Phase change fresh-keeping refrigerator, and control method therefor

Abstract

A phase change fresh-keeping refrigerator, comprising a freezing chamber and a refrigeration system. A phase change layer, metal phase change unit cells and a flow guide mechanism are arranged in the freezing chamber. The phase change layer has a plate-shaped structure and is arranged at the bottom and the side wall of the freezing chamber. The metal phase change unit cells have a polyhedron structure, are placed inside the freezing chamber, are stacked above food that require refrigeration for freshness, and are in close contact with the food. The phase change layer and the metal phase change unit cells all contain a metal shell and a low-temperature phase change material. The low-temperature phase change material is sealed inside the metal shell. Phase change is used for storage cooling capacity. By means of the metal shell, the low-temperature phase change material transfers phase change latent heat to the food, so as to achieve rapid cooling of the food. The flow guide mechanism can be arranged at the top, the side wall or the bottom of the freezing chamber to accelerate air circulation, so as to further increase the food cooling speed. Further provided is a fresh-keeping control method for the phase change fresh-keeping refrigerator, such that rapid cooling of the food can be achieved, and a stable freezing environment is maintained.

Description

Phase-change fresh-keeping refrigerator and control method thereof Technical field:

[0001] The present invention relates to the field of high-quality food preservation in refrigerators and freezers, and specifically to a phase-change fresh-keeping refrigerator. Background technology:

[0002] Refrigerators and freezers are the most commonly used household appliances for food preservation. With the diversification of user needs and improvements in living standards, people's expectations for food preservation are becoming increasingly stringent. The faster the food is cooled during the preservation process, the better the preservation effect. Currently, refrigerators primarily use air cooling for freezing and preservation, which is slow. Large ice crystals formed inside food can pierce cell walls, causing the loss of tissue fluid after thawing and reducing flavor. To maintain a low internal temperature, refrigerators generally use fixed-frequency compressors. This results in low temperature control accuracy and large temperature fluctuations, which can easily lead to repeated freezing and thawing of food during the freezing process, further affecting food quality.

[0003] Summary of the invention:

[0004] To address this issue, we propose a phase-change freshness-locking refrigerator to address the existing challenges. This technology encapsulates low-temperature phase-change material within a highly thermally conductive metal shell, allowing direct contact with the food to rapidly cool it down. A fan is used to enhance air convection heat transfer, coupling solid phase-change cooling with air-cooled technology to further accelerate food cooling. A metal phase-change unit cell flipping mechanism ensures uniform cooling. Furthermore, the constant temperature effect of the phase-change material significantly reduces freezer temperature fluctuations, preventing secondary crystallization of food caused by temperature fluctuations.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A phase change fresh-keeping refrigerator includes a freezer compartment and a refrigeration system. The freezer compartment is provided with a phase change layer, a metal phase change unit cell, and a drainage mechanism. The phase change layer is a plate-like structure and is arranged on the bottom and side walls of the freezer compartment. The metal phase change unit cell is a polyhedron structure. The metal phase change unit cell is placed in the freezer compartment and stacked around food that needs to be frozen and preserved, and is in close contact with the food. The phase change layer and the metal phase change unit cell both include a metal shell and a low-temperature phase change material. The low-temperature phase change material is sealed in the metal shell. The low-temperature phase change material transfers the phase change latent heat to the food through the metal shell to achieve rapid cooling of the food. The drainage mechanism can be arranged at the top, side, and bottom of the freezer compartment, and includes a flip cover, a drainage chamber, and a circulating fan. The lower surface of the flip cover is provided with an air outlet and an air inlet. The drainage chamber is arranged behind the flip cover. The drainage chamber is provided with a circulating fan. The circulating fan accelerates air circulation, further improving the cooling speed of the food. The refrigeration system uses a fixed frequency or variable frequency method to provide cooling capacity for the freezer compartment.

[0007] Specifically, a movable traction mechanism is provided in the freezing chamber, and the multiple metal phase change cells are placed in a mesh bag, and the mesh bag is connected to the traction mechanism. The traction mechanism includes two sets of retractable winding motors, and the output shafts of the two sets of retractable winding motors are both transmission-connected to the long axis in the drainage chamber. A retractable winding roller is provided in the middle part of the outer side of the two sets of long axis, and a traction rope is wound around the retractable winding roller. The positions of the multiple metal phase change cells in the mesh bag are flipped by retracting and releasing the traction rope to ensure that the phase change cells provide uniform cooling for the food.

[0008] Specifically, the freezer compartment is provided with a movable flipping mechanism, including a metal plate, a flipping shaft and a movable track. The multiple metal phase change cells are placed in a net bag. A metal plate is provided in the net bag. The metal plate is fixedly connected to the flipping shaft. The flipping shaft is connected to a track that can be moved up and down. The movable track is provided on the side wall of the freezer compartment. The metal plate splits the multiple metal phase change cells into two upper and lower cell clusters. The metal plate is driven to flip up and down by the flipping shaft to achieve the position flipping of the two cell clusters.

[0009] Specifically, a movable transmission mechanism is provided in the freezer compartment, including a fresh-keeping carrier, a conveying device and a movable track. The fresh-keeping carrier is a mesh structure composed of multiple metal phase change crystal cells connected in pairs by elastic materials. The fresh-keeping carrier is connected end to end and partially placed on the conveying device. The conveying device is provided with a protrusion for fixing the metal phase change crystal cells. The conveying device is connected to a track that can move up and down. When the transmission device is moved to the top as a whole, transmission can drive the position change of the metal phase change crystal cells.

[0010] Specifically, the phase change temperature of the low-temperature phase change material is 2-5° C. higher than the temperature of the freezer compartment of the refrigerator.

[0011] Specifically, a groove is provided on the surface of the phase change layer arranged on the side wall of the freezing chamber.

[0012] Specifically, the phase-change fresh-keeping refrigerator is provided with function buttons for poultry preservation, fruit and vegetable preservation, and aquatic product preservation according to the types of fresh-keeping food, and is provided with a quality input button according to the quality of the fresh-keeping food.

[0013] The fresh-keeping control method of the phase change fresh-keeping refrigerator, the freezing chamber is provided with an ambient temperature sensor T1, and the freezing layer temperature setting value is T set A temperature sensor T2 is provided on the surface of the phase change layer at the bottom of the freezing chamber, and a temperature sensor T3 is provided at the return air outlet of the circulating fan. The fresh-keeping operation control is divided into three operating modes: fast cooling mode, cold charging mode, and cold supplement mode. The specific modes are as follows:

[0014] 1) When there is no food in the freezer, the refrigerator door has been opened, and T2>Tset When the cooling mode is turned on, the compressor is turned on and the circulation fan is not turned on until T1 = T2 = T3 = T set ;

[0015] 2) When placing food that needs to be kept fresh in the freezer, turn on the quick cooling mode. At this time, the compressor is turned on and the circulation fan is also turned on. The specific operating steps are as follows:

[0016] S1. Place the food to be frozen and fresh-keeping on the upper surface of the phase change layer at the bottom of the freezing layer, and move the metal phase change unit cells to make them accumulate on the upper surface of the food. At this time, the refrigerator compressor is turned on, and the circulation fan is also turned on;

[0017] S2. Determine the type and quality of the food, and calculate the cooling capacity Q and estimated cooling time t required to cool the food to the set temperature of the freezing layer based on the food type and quality input by the user;

[0018] S3, when the cooling time reaches 1 / 2t and T2>T set , moving the metal phase change unit cells by flipping, so that the part of the metal phase change unit cells that originally did not contact the food directly contacts the food;

[0019] S4. When the cooling time reaches t, determine whether T3=T set If yes, the circulation fan will be turned off after 5 minutes. Otherwise, it will be re-judged after 30 seconds to see if T3=T set , until the requirements are met;

[0020] 3) When there is no food in the freezer, the surface temperature of the phase change layer T2>T set , start the cooling mode, at this time the compressor is turned on, the circulation fan is also turned on, until the surface temperature of the phase change layer T2 = T set After that, the compressor and circulation fan are turned off after a delay of m minutes (the latent heat of the phase change layer is related to the cooling capacity of the compressor and needs to be calculated).

[0021] The phase-change fresh-keeping refrigerator proposed in the present invention has the following advantages compared with the prior art:

[0022] 1. The metal phase change unit cell is a polyhedral particle with strong thermal conductivity. It can tightly wrap food. It contains low-temperature phase change material. When it comes into contact with food, it immediately changes phase and quickly absorbs the heat of the food. Combined with air convection heat transfer, it quickly crosses the maximum ice crystal formation zone and forms fine ice crystals inside the food without puncturing the cell wall, which helps to ensure the integrity and flavor of the food.

[0023] 2. The metal phase change unit cell can be automatically moved or flipped through a mechanical structure, which can ensure the uniformity of heat exchange between the upper and lower surfaces of the stacked metal phase change unit cells and provide uniform cooling for food;

[0024] 3. The metal phase change unit cell can be reused for a long time, reducing the cost of food preservation and having good environmental protection characteristics;

[0025] 4. The phase change layer set on the side walls and bottom of the freezer compartment helps maintain a stable low-temperature environment in the freezer compartment and reduces the impact of the refrigerator compressor start-up and shutdown on the freezer compartment temperature;

[0026] 5. Targeted control can be performed on food of different types and qualities to improve the food temperature control effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG1 is a front view schematic diagram of the freezer compartment structure of the present invention;

[0028] FIG2 is a schematic diagram of the internal structure of the freezing chamber of the present invention;

[0029] FIG3 is a schematic structural diagram of the drainage mechanism of the present invention;

[0030] FIG4 is a schematic structural diagram of a transmission mechanism of the present invention;

[0031] FIG5 is a schematic structural diagram of the traction mechanism of the present invention;

[0032] FIG6 is a schematic diagram of the structure of the flip mechanism of the present invention;

[0033] FIG7 is a schematic cross-sectional view of the freezing chamber of the present invention.

[0034] In the figure: 1. Freezer; 2. Phase change layer; 3. Drainage mechanism; 31. Flip cover; 32. Drainage chamber; 33. Circulation fan; 4. Traction mechanism; 41. Rewinding and unwinding motor; 42. Long shaft; 43. Rewinding and unwinding roller; 44. Traction rope; 5. Turning mechanism; 51. Metal plate; 52. Turning shaft; 53. Net bag; 6. Transmission mechanism; 61. Conveying device; 62. Fresh-keeping carrier. Specific implementation method:

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0036] Example 1

[0037] As shown in Figures 1 and 3, a phase change fresh-keeping refrigerator includes a freezer compartment 1 and a refrigeration system. The freezer compartment 1 is provided with a phase change layer 2, a metal phase change unit cell and a drainage mechanism 3. The phase change layer 2 is a plate-like structure and is arranged at the bottom and side walls of the freezer compartment 1. The metal phase change unit cell is a polyhedron structure. The metal phase change unit cell is placed in the freezer compartment 1 and stacked around the food that needs to be frozen and kept fresh, in close contact with the food. The phase change layer 2 and the metal phase change unit cell both include a metal shell and a low-temperature phase change material. The low-temperature phase change material is sealed in the metal shell. The low-temperature phase change material conducts the phase change latent heat to the food through the metal shell to achieve rapid cooling of the food. The drainage mechanism 3 can be arranged at the top, side or bottom of the freezer compartment 1, and includes a flip cover 31, a drainage chamber 32 and a circulation fan 33. The lower surface of the flip cover 31 is provided with an air outlet and an air inlet. The drainage chamber 32 is arranged behind the flip cover 31, and a circulation fan 33 is provided in the drainage chamber 32. The circulation fan 33 is used to speed up the air circulation and further improve the cooling speed of the food. The refrigeration system uses a fixed frequency or variable frequency method to provide cooling capacity for the freezing chamber;

[0038] The metal phase change cells are placed in a mesh bag and then stacked above the food in the freezer 1, so that the metal phase change cells can directly contact the food, conveniently and quickly cover the food, so that the metal phase change cells transfer the temperature to the food, thereby improving the rapid freezing of the food, and accelerating the flow of air through the drainage mechanism 3 to increase the cooling speed of the food.

[0039] Example 2

[0040] As shown in Figures 2, 5 and 7, a movable traction mechanism 4 is provided in the freezing chamber 1, and the multiple metal phase change cells are placed in a mesh bag, and the mesh bag is connected to the traction mechanism 4. The traction mechanism 4 includes two sets of retractable and rewinding motors 41. The output shafts of the two sets of retractable and rewinding motors 41 are both transmission-connected to the long shaft 42 in the drainage chamber 32. The middle part of the outer side of the two sets of long shafts 42 is provided with a retractable and rewinding roller 43, and a traction rope 44 is wound around the retractable and rewinding roller 43. The positions of the multiple metal phase change cells in the mesh bag 53 are flipped by retracting and releasing the traction rope 44, thereby ensuring that the metal phase change cells can evenly provide cooling for the food.

[0041] The metal phase change cells in the mesh bag are raised and lowered by the traction mechanism 4. At the beginning, the metal phase change cells are put down together and come into contact with the food. After a period of time, the rewinding motor 41 on the left drives the rewinding roller 43 to rewind the traction rope 44, and the rewinding motor 41 on the right drives the rewinding roller 43 to unwind the traction rope 44, so that it appears to be suspended on the left side. Then the above operation is reversed to make it appear to be suspended on the right side. In this way, the position of the metal phase change cells can be changed, so that the side of the metal phase change cells that was not originally in contact with the food can be in contact with the food. The operation is simple and convenient.

[0042] Example 3

[0043] As shown in Figures 2 and 6, the freezer compartment 1 is provided with a movable flip mechanism 5, including a metal plate 51, a flip shaft 52 and a movable track. The multiple metal phase change cells are placed in a net bag 53. A metal plate 51 is provided in the net bag 53. The metal plate 51 is fixedly connected to the flip shaft 52. The flip shaft 52 is connected to a track that can be moved up and down. The movable track is provided on the side wall of the freezer compartment 1. The metal plate 51 splits the multiple metal phase change cells into two upper and lower cell clusters. The metal plate 51 is driven to flip up and down by the flip shaft 52 to achieve position flipping of the two cell clusters.

[0044] The metal phase change unit cell is wrapped in two net bags 53 and fixed on both sides of the metal plate 51, and then the two ends of the metal plate 51 are lifted and lowered by the traction mechanism 4. At the same time, the metal plate 51 is composed of an outer rectangular frame and an inner plate. A magnet that is magnetically attracted to the inner plate is provided on the inner side of the outer metal frame, or the metal phase change unit cell is wrapped in a net bag 53. The lower end of the traction rope 44 of the traction mechanism 4 is fixed on the net bag. The metal plate 51 in the net bag 53 divides the metal phase change unit cell into two clusters, upper and lower. The metal plate 51 is connected to the traction mechanism 4 through the flip shaft 52, and then lifted and lowered by traction, and can be flipped by rotating the metal plate 51, so that the metal phase change unit cell that did not contact the food at the beginning can contact the food.

[0045] Example 4

[0046] As shown in FIG4 , a movable transmission mechanism 6 is provided in the freezing chamber 1, including a fresh-keeping carrier 62, a conveying device 61 and a movable track. The fresh-keeping carrier 62 is a mesh structure in which a plurality of metal phase change units are connected in pairs by elastic materials. The fresh-keeping carrier 62 is connected end to end and partially placed on the conveying device 61. The conveying device 61 is provided with a protrusion for fixing the metal phase change units. The conveying device 61 is connected to a track that can be moved up and down. When the transmission device as a whole moves to the upper side, the transmission can drive the position of the metal phase change units to change.

[0047] The metal phase change unit cells are transported by the mesh structure formed by the elastic structure through the conveying device 61, thereby changing the position of the closed loop of the mesh structure, and thus changing the contact range between the metal phase change unit cells and the food, so as to quickly cool the food.

[0048] The phase change temperature of the low-temperature phase change material is 2-5° C. higher than the temperature of the freezer compartment 1 of the refrigerator.

[0049] The surface of the phase change layer 2 arranged on the side wall of the freezing chamber 1 is provided with grooves to increase the heat exchange area and provide a flow path for air when there are many items in the freezing chamber.

[0050] The phase-change fresh-keeping refrigerator is provided with function buttons for poultry preservation, fruit and vegetable preservation, and aquatic product preservation according to the types of fresh-keeping food, and is provided with a quality input button according to the quality of the fresh-keeping food.

[0051] Based on the phase-change fresh-keeping refrigerator described above, the present invention also provides a fresh-keeping control method for a phase-change fresh-keeping refrigerator. The freezing chamber 1 is provided with an ambient temperature sensor T1, the freezing layer temperature setting value is Tset, a temperature sensor T2 is provided on the surface of the phase-change layer 2 at the bottom of the freezing chamber 1, and a temperature sensor T3 is provided at the return air outlet of the circulation fan 33. The fresh-keeping operation control is divided into three operating modes: fast cooling mode, cold charging mode, and cold supplement mode. The specific modes operate as follows:

[0052] 1) When there is no food in the freezer compartment 1, the refrigerator door has been opened, and T2>Tset, the supplementary cooling mode is turned on, the compressor is turned on, and the circulation fan 33 is not turned on until T1=T2=T3=Tset;

[0053] 2) When food that needs to be kept fresh is placed in the freezer compartment 1, the quick cooling mode is turned on. At this time, the compressor is turned on and the circulation fan 33 is also turned on. The specific operating steps are as follows:

[0054] S1. Place the food to be frozen and fresh-keeping placed on the upper surface of the phase change layer 2 at the bottom of the freezing layer. Move the metal phase change unit cells so that they accumulate on the upper surface of the food. At this time, the refrigerator compressor is turned on, and the circulation fan 33 is also turned on.

[0055] S2. Determine the type and quality of the food, and calculate the cooling capacity Q and estimated cooling time t required to cool the food to the set temperature of the freezing layer based on the food type and quality input by the user;

[0056] S3. When the cooling time reaches 1 / 2t and T2>Tset, the metal phase change unit cells are flipped and moved so that the part of the metal phase change unit cells that originally did not contact the food directly contacts the food;

[0057] S4. When the cooling time reaches t, determine whether T3 = Tset. If so, shut down the circulation fan 33 after 5 minutes. Otherwise, delay 30 seconds and re-determine whether T3 = Tset until the requirement is met.

[0058] 3) When there is no food in the freezer compartment 1 and the surface temperature of the phase change layer 2 is T2>Tset, the cold charging mode is turned on. At this time, the compressor is turned on and the circulation fan 33 is also turned on until the surface temperature of the phase change layer 2 is T2=Tset. Then, the compressor and the circulation fan 33 are turned off after a delay of m minutes (which is related to the latent heat of the phase change layer 2 and the cooling capacity of the compressor and needs to be calculated).

[0059] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A phase-change fresh-keeping refrigerator, characterized in that: The invention comprises a freezing chamber (1) and a refrigeration system, wherein a phase change layer (2), a metal phase change unit cell and a drainage mechanism (3) are arranged in the freezing chamber (1), wherein the phase change layer (2) is a plate-like structure and is arranged at the bottom and side walls of the freezing chamber (1), wherein the metal phase change unit cell is a polyhedral structure, wherein the metal phase change unit cell is placed in the freezing chamber (1) and is stacked around food that needs to be frozen and preserved, and is in close contact with the food, wherein the phase change layer (2) and the metal phase change unit cell both comprise a metal shell and a low-temperature phase change material, wherein the low-temperature phase change material is sealed in the metal shell and uses phase change to store cold energy, wherein the low-temperature phase The phase change material conducts the phase change latent heat to the food through the metal shell, thereby realizing rapid cooling of the food. The drainage mechanism (3) can be arranged on the top, side or bottom of the freezing chamber (1), and comprises a flip cover (31), a drainage chamber (32) and a circulation fan (33). The lower surface of the flip cover (31) is provided with an air outlet and an air inlet. The drainage chamber (32) is arranged behind the flip cover (31). A circulation fan (33) is arranged in the drainage chamber (32). The circulation fan (33) accelerates air circulation, thereby further improving the cooling speed of the food. The refrigeration system adopts a fixed frequency or variable frequency method to provide cooling capacity for the freezing chamber.

2. A phase-change fresh-keeping refrigerator as claimed in claim 1, characterized in that: A movable traction mechanism (4) is arranged in the freezing chamber (1), the plurality of metal phase change crystal cells are placed in a mesh bag, the mesh bag is connected to the traction mechanism (4), the traction mechanism (4) comprises two sets of retractable winding motors (41), the output shafts of the two sets of retractable winding motors (41) are both drivingly connected to the long shaft (42) in the drainage chamber (32), the middle parts of the outer sides of the two sets of long shafts (42) are both provided with retractable winding rollers (43), a traction rope (44) is wound around the retractable winding rollers (43), and the positions of the plurality of metal phase change crystal cells in the mesh bag (53) are flipped by retracting and releasing the traction rope (44), thereby ensuring that the phase change crystal cells uniformly provide cold air for the food.

3. A phase-change fresh-keeping refrigerator as claimed in claim 1, characterized in that: The freezing chamber (1) is provided with a movable flipping mechanism (5), comprising a metal plate (51), a flip shaft (52) and a movable track; the plurality of metal phase change crystal cells are placed in a net bag (53); a metal plate (51) is provided in the net bag (53); the metal plate (51) is fixedly connected to the flip shaft (52); the flip shaft (52) is connected to a track that can be moved up and down; the movable track is provided on a side wall of the freezing chamber (1); the metal plate (51) splits the plurality of metal phase change crystal cells into two upper and lower crystal cell clusters; the flip shaft (52) drives the metal plate (51) to flip up and down, thereby realizing the position flipping of the two crystal cell clusters.

4. A phase-change fresh-keeping refrigerator as claimed in claim 1, characterized in that: A movable transmission mechanism (6) is arranged in the freezing chamber (1), comprising a fresh-keeping carrier (62), a conveying device (61) and a movable track. The fresh-keeping carrier (62) is a mesh structure composed of a plurality of metal phase change crystal cells connected in pairs by elastic material. The fresh-keeping carrier (62) is partially placed on the conveying device (61) after being connected end to end. The conveying device (61) is provided with a protrusion for fixing the metal phase change crystal cells. The conveying device (61) is connected to a track that can be moved up and down. When the transmission device as a whole moves to the upper side, transmission can drive the position of the metal phase change crystal cells to change.

5. A phase-change fresh-keeping refrigerator as claimed in claim 1, characterized in that: The phase change temperature of the low-temperature phase change material is 2-5° C. higher than the temperature of the refrigerator freezer compartment (1).

6. A phase-change fresh-keeping refrigerator as claimed in claim 1, characterized in that: A groove is provided on the surface of the phase change layer (2) arranged on the side wall of the freezing chamber (1).

7. A phase-change fresh-keeping refrigerator as claimed in claim 1, characterized in that: The phase-change fresh-keeping refrigerator is provided with function buttons for preserving poultry, vegetables and fruits, and aquatic products according to the types of fresh-keeping foods, and is provided with a quality input button according to the quality of the fresh-keeping foods.

8. A fresh-keeping control method for a phase-change fresh-keeping refrigerator according to claims 1 to 7, characterized in that: The freezing chamber (1) is provided with an ambient temperature sensor T1, the freezing layer temperature setting value is Tset, a temperature sensor T2 is provided on the surface of the phase change layer (2) at the bottom of the freezing chamber (1), and a temperature sensor T3 is provided at the return air outlet of the circulation fan (33). The fresh-keeping operation control is divided into three operation modes: a quick cooling mode, a cold charging mode, and a cold supplementing mode. The specific operation modes are as follows: 1) When there is no food in the freezer compartment (1), the refrigerator door has been opened, and T2>Tset, the supplementary cooling mode is turned on, the compressor is turned on, and the circulation fan (33) is not turned on until T1=T2=T3=Tset; 2) When food that needs to be kept fresh is placed in the freezer (1), the quick cooling mode is turned on. At this time, the compressor is turned on and the circulation fan (33) is also turned on. The specific operating steps are as follows: S1, placing food to be frozen and fresh-keeping on the upper surface of the bottom phase change layer (2) of the freezing layer, and moving the metal phase change crystal cells to make them accumulate on the upper surface of the food, at which time the refrigerator compressor is turned on, and the circulation fan (33) is also turned on; S2, determining the type and quality of the food, and calculating the cooling amount Q and the estimated cooling time t required to cool the food to the set temperature of the freezing layer according to the type and quality of the food input by the user; S3, when the cooling time reaches 1 / 2t and T2>Tset, the metal phase change unit cell is moved by flipping, so that the part of the metal phase change unit cell that originally did not contact the food is in direct contact with the food; S4. When the cooling time reaches t, determine whether T3=Tset is satisfied. If so, shut down the circulation fan (33) after 5 minutes. Otherwise, delay 30 seconds and re-determine whether T3=Tset is satisfied until the requirement is met. 3) When there is no food in the freezer (1), the surface temperature of the phase change layer (2) T2>Tset, the cold charging mode is turned on, the compressor is turned on, and the circulation fan (33) is also turned on until the surface temperature of the phase change layer (2) T2=Tset, and then the compressor and the circulation fan (33) are turned off after a delay of m minutes (the latent heat of the phase change layer (2) is related to the refrigeration capacity of the compressor and needs to be calculated).

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