Novel single-system refrigerator refrigerating system and control method thereof

Abstract

The invention relates to the technical field of refrigerator refrigeration, in particular to a novel single-system refrigerator refrigeration system and a control method thereof, and can solve the problem that in the prior art, when a refrigerator is defrosted, the refrigerator cannot be defrosted. And residual liquid refrigerant of the evaporator can absorb heat radiated to the surface of the evaporator by a heating wire, so that the working time of the heating wire is prolonged, the temperature fluctuation of a refrigerator chamber is large, and the storage effect of food is influenced. The system comprises an electromagnetic three-way valve connected to an outlet of a condenser. The electromagnetic three-way valve is connected with the condenser through a first outlet; a second outlet of the electromagnetic three-way valve is connected with an inlet of a system throttling element, a third outlet of the electromagnetic three-way valve is connected with a bypass branch, and the bypass branch and a system main pipeline are converged in front of an inlet of an evaporator; an electromagnetic stop valve is further arranged in front of the compressor and used for controlling circulation of refrigerants between the outflow pipeline of the evaporator and the compressor. A pressure sensor is arranged at an outlet of the evaporator and used for sensing the refrigerant pressure of the outlet of the evaporator.

Description

Technical Field

[0001] The present application relates to the field of refrigerator refrigeration technology, and in particular to a novel single-system refrigerator refrigeration system and a control method thereof. Background Art

[0002] At present, electric heating wire is generally used for defrosting air-cooled frost-free refrigerators.

[0003] When the refrigerator is defrosting, the compressor stops and the refrigerator stops working, but there is still about 20% of liquid refrigerant stored in the refrigerator's evaporator. This part of the refrigerant will evaporate and absorb heat during the defrosting stage, causing part of the heat radiated to the evaporator by the heating wire to be absorbed by the refrigerant in the evaporator, resulting in reduced defrosting efficiency, increased defrosting time, and increased temperature rise in the room, which affects the storage effect on the one hand and increases energy consumption on the other.

[0004] However, in the prior art, when the refrigerator is shut down for defrosting, the liquid refrigerant remaining in the evaporator absorbs the heat radiated from the heating wire to the surface of the evaporator. This heat is ineffective for defrosting and is considered heat loss. This phenomenon will extend the working time of the heating wire and cause large fluctuations in the temperature of the refrigerator compartment, affecting the storage effect of food. On the other hand, it will increase energy consumption, which is not conducive to energy saving.

[0005] In addition, the refrigerator needs to be placed vertically during transportation. If it is laid down during transportation, the lubricating oil in the compressor will flow back into the evaporator. The oil cannot be returned quickly within a short period of time after startup, which will cause the compressor to lack oil and work abnormally. Moreover, the refrigerator itself is relatively high, and vertical transportation increases the difficulty and cost of transportation. Summary of the invention

[0006] In order to solve the problem that in the prior art refrigerator, when defrosting, the residual liquid refrigerant in the evaporator absorbs the heat radiated from the heating wire to the surface of the evaporator, resulting in prolonged working time of the heating wire, large temperature fluctuations in the refrigerator compartment, and affecting the storage effect of food, the present application provides a novel single-system refrigerator refrigeration system and a control method thereof.

[0007] The embodiment of the present application is implemented as follows:

[0008] In a first aspect, the present application provides a novel single-system refrigerator refrigeration system, including an electromagnetic three-way valve connected to a condenser outlet. The electromagnetic three-way valve is connected to the condenser through a first outlet;

[0009] The second outlet of the electromagnetic three-way valve is connected to the inlet of the system throttling element, and the third outlet of the electromagnetic three-way valve is connected to the bypass branch, and the bypass branch merges with the system main pipeline before the evaporator inlet;

[0010] An electromagnetic cut-off valve is also provided in front of the compressor to control the flow of refrigerant between the pipeline flowing out of the evaporator and the compressor;

[0011] A pressure sensor is provided at the outlet of the evaporator to sense the refrigerant pressure at the outlet of the evaporator.

[0012] In a possible implementation manner, the throttling element includes a capillary tube or an expansion valve or a combination of both.

[0013] In a second aspect, the present application provides a control method for a novel single-system refrigerator refrigeration system, which is applied to the novel single-system refrigerator refrigeration system described in any one of claims 1 or 2, and includes: a defrost control method and a transportation anti-oil leakage control method.

[0014] In a possible implementation manner, the defrost method includes:

[0015] The refrigerator usually uses the cumulative operation time of the compressor since the last defrost completion as the defrost control signal, presets the defrost cycle at this ambient temperature as T1, and the time Ta from the end of the last defrost to when the compressor is about to stop each time the refrigerator finishes refrigeration;

[0016] When the refrigerator is refrigerating and the compressor is about to stop, judge the magnitudes of T1 and Ta. When Ta < T1, the compressor stops normally. When Ta > T1, enter the defrost mode, increase the compressor speed, and concentrate the refrigerant in the condenser.

[0017] In a possible implementation manner, when the pressure sensor at the outlet of the evaporator senses that the pressure Pa in the evaporator reaches the preset cut-off pressure P, the electromagnetic cut-off valve is closed, the compressor stops, and the electric heating wire starts to work to start defrosting.

[0018] In a possible implementation manner, the defrost duration under normal conditions is T2. After this period of time, the frost on the evaporator will completely melt. The actual defrost start time is Tb. The maximum bypass defrost amount of the refrigerant in the condenser is preset as m, and the remaining frost amount on the evaporator is preset as n, where n < m, and the difference is the defrost remaining amount. The defrost time node is T3, where T3 < T2. When T3 > Tb, keep the electric heating for defrosting. When T3 < Tb, turn off the electric heating wire, open the bypass flow path of the electromagnetic three-way valve, open the electromagnetic cut-off valve, and the refrigerant flows from the outlet along the bypass pipe into the evaporator to melt the remaining frost using the sensible heat of the refrigerant.

[0019] In a possible implementation manner, the total defrost duration required from the start of defrosting to the complete ablation of the frost on the evaporator after bypassing the refrigerant is preset as T4. When Tb > T4, the refrigerator defrosting is completed, close the third outlet flow direction of the electromagnetic three-way valve, open the second outlet flow direction, and the refrigerator enters the normal refrigeration process.

[0020] In a possible implementation manner, the operation of the single-system refrigerator refrigeration includes:

[0021] The electromagnetic stop valve is opened, the electromagnetic three-way valve closes the third outlet flow direction and opens the second outlet flow direction. The refrigerant flowing out of the condenser passes through the electromagnetic three-way valve, is throttled and reduced in pressure by the throttling element, and enters the evaporator. After flowing through the electromagnetic stop valve, it enters the suction chamber of the compressor.

[0022] In a possible implementation, the defrosting operation of a single-system refrigerator includes:

[0023] In the first stage, the first electromagnetic three-way valve is closed, and the compressor increases the speed to concentrate the refrigerant in the evaporator in the condenser;

[0024] In the second stage, the electromagnetic stop valve is closed, the electromagnetic three-way valve is closed, the compressor is stopped, the electric heating wire starts to work, and the evaporator starts to defrost;

[0025] In the third stage, after defrosting for a period of time, the electromagnetic three-way valve is opened, and the refrigerant flows from the third outlet through the bypass branch into the evaporator;

[0026] In the fourth stage, defrosting is completed, the third outlet flow direction of the electromagnetic three-way valve is closed, the second outlet flow direction is opened, and the electromagnetic stop valve is opened.

[0027] In a possible implementation, the transportation oil leakage prevention method includes:

[0028] A dedicated transport button is set on the refrigerator main control panel. During the production process of the refrigerator, a power-on test will be carried out before the refrigerator leaves the factory. When the test shows that the refrigerator meets the exit standards, the staff presses the button and the refrigerator enters the transport preparation mode.

[0029] After the refrigerator detects the transport preparation signal, the compressor stops working, the electromagnetic three-way valve is closed, the electromagnetic stop valve is opened, and the pressure sensor at the evaporator outlet detects the pressure Pd in ​​the pipeline;

[0030] The time interval of the detection time cycle is defined as Td. In the time interval Td, the difference between the two detection pressures Pd is Pe. The critical minimum pressure difference between the compressor and the condenser when the lubricating oil flows out of the compressor after the electromagnetic shut-off valve is closed is defined as P3.

[0031] When it is detected that Pe≤P3, the refrigerator is automatically powered off and the electromagnetic stop valve is closed.

[0032] The technical solution provided by this application can at least achieve the following beneficial effects:

[0033] The present application provides a novel single-system refrigerator refrigeration system and a control method thereof, which adds an electromagnetic stop valve and an electromagnetic three-way valve in the refrigeration system, and controls the valves to centrally collect refrigerant to the high-temperature side before defrosting, thereby reducing the defrosting time and ineffective energy consumption, and achieving the effects of reducing compartment fluctuations and saving energy;

[0034] In the later stage of defrosting, the residual frost on the evaporator is removed by the heat of the working fluid on the high-temperature side, which reduces the working time of the electric heating wire, reduces energy consumption, and achieves energy-saving effect;

[0035] Through the shut-off effect of the shut-off valve when the power is cut off, the lubricating oil in the compressor cannot flow into the evaporator when the refrigerator is transported on its side, which makes it possible to transport the refrigerator on its side, enhances transportation convenience and reduces transportation costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0037] Figure 1 It is a structural schematic diagram of a novel single-system refrigerator refrigeration system shown in an exemplary embodiment of the present application;

[0038] Figure 2 is a flow chart of a defrosting control method shown in an exemplary embodiment of the present application;

[0039] Figure 3 It is a flow chart of a transport oil leakage prevention control method shown in an exemplary embodiment of the present application.

[0040] Reference numerals:

[0041] 1. Compressor; 11. Pressure sensor; 2. Condenser; 3. Solenoid three-way valve; 301. First outlet; 302. Second outlet; 303. Third outlet; 4. Throttling element; 5. Evaporator; 6. Solenoid stop valve. DETAILED DESCRIPTION

[0042] In order to make the purpose, implementation mode and advantages of the present application clearer, the exemplary implementation mode of the present application will be clearly and completely described below in conjunction with the drawings in the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only part of the embodiments of the present application, not all of the embodiments. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.

[0043] It should be noted that the brief description of terms in this application is only for the convenience of understanding the embodiments described below, and is not intended to limit the embodiments of this application. Unless otherwise specified, these terms should be understood according to their common and usual meanings.

[0044] The terms "first", "second", "third", etc. in the specification and claims of this application and the above drawings are used to distinguish similar or similar objects or entities, and do not necessarily mean to limit a specific order or sequence, unless otherwise noted. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances.

[0045] The terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover but not exclude inclusion, for example, a product or device comprising a list of components is not necessarily limited to all the components expressly listed but may include other components not expressly listed or inherent to such product or device.

[0046] Before explaining a novel single-system refrigerator refrigeration system and control method provided in an embodiment of the present application, the application scenario and implementation environment of the embodiment of the present application are first introduced.

[0047] At present, electric heating wire is generally used for defrosting air-cooled frost-free refrigerators.

[0048] When the refrigerator is defrosting, the compressor stops and the refrigerator stops working, but there is still about 20% of liquid refrigerant stored in the refrigerator's evaporator. This part of the refrigerant will evaporate and absorb heat during the defrosting stage, causing part of the heat radiated to the evaporator by the heating wire to be absorbed by the refrigerant in the evaporator, resulting in reduced defrosting efficiency, increased defrosting time, and increased temperature rise in the room, which affects the storage effect on the one hand and increases energy consumption on the other.

[0049] However, in the prior art, when the refrigerator is shut down for defrosting, the liquid refrigerant remaining in the evaporator absorbs the heat radiated from the heating wire to the surface of the evaporator. This heat is ineffective for defrosting and is considered heat loss. This phenomenon will extend the working time of the heating wire and cause large fluctuations in the temperature of the refrigerator compartment, affecting the storage effect of food. On the other hand, it will increase energy consumption, which is not conducive to energy saving.

[0050] In addition, the refrigerator needs to be placed vertically during transportation. If it is laid down during transportation, the lubricating oil in the compressor will flow back into the evaporator. The oil cannot be returned quickly within a short period of time after startup, which will cause the compressor to lack oil and work abnormally. Moreover, the refrigerator itself is relatively high, and vertical transportation increases the difficulty and cost of transportation.

[0051] Based on this, the present application provides a novel single-system refrigerator refrigeration system and a control method thereof. Through the cooperation of multiple valves and pipelines, the refrigerant in the evaporator is concentrated in the condenser before the start of defrosting, and the refrigerant in the condenser is bypassed to the evaporator in the second half of the defrosting stage, and the heat of the high-temperature refrigerant is used to assist defrosting, thereby reducing the energy consumption of defrosting and achieving the purpose of energy saving. The present invention operates the compressor to evacuate the refrigerant in the evaporator before defrosting, eliminate or substantially eliminate the absorption of defrosting heat by the vaporization of the refrigerant in the evaporator during the defrosting stage, improve the defrosting efficiency, shorten the defrosting time, reduce the energy consumption of the refrigerator, and reduce the temperature fluctuation in the room. In the late stage of electric heating defrosting, the refrigerant stored in the condenser is in a high-temperature and high-pressure state. When the bypass branch is opened, it will enter the evaporator under the drive of the pressure difference, and the heat of the high-temperature refrigerant in the condenser is used to remove the residual frost on the evaporator, reducing the running time of the defrosting heating wire, achieving the effect of energy saving, and the control of the valve can also be used to solve the problem of oil leakage when the refrigerator is overturned during the transportation stage, reducing transportation costs.

[0052] Next, the technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems will be described in detail through embodiments and in combination with the accompanying drawings. The embodiments may be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. Obviously, the described embodiments are part of the embodiments of the present application, not all of them.

[0053] Figure 1 It is a structural schematic diagram of a new single-system refrigerator refrigeration system shown in an exemplary embodiment of the present application.

[0054] In an exemplary embodiment, Figure 1 As shown, a novel single-system refrigerator refrigeration system is provided. In this embodiment, the system includes an electromagnetic three-way valve 3 connected to the outlet of the condenser 2. The electromagnetic three-way valve 3 is connected to the condenser 2 through a first outlet 301;

[0055] The second outlet 302 of the electromagnetic three-way valve 3 is connected to the inlet of the system throttling element 4, and the third outlet 303 of the electromagnetic three-way valve 3 is connected to the bypass branch, and the bypass branch merges with the system main pipeline before the evaporator inlet;

[0056] A solenoid stop valve 6 is also provided in front of the compressor 1 to control the flow of refrigerant between the outflow pipe of the evaporator 5 and the compressor 1;

[0057] A pressure sensor 11 is provided at the outlet of the evaporator 5 for sensing the refrigerant pressure at the evaporator outlet.

[0058] In a possible implementation, the throttling element 4 includes a capillary tube or an expansion valve or a combination of the two.

[0059] It should be understood that although the steps in the flowcharts involved in the above embodiments are displayed sequentially as indicated, these steps are not necessarily executed sequentially in the order indicated. Unless there is a clear indication in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential either, but can be executed alternately or in turn with at least a part of other steps or steps or stages in other steps.

[0060] This application also provides an embodiment of a control method for a refrigeration system of a new type of single-system refrigerator.

[0061] In an exemplary embodiment, the defrost control method and the transportation anti-oil leakage control method of the refrigeration system of the new type of single-system refrigerator are provided.

[0062] Figure 2 It is a schematic flow diagram of the defrost control method shown in an exemplary embodiment of this application.

[0063] In a possible implementation manner, as Figure 2 shown, there is only one evaporator in the refrigeration system of the single-system refrigerator, and the defrosting process is relatively simple. The refrigerator usually uses the cumulative running time after the last defrost of the compressor as the defrost control signal. When the refrigerator detects that defrosting is required, through the control of the valve, the refrigerant is concentrated and collected in the condenser, and then defrosting is carried out by heating with a heating wire. When it is detected that the defrosting amount has reached the critical value of the residual frost (for example, the residual frost amount ≤ 20%), the refrigerant in the condenser is bypassed by controlling the electromagnetic three-way valve to complete the ablation of the residual frost on the surface of the evaporator.

[0064] The defrosting method includes:

[0065] The refrigerator usually uses the cumulative running time after the last defrost of the compressor as the defrost control signal. The defrosting cycle at this ambient temperature is preset as T1, and the time Ta from the end of the last defrost to the time when the compressor is about to stop each time the refrigerator finishes refrigerating;

[0066] When the refrigerator is refrigerating and the compressor 1 is about to stop, judge the magnitudes of T1 and Ta. When Ta < T1, the compressor 1 stops normally. When Ta > T1, enter the defrost mode, increase the speed of the compressor 1, and concentrate the refrigerant into the condenser 2.

[0067] When the pressure sensor 11 at the outlet of the evaporator 5 senses that the pressure Pa in the evaporator 5 reaches the preset cut-off pressure P, close the electromagnetic cut-off valve 6, stop the compressor 1, and the electric heating wire starts to work to start defrosting.

[0068] Under normal operating conditions, the defrosting duration is T2. After this period of time, the frost on the evaporator 5 will completely melt. The actual defrosting start time is Tb. The preset maximum bypass defrosting amount of the refrigerant in the condenser 2 is m, and the preset remaining frost amount on the evaporator 5 is n, where n < m. The difference is the defrosting margin. The defrosting time node is T3, where T3 < T2. When T3 > Tb, keep the electric heating for defrosting. When T3 < Tb, turn off the electric heating wire, open the bypass flow path of the electromagnetic three-way valve 3, and open the electromagnetic stop valve 6. The refrigerant flows from the outlet along the bypass pipe into the evaporator, and the sensible heat of the refrigerant is used to melt the remaining frost.

[0069] The preset total defrosting duration required from the start of defrosting to the complete ablation of the frost on the evaporator after bypassing the refrigerant is T4. When Tb > T4, the defrosting of the refrigerator is completed, close the flow direction of the third outlet 303 of the electromagnetic three-way valve 3, open the flow direction of the second outlet 302, and the refrigerator enters the normal refrigeration process.

[0070] Figure 3 It is a schematic flow chart of the transportation anti-oil leakage control method shown in an exemplary embodiment of the present application.

[0071] In one possible implementation, as Figure 3 shown, the electromagnetic stop valve in front of the compressor is a normally closed valve. When the refrigerator is powered off, the electromagnetic stop valve will automatically be in the closed state, preventing the refrigerant and lubricating oil in the pipeline from flowing into the evaporator. If the direct transportation method after power-off is adopted, the refrigerant flow path from the compressor to the evaporator will be blocked. However, when the stop valve is directly closed, the evaporator side will be in a low-pressure state, and the compressor and condenser sides will be in a high-pressure state. Due to the existence of the high and low pressure difference, the lubricating oil in the compressor will also flow out with the working medium, resulting in compressor oil leakage and affecting the normal operation after power-on. Some embodiments of the present application also propose a transportation anti-oil leakage control method.

[0072] The transportation anti-oil leakage method includes:

[0073] Set a special transportation button on the refrigerator main control board. During the production process of the refrigerator, power-on detection will be carried out before leaving the factory. When it is tested that the refrigerator meets the factory standards, the staff presses the button, and the refrigerator enters the transportation preparation mode;

[0074] After the refrigerator detects the transportation preparation signal, the compressor stops working, the electromagnetic three-way valve closes, the electromagnetic stop valve opens, and the pressure sensor at the evaporator outlet detects the pressure Pd in the pipeline;

[0075] Define the time interval of the detection time period as Td. During the time interval Td, the difference between the two detected pressures Pd is Pe; define the critical minimum pressure difference between the compressor and the condenser when the lubricating oil flows out of the compressor after the electromagnetic stop valve is closed as P3;

[0076] When it is detected that Pe≤P3, the refrigerator is automatically powered off and the electromagnetic stop valve is closed.

[0077] In a possible implementation, the specific operation of the single-system refrigerator refrigeration is as follows:

[0078] The electromagnetic stop valve 6 is opened, the electromagnetic three-way valve 3 closes the flow direction of the third outlet 303 and opens the flow direction of the second outlet 302. The refrigerant flowing out of the condenser 2 passes through the electromagnetic three-way valve 3, is throttled and reduced in pressure by the throttling element 4, and enters the evaporator 5. After flowing through the electromagnetic stop valve 6, it enters the suction chamber of the compressor 1.

[0079] In a possible implementation, the specific operation of defrosting a single-system refrigerator is as follows:

[0080] In the first stage, the first electromagnetic three-way valve 3 is closed, the compressor 1 increases the speed, and the refrigerant in the evaporator 5 is concentrated in the condenser 2;

[0081] In the second stage, the electromagnetic stop valve 6 is closed, the electromagnetic three-way valve 3 is closed, the compressor 1 is shut down, the electric heating wire starts to work, and the evaporator starts to defrost;

[0082] In the third stage, after defrosting for a period of time, the electromagnetic three-way valve 3 is opened, and the refrigerant flows from the third outlet 303 through the bypass branch into the evaporator 5;

[0083] In the fourth stage, the defrosting is completed, the flow direction of the third outlet 303 of the electromagnetic three-way valve 3 is closed, the flow direction of the second outlet 302 is opened, and the electromagnetic stop valve 6 is opened.

[0084] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A novel single-system refrigerator refrigeration system, characterized in that: It includes an electromagnetic three-way valve connected to the condenser outlet. The electromagnetic three-way valve is connected to the condenser through the first outlet; The second outlet of the electromagnetic three-way valve is connected to the inlet of the system throttling element, the third outlet of the electromagnetic three-way valve is connected to a bypass branch, and the bypass branch converges with the main pipeline of the system in front of the evaporator inlet; An electromagnetic stop valve is also provided in front of the compressor to control the flow of refrigerant between the pipeline flowing out of the evaporator and the compressor; A pressure sensor is provided at the outlet of the evaporator to sense the refrigerant pressure at the evaporator outlet.

2. The novel single-system refrigerator refrigeration system according to claim 1, characterized in that: The throttling element includes a capillary tube or an expansion valve or a combination of both.

3. A novel single-system refrigerator refrigeration system control method, applied to the novel single-system refrigerator refrigeration system as claimed in any one of claims 1 or 2, characterized in that: It includes: A defrost control method and an anti-oil leakage control method during transportation.

4. The novel single-system refrigerator refrigeration system control method according to claim 3, characterized in that: The defrost method includes: The refrigerator usually uses the cumulative operating time after the last defrost of the compressor as the defrost control signal. The defrost cycle at this ambient temperature is preset as T1, and the time Ta from the end of the last defrost to when the compressor is about to stop each time the refrigerator finishes refrigeration; When the refrigerator is refrigerating and the compressor is about to stop, judge the magnitudes of T1 and Ta. When Ta < T1, the compressor stops normally. When Ta > T1, enter the defrost mode, increase the compressor speed, and concentrate the refrigerant in the condenser.

5. The novel single-system refrigerator refrigeration system control method according to claim 4, characterized in that: When the pressure sensor at the evaporator outlet senses that the pressure Pa in the evaporator reaches the preset cut-off pressure P, close the electromagnetic stop valve, the compressor stops, and the electric heating wire starts to work to start defrosting.

6. The novel single-system refrigerator refrigeration system control method according to claim 5, characterized in that: Under normal operating conditions, the defrost duration is T2. After this period of time, the frost on the evaporator will completely melt. The actual defrost start time is Tb. The maximum bypass defrost amount of refrigerant in the condenser is preset as m, and the remaining frost amount on the evaporator is preset as n, n < m, and the difference is the defrost remaining amount. The defrost time node is T3, T3 < T2. When T3 > Tb, keep the electric heating for defrosting. When T3 < Tb, turn off the electric heating wire, open the bypass flow path of the electromagnetic three-way valve, open the electromagnetic stop valve, and the refrigerant flows from the outlet along the bypass pipe into the evaporator to melt the remaining frost using the sensible heat of the refrigerant.

7. The novel single-system refrigerator refrigeration system control method according to claim 6, characterized in that: Preset the total defrost duration T4 required for the frost on the evaporator to completely melt after bypassing the refrigerant from the start of defrost. When Tb > T4, the refrigerator defrosting is completed, close the third outlet flow direction of the electromagnetic three-way valve, open the second outlet flow direction, and the refrigerator enters the normal refrigeration process.

8. The novel single-system refrigerator refrigeration system control method according to claim 3, characterized in that: The operation of a single-system refrigerator for refrigeration includes: The electromagnetic stop valve is opened, the third outlet flow direction of the electromagnetic three-way valve is closed, the second outlet flow direction is opened, the refrigerant flowing out of the condenser passes through the electromagnetic three-way valve, is throttled and depressurized by the throttling element and then enters the evaporator, and enters the compressor suction chamber after passing through the electromagnetic stop valve.

9. The novel single-system refrigerator refrigeration system control method according to claim 3, characterized in that: The operation of a single-system refrigerator for defrosting includes: In the first stage, the first electromagnetic three-way valve is closed, and the compressor speed is increased to concentrate the refrigerant in the evaporator in the condenser; In the second stage, close the electromagnetic stop valve, close the electromagnetic three-way valve, the compressor stops, and the electric heating wire starts to work, and the evaporator starts to defrost; In the third stage, after defrosting for a period of time, open the electromagnetic three-way valve, and the refrigerant flows from the third outlet through the bypass branch into the evaporator; In the fourth stage, after defrosting is completed, the third outlet flow direction of the electromagnetic three-way valve is closed, the second outlet flow direction is opened, and the electromagnetic stop valve is opened.

10. The novel single-system refrigerator refrigeration system control method according to claim 3, characterized in that: The anti-oil leakage method during transportation includes: A dedicated transport button is set on the refrigerator main control panel. During the production process of the refrigerator, a power-on test will be carried out before the refrigerator leaves the factory. When the test shows that the refrigerator meets the exit standards, the staff presses the button and the refrigerator enters the transport preparation mode. After the refrigerator detects the transport preparation signal, the compressor stops working, the electromagnetic three-way valve is closed, the electromagnetic stop valve is opened, and the pressure sensor at the evaporator outlet detects the pressure Pd in ​​the pipeline; The time interval of the detection time cycle is defined as Td. In the time interval Td, the difference between the two detection pressures Pd is Pe. The critical minimum pressure difference between the compressor and the condenser when the lubricating oil flows out of the compressor after the electromagnetic shut-off valve is closed is defined as P3. When it is detected that Pe≤P3, the refrigerator is automatically powered off and the electromagnetic stop valve is closed.

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