A refrigerator

Abstract

The present application relates to a kind of refrigerators, including cabinet, compressor, condenser, throttling and evaporator, the evaporator is equipped with evaporation pipe.The cabinet is equipped with storage room, and is provided with refrigerant cavity in the position adjacent to storage room, and refrigerant cavity is filled with constant temperature refrigerant.The evaporation pipe is at least partially arranged in refrigerant cavity, and carries out heat exchange with constant temperature refrigerant, and constant temperature refrigerant is used as intermediate medium to transfer cold quantity to storage room, so as to maintain storage room in preset temperature range.The structure helps to realize temperature stable, small fluctuation storage environment, and is suitable for micro frozen fresh-keeping and other applications.

Description

Technical Field

[0001] This invention relates to the field of refrigeration equipment, and more particularly to a freezer for micro-freezing and preservation. Background Technology

[0002] As residents pay increasing attention to food quality, soft freezing or "micro-freezing" preservation has become a new trend in the catering industry and home kitchens. Soft freezing typically controls the storage temperature at around -5°C to -3°C, preventing meat and other foods from freezing at low temperatures, thus extending shelf life and making them easier to cut and cook. Most existing micro-freezing freezers use direct cooling or water cooling, with their evaporators located directly inside or near the storage compartment, cooling through refrigerant evaporation absorbing heat. However, due to the low evaporator temperature and the direct heat exchange between the refrigerant and the air in the storage compartment, localized overcooling and frost formation often occur during operation. Some products also use a combination of upper and lower temperature zones; for example, in a four-door micro-freezing freezer, the upper micro-freezing zone at -2°C uses water cooling, while the lower freezing zone at -12°C to -18°C uses concealed pipe direct cooling. This type of structure exposes the evaporator or condenser coils directly near the storage compartment, easily leading to severe uneven temperature distribution and frost, affecting storage quality. Summary of the Invention

[0003] The purpose of this invention is to provide a freezer that solves the problems of large temperature difference, local overcooling, easy frost formation and unstable temperature control in existing micro-freezing freezers, thereby achieving stable operation of the storage compartment in the micro-freezing temperature zone.

[0004] To achieve the above objectives, this invention proposes a refrigerator, comprising a cabinet, a storage compartment disposed within the cabinet, a compressor, and a condenser, a throttling device, and an evaporator forming a refrigeration circuit with the compressor. The evaporator is composed of evaporating tubes. A refrigerant chamber is disposed within the cabinet adjacent to the storage compartment, and the refrigerant chamber is filled with a constant-temperature refrigerant. The evaporating tubes are at least partially arranged within the refrigerant chamber and exchange heat with the constant-temperature refrigerant, allowing the constant-temperature refrigerant to act as an intermediate medium to evenly transfer cooling energy to the storage compartment, thereby maintaining the temperature of the storage compartment within a preset range.

[0005] Preferably, the refrigerant chamber is a sealed, molded water box, equipped with a liquid injection port and a pipe interface communicating with the evaporator tubes; the evaporator tubes can be arranged in a serpentine or parallel multi-loop pattern within the refrigerant chamber to increase the heat exchange area. The refrigerant chamber can be located within the upper wall and / or side wall of the housing, with a cold-conducting plate on the side facing the storage chamber. The cold-conducting plate is made of a high thermal conductivity metal and forms an indirect heat exchange wall with the inner wall of the storage chamber to improve the efficiency of cold energy transfer.

[0006] Furthermore, the refrigerant chamber can be designed as a replaceable modular water box, which is fixed to the housing with fasteners and is equipped with a liquid injection port, a liquid drain port, and a wall-penetrating connector that connects to the evaporator pipe. The wall-penetrating connector is equipped with a seal to prevent leakage and facilitates maintenance and replacement.

[0007] To maintain a stable storage temperature, the freezer of this invention may further include a temperature controller that controls the compressor to start and stop based on the temperature signal inside the storage compartment, thereby maintaining the temperature stably within a preset sub-range of -5°C to -3°C. The constant-temperature refrigerant is a medium with latent heat of phase change or a large heat capacity near the target temperature, such as water, brine, organic phase change materials, or combinations thereof, to utilize its heat capacity or latent heat characteristics to achieve temperature buffering and stabilization.

[0008] Through the above technical solution, the freezer provided by the present invention can avoid the problems of large temperature difference, easy overcooling and frost formation in traditional direct cooling structures, achieve uniform and stable temperature control in the storage compartment, and improve the food preservation effect. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the overall structure of the freezer of the present invention.

[0010] Figure 2 For along Figure 1 Schematic diagram of the cross-sectional structure along line AA.

[0011] Figure 3 This is an exploded structural diagram of the modular water box in the freezer of the present invention.

[0012] Figure 4 This is a cross-sectional schematic diagram of the refrigerant cavity arrangement in the "three-ring structure" of the freezer of the present invention.

[0013] Figure 5 This is a schematic diagram of the temperature control system for the freezer of the present invention. Detailed Implementation

[0014] The technical solutions of this application will be further described in detail below with reference to the accompanying drawings, so that those skilled in the art can more clearly understand the structure and advantages of the present invention. However, it should be understood that these embodiments are only used to illustrate the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0015] Reference Figure 1 and Figure 2 The term "freezer" in this application broadly refers to refrigerators, freezers, freezer cabinets, refrigerated cabinets, and other various refrigeration and storage equipment. A freezer typically includes a cabinet body 100 and a storage compartment 101 located within the cabinet body. A compressor 102 and a condenser, throttling device, and evaporator 105, etc., forming a refrigeration circuit with the compressor, are located on the upper part or back of the cabinet body, creating a complete refrigeration circuit. The evaporator includes evaporation tubes 106. The cooling capacity generated by the refrigeration unit is transferred to the storage compartment 101 through heat exchange via the evaporation tubes, maintaining the storage compartment 101 within a set temperature range.

[0016] The storage compartment 101 can adopt a drawer-type or shelf-type structure 107, which facilitates the classified storage of food or items, and reduces cold loss through a sealing structure 108. The bottom of the freezer is usually equipped with a support or moving device 109, such as casters 110 or support feet, to meet the needs of moving or fixing in actual use. The overall structural design considers both refrigeration efficiency and accessibility and maintainability, making it suitable for various scenarios such as home, commercial, and catering.

[0017] A refrigerant cavity 112 is provided inside the cabinet, adjacent to the storage compartment 101, and is filled with a constant-temperature refrigerant 150. The cabinet body adopts a double-layer structure 114, with a sealable interlayer space 115 formed between the inner and outer walls. This interlayer space structurally constitutes the refrigerant cavity 112, which can be used to accommodate the constant-temperature refrigerant 150. By constructing a sealed cavity between the inner and outer walls, the refrigerant can exist stably within it and exchange heat with the evaporator tubes, thereby achieving buffering and uniform transfer of cooling capacity.

[0018] The inner wall 116, facing the storage chamber 101, is used for indirect heat exchange with the storage chamber 101; the outer wall 117 provides overall mechanical strength and thermal insulation. The double-walled structure maintains the stability and thermal insulation of the refrigerant cavity, while also enabling the interlayer space to function as a refrigerant container, thus giving the enclosure a triple function of support, insulation, and liquid storage.

[0019] In the freezer of this application, the refrigerant chamber can be constructed in different ways.

[0020] One approach is to directly utilize the double-walled structure 116 and 117 of the enclosure to form a sealed interlayer 118 between the inner and outer walls, using it as a space to accommodate the temperature-controlled refrigerant 150. This design utilizes the cavity formed by the enclosure itself, which not only saves space but also maximizes the loading capacity of the refrigerant to improve the temperature control effect.

[0021] Another approach is to design the refrigerant chamber as an independent modular box 119, namely the water box structure 120. The modular water box is fixed to the housing with fasteners and is equipped with a liquid filling port 122, a liquid drain port 123, and a pipe interface 124 connected to the evaporator pipe. This water box can be disassembled and replaced as needed, facilitating maintenance, while sealing prevents refrigerant leakage.

[0022] Furthermore, the refrigerant cavity is arranged within the upper wall 126 and / or side wall 127 of the housing. Specifically, a sealed cavity is formed between the inner and outer walls within the upper wall of the housing, and this area forms the upper refrigerant cavity. Cooling energy is conducted to the interior of the storage chamber via the constant-temperature refrigerant 150.

[0023] Furthermore, a cold-conducting plate 129 is provided on the side of the refrigerant cavity facing the storage chamber. The cold-conducting plate is a high thermal conductivity metal plate and forms an indirect heat exchange wall with the inner wall of the storage chamber. The cold-conducting plate is preferably made of a high thermal conductivity metal material, such as aluminum or copper, to ensure rapid and uniform conduction of cold energy. The thickness of the cold-conducting plate is moderate, ensuring both heat transfer efficiency and sufficient mechanical strength to prevent deformation due to frequent temperature changes. The cold-conducting plate is installed close to the inner wall of the storage chamber, making it in direct contact with the chamber and thus becoming part of the inner wall. The evaporator tube first exchanges heat with the constant-temperature refrigerant 150 in the refrigerant cavity. After absorbing the cold energy, the refrigerant conducts the cold energy to the storage chamber through the cold-conducting plate. This indirect heat exchange method avoids direct contact between the evaporator tube and the air, reducing localized overcooling and frost formation.

[0024] The cooling plate, acting as a uniform heat transfer surface, creates a more stable temperature field within the storage chamber. This prevents cold energy from concentrating around the evaporator tubes, improving the uniformity of cold energy distribution. Because the cooling plate is made of a highly thermally conductive metal, its surface temperature is less different from the air temperature in the storage chamber, thus reducing the likelihood of moisture in the air condensing into frost on its surface. This allows stored items to maintain a more stable temperature in the micro-freezing zone, improving preservation.

[0025] Furthermore, at the back of the cabinet, the refrigerant cavity is arranged along the rear wall of the storage compartment in a longitudinally extending structure. The refrigerant cavity at the back has a large area, which can cover the entire height of the storage compartment. Its function is to serve as a large-area cold exchange surface, so that the food deep in the storage compartment can also be cooled evenly.

[0026] Furthermore, independent or continuous refrigerant chambers can also be installed within the left and right side walls of the cabinet. These side wall refrigerant chambers are connected to or separated from the refrigerant chambers on the upper and back walls, forming a complete surrounding refrigerant layer, ensuring that the storage compartment receives cooling from all four directions: top, back, left, and right. The refrigerant chambers arranged on the side walls are particularly beneficial in preventing temperature differences in food stored near the side walls due to insufficient heat dissipation.

[0027] Furthermore, such as Figure 4 As shown, the refrigerant cavity of the freezer in this application adopts a "three-circle structure" 134 arrangement, that is, it is respectively set in the back wall and the left and right side walls of the cabinet to form a refrigerant layer surrounding the three sides of the storage compartment.

[0028] The refrigerant cavity 135 extends extensively along the rear of the storage chamber, serving as the primary surface for heat exchange. The refrigerant cavities 136 on the left and right sides correspond to the refrigerant cavity on the back, forming a continuous, encircling structure. Evaporator tubes are arranged within these refrigerant cavities, exchanging heat with the constant-temperature refrigerant 150 to allow heat to be transferred simultaneously from the back and sides into the storage chamber.

[0029] The advantages of this "three-circle" structure are that the cold energy is evenly distributed, and the cold energy is introduced from the back and sides at the same time, avoiding large temperature differences or local overcooling caused by a single cold source; the temperature of the storage room is stable, and the refrigerant cavity surrounding the three sides forms a structure similar to a cold energy barrier, which can better maintain the balance of the temperature field in the storage room.

[0030] The constant-temperature refrigerant 150 is a medium with latent heat of phase change or a large heat capacity within the target temperature range. Its phase change temperature or heat capacity characteristics are set within any range of -5℃ to -3℃ to ensure stable operation of the freezer in the slightly freezing temperature range. The constant-temperature refrigerant 150 can be water, brine, organic phase change materials, or a combination thereof. For example, using a brine solution allows the freezing point to be set at around -4℃ by adjusting the salt concentration; using organic phase change materials (such as fatty acids or polyols) can absorb latent heat during the solid-liquid phase change process, further improving temperature stability.

[0031] Furthermore, in this embodiment, the constant temperature refrigerant 150 is selected from one or more combinations of calcium chloride aqueous solution, methanol aqueous solution, ethanol aqueous solution, ethylene glycol aqueous solution and glycerol aqueous solution, with a phase change temperature in the range of -5°C to -3°C.

[0032] In another embodiment, the constant temperature refrigerant 150 is a 10% calcium chloride aqueous solution with a phase change temperature of approximately -4°C, which can ensure that the storage room temperature is stable within the sub-range of -5°C to -4°C.

[0033] In another embodiment, the constant temperature refrigerant 150 is a 5% ethylene glycol-water solution with a phase change temperature of approximately -3.5°C, used to maintain the storage compartment in the range of -4.5°C to -3.5°C.

[0034] In another embodiment, the constant temperature refrigerant 150 is an 8% glycerol aqueous solution with a phase change temperature of approximately -3°C, which can maintain the storage room temperature stable within the range of -3.8°C to -3°C.

[0035] Furthermore, the constant-temperature refrigerant 150 can be not only a medium with latent heat of phase change, but also a substance that does not have obvious phase change characteristics within the target temperature range of -5℃ to -3℃. This type of refrigerant relies on its large specific heat capacity to achieve a temperature buffering function, absorbing or releasing a large amount of heat during the operation of the freezer, thereby maintaining the stability of the storage compartment temperature.

[0036] In another embodiment, the constant temperature refrigerant 150 is selected as a 40% calcium chloride aqueous solution with a freezing point of approximately -40°C.

[0037] In one embodiment, the constant temperature refrigerant 150 is a 50% glycerol aqueous solution with a freezing point of approximately -20°C.

[0038] In one embodiment, the constant temperature refrigerant 150 is a 30% ethylene glycol aqueous solution with a freezing point of approximately -15°C.

[0039] Furthermore, the specific heat capacity of the constant temperature refrigerant 150 is in the range of higher than 2.05 kJ / (kg·℃); preferably, it is in the range of 3.1 kJ / (kg·℃) to 4.186 kJ / (kg·℃).

[0040] The constant-temperature refrigerant 150 utilizes its latent heat of phase change or large specific heat capacity to buffer temperature during operation: when the evaporator tube 106 transfers cold energy to the refrigerant, the constant-temperature refrigerant 150 absorbs or releases heat near the target temperature, resulting in minimal temperature change and thus maintaining stability. Refrigerants with phase change characteristics can absorb or release a large amount of latent heat during the solid-liquid phase change process, while refrigerants without phase change characteristics rely on their larger heat capacity to mitigate temperature fluctuations. Thus, when the compressor starts and stops intermittently, the constant-temperature refrigerant 150 can continuously release or absorb cold energy like a cold storage medium, maintaining a basically constant temperature in the storage compartment within the preset range of -5℃ to -3℃, avoiding localized overcooling and frost formation, and ensuring that the food is kept in an ideal soft-freezing preservation state.

[0041] like Figure 3 The refrigerant chamber shown is a sealed water box with an injection port and a pipe interface connecting to the evaporator tube. The refrigerant chamber is a sealed water box 120. This water box consists of a water box body 137, a sealing plate 138, and a cover plate 139. The water box body has a hollow structure, forming an internal space to accommodate a constant-temperature refrigerant 150. The body is integrally molded from metal or high-strength plastic to ensure pressure resistance and low-temperature performance. The inner surface of the body is treated with anti-corrosion coating to accommodate various refrigerants such as brine and organic phase change liquids.

[0042] The sealing plate 138 is used to seal the opening of the water box and is connected to the water box body 137 by welding, bolting or sealing adhesive. The cover plate 139 is detachable and can be installed to facilitate opening the water box during maintenance or replacement. A low-temperature resistant sealing ring is provided at the joint between the sealing plate and the cover plate to prevent refrigerant leakage.

[0043] The water box has a pre-installed injection port 122 and a drain port 123 for refrigerant injection and recovery; it is also equipped with a wall-penetrating connector that connects to the evaporator tube, allowing the evaporator tube to partially extend into the water box and directly exchange heat with the constant-temperature refrigerant 150; the interface is fitted with a seal to ensure that no leakage occurs during operation.

[0044] The water box is fixed to the upper or side wall of the enclosure with fasteners. It can be a single water box, or multiple water boxes connected in parallel or arranged around each other. When the water box module is damaged or the refrigerant needs to be replaced, it can be disassembled as a whole for easy maintenance and upgrades.

[0045] Furthermore, the modular water box design enables standardized production and rapid assembly; it allows for flexible replacement, preventing the entire cabinet from being scrapped due to refrigerant leakage; and it provides excellent sealing and maintainability, extending the service life of the freezer.

[0046] The evaporator tubes are arranged in a serpentine or parallel multi-loop pattern within the refrigerant cavity to increase the heat exchange area with the constant-temperature refrigerant 150. For example... Figure 1 and Figure 2 As shown, optionally, the evaporator tube 106 is at least partially disposed in the water box and exchanges heat with the constant temperature refrigerant 150.

[0047] like Figure 2 As shown, the evaporator tubes and modular water box are integrated into a single unit. The modular water box is located inside the upper or back wall of the housing, and its interior is a sealed refrigerant chamber filled with constant-temperature refrigerant 150. The evaporator tubes 106 are led out from the refrigeration system and extend into the water box through wall-penetrating connectors. They are arranged in a serpentine or multi-loop structure within the water box, allowing them to directly exchange heat with the constant-temperature refrigerant 150.

[0048] The water box is fixed to the inner and outer walls of the cabinet with screws or clips, forming a detachable modular unit. The evaporator tubes are connected to the pipe interfaces on the water box, and the interfaces are sealed by sealing rings or welding to prevent refrigerant leakage. The inlet and outlet of the evaporator tubes are connected to the refrigeration circuit, ensuring that the refrigerant can continuously circulate within the evaporator tubes, while the water box acts as an "indirect heat exchange chamber" for the refrigerant, playing a role in buffering and uniform heat transfer.

[0049] On one hand, the evaporator absorbs cold energy and transfers it to the constant-temperature refrigerant in the water box; on the other hand, a cold-conducting plate 129 is provided on the side of the refrigerant chamber facing the storage compartment. The cold-conducting plate 129 is a high thermal conductivity metal plate and forms an indirect heat exchange wall with the inner wall of the storage compartment. The water box, through contact with the cold-conducting plate 129 and the inner wall of the storage compartment, evenly conducts cold energy to the storage compartment, achieving an indirect and stable cooling effect. Furthermore, due to the modular design of the water box, when the evaporator or the water box needs maintenance or replacement, it can be easily replaced individually by disassembling the fasteners and pipe interfaces without affecting the overall cabinet structure.

[0050] Preferably, the volume of the refrigerant contained in the water tank is matched with the volume of the refrigerator compartment according to the following values.

[0051] small cabinet under the table 150L 12～22L Vertical single door 400L 32～60L Vertical double door 800～1000L 64～150L Four-door commercial 1200L 96～180L Horizontal freezer 300L 24～45L like Figure 5 As shown, the freezer also includes a temperature controller 153, which is used to control the start and stop of the compressor 102 based on the temperature signal of the storage compartment to maintain the preset temperature range, which is any sub-interval between −5℃ and -3℃.

[0052] Temperature controller 153 detects the temperature signal of the storage compartment or refrigerant cavity in real time through temperature sensor 154, and uses PID (proportional-integral-derivative) control algorithm 145 to adjust the compressor. The PID algorithm can quickly respond to temperature changes and eliminate steady-state errors, ensuring that the actual temperature of the storage compartment remains stable within a preset range. In this way, temperature fluctuations in the freezer compartment can be controlled within ±0.5℃, effectively avoiding the cycle of repeated ice crystal growth and melting. This control method, combined with the cold storage characteristics of the constant-temperature refrigerant, keeps the temperature uniform throughout the storage compartment, avoiding cold damage or spoilage caused by excessive temperature differences.

[0053] In one embodiment, the temperature controller's sensor is located inside the refrigerant chamber to directly monitor the temperature of the thermostatic refrigerant. Since the temperature of the thermostatic refrigerant is highly correlated with the storage chamber temperature, controlling the thermostatic state of the refrigerant can indirectly stabilize the ambient temperature of the storage chamber.

[0054] In another embodiment, the temperature sensor 154 of the temperature controller 153 is installed on the inner wall of the storage room or in the storage room space to directly detect the actual ambient temperature of the food. The controller adjusts the start and stop of the compressor according to the temperature signal to ensure that the temperature fluctuation in the storage room does not exceed ±0.5℃.

[0055] In a preferred embodiment, the temperature controller 154 includes two temperature sensors: one located in the refrigerant chamber (first temperature sensor 156) and the other located in the storage chamber (second temperature sensor 157). By collecting the two temperature signals and making a comprehensive judgment, the temperature controller 153 can ensure the stability of the refrigerant temperature while avoiding temperature fluctuations in the storage chamber caused by load changes (such as frequent door opening and closing or the addition of hot food). Through a PID control algorithm, the two sets of data are coordinated to precisely control the freezer temperature within ±0.5℃, ensuring the quality of food storage.

[0056] Furthermore, in the dual-temperature sensor PID control system, the storage compartment temperature (T2) is stabilized within a setpoint SP, such as ±0.5℃ within the range of −5℃ to −3℃. Two temperature sensors, the refrigerant chamber temperature T1 and the storage compartment temperature T2, participate in the control process through signal fusion and logical coordination. T2 directly reflects the actual temperature of the environment in which the food is located; T1 reflects the cold storage temperature of the constant-temperature refrigerant and can be used as a lead factor for process fluctuations to predict the trend of T2 changes. The raw signals collected by the two sensors need to undergo filtering and calibration compensation preprocessing to ensure the reliability of the signals input to the PID controller.

[0057] Two methods can be provided to control the target temperature using T1 and T2.

[0058] Furthermore, the first method is to fuse the signals of T1 and T2, using the deviation of T2 from the set value e_main=SP−T2 as the basic deviation, and at the same time, based on the deviation of T1 from the refrigerant target temperature T1_target, calculate the correction amount Δe=K_corr·(T1_target−T1), where K_corr is the correction coefficient. The two are then superimposed to obtain the total deviation e=e_main+Δe, so that the state of T1 dynamically compensates for the basic deviation of T2.

[0059] The second method is a dual-closed-loop PID control mode. The outer loop PID uses T2 as the process value and SP as the setpoint, with the output of the outer loop PID being T1_target. The inner loop uses T1_target as the process value, and its output directly controls the compressor's operation. Ultimately, the hierarchical logic of the outer loop control result and the inner loop control process suppresses load fluctuations and refrigerant-side disturbances.

[0060] After the above two methods integrate the T1 and T2 signals, the total deviation (e) is input into the PID algorithm. The proportional term (P) quickly adjusts the cooling intensity according to the current deviation, the integral term (I) accumulates historical deviations to eliminate steady-state errors, and the derivative term (D) predicts the trend based on the rate of change of deviation (such as increasing cooling in advance when T2 rises rapidly). Finally, the output control quantity (such as compressor operating frequency or start-stop time) coordinates the synergistic stability of T1 and T2. This not only avoids T2 fluctuations caused by abnormal refrigerant status through the early warning function of T1, but also ensures that the food environment temperature is accurately controllable through the feedback of T2, thereby achieving high-precision stability of the storage room temperature within ±0.5℃.

[0061] This application's refrigerator embodiment features a refrigerant cavity filled with constant-temperature refrigerant located adjacent to the cabinet and storage compartment. It employs a double-walled integrated or modular water box structure, supporting disassembly and maintenance. A serpentine / parallel multi-loop evaporator tube exchange heat with the constant-temperature refrigerant. It utilizes water, brine, or organic phase change materials, such as 10% calcium chloride aqueous solution or 5% ethylene glycol-aqueous solution, with a phase change temperature of -5℃ to -3℃, and their latent heat of phase change or high specific heat capacity as an intermediate medium. Combined with a cold-conducting plate, it achieves uniform cold air transfer. Temperature control employs single-sensor or dual-sensor PID collaborative control, integrating the refrigerant cavity temperature T1 and storage compartment temperature T2 signals to precisely stabilize the storage compartment temperature within a fluctuation range of ±0.5℃. This ultimately avoids the localized overcooling and frost problems of traditional direct-cooling structures, improving the micro-freezing preservation effect (-5℃ to -3℃). It is suitable for storing meat and other food items in home and catering settings, combining temperature uniformity, operational stability, and ease of maintenance.

[0062] Those skilled in the art will understand that the above description is merely a preferred embodiment of the present invention, and the embodiments are not intended to limit the scope of protection of the present invention. All equivalent substitutions, structural modifications, and functional extensions made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A refrigerator, comprising a cabinet, a storage compartment formed within the cabinet, a compressor, and a condenser, a throttling device, and an evaporator forming a refrigeration circuit with the compressor, characterized in that: The evaporator includes evaporation tubes; A refrigerant chamber is provided inside the box and adjacent to the storage chamber, and the refrigerant chamber is filled with constant temperature refrigerant; The evaporator tube is at least partially disposed within the refrigerant chamber and exchanges heat with the constant-temperature refrigerant, so that the constant-temperature refrigerant acts as an intermediate medium to transfer cooling capacity to the storage chamber, thereby maintaining the storage chamber within a preset temperature range.

2. The freezer according to claim 1, characterized in that, The refrigerant chamber is a sealed water box with an injection port and a pipeline interface connected to the evaporator tube.

3. The freezer according to claim 2, characterized in that, The evaporator tubes are arranged in a serpentine or parallel multi-loop pattern within the refrigerant cavity to increase the heat exchange area with the constant-temperature refrigerant.

4. The freezer according to claim 3, characterized in that, The refrigerant chamber is located inside the upper wall and / or side wall of the housing. A cold-conducting plate is provided on the side of the refrigerant chamber facing the storage chamber. The cold-conducting plate is a high thermal conductivity metal plate and forms an indirect heat exchange wall with the inner wall of the storage chamber.

5. The freezer according to claim 4, characterized in that, The refrigerant chamber is a replaceable modular water box. The water box is fixed to the housing by fasteners and is equipped with the liquid injection port, the liquid drain port, and the wall-penetrating connector connected to the evaporator tube. The wall-penetrating connector is equipped with a seal to prevent leakage.

6. The freezer according to any one of claims 1-5, characterized in that, The freezer also includes a temperature controller, which controls the compressor based on the temperature signal of the storage compartment to maintain the preset temperature range.

7. The freezer according to claim 6, characterized in that, The preset temperature range is any sub-interval between −5℃ and -3℃.

8. The freezer according to claim 1, characterized in that, The constant-temperature refrigerant is a medium that has phase change characteristics within a preset temperature range.

9. The freezer according to claim 1, characterized in that, The constant-temperature refrigerant is a medium with a specific heat capacity higher than 2.05 kJ / (kg·℃) within a preset temperature range. The constant-temperature refrigerant is selected from water, salt water, organic phase change materials, or combinations thereof.

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