Aquatic product cold-chain fresh-keeping cabin with temperature and humidity adjustment and fresh-keeping method

Abstract

The aquatic product cold-chain preservation cabin with temperature and humidity adjustment and the preservation method belong to the technical field of aquatic product cold-chain transportation and preservation, and comprise: the double-layer micro-porous flow guide wall is fixedly connected to the left and right side walls in the cabin body, the flow guide wall is composed of a solid baffle and a punched aluminum plate, and a static pressure cavity is arranged between the solid baffle and the punched aluminum plate; an evaporator is fixedly connected to the top of the cabin body, a variable frequency fan is fixed to the air inlet side of the evaporator, and a condensate water collecting groove is fixed directly below the evaporator, the bottom of the condensate water collecting groove is provided with a flow guide slot; a capillary evaporation net is clamped in the flow guide slot, the upper end of the capillary evaporation net is connected to the liquid water in the groove, and the lower end of the capillary evaporation net is flatly attached to the back of the punched aluminum plate; in addition, a phase change cold storage plate is fixed in the static pressure cavity and is arranged close to the inner side of the solid baffle; and a main control board is responsible for controlling the variable frequency fan and the compressor, the present application prevents the water loss of the aquatic products in the cold chain process, and simultaneously realizes the uniform distribution of the humidified cold air by means of the static pressure cavity and the punched aluminum plate, thereby significantly improving the preservation quality.

Description

Technical Field

[0001] This invention relates to the field of cold chain transportation and preservation of aquatic products, specifically to a cold chain preservation chamber for aquatic products with temperature and humidity control and a preservation method. Background Technology

[0002] Cold chain preservation compartments for aquatic products are mainly used to create low-temperature storage space and provide cold energy transfer, and are widely used in the logistics and transportation of aquatic products. Traditional preservation compartments mostly rely on evaporators to directly supply air for cooling. Although they can meet the basic low-temperature storage requirements, they still have many shortcomings in terms of high-quality preservation.

[0003] The core technical deficiency of traditional cold chain equipment lies in the mutual constraint between temperature control and humidity maintenance. On the one hand, direct cold air blowing onto the cargo area can easily cause rapid loss of moisture from the surface of aquatic products, resulting in severe drying. Moreover, the system's airflow adjustment relies heavily on manual experience and estimation, which cannot be accurately matched with the actual loading load. This can easily lead to excessive airflow exacerbating water loss or insufficient airflow resulting in inadequate cooling. On the other hand, adding an independent mechanical humidifier to maintain humidity would significantly increase the complexity of the water supply and electrical control structure. In addition, the meltwater generated during evaporator operation and defrosting is usually discharged as wastewater and is not effectively utilized. Furthermore, the compressor shutdown during defrosting can easily cause significant fluctuations in the internal temperature.

[0004] To address these shortcomings of traditional food storage compartments, internal air duct structure coupling and intelligent dynamic control are important technical approaches to improve equipment performance. Current improvement methods mainly include: constructing a combination of microporous flow-guiding static pressure chamber and capillary evaporation mesh to achieve passive condensate recovery and humidification; combining dynamic load inversion technology for micro-pressure differential airflow adaptive adjustment; and utilizing phase change cold storage materials for defrosting cold compensation, thereby maintaining a low-temperature and high-humidity environment without an independent humidifier. Summary of the Invention

[0005] To address the problems of temperature control and humidity maintenance being mutually restrictive in traditional cold chain preservation chambers, direct cold air blowing causing aquatic products to dry out and lose moisture, and large temperature fluctuations within the chamber during defrosting, this invention aims to establish a cold chain preservation mechanism that combines micro-pressure differential passive humidification with phase change cold storage compensation. By constructing a static pressure chamber and a capillary evaporation net combination within the preservation chamber, condensate can be recycled and passively humidified. Combined with adaptive airflow regulation and latent heat compensation during defrosting, this effectively overcomes the defects of traditional equipment where cooling is accompanied by moisture loss, significantly improving the preservation quality of aquatic products and the standardization level of storage and transportation. The technical solution of this invention includes:

[0006] The preservation chamber has a double-layer microporous flow guide wall fixedly connected to the left and right side walls inside. The double-layer microporous flow guide wall includes a solid baffle and a perforated aluminum plate, and a static pressure cavity is formed between the solid baffle and the perforated aluminum plate.

[0007] The evaporator is fixedly connected to the top of the preservation compartment;

[0008] A variable frequency fan is fixedly connected to the air inlet side of the evaporator;

[0009] A condensate collection tank is fixedly connected to the bottom of the evaporator, and a guide slit is provided at the bottom of the condensate collection tank;

[0010] A capillary evaporation mesh is snapped into the guide slit. The upper end of the capillary evaporation mesh receives the liquid water inside the condensate collection tank, and the lower end of the capillary evaporation mesh is laid flat against the back of the perforated aluminum plate.

[0011] A phase change cold storage plate is fixed inside the static pressure chamber and arranged close to the inner side of the solid baffle.

[0012] The main control board controls the variable frequency fan and compressor.

[0013] Furthermore, the solid baffle is made of polytetrafluoroethylene, and the thickness of the solid baffle is [missing information]. The thickness of the perforated aluminum plate is ;

[0014] The perforated aluminum plate has an anodized surface and uniformly distributed guide holes. The width of the static pressure chamber is [missing information]. .

[0015] Furthermore, the condensate collection tank is a V-shaped water guide channel.

[0016] The condensate collection tank is made of 316L stainless steel and is fixed by full welding.

[0017] Furthermore, the capillary evaporation mesh has a porosity of [missing information]. Hydrophilic polyester fiber interwoven web;

[0018] The capillary evaporation mesh is interference-fitted into the guide slit.

[0019] Furthermore, the phase change cold storage plate is an aluminum alloy microchannel flat tube, and the phase change cold storage plate is filled with tetradecane phase change medium.

[0020] The phase transition temperature of the tetradecane phase change medium is: The phase change cold storage plate is fixed by thermally conductive silicone grease and aluminum clamps.

[0021] Furthermore, the variable frequency fan adopts a brushless DC motor directly driving a multi-blade centrifugal impeller, and the variable frequency fan has no speed reduction or speed increase mechanism;

[0022] The variable frequency fan is fixedly connected to the end face of the evaporator via a flange, and the flange is fixed by high-strength bolts.

[0023] The preservation method, wherein the aquatic product cold chain preservation chamber with temperature and humidity regulation includes:

[0024] S1. After sealing the preservation chamber, control the variable frequency fan and the compressor to run at full load with maximum rated power to obtain the temperature drop trajectory inside the preservation chamber;

[0025] S2. Obtain the reciprocal of the reference slope under no-load conditions, and obtain the heat capacity change by subtracting the reciprocal of the reference slope from the reciprocal of the temperature drop trajectory slope. Calculate the load inertia parameter based on the heat capacity change.

[0026] S3. Calculate the target wind pressure based on the load inertia parameter, and obtain the target speed of the variable frequency fan based on the target wind pressure;

[0027] S4. Control the variable frequency fan to run at the target speed, and force the cooled air that has passed through the evaporator into the static pressure chamber to form a positive pressure environment;

[0028] S5. The cold air passes through the pores of the capillary evaporation mesh in the static pressure chamber, converting the liquid water adsorbed between the fibers of the capillary evaporation mesh into water vapor, and carrying the water vapor through the guide holes of the perforated aluminum plate and blowing it toward the aquatic products.

[0029] Furthermore, the S5 step is followed by:

[0030] S601. The stator current of the variable frequency fan drive motor is acquired in real time, and the relationship between the stator current drop and the preset resistance threshold is determined. When the stator current drop is greater than the preset resistance threshold, the compressor is controlled to stop. When the stator current drop is less than or equal to the preset resistance threshold, the compressor is kept running.

[0031] S602. After the compressor is stopped, the hot gas bypass valve of the refrigeration circuit is opened, and the evaporator is defrosted by heating it with high-temperature refrigerant gas. The frost on the surface of the evaporator melts and forms condensate.

[0032] S603, the condensate drips into the condensate collection tank and seeps into the capillary evaporation net along the guide slit.

[0033] Further, the step S603 is followed by:

[0034] S701. Obtain the equivalent temperature rise suppression rate and defrosting duration of the phase change process of the tetradecane phase change medium inside the phase change cold storage plate.

[0035] S702. Multiply the defrosting duration by the equivalent temperature rise suppression rate to calculate the temperature compensation amount;

[0036] S703. Determine the relationship between the temperature compensation amount and the preset safety boundary. When the temperature compensation amount is greater than or equal to the preset safety boundary, close the hot gas bypass valve and restore the compressor's normal refrigeration cycle. When the temperature compensation amount is less than the preset safety boundary, keep the hot gas bypass valve open.

[0037] Furthermore, the step of calculating the load inertia parameter in S2 specifically includes:

[0038] S801. Obtain the conversion coefficient of aquatic product types and the heat leakage coefficient of the preservation compartment;

[0039] S802. Multiply the change in heat capacity by the conversion factor for the type of aquatic product, and calculate the load inertia parameter by combining it with the heat leakage coefficient.

[0040] This invention provides a cold chain preservation chamber for aquatic products with temperature and humidity control and a preservation method, which has the following improvements and advantages compared with the prior art:

[0041] 1. This invention utilizes a double-layer microporous guide wall, a condensate collection tank, and a capillary evaporation mesh. The capillary evaporation mesh collects the liquid water inside the condensate collection tank. A variable frequency fan forces the cooled air from the evaporator into the static pressure chamber to create a positive pressure environment. The cold air passes through the pores of the capillary evaporation mesh, converting the liquid water adsorbed between the fibers into water vapor, which is then carried through the perforated aluminum plate guide holes and blown onto the aquatic products. This structure effectively recycles the condensate generated by the evaporator, preventing the aquatic products from drying out during the cold chain process. At the same time, the static pressure chamber and perforated aluminum plate achieve uniform distribution of humidifying cold air, significantly improving the preservation quality.

[0042] 2. The main control board of this invention obtains the change in heat capacity by subtracting the temperature drop trajectory inside the preservation compartment and the reciprocal of the baseline slope under no-load conditions, and then calculates the load inertia parameter. The system calculates the target wind pressure based on the load inertia parameter, converts it to obtain the target speed of the variable frequency fan, and controls it to run at the target speed. This method can dynamically adjust the air supply state according to the actual load inertia of the aquatic products, avoiding unnecessary energy consumption caused by constant air volume operation, and also preventing excessive air volume from causing water loss on the surface of the aquatic products or insufficient air volume from causing slow cooling, thus achieving efficient matching of cooling capacity.

[0043] 3. In this invention, phase change cold storage plates are arranged closely against a solid baffle in the static pressure chamber, and the interior is filled with tetradecane phase change medium that undergoes phase change. When the compressor is stopped and the hot gas bypass valve is opened to defrost the evaporator by heating it with high-temperature refrigerant gas, the system obtains the equivalent temperature rise suppression rate and defrosting duration of the phase change process of the solution, calculates the temperature compensation amount, and controls the working state of the hot gas bypass valve and the compressor in combination with the preset safety boundary. This allows the cold storage compartment to effectively suppress temperature fluctuations in the compartment during the defrosting of the evaporator by utilizing the phase change cold storage plates, prevents a sudden rise in ambient temperature, and ensures that aquatic products are always in a stable low-temperature environment. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the structure of the preservation compartment of the device;

[0045] Figure 2 This is a schematic diagram of the double-layer microporous flow guide wall structure of the device;

[0046] Figure 3 This is a schematic diagram of the structure of the device's solid baffle and perforated aluminum plate;

[0047] Figure 4 This is a schematic diagram of the evaporator structure of the device;

[0048] Figure 5 This is a schematic diagram of the process flow of the method of the present invention.

[0049] In the diagram: 1. Fresh-keeping compartment; 2. Double-layer microporous flow guide wall; 3. Solid baffle; 4. Perforated aluminum plate; 5. Static pressure chamber; 6. Evaporator; 7. Variable frequency fan; 8. Condensate collection tank; 9. Flow guide slit; 10. Capillary evaporation mesh; 11. Phase change cold storage plate; 12. Main control board; 13. Compressor; 14. Flow guide hole; 15. V-shaped cross-section water guide trough; 16. Aluminum alloy microchannel flat tube; 17. Thermal grease; 18. Aluminum clamp; 19. Brushless DC motor; 20. Multi-blade centrifugal impeller; 21. Flange; 22. High-strength bolt; 23. Hot gas bypass valve. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0051] Example 1:

[0052] Please see Figure 1-4 A cold chain preservation compartment for aquatic products with temperature and humidity control, including:

[0053] The preservation chamber 1 has a double-layer microporous flow guide wall 2 fixedly connected to the left and right side walls inside the preservation chamber 1. The double-layer microporous flow guide wall 2 includes a solid baffle 3 and a perforated aluminum plate 4. A static pressure cavity 5 is formed between the solid baffle 3 and the perforated aluminum plate 4.

[0054] Evaporator 6 is fixedly connected to the top of the preservation compartment 1; variable frequency fan 7 is fixedly connected to the air inlet side of evaporator 6;

[0055] A condensate collection tank 8 is fixedly connected to the bottom of the evaporator 6, and a guide slit 9 is provided at the bottom of the condensate collection tank 8.

[0056] The capillary evaporation mesh 10 is snapped into the guide slit 9. The upper end of the capillary evaporation mesh 10 receives the liquid water inside the condensate collection tank 8, and the lower end of the capillary evaporation mesh 10 is laid flat and attached to the back of the perforated aluminum plate 4.

[0057] Phase change cold storage plate 11 is fixed in the static pressure chamber 5 and arranged close to the inner side of solid baffle 3;

[0058] The main control board 12 controls the variable frequency fan 7 and the compressor 13.

[0059] This embodiment provides an overall structure for a cold storage compartment for cold chain transportation of aquatic products; the cold storage compartment 1 serves as an external insulation shell, used to enclose a low-temperature storage space, and provides an installation foundation for internal airflow organization, cold energy transfer and moisture recovery;

[0060] Compared with traditional cold storage compartments that rely solely on evaporator 6 for direct air supply, this structure features double-layered microporous guide walls 2 on the left and right side walls inside the preservation compartment 1, allowing cold air to enter the static pressure chamber 5, which is formed by solid baffle 3 and perforated aluminum plate 4, before entering the cargo area.

[0061] In the technical context of this invention, the static pressure chamber 5 refers to the buffer space where the cold air delivered by the fan forms a relatively balanced pressure before entering the cargo area. This space is not only used for air guidance, but also serves to drive the capillary evaporation net 10 to release water under a small pressure difference. Therefore, it has a functional difference from the simple cavity in the conventional air duct.

[0062] Evaporator 6 is fixed to the top of the preservation chamber 1 and is used to cool the circulating air; variable frequency fan 7 is fixedly connected to the air inlet side of evaporator 6, and main control board 12 coordinates and controls variable frequency fan 7 and compressor 13 to enable evaporator 6 to form a stable heat exchange capacity and to adjust the flow rate of cold air entering static pressure chamber 5 according to the load status.

[0063] A condensate collection tank 8 is set directly below the evaporator 6 to collect the liquid water formed after the evaporator 6 is frosted and defrosted, so as to prevent the liquid water from falling directly to the bottom of the tank and causing liquid accumulation. A guide slit 9 is opened at the bottom of the condensate collection tank 8, and a capillary evaporation mesh 10 is clipped into the guide slit 9. Its upper end continuously collects the liquid water in the condensate collection tank 8, and its lower end is laid flat and attached to the back of the perforated aluminum plate 4.

[0064] This forms a passive water supply path based on capillary action, enabling the recovered condensate to be distributed downwards along the capillary evaporation net 10 and forming a wetted interface on the back of the perforated aluminum plate 4 that can be carried away by airflow.

[0065] The phase change cold storage plate 11 is fixed inside the static pressure chamber 5 and arranged close to the inner side of the solid baffle 3. The phase change cold storage plate 11 is used to absorb the heat in the air flowing through the static pressure chamber 5 during the defrosting period when the compressor 13 is interrupted, thereby slowing down the temperature rise of the air in the cabin. In addition to controlling the start and stop of the compressor 13, the main control board 12 also performs load status calibration, target air pressure conversion, stator current determination and defrosting duration control.

[0066] The above-mentioned structural combination is not set up in isolation, but is designed collaboratively around the same technical problem: the evaporator 6 is responsible for cooling, the condensate collection tank 8 is responsible for recovering moisture, the capillary evaporation net 10 is responsible for converting the recovered moisture into a liquid source that can participate in air humidification, the static pressure chamber 5 and the variable frequency fan 7 jointly provide micro-pressure difference drive, and the phase change cold storage plate 11 is responsible for cold energy compensation during the defrosting period; this combination enables the cold chain preservation compartment to maintain a low temperature and high humidity environment without adding an independent mechanical humidifier, reducing the rate of water loss from the surface of aquatic products;

[0067] In one implementation, after the aquatic products are loaded into the refrigeration compartment 1, the main control board 12 controls the compressor 13 and the variable frequency fan 7 to run. The evaporator 6 cools the return air in the compartment, and the variable frequency fan 7 presses the cold air into the static pressure chamber 5. A relatively uniform positive pressure is formed in the static pressure chamber 5. The cold air enters the cargo area after passing through the capillary evaporation net 10 and the perforated aluminum plate 4.

[0068] When the cold air passes through the capillary evaporation net for 10 minutes, it carries away the surface moisture, thereby converting some of the liquid water into water vapor in the air and increasing the relative humidity of the cargo area.

[0069] The condensate and defrost water generated during the operation of evaporator 6 are recovered again by condensate collection tank 8 and supplied to capillary evaporation net 10 through guide slit 9, realizing the reuse of recycled water in the cabin; this structure enables the humidification path and the refrigeration path to be coupled in the same air duct system, reducing the complexity of additional electrical control and additional water supply structures.

[0070] The aquatic product cold chain preservation compartment is equipped with temperature and humidity control. The solid baffle 3 is made of polytetrafluoroethylene and has a thickness of [missing information]. The thickness of the perforated aluminum plate is 4. The perforated aluminum plate 4 has an anodized surface and uniformly distributed guide holes 14 on it. The width of the static pressure chamber 5 is... .

[0071] This embodiment further defines the material and dimensions of the double-layer microporous guide wall 2; the solid baffle 3 is made of polytetrafluoroethylene material with a thickness of [missing information]. In this invention, polytetrafluoroethylene is used to form the outer isolation wall of the static pressure cavity 5. Its technical functions include blocking the airflow in the static pressure cavity 5 from directly impacting the cabin wall, reducing the risk of corrosion after condensation adheres, and maintaining structural stability in a high salt spray transportation environment.

[0072] Set the thickness of solid baffle 3 to... It can control the space occupied by the plate while ensuring the flatness and fixing strength of the plate, and avoid excessively thick components from squeezing the effective cross section of the static pressure cavity 5.

[0073] Perforated aluminum plate 4 has a thickness of Its surface is anodized, and the perforated aluminum plate 4 has evenly distributed guide holes 14; the perforated aluminum plate 4 is located inside the static pressure chamber 5 and is the final guide interface for cold air before entering the cargo area.

[0074] The reason for using aluminum plates instead of ordinary steel plates is that aluminum is lighter and has higher thermal conductivity, which can work with the capillary evaporation mesh 10 attached to the back to form a relatively uniform wet evaporation surface; the anodizing treatment is used to improve the resistance to salt spray corrosion and avoid corrosion spots on the perforation edges due to long-term moisture and salt spray environment.

[0075] Set the thickness of the perforated aluminum plate 4 to... It can balance the strength of the plate surface after the opening and the air passage resistance; if the plate is too thin, it is easy to deform during use, which will affect the adhesion with the capillary evaporation mesh 10; if the plate is too thick, the flow resistance formed by the guide hole 14 will increase, which is not conducive to uniform moisture release under micro pressure difference.

[0076] The solid baffle 3 and the perforated aluminum plate 4 form a width of The static pressure chamber 5; the width corresponds to the combined size of the static pressure forming space and the phase change cold storage plate 11 arrangement space in this invention; if the width is too small, the pressure distribution capacity will decrease after the cold air enters, resulting in uneven air outlet at different positions of the perforated aluminum plate 4 and insufficient moisture release in some areas of the capillary evaporation net 10.

[0077] If the width is too large, the usable storage volume inside the refrigeration compartment 1 will be reduced, and the air volume requirement will increase accordingly. The static pressure chamber 5 can form a relatively stable positive pressure zone under the air supply conditions of the variable frequency fan 7 of the present invention, so that the cold air is redistributed in the static pressure chamber 5 and then enters the cargo area through the guide hole 14, thereby reducing the flow difference between the near air outlet area and the far air outlet area.

[0078] In the actual manufacturing process, the double-layer microporous flow guide wall 2 is fixed to the left and right side walls of the preservation compartment 1 by stainless steel rivets, the polytetrafluoroethylene solid baffle 3 is located on the side closer to the compartment wall, and the perforated aluminum plate 4 is located on the side closer to the cargo area. The two are held together by spacers or folded edge structures. spacing;

[0079] The guide holes 14 are evenly distributed on the plate surface, so that the airflow at different positions in the static pressure chamber 5 can obtain a release channel. Since the capillary evaporation mesh 10 is attached to the back of the perforated aluminum plate 4, the cold air comes into contact with the capillary evaporation mesh 10 before passing through the guide holes 14. Therefore, the perforated aluminum plate 4 is both a guide element and a support element for the moisture release interface. The combination of the above materials, thickness and spacing makes the guide wall simultaneously meet the requirements of corrosion resistance, low resistance, pressure equalization and support of the evaporation mesh.

[0080] The aquatic product cold chain preservation compartment is equipped with temperature and humidity regulation. The condensate collection tank 8 is a V-shaped water guide trough 15. The condensate collection tank 8 is made of 316L stainless steel and is fixed by full welding process.

[0081] This embodiment further explains the structure and fixing method of the condensate collection tank 8; the condensate collection tank 8 is located directly below the evaporator 6 and adopts a V-shaped water guide tank; the V-shaped water guide tank refers to the liquid guide slope that forms towards the middle along the width of the tank, so that the condensate and defrost melt water dripping from the evaporator 6 gathers to the lowest point of the tank bottom under the action of gravity.

[0082] Compared with the flat-bottomed water collection tray, the V-shaped structure can reduce the large area of ​​liquid water retention at the bottom of the tank, which is conducive to the concentrated transportation of liquid water to the bottom guide slit 9 and improves the continuity of water replenishment to the capillary evaporation net 10.

[0083] The condensate collection tank 8 is made of 316L stainless steel. In this invention, 316L stainless steel is mainly used to cope with the high humidity and salt spray environment in the cold chain transportation of aquatic products. The area below the evaporator 6 is in long-term contact with condensate and defrost water. Ordinary carbon steel is prone to rust, and aluminum is prone to corrosion points in local gaps. 316L stainless steel can maintain high corrosion resistance and welding stability, reducing the risk of water leakage caused by corrosion and perforation of the tank.

[0084] The condensate collection tank 8 is fixed to the corresponding support structure directly below the evaporator 6 by a full welding process; the full welding process in this invention not only forms a mechanical connection, but also serves to achieve a continuous seal between the tank and the installation position, preventing condensate from overflowing along the connection gap.

[0085] Because the refrigeration compartment experiences vibration and bumps during transportation, if partial spot welding or discontinuous connection is used, cracks and leaks are likely to occur at the connection edges after long-term use, affecting the complete introduction of recycled water; the collection tank, after being fully welded and fixed, can stably receive liquid water dripping from different parts of the evaporator 6 and guide it to the guide slit 9.

[0086] In one implementation, a large amount of melt water formed during the defrosting of evaporator 6 falls from the lower surface of evaporator 6 into V-shaped condensate collection tank 8. The liquid water gathers at the bottom of the tank along both sides of the slope and forms a continuous liquid flow at the guide slit 9.

[0087] After the liquid flows into the guide slit 9, it comes into direct contact with the capillary evaporation net 10. The fiber bundles of the capillary evaporation net 10 adsorb and transport the liquid water, thereby converting the defrosting wastewater into the next round of moisturizing water. It can be seen that the combination of the V-shaped water guide trough and the full welding fixing method not only improves the reliability of water collection, but also makes the water recovery path have a clear and sustainable flow direction.

[0088] A cold chain preservation compartment for aquatic products with temperature and humidity control, and a capillary evaporation mesh with a porosity of 10. A hydrophilic polyester fiber interwoven web; wherein, the capillary evaporation web 10 is interference-fitted into the guide slit 9.

[0089] This embodiment further defines the material, porosity, and assembly method of the capillary evaporation mesh 10; the capillary evaporation mesh 10 adopts a porosity of The hydrophilic polyester fiber interwoven web; in this invention, the hydrophilic polyester fiber interwoven web refers to a continuous mesh structure formed by interweaving multiple polyester fibers with hydrophilic properties on their surfaces. This structure can generate capillary action through the tiny gaps between the fibers, continuously transporting liquid water from the upper end to the lower spreading area. Compared with hydrophobic fibers, hydrophilic polyester fibers spread condensate water faster, which can shorten the time for the evaporation mesh to return to a moist state after defrosting.

[0090] Set the porosity to This is to achieve a balance between water retention capacity and ventilation capacity. When the porosity is low, the fibers are arranged too densely. Although the water storage capacity increases, the resistance to cold air penetration increases, which is not conducive to the formation of stable moisture release by the cold air in the static pressure chamber 5 through the evaporation net. When the porosity is too high, the airflow resistance decreases, but the fiber contact points decrease, the capillary water transport capacity decreases, and the evaporation net is prone to local dryness.

[0091] The porosity of the capillary evaporation net 10 enables it to both collect liquid water from the condensate collection tank 8 and stably release moisture to the passing cold air under the micro-pressure difference provided by the variable frequency fan 7.

[0092] The capillary evaporation mesh 10 is interference-fitted into the guide slit 9; the interference fit in this invention means that the thickness or compression size of the capillary evaporation mesh 10 is slightly larger than the corresponding assembly size of the guide slit 9, so that it is fixed by elastic clamping force after being inserted into the guide slit 9.

[0093] This assembly method ensures close contact between the upper end of the capillary evaporation net 10 and the edge of the guide slit 9, reducing the leakage of liquid water by bypass; on the other hand, it avoids the failure of adhesives after long-term immersion in water; during the transportation process, when the cabin vibrates, the interference fit can maintain the stable position of the evaporation net in the guide slit 9 and prevent the evaporation net from loosening.

[0094] In actual work, the liquid water in the condensate collection tank 8 contacts the upper end of the capillary evaporation net 10 through the guide slit 9. The liquid water spreads along the length direction between the fibers. The lower end of the evaporation net is laid flat against the back of the perforated aluminum plate 4, forming a large wet contact surface.

[0095] When the cold air in the static pressure chamber 5 passes through the pores of the evaporation mesh, the airflow shearing action causes the moisture on the surface of the evaporation mesh to be transferred into the air, increasing the air humidity. Since the capillary evaporation mesh 10 is supplied by the recovered condensate and does not require separate nozzles, pumps and humidification spray components, the number of failure points under transportation bumpy conditions can be reduced.

[0096] The aquatic product cold chain preservation compartment is equipped with temperature and humidity control. The phase change cold storage plate 11 is an aluminum alloy microchannel flat tube 16, and the phase change cold storage plate 11 is filled with tetradecane phase change medium; wherein, the phase change temperature of the tetradecane phase change medium is... The phase change cold storage plate 11 is fixed by thermally conductive silicone grease 17 and aluminum clamps 18.

[0097] This embodiment further describes the internal medium, external structure and installation method of the phase change cold storage plate 11; the phase change cold storage plate 11 adopts an aluminum alloy microchannel flat tube 16 structure, and is filled with tetradecane phase change medium; the aluminum alloy microchannel flat tube 16 refers to the formation of multiple micro channels or chambers extending along the length direction in a flat metal tube body, which are used to accommodate the phase change material and expand the heat transfer area.

[0098] In this invention, the structure is not used for fluid circulation, but rather as a container for encapsulating phase change material, so that there is a small thermal resistance between the phase change material and the air in the static pressure chamber 5; the aluminum alloy material has good thermal conductivity, which is suitable for rapidly transferring the heat of the air to the internal phase change medium.

[0099] The phase transition temperature of tetradecane phase change medium is The phase transition temperature was selected at... This is because the present invention is designed for ice-temperature preservation of aquatic products, with the target temperature inside the chamber being close to... In this way, during normal refrigeration operation, the tetradecane phase change medium inside the phase change cold storage plate 11 can be in a solid-state cold storage state.

[0100] During defrosting, when the compressor 13 stops and the air temperature in the static pressure chamber 5 tends to rise, the tetradecane phase change medium changes from solid to liquid and absorbs heat, thereby providing a temperature rise suppression effect on the air flowing through the static pressure chamber 5. If the phase change temperature is significantly higher than the target temperature inside the chamber, the cold storage plate will have difficulty completing cold storage in the normal fresh-keeping temperature zone. If the phase change temperature is significantly lower than the target temperature, the effective phase change heat absorption cannot be activated in time during defrosting.

[0101] The phase change cold storage plate 11 is fixed in the static pressure chamber 5 by thermally conductive silicone grease 17 and aluminum clamps 18, and is arranged close to the inner side of the solid baffle 3. The thermally conductive silicone grease 17 is used to fill the tiny gap between the phase change cold storage plate 11 and the mounting contact surface to reduce the contact thermal resistance. The aluminum clamps 18 are used to provide stable clamping force to prevent the cold storage plate from shifting due to transportation vibration.

[0102] Arranged close to the inner side of the solid baffle 3, the phase change cold storage plate 11 can form a distributed heat exchange surface along the longitudinal or transverse direction of the static pressure cavity 5, so that the air in different areas of the static pressure cavity 5 can exchange heat with it during the flow process.

[0103] In a defrosting operation, the main control board 12 determines the defrosting time of the evaporator 6 based on the stator current, controls the compressor 13 to stop and opens the hot gas bypass valve 23; at this time, the evaporator 6 is heated and defrosted, the circulating air has a rising temperature trend, the air in the static pressure chamber 5 flows through the surface of the phase change cold storage plate 11, and the tetradecane phase change medium inside the cold storage plate absorbs the heat of the air and undergoes a phase change.

[0104] Because the heat absorbed during the phase change process is higher than that of ordinary metals of the same mass, it can provide continuous cooling compensation during defrosting and reduce the temperature fluctuation range inside the cabin. When this structure is combined with the condensate collection tank 8, it enables both cooling buffering and moisture recovery during the defrosting stage.

[0105] The aquatic product cold chain preservation compartment is equipped with temperature and humidity control. The variable frequency fan 7 uses a brushless DC motor 19 to directly drive the multi-blade centrifugal impeller 20. The variable frequency fan 7 has no speed reduction or speed increase mechanism. The variable frequency fan 7 is fixedly connected to the end face of the evaporator 6 via a flange 21, which is fixed by high-strength bolts 22. This embodiment further explains the drive form, impeller form, and installation method of the variable frequency fan 7. The variable frequency fan 7 uses a brushless DC motor 19 to directly drive the multi-blade centrifugal impeller 20, and has no speed reduction or speed increase mechanism. The brushless DC motor 19 directly drives the multi-blade centrifugal impeller 20, meaning that the motor output shaft is directly connected to the multi-blade centrifugal impeller 20 without passing through a gearbox, pulley, or other transmission stages.

[0106] This design has two technical significances in this invention: First, it reduces intermediate transmission components, improves the stability of the correspondence between the fan speed and the input control signal, and makes it easier for the main control board 12 to accurately calculate the target speed based on the target wind pressure; Second, it reduces the interference of mechanical friction and transmission gap on the current detection results, so that the stator current can more accurately reflect the changes in aerodynamic resistance caused by frost on the evaporator 6.

[0107] The multi-blade centrifugal impeller 20 is used to form a relatively stable static pressure output within a limited installation space. Since the present invention requires cold air to be forced into the double-layer microporous guide wall 2 to form a positive pressure environment in the static pressure chamber 5, an axial flow fan that simply pursues a large flow rate but has insufficient static pressure is not conducive to driving the capillary evaporation net 10 to release moisture.

[0108] Under conditions of low vibration and high static pressure, the multi-bladed centrifugal impeller 20 allows cold air to enter the static pressure chamber 5 after passing through the evaporator 6, and then through the capillary evaporation mesh 10 and the guide holes 14 of the perforated aluminum plate 4; without a deceleration or speed-increasing mechanism, the speed set by the main control board 12 can directly correspond to the actual speed of the impeller, avoiding conversion deviations caused by changes in the transmission ratio.

[0109] The variable frequency fan 7 is fixedly connected to the end face of the evaporator 6 via a flange 21, which is secured by high-strength bolts 22. This fixing method allows the variable frequency fan 7 and the evaporator 6 to form a relatively stable air inlet connection interface, reducing air leakage at the interface.

[0110] Since the resistance threshold determination of this invention depends on the change of the stator current of the fan, if the connection between the fan and the evaporator 6 is not sealed enough, the total resistance of the system will be affected by external air leakage, reducing the accuracy of the frosting determination; the combination of flange 21 and high-strength bolt 22 helps to ensure the coaxiality and sealing of the fan during long-term vibration transportation, and maintain the stability of the reference aerodynamic resistance.

[0111] In a set of calibration implementations, the main control board 12 sends a full-load operation command to the variable frequency fan 7. The brushless DC motor 19 drives the multi-blade centrifugal impeller 20 to rotate at the set speed, and the cold air forms a stable flow rate through the evaporator 6. Since there is no deceleration or speed-up mechanism, the fan output characteristics are stable, and the slope of the temperature drop trajectory inside the cabin is mainly determined by the cooling capacity and the loaded heat capacity, making it less susceptible to transmission fluctuation interference. This condition provides a repeatable data basis for the subsequent inversion of load inertia parameters through the temperature drop trajectory.

[0112] Example 2:

[0113] Please see Figure 1-5 The preservation method includes: S1, after sealing the preservation chamber 1, controlling the variable frequency fan 7 and compressor 13 to run at full load with maximum rated power to obtain the temperature drop trajectory inside the preservation chamber 1;

[0114] S2. Obtain the reciprocal of the reference slope under no-load conditions. Subtract the reciprocal of the reference slope from the reciprocal of the slope of the temperature drop trajectory to obtain the change in heat capacity. Calculate the load inertia parameter based on the change in heat capacity.

[0115] S3. Calculate the target wind pressure based on the load inertia parameter, and obtain the target speed of the variable frequency fan 7 based on the target wind pressure;

[0116] S4. Control the variable frequency fan 7 to run at the target speed, and press the cooled air that has passed through the evaporator 6 into the static pressure chamber 5 to form a positive pressure environment; S5. The cold air passes through the pores of the capillary evaporation net 10 in the static pressure chamber 5, converts the liquid water adsorbed between the fibers of the capillary evaporation net 10 into water vapor, and carries the water vapor through the guide hole 14 of the perforated aluminum plate 4 and blows it toward the aquatic products.

[0117] This embodiment provides a method for preserving food in a food storage compartment. This method addresses the problem of mutual constraints between temperature control and humidity maintenance in traditional cold chain equipment by combining load condition calibration and micro-pressure differential dynamic humidification, so that air volume adjustment no longer depends on manual estimation.

[0118] In S1, after the aquatic products are loaded and the preservation compartment 1 is sealed, the main control board 12 controls the variable frequency fan 7 and the compressor 13 to run at full load with maximum rated power and acquire the temperature drop trajectory inside the preservation compartment 1; the temperature drop trajectory refers to the temperature change data sequence continuously recorded by the temperature sensor inside the compartment at a predetermined sampling interval.

[0119] This trajectory is used to reflect the effect of the total heat capacity inside the cabin on the cooling rate under constant cooling capacity and constant large air volume conditions; the temperature sensor can be set at a representative position in the cargo area, and the sampling results are transmitted to the main control board 12 for storage; the full-load operating conditions keep the heat exchange capacity of the evaporator 6 and the air supply capacity of the fan in a relatively fixed state, which is convenient for subsequent comparison.

[0120] In S2, the reciprocal of the baseline slope under no-load conditions is obtained. The difference between the reciprocal of the baseline slope and the reciprocal of the slope of the current temperature drop trajectory is used to obtain the change in heat capacity. The load inertia parameter is then calculated based on the change in heat capacity. The reciprocal of the baseline slope here comes from the factory calibration or empty cabin calibration data of the refrigeration compartment and represents the cooling response of the refrigeration compartment's own structure and the residual air load under the condition of no water product loading.

[0121] Since a smaller slope of the temperature drop trajectory indicates a slower temperature drop per unit time, a larger inverse slope corresponds to a larger total heat capacity inside the cabin. By comparing the current inverse slope with the inverse slope of the reference slope, the heat capacity increment caused by the loading of aquatic products can be separated. The load inertia parameter in this invention is a control parameter used to characterize the current heat capacity of the cargo inside the cabin and its corresponding air volume requirement. It is not equivalent to a simple mass value, but a comprehensive control quantity obtained by combining the aquatic product category factor.

[0122] In S3, the main control board 12 calculates the target wind pressure based on the load inertia parameter, and then converts the target wind pressure to obtain the target speed of the variable frequency fan 7; the target wind pressure corresponds to the positive pressure that should be established in the static pressure chamber 5, and its magnitude determines the ability of cold air to pass through the capillary evaporation mesh 10 and the perforated aluminum plate 4.

[0123] The causal relationship here is as follows: a larger load inertia parameter indicates a denser cargo stacking and a larger total heat capacity within the compartment, leading to increased resistance to airflow penetrating the cargo area and a greater cooling capacity required. Therefore, the target air pressure within the static pressure chamber 5 must be increased accordingly. Only by establishing a higher positive pressure environment can sufficient cold air be forced to overcome the resistance of the capillary evaporation mesh 10 and the cargo stacking, achieving deep penetration cooling. Simultaneously, the liquid water between the fibers of the capillary evaporation mesh 10 will evaporate more rapidly under the shearing action of the micro-pressure difference airflow.

[0124] Therefore, high wind pressure directly determines the rate at which moisture is transferred into the air, thus ensuring a high-humidity environment in the cargo area; when the load inertia parameter is large, it indicates that the heat load of aquatic products in the hold is high and the initial cooling process is long, increasing the risk of drying out. Therefore, it is necessary to increase the target wind pressure accordingly so that the capillary evaporation net 10 releases more moisture into the cold air; the conversion relationship between the target wind pressure and the target rotation speed can be pre-calibrated and stored in the main control board 12.

[0125] In S4, the main control board 12 controls the variable frequency fan 7 to run at the target speed, pressing the cooled air from the evaporator 6 into the static pressure chamber 5 to create a positive pressure environment. The presence of the static pressure chamber 5 ensures that the airflow output by the variable frequency fan 7 is pressure-homogenized before entering the cargo area, reducing water loss caused by strong local winds blowing directly onto the surface of the aquatic products. The cold air first passes through the evaporator 6 to reach the set preservation temperature zone, and then enters the interior of the double-layer microporous guide wall 2. The positive pressure environment is a prerequisite for the subsequent passive humidification structure to function.

[0126] In S5, cold air passes through the pores of the capillary evaporation net 10 in the static pressure chamber 5, converting the liquid water adsorbed between the fibers of the capillary evaporation net 10 into water vapor, which is then carried through the guide holes 14 of the perforated aluminum plate 4 and blown toward the aquatic products. This process does not use a separate evaporator 6 to heat the water, but rather uses the contact between the flowing cold air and the surface of the wet fibers to achieve moisture transfer. Since the capillary evaporation net 10 is continuously replenished with water by the condensate collection tank 8, the moisture carried away by the cold air can be replenished.

[0127] After the humidified cold air enters the cargo area, it can reduce the water vapor pressure difference between the surface of aquatic products and the environment, thereby reducing the rate of water loss. Combined with the target speed control calculated by the load inertia parameters, the humidification capacity and cold air conveying capacity can be matched under different loading conditions.

[0128] In one implementation, the inverse of the baseline slope is obtained in advance with the cabin empty. After loading a certain type of aquatic product and sealing the cabin, S1 to S5 are executed. The main control board 12 collects the temperature drop trajectory and calculates the inverse of the slope. It is compared with the baseline value to obtain the change in heat capacity, and then the load inertia parameter is calculated.

[0129] The main control board 12 sets the target speed of the fan accordingly, the static pressure chamber 5 forms a positive pressure level that is compatible with the loading state, and the capillary evaporation net 10 passively releases moisture; this method enables the same preservation compartment to maintain high humidity and stable low temperature under different loads, and reduces the air volume deviation caused by manual experience setting;

[0130] Furthermore, the extraction of the slope of the temperature drop trajectory is not a direct average of the data over the entire period, but is obtained according to a fixed processing procedure; its input data includes at least the temperature sampling value output by the temperature sensor in the cargo area, the corresponding timestamp, and the reciprocal of the benchmark slope obtained from the empty cabin calibration; the main control board 12 first removes the transition sampling segment after the compressor 13 and the fan have just started, in order to avoid the start-up transient causing deviation in the judgment of the cooling rate;

[0131] In subsequent continuous sampling points, a time window in which the temperature decreases monotonically and the evaporator 6 is in stable cooling is selected; then, multiple local cooling slopes are calculated based on the temperature difference and time interval between adjacent sampling points within this time window; finally, the multiple local cooling slopes are smoothed to obtain the current temperature drop trajectory slope; the slope obtained in this way corresponds to the actual cooling capacity within the stable heat exchange interval and is more suitable as the input of S2.

[0132] The physical meaning of the change in heat capacity in this invention is the equivalent heat storage capacity added by the current loading condition compared to the empty cargo condition; the main control board 12 does not directly calculate the absolute heat capacity of the cargo, but uses the change in cooling response speed to reflect the ease or difficulty of removing the total heat in the cargo compartment.

[0133] Specifically, the main control board 12 first reads the reciprocal of the empty cabin reference slope, and then reads the reciprocal of the current operating condition slope. When the reciprocal of the current operating condition slope is greater than the reciprocal of the reference slope, the difference between the two is recorded as the positive heat capacity change. When the difference between the two is less than or equal to zero, it indicates that the current operating condition does not show an effective heat capacity increment higher than that of the empty cabin. At this time, the heat capacity change is recorded as zero or as the minimum control quantity.

[0134] The purpose of this limitation is to avoid sensor noise or short-term environmental disturbances causing meaningless negative inputs in subsequent wind pressure calculations;

[0135] The logical function of the load inertia parameter is to convert the change in heat capacity into a demand level that can be directly used in wind turbine control; its generation process may include:

[0136] The main control board 12 matches the change in heat capacity with the pre-stored category correction information to obtain the corrected heat capacity corresponding to the current aquatic product category.

[0137] The main control board 12 then combines the heat leakage level of the cabin to make a second correction to the corrected heat capacity, thereby obtaining a comprehensive control quantity that reflects the current loading conditions.

[0138] The integrated control quantity is mapped to a preset load inertia parameter range. This range can be divided into three levels from low to high: light load, medium load, and heavy load, or it can be divided into more discrete levels. The mapped load inertia parameter is output to S3 to select the corresponding target wind pressure calculation table or interpolation range. Thus, the load inertia parameter retains the thermal response difference and avoids the controller directly processing unstable raw temperature drop data.

[0139] The target wind pressure is determined by looking up a calibration table or by segmented interpolation. Its input includes at least the load inertia parameter, the rated volume of the preservation compartment, and the corresponding air duct resistance level of the evaporator 6. Its output is the target positive pressure value in the static pressure chamber 5. The main control board 12 first determines the load range based on the load inertia parameter, and then reads the corresponding target wind pressure base value in the load range.

[0140] When the cargo compartment is nearly full or the capillary evaporation net 10 is in a high moisture content state, the main control board 12 can add a small correction amount to the base value to ensure that the cold air still has the ability to penetrate the evaporation net and the perforated aluminum plate 4; the target wind pressure does not exist independently, but is an intermediate control amount for subsequent fan speed calculation, used to convert the cargo heat load demand into the driving force required by the air duct.

[0141] The conversion between the target wind pressure and the target speed of the variable frequency fan 7 is also performed step by step; the main control board 12 pre-stores the static pressure output calibration data of the fan at different speeds and the corresponding system duct resistance data.

[0142] During operation, the main control board 12 first retrieves the closest static pressure calibration point based on the target air pressure, then determines which calibration range the combined resistance of the evaporator 6 and the guide wall belongs to, and then outputs the corresponding target fan speed. If the target air pressure is between two adjacent calibration points, linear interpolation is used to obtain the intermediate speed value. The final output of this conversion process is the target speed of the variable frequency fan 7, which is directly transmitted to the fan drive module to execute the positive pressure air supply control of S4.

[0143] To ensure that the acquisition process of the inverse slope of the temperature drop trajectory has a reliable data flow and interaction basis, the main control board 12 is equipped with a dedicated temperature feature extraction module; the specific data interaction method is as follows: the high-precision NTC temperature sensor in the cargo area sends the original temperature sampling sequence to the main control board 12 at a fixed frequency through the I2C bus protocol.

[0144] After receiving the data, the main control board 12 first stores the data in a FIFO circular buffer and calls the median filtering algorithm to remove the glitch data caused by communication interference.

[0145] After determining that the evaporator 6 has entered the stable cooling time window, the main control board 12 performs linear fitting on the continuous effective temperature data in the buffer using the least squares method, outputs the slope of the current temperature drop trajectory, and then calculates the reciprocal.

[0146] To verify the effectiveness of this technology, in the prototype comparison test, after adopting the above-mentioned dynamic resistance inversion and micro-pressure difference humidification methods, the surface water loss rate of fully loaded ribbonfish during 48 hours of cold chain transportation was significantly lower than that of traditional constant air volume direct blowing equipment. Descending to the following;

[0147] The comparative data fully demonstrates that the preservation method of the present invention effectively solves the technical problem that traditional cold storage compartments easily cause aquatic products to dry out through precise load identification and dynamic wind pressure adjustment.

[0148] The preservation method, after step S5, includes: S601, real-time acquisition of the stator current of the variable frequency fan 7 drive motor, determining the relationship between the stator current drop and the preset resistance threshold, controlling the compressor 13 to stop when the stator current drop is greater than the preset resistance threshold, and keeping the compressor 13 running when the stator current drop is less than or equal to the preset resistance threshold.

[0149] S602. After the compressor 13 stops, the hot gas bypass valve 23 of the refrigeration circuit is opened. The high-temperature refrigerant gas is used to heat the evaporator 6 to defrost. The frost on the surface of the evaporator 6 melts and forms condensate.

[0150] S603. Condensate drips into the condensate collection tank 8 and seeps into the capillary evaporation net 10 along the guide slit 9.

[0151] This implementation adds an adaptive defrosting and moisture recovery step; its purpose is to avoid a decrease in heat exchange efficiency after the evaporator 6 is frosted, and at the same time, the defrost melt water is reused for humidification.

[0152] In S601, the main control board 12 acquires the stator current of the variable frequency fan 7 drive motor in real time and determines the relationship between the stator current drop and the preset resistance threshold. The preset resistance threshold is an equivalent aerodynamic resistance judgment parameter obtained by pre-calibrating the duct sealing state, the dynamic balance state of the fan impeller, and the no-load reference aerodynamic resistance.

[0153] In this invention, frost formation on the surface of evaporator 6 reduces the effective cross-sectional area of ​​the flow channel, increasing the aerodynamic resistance of the system. This leads to a change in the load state of the variable frequency fan 7 under constant speed operation, which is reflected in a downward trend in the stator current. The main control board 12 compares the current stator current with the reference current to obtain the amount of stator current decrease. When the amount of stator current decrease is greater than the preset resistance threshold, it indicates that the degree of frost formation has reached the critical state affecting heat exchange, and the main control board 12 controls the compressor 13 to stop.

[0154] When the stator current drop is less than or equal to the threshold, the compressor 13 is kept running. This determination method does not require an additional frost thickness sensor on the evaporator 6 surface, which can reduce the risk of sensor failure in low-temperature and humid environments.

[0155] In S602, after the compressor 13 is stopped, the main control board 12 opens the hot gas bypass valve 23 of the refrigeration circuit to heat the evaporator 6 with high-temperature refrigerant gas for defrosting. Here, the hot gas bypass valve 23 is used to change the direction of refrigerant flow so that the high-temperature refrigerant gas discharged from the compressor 13 enters the corresponding circuit of the evaporator 6 to melt the frost layer.

[0156] As the surface temperature of evaporator 6 rises, the frost adhering to it turns into liquid water; using hot gas bypass defrosting can shorten defrosting time and reduce the need for external electric heating devices.

[0157] In S603, condensate drips into the condensate collection tank 8 and seeps into the capillary evaporation net 10 along the guide slit 9. Since the condensate collection tank 8 is located directly below the evaporator 6 and its bottom guide slit 9 is directly connected to the capillary evaporation net 10, meltwater can enter the fiber structure of the capillary evaporation net 10 along a predetermined path. In this way, the defrosting wastewater that originally needed to be discharged is directly converted into a water source for subsequent humidification. After defrosting, the capillary evaporation net 10 is in a resaturated or near-saturated state, which facilitates the restoration of the passive moisture release process in S5.

[0158] In a set of operational implementations, the main control board 12 reads the stator current every set sampling interval during the constant speed operation of the fan, compares the consecutive sampled values ​​with the current operating condition reference value, and obtains the stator current drop. When the drop exceeds the preset resistance threshold, the defrosting process is triggered. The liquid water formed by the melting of the frost layer on the evaporator 6 flows into the condensate collection tank 8 within a few minutes, and then seeps into the capillary evaporation net 10 through the guide slit 9. This step connects the defrosting control and the humidification water supply in the same control process, reducing manual drainage and manual water replenishment operations.

[0159] The reference current is not an instantaneous current value at any time, but a reference current collected when the evaporator 6 is in a clean, frost-free or lightly frosted state and the fan is running stably at the current target speed. The main control board 12 can sample the stator current multiple times and calculate the average value within a predetermined time window after each defrosting and restoration of stable cooling, and record the average value as the reference current under the speed condition.

[0160] The purpose of this setting is to ensure that subsequent comparisons are based on the same fan speed, the same duct sealing conditions, and approximately the same ambient temperature, thereby reducing misjudgments caused by changes in speed.

[0161] The physical meaning of the stator current drop is the load offset exhibited by the current fan at a given speed relative to the reference ventilation state; its processing flow may include: the main control board 12 first reads the reference current corresponding to the current fan target speed; then it collects the actual stator current at multiple consecutive moments;

[0162] Then, invalid samples corresponding to single abnormal peak values ​​or communication loss points are removed; then, the moving average current is calculated for the remaining sample values; the reference current is compared with the moving average current to obtain the stator current drop; the stator current drop is then sent to the threshold judgment module as the direct input for whether to trigger S602 defrosting; continuous sampling and smoothing processing can avoid false triggering caused by transportation vibration or instantaneous power fluctuations.

[0163] The preset resistance threshold is a metric used to characterize the degree to which the evaporator 6 has reached the critical level where the air duct resistance requires defrosting due to frost formation. The threshold can be determined by recording the stator current changes when the evaporator 6 is clean, lightly frosted, or reaches the predetermined defrosting state during the factory calibration phase. Then, the current drop corresponding to the predetermined defrosting state is selected as the preset resistance threshold, or the median value after a safety margin is selected between the two sets of data: lightly frosted and severely frosted.

[0164] If the equipment has multiple target speed ranges, the main control board 12 can store multiple preset resistance thresholds respectively, and call the threshold that matches the current speed range during operation; thus, the preset resistance threshold is no longer an isolated empirical value, but a judgment boundary corresponding to the fan speed and the duct structure.

[0165] The S601 judgment process is executed in causal order. The main control board 12 first confirms that the current fan is in constant speed operation, then confirms that the compressor 13 is in cooling mode, and then starts reading the stator current. If the fan speed has just changed or the compressor 13 has just started or stopped, the threshold judgment is suspended and resampled after the system enters the stable section. When the stator current decrease is greater than the preset resistance threshold in several consecutive sampling cycles, the main control board 12 outputs the compressor 13 shutdown command. By adding stable section confirmation and continuous over-limit confirmation, the probability of malfunction caused by a single random sampling can be reduced.

[0166] In S603, the main control board 12 can also monitor the rehumidification process of the capillary evaporation net 10 downstream of the condensate collection tank 8. Its logical function is not to add an extra component, but to determine whether the capillary evaporation net 10 has received enough water by statistically analyzing the duration from the start to the end of defrosting and the water replenishment time of the guide slit 9. When defrosting ends and the system resumes normal cooling, the main control board 12 continues to keep the fan running at the target speed, so that the liquid water that has been recovered into the capillary evaporation net 10 participates again in the dehumidification process in S5, thereby realizing the sequential connection of the three links of defrosting, water return and dehumidification.

[0167] The preservation method, after step S603, includes: S701, obtaining the equivalent temperature rise suppression rate and defrosting duration of the phase change process of the tetradecane phase change medium inside the phase change cold storage plate 11; S702, multiplying the defrosting duration by the equivalent temperature rise suppression rate to calculate the temperature compensation amount; S703, determining the relationship between the temperature compensation amount and the preset safety boundary. When the temperature compensation amount is greater than or equal to the preset safety boundary, closing the hot gas bypass valve 23 and restoring the compressor 13 to its normal refrigeration cycle; when the temperature compensation amount is less than the preset safety boundary, keeping the hot gas bypass valve 23 open.

[0168] This embodiment introduces a defrosting duration control method based on the phase change cold storage plate 11 after the defrosting recovery step, which is used to constrain the temperature rise inside the cabin during defrosting. Its core is to use the heat absorption capacity of the phase change cold storage plate 11 during defrosting to calculate the temperature compensation amount, and determine the timing of the end of defrosting accordingly.

[0169] In S701, the main control board 12 acquires the equivalent temperature rise suppression rate and defrosting duration of the phase change process of the tetradecane phase change medium inside the phase change cold storage plate 11. The equivalent temperature rise suppression rate can be calibrated at the factory based on the model, material, installation position and wind speed of the static pressure chamber 5 of the phase change cold storage plate 11, and stored in the main control board 12. The defrosting duration starts counting from the opening of the hot gas bypass valve 23 and ends at the current judgment time.

[0170] Since the phase change cold storage plate 11 is in a heat absorption state during the defrosting stage, the amount of cold it can provide to the air side per unit time is related to the equivalent temperature rise suppression rate. Therefore, this parameter can be used to estimate the temperature compensation capability during the defrosting stage.

[0171] In S702, the main control board 12 multiplies the defrosting duration by the equivalent temperature rise suppression rate to calculate the temperature compensation amount. The temperature compensation amount in this invention means the control amount corresponding to the ability of the phase change cold storage plate 11 to offset the temperature rise in the cabin during the current defrosting duration. This control amount is used to indicate the degree to which defrosting can be allowed to continue, rather than being directly equal to the actual temperature value.

[0172] Since the defrosting duration increases, it will continuously consume the latent heat reserve of the phase change cold storage plate 11. Multiplying the two together will give a value corresponding to the consumed compensation capacity.

[0173] In S703, the main control board 12 determines the relationship between the temperature compensation amount and the preset safety boundary. When the temperature compensation amount is greater than or equal to the preset safety boundary, it indicates that the current defrosting process has approached the upper limit of the safety compensation that the phase change cold storage plate 11 can provide. At this time, the hot gas bypass valve 23 is closed and the compressor 13 resumes its normal refrigeration cycle. When the temperature compensation amount is less than the preset safety boundary, the hot gas bypass valve 23 is kept open to continue defrosting the evaporator 6.

[0174] The preset safety boundary can be set in advance based on the allowable fluctuation range of the target cabin temperature and the capacity of the phase change cold storage plate 11; through this judgment, it can be prevented that the cabin temperature will exceed the requirements for the preservation of aquatic products just for the purpose of defrosting.

[0175] In one implementation, the main control board 12 continuously accumulates the defrosting duration after defrosting begins, while simultaneously retrieving the equivalent temperature rise suppression rate corresponding to the phase change cold storage plate 11 and calculating the temperature compensation amount according to a set cycle. When this value reaches the preset safety boundary, even if there is still a small amount of residual moisture in the evaporator 6, the system ends the hot gas defrosting and resumes normal cooling.

[0176] In subsequent operating cycles, the frosting determination is continued based on the stator current; this control method constrains the defrosting process by the phase change cold storage capacity, reducing the risk of cargo temperature rise due to excessively long defrosting time.

[0177] The logical role of the equivalent temperature rise suppression rate in this invention is to convert the temperature rise suppression capability that the phase change cold storage plate 11 can provide to the air in the static pressure chamber 5 per unit time into a calibrated quantity that can be used for the controller to judge.

[0178] It should be clarified that the equivalent temperature rise suppression rate of the present invention is not the thermal conductivity, which characterizes the heat transfer capacity per unit area temperature difference in traditional engineering thermodynamics. Instead, it is the equivalent temperature rise suppression rate calculated by converting the phase change cold storage plate 11 absorbs ambient heat per unit time under specific wind speeds and installation boundaries in order to simplify the calculation logic of the main control board 12. Its source is not a complex thermal formula solved in real time during operation, but is obtained from factory tests. Specifically, under the conditions of known fan speed, static pressure chamber 5 wind speed and fixed phase change cold storage plate 11 structure, the suppression effect of the phase change cold storage plate 11 on air temperature rise during defrosting can be recorded, and the effect can be converted into the equivalent temperature rise suppression rate of the corresponding operating condition per unit time.

[0179] Therefore, the formula is:

[0180]

[0181] The direct conversion between time and equivalent temperature rise suppression rate is realized in terms of physical dimensions, avoiding complex phase change latent heat integral calculation; if the equipment corresponds to multiple fan speed ranges, the main control board 12 can store multiple sets of equivalent temperature rise suppression rates for different speeds, so that the calibration value consistent with the current operating condition can be called in S701.

[0182] The defrosting duration is also obtained according to a fixed procedure; the main control board 12 writes the defrosting start timestamp at the same time as the hot gas bypass valve 23 is opened; during the defrosting process, the current timestamp is read at a predetermined cycle; and the current timestamp is subtracted from the start timestamp to obtain the current cumulative defrosting duration.

[0183] Then use the accumulated time as the input of S702; if the hot gas bypass valve 23 closes abnormally, the compressor 13 stops for protection or the power supply is interrupted during the defrosting process, the current timer is invalidated or the timer is restarted after the power is restored, so as to avoid the non-continuous defrosting time being mistakenly included in the temperature compensation amount.

[0184] Temperature compensation is a control quantity used to represent the safe consumption level of the phase change cold storage plate 11, and its calculation relationship can be expressed as follows:

[0185]

[0186] The output of this control variable is not directly used as the displayed temperature, but is passed to the boundary comparison module of S703 to determine whether the current defrosting has approached the allowable compensation limit of the phase change heat storage plate 11. By combining time with the calibrated heat transfer capacity, the controller can constrain the defrosting time without introducing an additional complex temperature field model.

[0187] The preset safety boundary is a limit value determined jointly based on the allowable fluctuation range of the target cabin temperature, the total cold storage capacity of the phase change cold storage plate 11, and the maximum acceptable temperature rise risk during the defrosting stage. The determination method can be as follows: first, record the temperature change of the cargo area under different defrosting durations in the prototype test; then find the longest safe defrosting range that does not affect the freshness requirements of aquatic products.

[0188] The temperature compensation amount corresponding to this range is set as the preset safety boundary and written to the main control board 12. If the equipment has multiple compartment volumes or multiple phase change cold storage plate 11 configurations, the corresponding preset safety boundaries can be set respectively. Thus, the preset safety boundary represents the termination criterion of defrosting control, rather than a general empirical upper limit.

[0189] The judgment process in S703 can be refined as follows: The main control board 12 first reads the current defrosting duration and the equivalent temperature rise suppression rate of the corresponding operating condition, and then calculates the current temperature compensation amount; then compares the temperature compensation amount with the preset safety boundary; when the comparison result reaches or exceeds the safety boundary, the main control board 12 outputs the command to close the hot gas bypass valve 23 and restores the compressor 13 to normal refrigeration cycle.

[0190] When the comparison result does not reach the safety boundary, the hot gas bypass valve 23 is kept open and recalculated in the next sampling cycle; the final output of this process is the defrosting end control signal, which is directly used to limit the duration of the defrosting process, so as to maintain a balance between the degree of defrosting completion and the risk of cargo temperature rise.

[0191] To ensure that the control logic for defrosting duration has clear executableness at the software level, the judgment process of S701 to S703 mentioned above is reflected in the main control board 12 as an adaptive defrosting state machine. This state machine includes three core states: defrosting heating state, boundary evaluation state, and cooling recovery state. The specific control flow is as follows: After entering the defrosting heating state, the main control board 12 starts the internal timer, triggering an interrupt once every set period to enter the boundary evaluation state.

[0192] In the boundary evaluation state, the main control board 12 extracts the defrosting duration accumulated by the current timer, calls the pre-stored equivalent temperature rise suppression rate to perform a product operation to obtain the current temperature compensation amount; sends the compensation amount to the comparator function to compare with the preset safety boundary; if the comparator output is not out of bounds, the state machine returns to the defrosting heating state; if the output is out of bounds, the state machine immediately transitions to the cooling recovery state and outputs a PWM control signal to close the electromagnetic coil of the hot gas bypass valve 23.

[0193] Through the above state machine design and specific evaluation constants, it is not only proven that the defrosting time control based on the phase change cold storage plate 11 can theoretically strictly limit the temperature rise inside the cabin to a safe range, but also eliminates the need for complex temperature field prediction algorithms, thus reducing the computational overhead of the control module.

[0194] The specific steps in S2 for calculating the load inertia parameter in the preservation method include: S801, obtaining the conversion coefficient of aquatic product type and the heat leakage coefficient of preservation compartment 1; S802, multiplying the change in heat capacity by the conversion coefficient of aquatic product type and combining it with the heat leakage coefficient to calculate the load inertia parameter.

[0195] This embodiment provides a detailed explanation of the calculation process of the load inertia parameter in step S2. The load inertia parameter is not a direct weighing value of the loaded mass, but a control parameter obtained by combining the change in heat capacity, the differences in the types of aquatic products, and the heat leakage characteristics of the preservation compartment 1. It is used to guide the subsequent calculation of target wind pressure and target rotation speed.

[0196] In S801, the main control board 12 obtains the conversion coefficient of aquatic product types and the heat leakage coefficient of the preservation compartment 1; the conversion coefficient of aquatic product types is used to correct the influence of the differences in water content, tissue structure and specific heat of different types of aquatic products on the change in heat capacity.

[0197] For example, aquatic products with higher water content have a larger heat capacity for the same weight, and their conversion factor can be set to a higher value; aquatic products with dense muscle fibers and relatively low heat capacity per unit volume have a conversion factor set to a lower value; this factor can be provided by a pre-established category database and entered by the operator during loading, or issued by the transportation management system.

[0198] The heat leakage coefficient of the preservation compartment 1 is used to characterize the degree of heat transferred from the external environment to the compartment through the compartment wall. This parameter can be calibrated by factory testing after the compartment structure is determined and stored as a constant parameter in the main control board 12.

[0199] In S802, the main control board 12 multiplies the change in heat capacity by the conversion factor for the type of aquatic product, and calculates the load inertia parameter in combination with the heat leakage coefficient.

[0200] Specifically, the calculation process is not a simple linear superposition, but is based on a built-in load inertia conversion logic model. This model logically includes two processing steps: multiplying the change in heat capacity with the conversion coefficient of aquatic product type to obtain the effective cargo heat load. This step characterizes the actual absorption capacity of aquatic products with different moisture content and tissue density to cold energy.

[0201] The model receives the heat leakage coefficient and the current temperature difference between the inside and outside of the cabin as inputs and calculates the environmental heat leakage compensation value. To ensure the rigor of the calculation logic, before performing weighted summation, the model performs a dimensionless mapping of the effective cargo heat load and the environmental heat leakage compensation value, transforming them into control parameter components under a unified dimension, thereby eliminating the calculation logic conflict caused by the inconsistency of the physical dimensions of the heat capacity attribute and the heat leakage compensation attribute.

[0202] The main control board 12 performs a weighted summation of the effective cargo heat load and the environmental heat leakage compensation value, and outputs the final load inertia parameter.

[0203] The logical model as a whole represents the comprehensive physical distribution relationship of the cooling capacity of the refrigeration compartment during the cooling process, which is consumed by the sensible heat of the internal cargo and the heat leakage of the external environment. The combined heat leakage coefficient here refers to the correction of the temperature drop deviation caused by the heat leakage of the compartment itself on the basis of the change in heat capacity, so that the final load inertia parameter more accurately reflects the control requirements caused by loading aquatic products.

[0204] If the heat leakage coefficient is not introduced, when the ambient temperature changes significantly, the heat capacity inversion results obtained for the same batch of goods under different environments will be deviated, which will affect the calculation of the target wind pressure.

[0205] In one implementation, the inverse of the empty cabin reference slope has been pre-recorded. After loading a certain type of aquatic product, the inverse of the slope of the temperature drop trajectory is obtained. The main control board 12 calculates the difference between the two to obtain the change in heat capacity. The type conversion coefficient corresponding to the aquatic product is called, and the heat leakage coefficient of the preservation compartment 1 is read at the same time to correct the change in heat capacity and obtain the load inertia parameter.

[0206] This parameter varies with the type of cargo and the thermal properties of the cargo compartment, so it can reflect the air volume requirement more accurately than simply setting the fan speed based on the cargo volume or human experience. After using this parameter to participate in the target air pressure calculation in S3, the micro-pressure difference dynamic humidification process can be matched with the actual cargo condition, reducing water loss caused by excessive air volume and insufficient cooling caused by insufficient air volume.

[0207] To enable programmability of the above logical model, the calculation of load inertia parameters is performed according to the following explicit data flow rules:

[0208] The main control board 12 reads the current temperature difference between the inside and outside of the compartment, multiplies it by the heat leakage coefficient of the preservation compartment 1, and obtains the environmental heat leakage compensation value.

[0209] The effective cargo heat load is obtained by multiplying the change in heat capacity by the conversion factor for the type of aquatic product.

[0210] The final load inertia parameters are calculated using the formula: ,in, and These are the preset system load weight and leakage heat response weight, respectively, and the sum of the two is one;

[0211] In the specific software implementation, the main control board 12 acquires the internal and external temperature difference data once per second through the analog-to-digital conversion interface. After passing through the moving average filter, the data is input into the above logic to ensure smooth calculation output. In terms of hardware, the real-time requirements can be met by using a conventional microcontroller, and the data flow and calculation rules are clearly defined.

[0212] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A cold chain preservation compartment for aquatic products with temperature and humidity control, characterized in that, include: The preservation chamber (1) has a double-layer microporous flow guide wall (2) fixedly connected to the left and right side walls inside the preservation chamber (1). The double-layer microporous flow guide wall (2) includes a solid baffle (3) and a perforated aluminum plate (4). A static pressure cavity (5) is formed between the solid baffle (3) and the perforated aluminum plate (4). Evaporator (6) is fixedly connected to the top of the preservation chamber (1); A variable frequency fan (7) is fixedly connected to the air inlet side of the evaporator (6); A condensate collection tank (8) is fixedly connected to the evaporator (6) directly below it, and a guide slit (9) is provided at the bottom of the condensate collection tank (8). The capillary evaporation mesh (10) is snapped into the guide slit (9). The upper end of the capillary evaporation mesh (10) receives the liquid water inside the condensate collection tank (8), and the lower end of the capillary evaporation mesh (10) is laid flat against the back of the perforated aluminum plate (4). A phase change cold storage plate (11) is fixed inside the static pressure chamber (5) and arranged close to the inner side of the solid baffle (3); The main control board (12) controls the variable frequency fan (7) and the compressor (13).

2. The aquatic product cold chain preservation compartment with temperature and humidity regulation according to claim 1, characterized in that, The solid baffle (3) is made of polytetrafluoroethylene, and the thickness of the solid baffle (3) is [missing information]. The thickness of the perforated aluminum plate (4) is ; The surface of the perforated aluminum plate (4) is anodized, and the perforated aluminum plate (4) has uniformly distributed guide holes (14). The width of the static pressure chamber (5) is... .

3. The aquatic product cold chain preservation compartment with temperature and humidity regulation according to claim 1, characterized in that, The condensate collection tank (8) is a V-shaped water guide channel (15). The condensate collection tank (8) is made of 316L stainless steel and is fixed by full welding.

4. The aquatic product cold chain preservation compartment with temperature and humidity regulation according to claim 1, characterized in that, The capillary evaporation mesh (10) has a porosity of Hydrophilic polyester fiber interwoven web; The capillary evaporation mesh (10) is press-fitted into the guide slit (9).

5. The aquatic product cold chain preservation compartment with temperature and humidity regulation according to claim 1, characterized in that, The phase change cold storage plate (11) is an aluminum alloy microchannel flat tube (16), and the phase change cold storage plate (11) is filled with tetradecane phase change medium; The phase transition temperature of the tetradecane phase change medium is: The phase change cold storage plate (11) is fixed by thermally conductive silicone grease (17) and aluminum clamps (18).

6. The aquatic product cold chain preservation compartment with temperature and humidity regulation according to claim 1, characterized in that, The variable frequency fan (7) uses a brushless DC motor (19) to directly drive a multi-bladed centrifugal impeller (20), and the variable frequency fan (7) has no speed reduction or speed increase mechanism; The variable frequency fan (7) is fixedly connected to the end face of the evaporator (6) by a flange (21), and the flange (21) is fixed by high-strength bolts (22).

7. A method for cold chain preservation of aquatic products with temperature and humidity regulation, applied to the cold chain preservation chamber for aquatic products with temperature and humidity regulation as described in claim 1, characterized in that, include: S1. After sealing the preservation chamber (1), control the variable frequency fan (7) and the compressor (13) to run at full load with maximum rated power to obtain the temperature drop trajectory inside the preservation chamber (1); S2. Obtain the reciprocal of the reference slope under no-load conditions, and obtain the heat capacity change by subtracting the reciprocal of the reference slope from the reciprocal of the temperature drop trajectory slope. Calculate the load inertia parameter based on the heat capacity change. S3. Calculate the target wind pressure based on the load inertia parameters, and calculate the target speed of the variable frequency fan (7) based on the target wind pressure; S4. Control the variable frequency fan (7) to run at the target speed, and press the cooled air that has passed through the evaporator (6) into the static pressure chamber (5) to form a positive pressure environment; S5. The cold air passes through the pores of the capillary evaporation net (10) in the static pressure chamber (5), converts the liquid water adsorbed between the fibers of the capillary evaporation net (10) into water vapor, and carries the water vapor through the guide hole (14) of the perforated aluminum plate (4) and blows it toward the aquatic products.

8. The cold chain preservation method for aquatic products with temperature and humidity regulation according to claim 7, characterized in that, Following step S5: S601. Real-time acquisition of the stator current of the variable frequency fan (7) drive motor, determination of the relationship between the stator current drop and the preset resistance threshold, control the compressor (13) to stop when the stator current drop is greater than the preset resistance threshold, and keep the compressor (13) running when the stator current drop is less than or equal to the preset resistance threshold. S602. After the compressor (13) is stopped, the hot gas bypass valve (23) of the refrigeration circuit is opened, and the evaporator (6) is defrosted by heating it with high-temperature refrigerant gas. The frost on the surface of the evaporator (6) melts and forms condensate. S603, the condensate drips into the condensate collection tank (8) and seeps into the capillary evaporation net (10) along the guide slit (9).

9. The cold chain preservation method for aquatic products with temperature and humidity regulation according to claim 8, characterized in that, Following step S603: S701. Obtain the equivalent temperature rise suppression rate and defrosting duration of the phase change process of the tetradecane phase change medium inside the phase change cold storage plate (11). S702. Multiply the defrosting duration by the equivalent temperature rise suppression rate to calculate the temperature compensation amount; S703. Determine the relationship between the temperature compensation amount and the preset safety boundary. When the temperature compensation amount is greater than or equal to the preset safety boundary, close the hot gas bypass valve (23) and restore the compressor (13) to normal refrigeration cycle. When the temperature compensation amount is less than the preset safety boundary, keep the hot gas bypass valve (23) open.

10. The cold chain preservation method for aquatic products with temperature and humidity regulation according to claim 7, characterized in that, The specific steps in S2 for calculating the load inertia parameters include: S801. Obtain the conversion coefficient of aquatic product types and the heat leakage coefficient of the preservation chamber (1); S802. Multiply the change in heat capacity by the conversion factor for the type of aquatic product, and calculate the load inertia parameter by combining it with the heat leakage coefficient.

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