High-precision wind temperature control cold storage type fresh-keeping refrigerator

Abstract

The application relates to the technical field of commercial refrigeration preservation equipment, in particular to a high-precision air temperature control cold accumulation type preservation refrigerator, the air temperature control precision of the high-precision air temperature control cold accumulation type preservation refrigerator is remarkably improved: through constant-temperature buffering of cold accumulation medium and a secondary circulation cooling structure, in combination with unique cold accumulation medium temperature feedback control logic and heat load impact compensation logic, the air temperature fluctuation of a preservation chamber is less than or equal to 0.5 DEG C, which is reduced by more than 80% compared with ordinary air-cooled refrigerators (2-6 DEG C fluctuation), and the special preservation scene requirements are fully met. The cold accumulation medium can effectively buffer the instantaneous heat load, the start-stop frequency of the main refrigeration system is reduced by more than 60% compared with ordinary air-cooled refrigerators, and the service life of core components such as compressors is remarkably prolonged by more than 30%; meanwhile, the secondary circulation cooling structure reduces the cooling capacity loss, and the energy consumption is reduced by 15-20% compared with ordinary air-cooled refrigerators.

Description

Technical Field

[0001] This invention relates to the field of commercial refrigeration and preservation equipment technology, and in particular to a high-precision air temperature control cold storage type refrigerator. Background Technology

[0002] In special preservation scenarios for high-end ingredients, such as Wagyu beef, premium seafood, premium mushrooms, berries, and precision-cultured foods, temperature fluctuations must be strictly controlled within 0.5℃; otherwise, spoilage and a shortened shelf life will occur. Currently, the mainstream commercial refrigerated display cases on the market are ordinary air-cooled freezers. Their working principle involves a compressor driving refrigerant through a throttling device to the evaporator for cooling, and then a fan delivering cold air into the chamber. However, this type of freezer has a core flaw that prevents it from meeting specific preservation needs: First, large temperature fluctuations: Ordinary air-cooled freezers are affected by the heat load impact of compressor start-up and shutdown, defrosting, and door opening, resulting in temperature fluctuations generally ranging from ±2 to ±4℃, and even reaching ±5 to ±6℃ under some operating conditions, far exceeding those of special preservation scenarios. The first issue is the ±0.5℃ accuracy requirement. The second is the lag in control logic: existing conventional air-cooled freezers use "chamber temperature" as the core feedback signal to control the compressor's start and stop. The compressor only responds after the chamber temperature changes, resulting in a significant lag and easily causing sudden rises and falls in air temperature. The third issue is the lack of a cooling buffer mechanism: cooling is directly transferred to the air from the evaporator, failing to buffer instantaneous heat loads (such as frequent door openings or the placement of large amounts of room-temperature food). The refrigerant's evaporation temperature is generally 7-10℃ (K value) lower than the actual required temperature of the freezer, causing the temperature at the air outlet to be much lower than other areas, further exacerbating air temperature fluctuations.

[0003] Therefore, there is an urgent need to address the core pain points of existing ordinary air-cooled freezers by proposing a cold storage-type freezer with features such as cold load buffering, high-precision air temperature control, and high-precision air temperature control that can be adapted to special preservation scenarios, thus filling a market gap. Summary of the Invention

[0004] The purpose of this invention is to provide a cold storage refrigerator with high-precision air temperature control to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides a high-precision air temperature control cold storage refrigerator, comprising: The main body of the freezer has a closed preservation chamber, and a fan assembly is built into the top of the preservation chamber; A cold storage liquid unit includes a storage tank, a cold storage medium, a main refrigeration coil, and an insulation layer. The cold storage medium is filled in the storage tank, the main refrigeration coil is completely immersed in the cold storage medium, and the insulation layer is tightly wrapped around the outside of the storage tank. A circulating cooling unit includes a cooling pump, a heat exchange coil, and a circulating pipeline. The inlet of the cooling pump is connected to the bottom of the storage tank through the circulating pipeline. The outlet of the cooling pump is connected to the inlet of the heat exchange coil, and the outlet of the heat exchange coil is connected to the top of the storage tank. The main refrigeration system is connected in series with the main refrigeration coil to form a refrigeration cycle; The control unit is electrically connected to the main refrigeration system, the cooling pump, and the fan assembly. It controls the start and stop of the main refrigeration system and the operation of the cooling pump and the fan assembly based on the temperature of the cold storage medium.

[0006] Preferably, the cold storage medium is a non-toxic, non-corrosive fluid that does not freeze at zero degrees Celsius, and is at least one of an alcohol aqueous solution or a composite phase change material.

[0007] Preferably, the aqueous alcohol solution includes one or more mixtures of propylene glycol aqueous solution, ethylene glycol aqueous solution, and glycerol aqueous solution; the volume concentration of the propylene glycol aqueous solution is 30%-40%, the volume concentration of the ethylene glycol aqueous solution is 25%-35%, and the volume concentration of the glycerol aqueous solution is 40%-50%.

[0008] Preferably, the composite phase change material includes a mixture of alcohols and phase change microcapsules, or a composite mixture of alcohols; the phase change microcapsules have a particle size of 5-20 μm, and the mass ratio of alcohols to phase change microcapsules is 8:2-9:1.

[0009] Preferably, the volume of the liquid storage tank is 15%-35% of the volume of the preservation chamber, and the material is a food-grade low-temperature resistant material, including at least one of 304 stainless steel, 316 stainless steel, PP engineering plastic, and ABS plastic; the liquid storage tank is provided with a liquid replenishment port and an exhaust port at the top, and a sewage discharge port at the bottom; the volume of the preservation chamber is 50-1000L; the fan blades of the fan assembly are centrifugal or axial.

[0010] Preferably, the main cooling coil and the heat exchange coil are made of high thermal conductivity metals, including at least one of copper tubes, aluminum tubes, and stainless steel tubes; the main cooling coil has a structure of one of serpentine tubes, spiral tubes, or U-shaped tubes; and the heat exchange coil is one of finned coils, microchannel coils, and threaded coils.

[0011] Preferably, the insulation layer is made of a low thermal conductivity insulation material, including at least one of rigid polyurethane foam, polystyrene foam, and vacuum insulation board, and the insulation layer has a thickness of ≥40mm and a thermal conductivity of ≤0.025W / (m·K).

[0012] Preferably, the cooling pump is a miniature low-temperature resistant pump, including one of a variable frequency water pump, a magnetic drive pump, and a diaphragm pump, with an adjustable flow rate range of 0.5-5 L / min; the circulation pipeline is made of food-grade low-temperature resistant pipeline, including at least one of PE pipe, PP pipe, 304 stainless steel pipe, and silicone pipe.

[0013] Preferably, the main refrigeration system includes a fully enclosed compressor, a heat dissipation device, and a throttling element; the fully enclosed compressor includes one of a scroll compressor, a reciprocating compressor, and a rotary compressor; the heat dissipation device includes one of an air-cooled condenser, a water-cooled condenser, and an evaporative condenser; and the throttling element includes one of an electronic expansion valve, a thermostatic expansion valve, and a capillary tube.

[0014] Preferably, the control unit includes a sensor group and a controller; the sensor group includes at least a cold storage medium temperature sensor and a chamber temperature sensor, the cold storage medium temperature sensor being immersed in the middle of the cold storage medium or closely attached to the outer wall of the storage tank and the insulation layer, the chamber temperature sensor being installed in the middle of the preservation chamber and avoiding the air outlet, and the measurement accuracy being ≥ ±0.1℃; the control logic of the controller includes: The cooling pump is controlled to operate continuously at a stable flow rate adapted to the cooling load, and the fan assembly operates continuously at a constant speed of 600-1200 r / min to ensure stable output of cooling capacity. The main refrigeration system starts when the temperature of the cold storage medium is 0.5°C higher than the set temperature, and stops when the temperature is 0.5°C lower than the set temperature. When opening the door causes the temperature of the preservation chamber to rise sharply by ≥1℃, increase the flow rate of the cooling pump by 10-15% and continue for 3-5 minutes before restoring the normal flow rate.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. The high-precision air temperature control of the cold storage refrigerator provided by this invention significantly improves the air temperature control accuracy: by combining the constant temperature buffer of the cold storage medium with the secondary circulation cooling structure, combined with the unique cold storage medium temperature feedback control logic and heat load impact compensation logic, the air temperature fluctuation of the preservation chamber is ≤0.5℃, which is more than 80% lower than that of ordinary air-cooled refrigerators (2-6℃ fluctuation), and fully meets the needs of special preservation scenarios. 2. The high-precision air temperature control cold storage refrigerator provided by this invention has strong scene adaptability: the cold storage medium and component type can be flexibly selected according to different preservation needs and cost budgets, and it is suitable for preservation chambers with different volumes of 50-1000L. It is suitable for high-end food, beef, mushrooms, berries, precision-cultivated food and other special preservation scenarios or other scenarios that require precise constant temperature. 3. The high-precision air-temperature control cold storage refrigerator provided by this invention has a long service life and low energy consumption: the cold storage medium can effectively buffer instantaneous heat load, and the start-stop frequency of the main refrigeration system is reduced by more than 60% compared with ordinary air-cooled refrigerators, significantly extending the life of core components such as compressors by more than 30%; at the same time, the secondary circulation cooling structure reduces cold energy loss, and energy consumption is reduced by 15-20% compared with ordinary air-cooled refrigerators; 4. The high-precision air temperature control cold storage refrigerator provided by this invention has high safety and stability: it uses food-grade low-temperature resistant materials, and the cold storage medium is non-toxic and non-corrosive; by setting up an insulation layer and combining it with heat load impact compensation logic, the temperature stability is further improved. Attached Figure Description

[0016] Figure 1 A schematic diagram of the overall structure of a cold storage refrigerator with high-precision air temperature control provided for an embodiment of the present invention. Figure 2 A schematic diagram of the internal structure of a cold storage refrigerator with high-precision air temperature control provided for an embodiment of the present invention. Figure 3 The control logic flowchart of the control unit of the high-precision air temperature control cold storage refrigerator provided for the embodiments of the present invention is shown.

[0017] The markings in the diagram are as follows: 1-Refrigerator body, 2-Preservation chamber, 3-Fan assembly, 4-Cold storage liquid unit, 5-Circulating cooling unit, 6-Main refrigeration system. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Figure 1 A schematic diagram of the overall structure of a high-precision air temperature control cold storage refrigerator provided for an embodiment of the present invention. Figure 2 A schematic diagram of the internal structure of a high-precision air-temperature control cold storage refrigerator provided for embodiments of the present invention. Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a high-precision air-temperature control cold storage refrigerator, comprising: The main body of the freezer is 1, which has a closed preservation chamber 2. The top of the preservation chamber 2 has a built-in fan assembly 3. The main body of the freezer is a closed insulated box structure. The volume of the preservation chamber 2 is the size of a conventional freezer and can be flexibly adapted according to actual preservation needs. The fan assembly 3 includes a drive motor and fan blades, which are used to evenly deliver the cooled energy after heat exchange to the preservation chamber to ensure uniform temperature in the chamber. The cold storage liquid unit 4 includes a liquid storage tank, a cold storage medium, a main refrigeration coil, and an insulation layer. The cold storage medium is filled in the liquid storage tank, the main refrigeration coil is completely immersed in the cold storage medium, and the insulation layer is tightly wrapped around the outside of the liquid storage tank. The cold storage liquid unit 4 is the core of cold capacity buffer and is installed at the bottom of the main body 1 of the freezer for easy maintenance in the future. The circulating cooling unit 5 includes a cooling pump, a heat exchange coil, and a circulation pipeline. The inlet of the cooling pump is connected to the bottom of the storage tank through the circulation pipeline, the outlet of the cooling pump is connected to the inlet of the heat exchange coil, and the outlet of the heat exchange coil is connected to the top of the storage tank, thus forming a closed loop of "bottom of storage tank → inlet of cooling pump → outlet of cooling pump → inlet of heat exchange coil → outlet of heat exchange coil → top of storage tank" to achieve secondary circulating cooling. The circulating cooling unit 5 is a cold energy transport carrier to achieve indirect heat exchange between the cold storage medium and the preservation chamber 2. The main refrigeration system 6 is connected in series with the main refrigeration coil to form a refrigeration cycle; the main refrigeration system 6 is the core of cooling capacity generation. The control unit is electrically connected to the main refrigeration system 6, the cooling pump, and the fan assembly 3. It controls the start and stop of the main refrigeration system 6 and the operation of the cooling pump and fan assembly 3 based on the temperature of the cold storage medium. The control unit is the core control module for system operation, realizing the coordinated operation of each unit.

[0020] The high-precision air temperature control cold storage refrigerator provided by this invention uses a constant temperature buffer of cold storage medium 2 combined with a secondary circulation cooling structure, combined with the control logic of the control unit to make the air temperature fluctuation of the freshness chamber 2 ≤0.5℃, which is more than 80% lower than that of ordinary air-cooled refrigerators (fluctuation of 2-6℃), and fully meets the needs of special freshness preservation scenarios.

[0021] In one embodiment of the present invention, the cold storage medium is a non-toxic, non-corrosive fluid that does not freeze at zero degrees Celsius, and is at least one of an alcohol aqueous solution and a composite phase change material. Specifically, the cold storage medium is a high-efficiency cold storage medium that does not freeze at the evaporation temperature of commonly used refrigerants, meeting the requirements of no risk of freezing expansion at the refrigerant evaporation temperature, non-toxicity, non-corrosiveness, and good fluidity. The present invention uses a control unit to precisely maintain the temperature of the cold storage medium within ±0.5°C of the set temperature, ensuring that it is always in a liquid state, maintaining good fluidity, and ensuring the stable operation of the circulating cooling system, while using the sensible heat storage characteristics of the medium itself to achieve cold load buffering.

[0022] Further, in one embodiment of the present invention, the alcohol aqueous solution includes one or more mixtures of propylene glycol aqueous solution, ethylene glycol aqueous solution, and glycerol aqueous solution; the volume concentration of the propylene glycol aqueous solution is 30%-40%, the volume concentration of the ethylene glycol aqueous solution is 25%-35%, and the volume concentration of the glycerol aqueous solution is 40%-50%. The composite phase change material includes a mixture of alcohol and phase change microcapsules, and a composite mixture of alcohols; the particle size of the phase change microcapsules is 5-20 μm, and the mass ratio of alcohol to phase change microcapsules is 8:2-9:1.

[0023] In one embodiment of the present invention, the volume of the storage tank is 15%-35% of the volume of the preservation chamber 2, and the material is a food-grade low-temperature resistant material, including at least one of 304 stainless steel, 316 stainless steel, PP engineering plastic, and ABS plastic; the top of the storage tank is provided with a liquid replenishment port and an exhaust port, and the bottom is provided with a drain port; the volume of the preservation chamber is 50-1000L; the fan blades of the fan assembly are centrifugal or axial.

[0024] The volume of the storage tank is 15%-35% of the volume of the preservation chamber 2, and this volume must meet the following requirements: it can completely absorb the instantaneous heat load generated when the door is opened or room temperature food is placed in, ensuring that the air temperature fluctuation of the preservation chamber is ≤±0.5℃; the liquid replenishment port at the top of the storage tank is used for replenishing and replacing the cold storage medium, and the drain port at the bottom facilitates the cleaning of impurities. This invention allows for flexible selection of the cold storage medium and component types according to different preservation needs and cost budgets, adapting to preservation chambers with different volumes from 50-1000L, and is suitable for various special preservation scenarios such as high-end food, beef, mushrooms, berries, precision-cultivated food, or other scenarios requiring precise temperature control.

[0025] In one embodiment of the present invention, the main refrigeration coil and the heat exchange coil are made of high thermal conductivity metals, including at least one of copper tubes, aluminum tubes, and stainless steel tubes; the main refrigeration coil has a structure of one of serpentine tubes, spiral tubes, or U-shaped tubes; and the heat exchange coil is one of finned coils, microchannel coils, or threaded coils. Through the structural and parameter design of the main refrigeration coil and the heat exchange coil, efficient transfer of cooling capacity is ensured.

[0026] In one embodiment of the present invention, the insulation layer is made of a low thermal conductivity insulation material, including at least one of rigid polyurethane foam, polystyrene foam, and vacuum insulation board. The insulation layer thickness is ≥40mm, and the thermal conductivity is ≤0.025W / (m·K). The insulation layer can reduce the heat exchange between the cold storage medium and the outside environment, thus maintaining temperature stability.

[0027] In one embodiment of the present invention, the cooling pump is a miniature low-temperature resistant pump, including one of a variable frequency water pump, a magnetic drive pump, and a diaphragm pump, with an adjustable flow rate range of 0.5-5 L / min; the circulation pipeline is made of food-grade low-temperature resistant pipeline, including at least one of PE pipe, PP pipe, 304 stainless steel pipe, and silicone pipe.

[0028] In one embodiment of the present invention, the main refrigeration system 6 includes a fully enclosed compressor, a heat dissipation device, and a throttling element; the fully enclosed compressor includes one of a scroll compressor, a piston compressor, and a rotary compressor, and the refrigerant can be environmentally friendly refrigerants such as R290, R134a, and R404A, providing power for the refrigeration cycle; the heat dissipation device is used to cool and liquefy the high-temperature and high-pressure gaseous refrigerant discharged from the fully enclosed compressor, including one of an air-cooled condenser, a water-cooled condenser, and an evaporative condenser, to ensure efficient operation of the refrigeration cycle; the throttling element includes one of an electronic expansion valve, a thermostatic expansion valve, and a capillary tube, which can precisely adjust the refrigerant flow rate according to the heat exchange requirements of the main refrigeration coil.

[0029] Figure 3 A control logic flowchart of the control unit for a high-precision air-temperature control cold storage refrigerator provided for an embodiment of the present invention. In one embodiment of the present invention, as... Figure 3 As shown, the control unit includes a sensor group and a controller; the sensor group includes at least a cold storage medium temperature sensor and a chamber temperature sensor. The cold storage medium temperature sensor is immersed in the middle of the cold storage medium or closely attached to the outer wall of the storage tank and the insulation layer. The chamber temperature sensor is installed in the middle of the preservation chamber 2 and avoids the air outlet. The measurement accuracy of both is ≥ ±0.1℃. The control logic of the controller includes: The cooling pump is controlled to operate continuously at a stable flow rate adapted to the cooling load, and the fan assembly 3 operates continuously at a constant speed of 600-1200 r / min to ensure stable output of cooling capacity. The main refrigeration system 6 starts when the temperature of the cold storage medium is 0.5℃ higher than the set temperature, and stops when it is 0.5℃ lower than the set temperature. When opening the door causes the temperature of the preservation chamber 2 to rise sharply by ≥1℃, increase the flow rate of the cooling pump by 10-15% and continue for 3-5 minutes before restoring the normal flow rate.

[0030] The controller in this invention can be a microcontroller or a PLC controller. Through unique cold storage medium temperature feedback control logic and heat load impact compensation logic, the air temperature fluctuation in the preservation chamber 2 is ≤0.5℃, which fully meets the needs of special preservation scenarios.

[0031] The cold storage medium of this invention can effectively buffer instantaneous heat loads, reducing the start-stop frequency of the main refrigeration system by more than 60% compared to ordinary air-cooled freezers, and significantly extending the lifespan of core components such as compressors by more than 30%. At the same time, the secondary circulation cooling structure reduces cold energy loss, reducing energy consumption by 15-20% compared to ordinary air-cooled freezers. Food-grade low-temperature resistant materials are used, and the cold storage medium is non-toxic and non-corrosive. By setting an insulation layer combined with heat load impact compensation logic, temperature stability is further improved.

[0032] In practical applications, the working principle of the high-precision air temperature control cold storage refrigerator provided by this invention is as follows: During operation, the preservation chamber 2 of this high-precision temperature-controlled cold storage refrigerator is used to store food. The main refrigeration system 6 generates cold energy and forms a refrigeration cycle with the main refrigeration coil 42 in series, thereby efficiently transferring the cold energy of the main refrigeration system 6 to the cold storage medium. The cold storage medium undergoes a secondary circulation cooling through a closed loop: bottom of the storage tank → inlet of the cooling pump → outlet of the cooling pump → inlet of the heat exchange coil → outlet of the heat exchange coil → top of the storage tank. The cold energy of the cold storage medium is efficiently transferred to the air, and the fan assembly 3 evenly delivers the cold energy into the preservation chamber 2, ensuring temperature uniformity in the preservation chamber 2. The controller controls the cooling pump to operate continuously at a stable flow rate adapted to the cooling load, and the fan assembly 3 operates continuously at a constant speed of 600-1200 r / min to ensure stable output of cold energy. Furthermore, when the temperature of the cold storage medium is higher than the set temperature by 0.5℃, the controller starts the main refrigeration system 6, and stops it when the temperature is lower than the set temperature by 0.5℃. Also, when opening the door causes the temperature of the preservation chamber 2 to rise sharply by ≥1℃, the controller increases the flow rate of the cooling pump by 10-15%, which continues for 3-5 minutes before returning to normal flow rate. The control logic of the control unit ensures that the temperature fluctuation of the preservation chamber 2 is ≤0.5℃, which is more than 80% lower than that of ordinary air-cooled freezers (2-6℃ fluctuation), fully meeting the needs of special preservation scenarios.

[0033] The present invention is further illustrated below with specific embodiments: Example 1: 200L High-End Mushroom Preservation Refrigerator This embodiment addresses the preservation needs of high-end mushrooms (such as matsutake and morels), selecting propylene glycol aqueous solution as the cooling medium, with the specific configuration as follows: The main body of the freezer has a 200L fresh-keeping compartment with a built-in centrifugal fan assembly at the top of the compartment, with a speed set to 900r / min. Cold storage liquid unit: The liquid storage tank is made of PP engineering plastic with a volume of 50L (25% of the volume of the fresh food compartment); the cold storage medium is a 50% volume concentration ethylene glycol aqueous solution; the main refrigeration coil is a Φ8mm copper serpentine tube with a heat exchange area of ​​2.5㎡; the insulation layer is 60mm thick rigid polyurethane foam (thermal conductivity 0.020W / (m·K)). Circulating cooling unit: The cooling pump is a miniature variable frequency water pump with a flow rate set to 2.5L / min; the heat exchange coil is a finned copper tube coil (fin spacing 2mm, number of fins 120 / m); the circulation pipeline is a Φ10mm food-grade PE pipe, and the outer wall of the pipeline is wrapped with 20mm thick insulation cotton. Main refrigeration system: 1.5HP fully enclosed scroll compressor (compatible with R290 environmentally friendly refrigerant), air-cooled condenser (heat exchange area 3㎡), capillary tube as the throttling element; Control Unit: The controller uses an STM32 microcontroller with a built-in PID control algorithm. The temperature threshold of the cold storage medium is set to 0℃±0.5℃. The chamber temperature sensor is installed in the middle of the preservation chamber.

[0034] Operational testing (ambient temperature 25℃, door opening frequency 2 times / hour): The temperature of the cold storage medium remained stable at 0±0.2℃, and the air outlet temperature of the preservation chamber fluctuated at 0.3±0.2℃; the comparison data with mainstream ordinary air-cooled freezers on the market is shown in Table 1 below: Table 1 Comparison data between Example 1 and mainstream ordinary air-cooled freezers on the market Example 2: 100L High-End Berry Preservation Refrigerator This embodiment addresses the preservation needs of high-end berries (such as blueberries and strawberries) by selecting ethylene glycol composite phase change material as the cold storage medium, with the specific configuration as follows: Freezer body: 100L fresh-keeping compartment with an axial flow fan assembly built into the top of the compartment, with a speed set to 800r / min; Cold storage liquid unit: The liquid storage tank is made of 304 stainless steel with a volume of 25L (25% of the volume of the preservation chamber); the cold storage medium is ethylene glycol composite phase change material, prepared by heating a 30% volume concentration ethylene glycol aqueous solution to 45℃, adding 1.0% mass fraction CMC, stirring at 350r / min for 25min, and cooling to room temperature; the main refrigeration coil is a Φ6mm copper spiral tube with a heat exchange area of ​​1.2㎡; the insulation layer is a 40mm thick polyurethane cold storage panel (thermal conductivity 0.025W / (m·K)); Circulating cooling unit: The cooling pump is a miniature magnetic drive pump with a flow rate set to 1.5L / min; the heat exchange coil is a microchannel aluminum tube coil; the circulation pipeline is a Φ8mm 304 stainless steel pipe, and the outer wall of the pipeline is wrapped with 15mm thick insulation cotton. Main refrigeration system: 1.0HP fully enclosed rotary compressor (compatible with R134a refrigerant), water-cooled condenser for heat dissipation, and thermostatic expansion valve for throttling element; Control Unit: The controller adopts a PLC controller with a built-in PID adjustment algorithm. The temperature threshold of the cold storage medium is set to 0℃±0.5℃. A humidity sensor is optional, and the humidity setting threshold is 85-90%.

[0035] Operational testing (ambient temperature 25℃, door opening frequency 8 times / hour): The temperature of the cold storage medium remained stable at 0±0.3℃, the air outlet temperature of the preservation chamber fluctuated at 0.4±0.1℃, and the humidity remained stable at 86-89%; the comparison data with mainstream ordinary air-cooled freezers on the market is shown in Table 2 below: Table 2 Comparison data between Example 2 and mainstream ordinary air-cooled freezers on the market It should be stated that the technical concept and key points of this invention can also be applied to commercial refrigeration and preservation equipment or systems that require maintaining a refrigerated or frozen environment, such as cold storage and refrigerated transport vehicles. In particular, the secondary circulation cooling structure and control logic of the control unit in this invention can be easily adapted by those skilled in the art without departing from the protection scope of this invention.

[0036] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-precision air temperature control cold storage refrigerator, characterized in that, include: The main body of the freezer has a closed preservation chamber, and a fan assembly is built into the top of the preservation chamber; A cold storage liquid unit includes a storage tank, a cold storage medium, a main refrigeration coil, and an insulation layer. The cold storage medium is filled in the storage tank, the main refrigeration coil is completely immersed in the cold storage medium, and the insulation layer is tightly wrapped around the outside of the storage tank. A circulating cooling unit includes a cooling pump, a heat exchange coil, and a circulating pipeline. The inlet of the cooling pump is connected to the bottom of the storage tank through the circulating pipeline. The outlet of the cooling pump is connected to the inlet of the heat exchange coil, and the outlet of the heat exchange coil is connected to the top of the storage tank. The main refrigeration system is connected in series with the main refrigeration coil to form a refrigeration cycle; The control unit is electrically connected to the main refrigeration system, the cooling pump, and the fan assembly. It controls the start and stop of the main refrigeration system and the operation of the cooling pump and the fan assembly based on the temperature of the cold storage medium.

2. The high-precision air temperature control cold storage refrigerator according to claim 1, characterized in that, The cold storage medium is a non-toxic, non-corrosive fluid that does not freeze at zero degrees Celsius, and is at least one of an alcohol aqueous solution or a composite phase change material.

3. The high-precision air temperature control cold storage refrigerator according to claim 2, characterized in that, The aqueous alcohol solution includes one or more mixtures of propylene glycol aqueous solution, ethylene glycol aqueous solution, and glycerol aqueous solution; the volume concentration of the propylene glycol aqueous solution is 30%-40%, the volume concentration of the ethylene glycol aqueous solution is 25%-35%, and the volume concentration of the glycerol aqueous solution is 40%-50%.

4. The high-precision air temperature control cold storage refrigerator according to claim 2, characterized in that, The composite phase change material includes a mixture of alcohols and phase change microcapsules, and a composite mixture of alcohols; the phase change microcapsules have a particle size of 5-20 μm, and the mass ratio of alcohols to phase change microcapsules is 8:2-9:

1.

5. The high-precision air temperature control cold storage refrigerator according to claim 1, characterized in that, The volume of the storage tank is 15%-35% of the volume of the preservation chamber, and the material is food-grade low-temperature resistant material, including at least one of 304 stainless steel, 316 stainless steel, PP engineering plastic, and ABS plastic; the top of the storage tank is provided with a liquid replenishment port and an exhaust port, and the bottom is provided with a drain port; the volume of the preservation chamber is 50-1000L; the fan blades of the fan assembly are centrifugal or axial.

6. The high-precision air temperature control cold storage refrigerator according to claim 1, characterized in that, The main cooling coil and heat exchange coil are made of high thermal conductivity metals, including at least one of copper tubes, aluminum tubes, and stainless steel tubes; the main cooling coil has a structure of one of serpentine tubes, spiral tubes, or U-shaped tubes; and the heat exchange coil is one of finned coils, microchannel coils, and threaded coils.

7. The high-precision air temperature control cold storage refrigerator according to claim 1, characterized in that, The insulation layer is made of a low thermal conductivity insulation material, including at least one of rigid polyurethane foam, polystyrene foam, and vacuum insulation board. The insulation layer has a thickness of ≥40mm and a thermal conductivity of ≤0.025W / (m·K).

8. The high-precision air temperature control cold storage refrigerator according to claim 1, characterized in that, The cooling pump is a miniature low-temperature resistant pump, including one of a variable frequency water pump, a magnetic drive pump, and a diaphragm pump, with an adjustable flow rate range of 0.5-5 L / min; the circulation pipeline is made of food-grade low-temperature resistant pipeline, including at least one of PE pipe, PP pipe, 304 stainless steel pipe, and silicone pipe.

9. The high-precision air temperature control cold storage refrigerator according to claim 1, characterized in that, The main refrigeration system includes a fully enclosed compressor, a heat dissipation device, and a throttling element; the fully enclosed compressor includes one of a scroll compressor, a reciprocating compressor, and a rotary compressor; the heat dissipation device includes one of an air-cooled condenser, a water-cooled condenser, and an evaporative condenser; the throttling element includes one of an electronic expansion valve, a thermostatic expansion valve, and a capillary tube.

10. The high-precision air temperature control cold storage refrigerator according to claim 1, characterized in that, The control unit includes a sensor group and a controller; the sensor group includes at least a cold storage medium temperature sensor and a chamber temperature sensor, the cold storage medium temperature sensor being immersed in the middle of the cold storage medium or closely attached to the outer wall of the storage tank and the insulation layer, the chamber temperature sensor being installed in the middle of the preservation chamber and avoiding the air outlet, and the measurement accuracy being ≥ ±0.1℃; the control logic of the controller includes: The cooling pump is controlled to operate continuously at a stable flow rate adapted to the cooling load, and the fan assembly operates continuously at a constant speed of 600-1200 r / min to ensure stable output of cooling capacity. The main refrigeration system starts when the temperature of the cold storage medium is 0.5°C higher than the set temperature, and stops when the temperature is 0.5°C lower than the set temperature. When opening the door causes the temperature of the preservation chamber to rise sharply by ≥1℃, increase the flow rate of the cooling pump by 10-15% and continue for 3-5 minutes before restoring the normal flow rate.

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