidification mainly occurs in the first return air path, and supplementary cooling and humidity buffering mainly occur in the second return air path and the air supply mixing chamber, thereby achieving the separation of the cooling process and the dehumidification process in the air flow path.

[0027] Based on the above implementation, the air supply mixing chamber can be divided into an upstream side and a downstream side according to the air supply direction. The upstream and downstream sides are determined by the direction in which the air in the air supply mixing chamber flows from the air inlet to the air outlet. The air processed by the first return air path enters the upstream side of the air supply mixing chamber after dehumidification, allowing the low dew point air to participate in mixing within the air supply mixing chamber first. The air processed by the second return air path enters the downstream side of the air supply mixing chamber and is located near the air outlet, so that the airflow near the air outlet is mainly formed by the air processed by the second return air path. The inlet of the second return air path on the downstream side of the air supply mixing chamber can be set as an annular inlet, a lateral inlet, or multiple dispersed inlets arranged circumferentially along the air outlet, so that the air processed by the second return air path forms a covering airflow outside the low dew point air. Since the return air in the second return air path has not undergone strong dehumidification treatment in the first heat exchange zone, or is supplemented with cooling in the second heat exchange zone using a non-water separation heat exchange method, this part of the air has a higher dew point temperature than the air processed by the first return air path. This arrangement allows for a humidity-buffered airflow to be formed on the outer side or front end of the air outlet in the vegetable storage area, reducing the direct impact of low dew point air on the vegetable surface, thereby reducing the risk of moisture loss and localized dryness on the vegetable surface.

[0028] Based on the above implementation, the second return air path can be configured to selectively connect to the second heat exchange zone via a second path damper, bypass damper, or guide vane. When the return air in the second return air path is connected to the second heat exchange zone, the control system acquires the vegetable surface temperature, return air dew point temperature, and vegetable storage zone temperature. When the difference between the vegetable surface temperature and the return air dew point temperature is less than a first preset threshold, and the vegetable storage zone temperature does not exceed the preset upper temperature limit, the control system suspends the return air in the second return air path from entering the second heat exchange zone, allowing the return air in the second return air path to bypass the second heat exchange zone and enter the air supply mixing chamber, where it mixes with the air processed by the first return air path. The first preset threshold can be pre-stored in the control system according to the vegetable type, target refrigeration temperature, and allowable dry loss, or it can be selected by the user in the refrigeration mode. Through the above control method, the continued cooling effect of the second heat exchange zone on the air in the second return air path can be reduced, avoiding excessive reduction in the dew point temperature of the air supplied to the vegetable storage zone, thereby reducing the risk of water loss or local temperature fluctuations near the vegetable surface.

[0029] During the suspension of the return air connection between the second return air path and the second heat exchange zone, the return air in the second return air path enters the air mixing chamber along the air outlet side and surrounds the air processed by the first return air path along its outer periphery. Since the return air in the second return air path does not undergo further heat exchange in the second heat exchange zone, its dew point temperature is higher than that of the air processed by the first return air path. When the air from both paths is delivered through the air mixing chamber, a moisturizing layer forms on the outside of the air entering the vegetable storage area. The dew point temperature of this moisturizing layer is higher than that of the air inside, thus creating a humidity buffer zone between the low-dew-point air and the vegetable surface, reducing the direct effect of the low-dew-point air on the vegetable surface.

[0030] When the dew point temperature of the mixed air falls below the recovery judgment temperature obtained by using the vegetable surface temperature as a reference and offsetting it downwards by a second preset threshold, the control system restores the connection between the second return air path and the second heat exchange zone. The second preset threshold is used to form a control hysteresis to avoid frequent switching between the second return air path connecting to the second heat exchange zone and bypassing the second heat exchange zone. During the recovery process, a preset proportion of return air in the second return air path is first connected to the second heat exchange zone according to a preset start-stop cycle, allowing the second heat exchange zone to gradually participate in supplementing the cooling of the air in the second return air path. Subsequently, the control system increases the proportion of airflow in the second return air path connected to the second heat exchange zone according to a preset gradient, so that the heat exchange effect of the second heat exchange zone is restored smoothly, and the rate of decrease in vegetable surface temperature is within a preset rate range. The preset proportion, preset start-stop cycle, preset gradient, and preset rate range can be pre-stored in the control system according to the vegetable type, loading amount, target temperature of the vegetable storage area, and target humidity range, and are called by the control system during operation.

[0031] Before reconnecting the second return air path with the second heat exchange zone, the return air in the second return air path can be mixed with the air processed by the first return air path in the air supply mixing chamber to form a primary mixed air. Subsequently, a preset proportion of the primary mixed air is introduced into the second heat exchange zone through a return branch or bypass branch connected to the air supply mixing chamber for secondary cooling. This makes the dew point and temperature of the air entering the second heat exchange zone more stable, thereby reducing the sudden changes in the air supply status of the vegetable storage area when the second heat exchange zone resumes heat exchange.

[0032] Based on the above implementation method, a buffer air layer can be formed between the vegetable storage area and the inlet of the first return air path. The buffer air layer is composed of return air from the second return air path. This return air can enter the buffer air layer formation area through buffer outlets, slit outlets, or deflectors located near the inlet of the first return air path, and is situated between the vegetable storage area and the first return air path, thus creating airflow isolation between them. By adjusting the airflow entering the buffer air layer, the degree to which the first return air path draws humid air from the vegetable storage area can be altered. When the airflow entering the buffer air layer increases, the airflow isolation between the vegetable storage area and the first return air path is enhanced, and the dehumidification intensity of the first return air path on the vegetable storage area decreases. When the airflow entering the buffer air layer decreases, the traction effect of the first return air path on the return air of the vegetable storage area is enhanced, and the dehumidification intensity of the first return air path on the vegetable storage area is increased.

[0033] A buffer air layer creates a decreasing air velocity along the first return air path towards the vegetable storage area, ensuring that the air velocity near the vegetable storage area is lower than the air velocity near the first return air path. This decreasing air velocity can be achieved by using air outlets with different opening areas along the thickness of the buffer air layer, guide vanes with different guide angles, or dampers with different opening degrees. The higher velocity near the first return air path stabilizes the airflow boundary near the inlet of the first return air path, while the lower velocity near the vegetable storage area reduces airflow disturbance to the vegetable surface. This velocity distribution weakens the reverse diffusion of low-temperature, low-dew-point air from the first heat exchange zone towards the vegetable storage area, reducing the direct impact of this air on the vegetable surface within the storage area.

[0034] When the proportion of airflow entering the first return air path increases, the dehumidification effect of the first heat exchange zone on the return air is enhanced. At this time, within the same control cycle or in the next control cycle after the increase in the proportion of airflow in the first return air path, the control system synchronously increases the return air volume in the second return air path, which forms a buffer air layer. This causes the thickness of the buffer air layer to increase with the increase in the dehumidification intensity of the first return air path. The increased thickness of the buffer air layer expands the isolation range between the vegetable storage area and the first return air path, thereby maintaining the stability of the air humidity in the vegetable storage area even when the dehumidification intensity of the first return air path increases.

[0035] When increasing the return air volume in the second return air path that forms the buffer air layer, the increase in air intake volume on the side of the buffer air layer closer to the vegetable storage area can be greater than the increase on the side closer to the first return air path. This increase in air intake volume can be achieved by increasing the opening of the buffer air outlet on the side closer to the vegetable storage area, increasing the air supply time of the outlet on that side, or decreasing the relative opening of the outlet on the side closer to the first return air path. As a result, the thickness increment of the buffer air layer on the side closer to the vegetable storage area is greater than the thickness increment on the side closer to the first return air path, causing the buffer air layer to expand preferentially towards the vegetable storage area. This configuration can prioritize strengthening humidity protection near the vegetable surface when the dehumidification intensity of the first return air path increases, reducing the risk of desiccation of vegetables due to low dew point air diffusion.

[0036] Example 1: In this embodiment, the refrigeration system includes a vegetable storage area, an evaporator, a return air duct, a supply air duct, a supply air mixing chamber, a control system, a return air temperature and humidity sensor, a vegetable surface temperature sensor, and an airflow regulation component. The air side of the evaporator is divided into a first heat exchange zone and a second heat exchange zone. The return air duct connects to the first return air path and the second return air path before entering the evaporator. The airflow regulation component is used to adjust the proportion of return air entering the first return air path and the second return air path.

[0037] In this embodiment, the return air from the vegetable storage area is distributed to the first return air path and the second return air path after returning through the return air duct. The return air in the first return air path contacts the first heat exchange zone of the evaporator. The temperature of the heat exchange surface of the first heat exchange zone is lower than the dew point temperature of the return air in the first return air path, causing moisture in the return air to precipitate on the heat exchange surface of the first heat exchange zone, thus making the first return air path the main dehumidification function. The return air in the second return air path bypasses the first heat exchange zone and contacts the second heat exchange zone of the evaporator when supplemental cooling is needed. The temperature of the heat exchange surface of the second heat exchange zone is higher than or equal to the dew point temperature of the return air in the second return air path, so that the return air in the second return air path does not experience significant water precipitation during supplemental cooling.

[0038] like Figure 2 As shown, the vegetable storage area, return air distribution location, first heat exchange zone, second heat exchange zone, air supply mixing chamber, and air supply outlet form a closed loop along the air handling direction. Figure 2The first return air path is guided to the first heat exchange zone, corresponding to the main dehumidification path; the second return air path is guided to the second heat exchange zone or a bypass direction, corresponding to the supplementary cooling path; the return air circulation path returns to the vegetable storage area, thus allowing a clear distinction between the positional relationships of the dehumidification airflow, the supplementary cooling airflow, and the return air circulation flow within the refrigeration system. The accompanying diagram also divides the air mixing chamber into an upstream and downstream side, and shows a moisturizing air layer outside the air outlet, ensuring that the sequential mixing relationship of the two air streams within the mixing chamber corresponds to the coverage relationship at the air outlet in this embodiment.

[0039] In this embodiment, the low dew point air processed by the first return air path enters the upstream side of the air supply mixing chamber, and the air processed by the second return air path enters the downstream side of the air supply mixing chamber, located near the air supply outlet. Thus, the low dew point air first participates in mixing within the air supply mixing chamber, and the air processed by the second return air path forms an outer airflow near the air supply outlet. This creates a moisturizing air layer with a higher dew point temperature on the outer side of the air supplied to the vegetable storage area, thereby reducing the direct scouring effect of the low dew point air on the vegetable surface.

[0040] In this embodiment, the control system acquires parameters such as vegetable surface temperature, return air dew point temperature, vegetable storage area temperature, and return air humidity, and adjusts the airflow ratio of the first and second return air paths based on these parameters. The return air dew point temperature can be obtained by the control system using a preset dew point conversion table based on the return air temperature and humidity parameters. The vegetable surface temperature can be obtained by a non-contact temperature sensor installed in the vegetable storage area. The control system uses these parameters to determine whether the second return air path needs to continue contacting the second heat exchange area, to avoid further lowering of the supply air dew point when the humidity margin near the vegetable surface is low.

[0041] When the second return air path is in contact with the second heat exchange zone, the control system determines the temperature margin between the vegetable surface temperature and the return air dew point temperature according to the following formula:

[0042] in, This indicates the temperature margin between the surface temperature of vegetables and the dew point temperature of the return air, expressed in °C. This indicates the surface temperature of vegetables, expressed in °C. This represents the return air dew point temperature, in °C. The derivation of this formula is based on subtracting the return air dew point temperature from the vegetable surface temperature to determine whether the air near the vegetable surface is close to high humidity saturation; when... Less than the first preset threshold And the temperature in the vegetable storage area The preset temperature limit has not been exceeded. This indicates that continuing to allow the second return air path to contact the second heat exchange zone may cause the supply air dew point to drop too quickly.

[0043] During one operation, the control system detected... , First preset threshold Temperature in vegetable storage area Preset upper temperature limit Substituting into the above formula, we get... .because Less than ,and Not exceeding The control system pauses the return air in the second return air path from contacting the second heat exchange zone, so that the return air in the second return air path bypasses the second heat exchange zone and enters the downstream side of the supply air mixing chamber, where it mixes with the air processed by the first return air path.

[0044] like Figure 3 As shown, temperature margin As the consecutive sampling sequence number changes, the first preset threshold As the boundary for pausing the decision, the shaded area in the figure represents the pausing decision zone when the temperature margin is lower than the first preset threshold. Figure 3 At the 4th consecutive sampling point, Descending to Meanwhile, the temperature in the vegetable storage area Still below the preset upper limit of temperature This point corresponds to the control system triggering a pause in the second heat exchange zone. As can be seen from the diagram, the pause control is not based solely on a single temperature change, but is jointly limited by the vegetable surface temperature, the return air dew point temperature, and the vegetable storage area temperature. This prevents further dew point reduction in the second return air path while the storage area remains within the allowable temperature range.

[0045] During the pause of the second return air path contacting the second heat exchange zone, the return air in the second return air path enters the air mixing chamber along the air outlet side of the air mixing chamber and surrounds the air processed by the first return air path along its outer periphery. Since this part of the return air does not continue to cool down through the second heat exchange zone, its dew point temperature is higher than that of the air processed by the first return air path. Therefore, a moisturizing air layer is formed on the outside of the air supplied to the vegetable storage area, creating a humidity buffer zone between the low dew point air and the vegetable surface.

[0046] When the dew point temperature of the mixed air falls below the recovery judgment temperature obtained by using the vegetable surface temperature as a reference and offsetting it downward by a second preset threshold, the control system restores the connection between the second return air path and the second heat exchange zone. During the recovery process, the control system first ensures that a preset proportion of return air in the second return air path contacts the second heat exchange zone according to a preset start-stop cycle, and then gradually increases the proportion of airflow in contact with the second heat exchange zone, so that the heat exchange effect of the second heat exchange zone is restored smoothly and the rate of decrease in vegetable surface temperature is kept within a preset range.

[0047] In this embodiment, the proportion of air volume in contact with the second heat exchange zone through the second return air path is determined according to the following formula:

[0048] in, Indicates the first The percentage of air volume in the second return air path contacting the second heat exchange zone during each recovery phase, expressed in % . This indicates the percentage of airflow in contact with the second heat exchange zone during the initial recovery phase, expressed in % (%). Indicates the recovery phase sequence number; This represents the percentage increase in airflow during each recovery phase, expressed as a percentage. The derivation of this formula is based on the idea that, to avoid a rapid drop in vegetable surface temperature due to a sudden recovery of heat exchange in the second heat exchange zone, the percentage of airflow in the second return air path contacting the second heat exchange zone is increased step by step according to the recovery phase, starting from the initial percentage.

[0049] During a control recovery process, the following settings are configured. , , Substituting into the above formula, we get... In the third recovery phase, the control system ensures that the second return air path... The return air contacts the second heat exchange zone, while the remaining return air still enters the supply air mixing chamber through the bypass path. Thus, the second heat exchange zone gradually participates in supplementing and cooling the air in the second return air path, preventing sudden changes in the air temperature and dew point temperature delivered to the vegetable storage area.

[0050] like Figure 4 As shown, the second return air path is divided into the air volume portion that contacts the second heat exchange zone and the air volume portion that bypasses into the supply air mixing chamber during different recovery stages. Figure 4 The air volume ratio in the middle contact with the second heat exchange zone is changed from the initial Increase step by step to subsequent stages , , and The proportion of airflow bypassing into the air mixing chamber decreases accordingly at each stage. Figure 4 The third phase The location corresponds to the above calculation results, indicating that the second heat exchange zone has participated in the supplementary cooling of half of the return air in the second return air path, while the other half of the return air is still used to maintain the humidity buffering effect on the downstream side of the supply air mixing chamber. Through this staged recovery relationship, the heat exchange effect of the second heat exchange zone can be gradually enhanced during the recovery process, avoiding abrupt changes in the supply air state.

[0051] Before reconnecting the second return air path with the second heat exchange zone, the return air in the second return air path can be mixed once with the air processed by the first return air path in the air supply mixing chamber to form a primary mixed air. Subsequently, a preset proportion of the primary mixed air is introduced into the second heat exchange zone for secondary cooling, making the dew point and temperature of the air entering the second heat exchange zone more stable, thereby reducing the impact on the air supply status of the vegetable storage area when the second heat exchange zone resumes heat exchange.

[0052] Through the above control method, the first return air path is mainly used for dehumidification, while the second return air path is mainly used for supplementing cooling, humidity buffering, and transitional adjustment during heat exchange. The first and second heat exchange zones perform different processing functions on the air flow paths, and the air supply mixing chamber further performs stratified mixing and moisture coating of the two air streams. This achieves decoupled control of the cooling and dehumidification processes in the vegetable cold storage environment and reduces the risk of desiccation caused by low dew point air directly acting on the vegetable surface.

[0053] Example 2: In this embodiment, the refrigeration system includes a vegetable storage area, an evaporator, a return air duct, a first return air path, a second return air path, an air supply duct, an air supply mixing chamber, a control system, and an airflow regulation component. The return air from the vegetable storage area is returned through the return air duct and then distributed to the first and second return air paths. The first return air path is used to ensure the return air contacts the first heat exchange zone of the evaporator and performs the main dehumidification function, while the second return air path is used to form supplementary cooling airflow and humidity buffering airflow.

[0054] In this embodiment, a buffer air outlet is provided between the vegetable storage area and the inlet of the first return air path, and the buffer air outlet is connected to the second return air path. Part of the return air in the second return air path enters the area between the vegetable storage area and the inlet of the first return air path through the buffer air outlet, forming a buffer air layer. This buffer air layer is located between the vegetable storage area and the inlet of the first return air path and is used to form airflow isolation, rather than for direct forced dehumidification.

[0055] like Figure 5 As shown, the second return air path is located on the air supply side of the buffer air layer. The return air in the second return air path enters the area between the vegetable storage area and the inlet of the first return air path through the buffer air outlet. Figure 5In this system, a buffer air layer is arranged between the vegetable storage area and the inlet of the first return air path. A higher velocity region is formed on the side closer to the inlet of the first return air path to stabilize the airflow boundary near the inlet of the first return air path, while a lower velocity region is formed on the side closer to the vegetable storage area to reduce airflow disturbance near the vegetable surface. Figure 5 The direction of the return air traction after isolation is also shown, indicating that the buffer air layer does not replace the first return air path for dehumidification, but rather forms an adjustable airflow barrier in front of the inlet of the first return air path.

[0056] In this embodiment, the control system adjusts the return air volume of the second return air path supplied to the buffer air layer via an air volume regulating component. When the return air volume supplied to the buffer air layer increases, the isolation effect of the buffer air layer on the inlet of the first return air path is enhanced, and the traction effect of the first return air path on the humid air in the vegetable storage area is weakened; when the return air volume supplied to the buffer air layer decreases, the traction effect of the first return air path on the return air in the vegetable storage area is enhanced, and the dehumidification effect of the first heat exchange zone on the vegetable storage area is correspondingly increased.

[0057] In this embodiment, the buffer air layer forms a decreasing wind speed along the first return air path toward the vegetable storage area, so that the air velocity near the vegetable storage area is lower than the air velocity near the first return air path. The higher velocity near the first return air path is used to stabilize the airflow boundary near the inlet of the first return air path, while the lower velocity near the vegetable storage area is used to reduce the disturbance of airflow on the vegetable surface.

[0058] In this embodiment, the control system determines whether a decreasing wind speed distribution is formed in the buffer air layer according to the following calculation formula:

[0059] in, The coefficient representing the decreasing wind speed determination of the buffer air layer is dimensionless. This indicates the air velocity on the side of the buffer zone closest to the vegetable storage area, expressed in m / s. This represents the air velocity in the buffer air layer near the first return air path, expressed in m / s. The derivation of this formula involves comparing the air velocity near the vegetable storage area with the air velocity near the first return air path to determine whether the buffer air layer exhibits a decreasing wind speed distribution from the inlet side of the first return air path towards the vegetable storage area. When the value is less than 1, it indicates that the air velocity on the side closer to the vegetable storage area is lower than the air velocity on the side closer to the first return air path.

[0060] During one operation, the control system detected... , Substituting into the above formula, we get... A value less than 1 indicates that the airflow disturbance on the side of the buffer air layer closer to the vegetable storage area is lower than that on the side closer to the first return air path. The control system maintains the air supply state of this buffer air layer, thereby weakening the reverse diffusion of low-temperature, low-dew-point air to the vegetable storage area and reducing the direct disturbance of airflow to the vegetable surface.

[0061] like Figure 6 As shown, the air velocity near the first return air path side is The air velocity near the vegetable storage area is The flow velocities on both sides are contrasted by the height of the bars and the trend line. Figure 6 The low-disturbance region in the image corresponds to the low-velocity region near the vegetable storage area, indicating that the buffer air layer can reduce airflow disturbance on the side closer to the vegetable surface; at the same time, The result of less than 1 is consistent with the decreasing wind speed trend in the figure, which can support the control system in judging the decreasing wind speed state of the buffer air layer.

[0062] In this embodiment, when the proportion of airflow entering the first return air path increases, the dehumidification effect of the first heat exchange zone on the return air is enhanced. The control system simultaneously increases the return air volume in the second return air path, which forms a buffer air layer, causing the thickness of the buffer air layer to increase with the increase in the dehumidification intensity of the first return air path. With the increased thickness of the buffer air layer, the isolation range between the vegetable storage area and the inlet of the first return air path expands, thereby reducing the impact of low-temperature, low-dew-point air on the humidity environment near the vegetable surface.

[0063] In this embodiment, the control system determines the adjusted buffer gas layer thickness according to the following calculation formula:

[0064] in, This indicates the adjusted thickness of the buffer air layer, in mm. This indicates the initial thickness of the buffer air layer, in mm; The adjustment coefficient, expressed in mm·h / m, represents the change in buffer layer thickness as the return air volume supplied to the buffer layer via the second return air path increases. 3 ; This indicates the return air volume of the second return air path currently supplied to the buffer air layer, in meters. 3 / h; This indicates the return air volume of the second return air path initially supplied to the buffer air layer, in meters. 3 / h. The derivation of this formula is based on the initial buffer air layer thickness, converting the increase in the current return air volume relative to the initial return air volume into the buffer air layer thickness increment, so as to characterize the extent of expansion of the buffer air layer isolation range after the air supply volume is increased.

[0065] During an adjustment process, set , , , Substituting into the above formula, we get... That is, when the return air volume supplied to the buffer air layer is... Increase to At that time, the thickness of the buffer gas layer was changed from Increase to The control system maintains or continues to fine-tune the opening of the buffer air outlet to ensure that the buffer air layer covers the main airflow exchange area between the first return air path inlet and the vegetable storage area.

[0066] like Figure 7 As shown, the return air volume supplied to the buffer air layer is from When increased to [value], the thickness of the buffer gas layer is [value]. Gradually increase to ,in The corresponding buffer gas layer thickness is . Figure 7 The initial thickness line in the diagram is used to indicate the baseline thickness of the buffer air layer, and the shaded area represents the thickness increment that occurs with the increase of return air volume. This relationship shows that after the control system increases the return air volume supplied to the buffer air layer through the second return air path, not only does the flow velocity of the buffer air layer change, but its isolation range also expands, making it more suitable for handling conditions where the dehumidification intensity of the first return air path is increased.

[0067] In this embodiment, when increasing the return air volume in the second return air path that forms the buffer air layer, the increase in the opening of the buffer air outlet near the vegetable storage area can be greater than the increase in the opening of the buffer air outlet near the first return air path. Similarly, the increase in the air supply time near the vegetable storage area can be greater than the increase in the air supply time near the first return air path. Therefore, the thickness increment of the buffer air layer near the vegetable storage area is greater than the thickness increment near the first return air path, causing the buffer air layer to preferentially expand towards the vegetable storage area.

[0068] In this embodiment, when the vegetable loading is large or the dehumidification air volume ratio of the first return air path increases, the control system prioritizes increasing the air intake volume of the buffer air layer near the vegetable storage area to provide humidity protection for the vegetable surface first. A higher flow velocity is maintained near the first return air path to stabilize the return air boundary at the entrance of the first return air path, while a lower flow velocity is maintained near the vegetable storage area to reduce localized purging and water loss from the vegetable surface.

[0069] In this way, the return air in the second return air path can form a buffer air layer with decreasing wind speed and adjustable thickness between the vegetable storage area and the inlet of the first return air path. This allows the dehumidification intensity of the first return air path on the vegetable storage area to be indirectly adjusted through the air intake of the buffer air layer. When the dehumidification intensity of the first return air path is increased, priority is given to strengthening the humidity protection near the vegetable surface, thereby reducing the risk of vegetable dehydration caused by the reverse diffusion of low temperature and low dew point air.

Claims

1. A method for decoupled control of temperature and humidity in a vegetable cold storage environment, applied to a cold storage system having a vegetable storage area, an evaporator, a return air duct, an air supply duct, and an air supply mixing chamber, characterized in that: Before entering the evaporator, the return air from the vegetable storage area is distributed to the first return air path and the second return air path, so that the return air in the first return air path comes into contact with the first heat exchange zone of the evaporator. The temperature of the heat exchange surface of the first heat exchange zone is lower than the dew point temperature of the return air in the first return air path, so as to remove moisture from the return air. The return air in the second return air path bypasses the first heat exchange zone and comes into contact with the second heat exchange zone of the evaporator when additional cooling is needed. The heat exchange surface temperature of the second heat exchange zone is higher than or equal to the dew point temperature of the return air in the second return air path. The air processed by the first and second return air paths is introduced into the air mixing chamber, mixed, and then sent to the vegetable storage area. The air volume ratio of the first and second return air paths is adjusted according to the return air dew point temperature, vegetable surface temperature, and return air humidity parameters to separate the cooling process and the dehumidification process in the air flow path.

2. The method for decoupling and controlling temperature and humidity in vegetable cold storage environment according to claim 1, characterized in that: The air processed by the first return air path enters the upstream side of the air supply mixing chamber, and the air processed by the second return air path enters the downstream side of the air supply mixing chamber, so that the air near the air supply outlet is formed by the air processed by the second return air path, thereby reducing the direct scouring of the vegetable surface by the low dew point air.

3. The method for decoupling and controlling temperature and humidity in vegetable cold storage environment according to claim 1, characterized in that: When the return air in the second return air path is configured to contact the second heat exchange zone, if the difference between the vegetable surface temperature and the return air dew point temperature is less than the first preset threshold and the vegetable storage area temperature does not exceed the preset upper temperature limit, the return air in the second return air path is suspended from contacting the second heat exchange zone, so that the return air in the second return air path is used to mix with the air processed by the first return air path. Once the dew point temperature of the mixed air is lower than the second preset threshold of the vegetable surface temperature, the contact between the second return air path and the second heat exchange zone is restored.

4. The method for decoupling and controlling temperature and humidity in vegetable cold storage environment according to claim 1, characterized in that: Between the vegetable storage area and the entrance of the first return air path, a buffer air layer is formed by the return air from the second return air path. By adjusting the air intake of the buffer air layer, the dehumidification intensity of the first return air path on the vegetable storage area is changed.

5. The method for decoupling and controlling temperature and humidity in vegetable cold storage environment according to claim 3, characterized in that: During the pause of the return air in the second return air path contacting the second heat exchange zone, the return air in the second return air path enters along the air outlet side of the air supply mixing chamber and surrounds the air processed by the first return air path along the outer periphery, so that a moisturizing air layer with a dew point temperature higher than that of the inner air is formed on the outside of the air supplied to the vegetable storage area.

6. The method for decoupling and controlling temperature and humidity in vegetable cold storage environment according to claim 3, characterized in that: After the dew point temperature of the mixed air is lower than the second preset threshold of the vegetable surface temperature, the preset proportion of return air in the second return air path is first made to contact the second heat exchange zone according to the preset start-stop cycle, and then the proportion of air volume in contact with the second heat exchange zone is increased according to the preset gradient, so that the rate of decrease of the vegetable surface temperature when the second heat exchange zone resumes heat exchange is within the preset rate range.

7. The method for decoupling and controlling temperature and humidity in vegetable cold storage environment according to claim 3, characterized in that: Before restoring the second return air path to contact the second heat exchange zone, the return air in the second return air path is first mixed with the air processed by the first return air path in the air supply mixing chamber, and then the pre-mixed air of the preset ratio is introduced into the second heat exchange zone for secondary cooling.

8. The method for decoupling and controlling temperature and humidity in vegetable cold storage environment according to claim 4, characterized in that: The buffer air layer forms a decreasing wind speed along the first return air path toward the vegetable storage area, so that the air velocity on the side closer to the vegetable storage area is less than the air velocity on the side closer to the first return air path, thereby weakening the reverse diffusion of the low temperature and low dew point air formed in the first heat exchange zone toward the vegetable storage area.

9. The method for decoupling and controlling temperature and humidity in vegetable cold storage environment according to claim 4, characterized in that: When the proportion of airflow entering the first return air path increases, the return airflow in the second return air path that forms the buffer air layer is increased simultaneously, so that the thickness of the buffer air layer increases with the increase of the dehumidification intensity of the first return air path.

10. The method for decoupling and controlling temperature and humidity in vegetable cold storage environment according to claim 9, characterized in that: When increasing the return air volume in the second return air path that forms the buffer air layer, the increase in the air intake volume on the side of the buffer air layer closer to the vegetable storage area is greater than the increase in the air intake volume on the side closer to the first return air path, so that the thickness increment of the buffer air layer on the side closer to the vegetable storage area is greater than the thickness increment on the side closer to the first return air path.

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