Energy-saving defrosting system and method based on primary and secondary evaporators

Abstract

The application discloses an energy-saving defrosting system based on a primary and auxiliary evaporator, which has two modes of refrigeration and defrosting. In the refrigeration mode, the first on-off valve is opened, and the second on-off valve and the third on-off valve are closed, the primary evaporator runs to undertake the refrigeration task, and the auxiliary evaporator is maintained in a low-temperature state through a bypass flow limiting branch, so that the refrigeration operation can be immediately started when switching to the defrosting mode, and the temperature rise in the cabinet is inhibited. When the primary evaporator is frosted to a set thickness, the defrosting mode is switched, the first on-off valve is closed, and the second on-off valve and the third on-off valve are opened. In this mode, the primary evaporator stops working, and the auxiliary evaporator works, high-temperature refrigerant gas (system waste heat) discharged by the compressor is used to defrost the primary evaporator through the defrosting circuit, and the auxiliary evaporator independently refrigerates to maintain the temperature in the cabinet, replacing the traditional electric heating mode, so that the energy-saving effect is remarkable, and the defrosting efficiency is greatly improved.

Description

Technical Field

[0001] This application relates to the field of refrigeration technology, and in particular to an energy-saving defrosting system and method based on main and auxiliary evaporators. Background Technology

[0002] During operation, frost will form on the surface of the evaporator due to the condensation of water vapor in the air. The presence of frost will significantly reduce the heat exchange efficiency of the evaporator, leading to a decrease in system performance and an increase in energy consumption. Therefore, regular defrosting is necessary.

[0003] Existing refrigeration equipment typically uses electric heating for defrosting. This method can cause a rapid rise in internal temperature during defrosting, affecting the refrigeration effect on food and potentially leading to spoilage. Furthermore, this electric heating defrosting method is energy-intensive. Therefore, there is room for improvement. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this application provides an energy-saving defrosting system and method based on main and auxiliary evaporators to solve the problems in the prior art.

[0005] Firstly, this application provides an energy-saving defrosting system based on main and auxiliary evaporators, employing the following technical solution:

[0006] An energy-saving defrosting system based on a main and auxiliary evaporator has two modes: refrigeration and defrosting. It includes a main refrigeration circuit formed by a compressor, condenser, main throttling device, and main evaporator connected in series. An auxiliary evaporator is connected in parallel to the main evaporator, forming an auxiliary refrigeration circuit with the compressor, condenser, and main throttling device. A first on / off valve is installed between the main throttling device and the main evaporator, and a second on / off valve is installed between the main throttling device and the auxiliary evaporator. It also includes a defrosting circuit, where refrigerant flows from the compressor into the main evaporator and then back from the main evaporator to the compressor circuit. The flow of high-temperature refrigerant into the main evaporator in the defrosting circuit is controlled by a third on / off valve.

[0007] By adopting the above technical solution, in cooling mode, the first on-off valve is opened, while the second and third on-off valves are closed simultaneously. In this mode, the main evaporator in the main refrigeration circuit operates and undertakes the cooling task. When the main evaporator reaches a set frost thickness, the system switches from cooling mode to defrost mode, closing the first on-off valve and simultaneously opening the second and third on-off valves. In this mode, the main evaporator stops working, and the auxiliary evaporator operates. Through the defrost circuit, the high-temperature refrigerant gas discharged from the compressor (system waste heat) is used to defrost the main evaporator. At the same time, the auxiliary evaporator independently cools to maintain the cabinet temperature, replacing the traditional electric heating method, resulting in significant energy savings and a substantial improvement in defrost efficiency.

[0008] Optionally, a gas-liquid separator is also included, which is installed on the return gas line of the compressor; after the self-evaporator flows out in the defrosting circuit, it first flows into the gas-liquid separator and then into the compressor circuit.

[0009] By adopting the above technical solution and installing a gas-liquid separator in the compressor circuit, it is ensured that only pure gaseous refrigerant enters the compressor, thus completely eliminating the risk of liquid slugging and ensuring the safe operation of the system.

[0010] Optionally, a flow-limiting bypass branch is connected in parallel to the second on / off valve. The flow-limiting bypass branch is composed of a capillary tube and a one-way valve connected in series. The conduction direction of the one-way valve is from the main throttling device to the auxiliary evaporator.

[0011] By adopting the above technical solution, on the one hand, in cooling mode, thanks to the capillary tube and one-way valve in the flow-limiting bypass branch, a small portion of the refrigerant enters the auxiliary evaporator through the flow-limiting bypass branch to provide auxiliary cooling, while simultaneously maintaining the auxiliary evaporator at a low temperature. Therefore, when switching from cooling mode to defrost mode, the auxiliary evaporator can be activated immediately, avoiding the delay and energy loss of starting from room temperature, and improving defrost efficiency. On the other hand, in defrost mode, due to the pressure difference between the second on / off valve and the flow-limiting bypass branch, combined with the one-way conduction principle of the one-way valve, the pressure difference is cut off, closing the flow-limiting bypass branch and preventing backflow.

[0012] Optionally, the heat exchange power of the auxiliary evaporator is less than that of the main evaporator.

[0013] Secondly, this application provides an energy-saving defrosting method based on main and auxiliary evaporators, employing the following technical solution:

[0014] An energy-saving defrosting method based on a main and auxiliary evaporator, and based on the aforementioned energy-saving defrosting system based on a main and auxiliary evaporator, includes the following steps:

[0015] S1. In the initial state, the system is in normal cooling mode. The first on-off valve is open, and the second and third on-off valves are closed. The main cooling circuit and the flow-limiting bypass branch work together, and the main evaporator and the auxiliary evaporator work together to achieve cabinet cooling.

[0016] S2. After the refrigeration system has been running normally for 4 hours, the system switches to defrost mode;

[0017] S3. In defrost mode, the first on / off valve is closed, and the second and third on / off valves are open, so that the auxiliary refrigeration circuit operates and the defrost circuit operates at the same time.

[0018] S4. When the temperature of the main evaporator reaches the set defrosting termination temperature, the system switches back to normal cooling mode and repeats steps S1-S3.

[0019] Optionally, in step S1, when the main refrigeration circuit and the flow-limiting bypass branch operate in tandem, the high-temperature and high-pressure refrigerant gas discharged from the compressor enters the condenser, releases heat to the environment, and condenses into a high-pressure liquid. The high-pressure liquid refrigerant is throttled and depressurized by the main throttling device, becoming a low-temperature and low-pressure gas-liquid two-phase fluid. Most of the refrigerant enters the main evaporator, absorbs heat from the cabinet, and evaporates into low-temperature and low-pressure superheated steam, undertaking the main refrigeration task. A small portion of the refrigerant enters the auxiliary evaporator through the flow-limiting bypass branch to maintain its low-temperature state and provide auxiliary refrigeration. The two return gases are mixed in the gas-liquid separator to ensure that pure gaseous refrigerant returns to the compressor, completing the refrigeration cycle.

[0020] Optionally, in step S3, when the auxiliary refrigeration circuit is running, part of the high-temperature and high-pressure gas discharged from the compressor enters the condenser and is condensed into a high-pressure liquid. After the high-pressure liquid is throttled by the main throttling device, it becomes a low-temperature and low-pressure gas-liquid two-phase fluid. The refrigerant enters the auxiliary evaporator through the second on / off valve, absorbs heat in the cabinet, evaporates and refrigerates to maintain refrigeration. The evaporated low-temperature and low-pressure superheated vapor enters the gas-liquid separator, and the separated gaseous refrigerant returns to the compressor.

[0021] Optionally, in step S3, when the defrosting circuit is running, part of the high-temperature and high-pressure refrigerant gas discharged from the compressor directly enters the main evaporator through the third on / off valve. The high-temperature gas releases heat and condenses in the main evaporator, melting the frost layer. The defrosted gas-liquid mixed refrigerant enters the gas-liquid separator, and the separated gaseous refrigerant returns to the compressor.

[0022] In summary, this application includes at least one of the following beneficial technical effects:

[0023] 1. Defrosting without temperature rise: In defrosting mode, the auxiliary evaporator independently undertakes the cooling task during defrosting, and the temperature fluctuation inside the cabinet is small during defrosting, achieving true "unobtrusive defrosting";

[0024] 2. Significant energy saving effect: In defrost mode, the system waste heat converted from refrigeration during defrost by the auxiliary evaporator is fully utilized through the defrost circuit to defrost the main evaporator, replacing the traditional electric heating method, resulting in significant energy saving and a substantial improvement in defrost efficiency;

[0025] 3. Fast defrosting speed: In defrosting mode, high-temperature refrigerant gas directly enters the evaporator for defrosting, greatly improving defrosting efficiency;

[0026] 4. Safe and reliable: By installing a gas-liquid separator, the compressor is ensured to draw in pure gaseous refrigerant, completely eliminating the risk of liquid slugging and ensuring safe system operation;

[0027] 5. Simplified system structure: Complex functions are achieved using only three on / off valves, the control logic is simple and clear, which greatly improves system reliability and reduces manufacturing and maintenance costs.

[0028] 6. By setting up a flow-limiting bypass branch, on the one hand, in cooling mode, thanks to the capillary tube and one-way valve in the flow-limiting bypass branch, a small portion of the refrigerant enters the auxiliary evaporator through the flow-limiting bypass branch to provide auxiliary cooling, while maintaining the auxiliary evaporator at a low temperature. Therefore, when switching from cooling mode to defrost mode, the auxiliary evaporator can be activated immediately, avoiding the delay and energy loss of starting from room temperature, and improving defrost efficiency. On the other hand, in defrost mode, due to the pressure difference between the second on / off valve and the flow-limiting bypass branch, combined with the one-way conduction principle of the one-way valve, the pressure difference is cut off, closing the flow-limiting bypass branch and preventing backflow. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the system structure of an energy-saving defrosting system based on a main and auxiliary evaporator according to this application.

[0030] Figure 2 This is a system diagram of an energy-saving defrosting system based on main and auxiliary evaporators in refrigeration mode according to this application.

[0031] Figure 3 This is a system diagram of an energy-saving defrosting system based on main and auxiliary evaporators in defrosting mode according to this application.

[0032] Figure 4 This is a flowchart of an energy-saving defrosting method based on a main and auxiliary evaporator according to this application.

[0033] Explanation of reference numerals in the attached figures:

[0034] 1. Compressor; 2. Condenser; 3. Main throttling device; 4. Main evaporator; 5. Gas-liquid separator; 6. Auxiliary evaporator; 7. Capillary tube; 8. Check valve; 9. First on / off valve; 10. Second on / off valve; 11. Third on / off valve; 100. Main refrigeration circuit; 200. Auxiliary refrigeration circuit; 300. Defrosting circuit; 400. Flow-limiting bypass branch. Detailed Implementation

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] This application discloses an energy-saving defrosting system based on a main and auxiliary evaporator.

[0037] Reference Figure 1An energy-saving defrosting system based on main and auxiliary evaporators has two modes: refrigeration and defrosting. It includes a main refrigeration circuit 100, an auxiliary refrigeration circuit 200, a defrosting circuit 300, and a current-limiting bypass branch 400.

[0038] The main refrigeration circuit 100 consists of compressor 1, condenser 2, main throttling device 3, main evaporator 4, and gas-liquid separator 5 connected in series. An auxiliary evaporator 6 is connected in parallel to the main evaporator 4. The heat exchange capacity of the auxiliary evaporator 6 is less than that of the main evaporator 4. The compressor 1, condenser 2, main throttling device 3, auxiliary evaporator 6, and gas-liquid separator 5 constitute an auxiliary refrigeration circuit 200. A first on / off valve 9 is installed between the main throttling device 3 and the main evaporator 4, and a second on / off valve 10 is installed between the main throttling device 3 and the auxiliary evaporator 6.

[0039] The defrost circuit 300 receives fluid from the compressor 1 into the main evaporator 4, then flows out of the main evaporator 4 and first into the gas-liquid separator 5 before returning to the compressor 1 circuit. The inflow and outflow of the main evaporator 4 in the defrost circuit 300 are controlled by a third on-off valve 11. Specifically, in the defrost circuit 300, the section from the compressor 1 to the main evaporator 4 is used for introducing the defrost heat source, and the section from the main evaporator 4 to the gas-liquid separator 5 is used for recovering the defrost fluid.

[0040] The flow-limiting bypass branch 400 is connected in parallel to the second on / off valve 10. The flow-limiting bypass branch 400 is composed of a capillary tube 7 and a one-way valve 8 connected in series. The conduction direction of the one-way valve 8 is from the main throttling device 3 to the auxiliary evaporator 6.

[0041] In cooling mode, open the first on / off valve 9, and simultaneously close the second on / off valve 10 and the third on / off valve 11.

[0042] Reference Figure 2 In this mode, the workflow is as follows:

[0043] The high-temperature, high-pressure refrigerant gas discharged from compressor 1 enters condenser 2, where it releases heat to the environment and condenses into a high-pressure liquid. The high-pressure liquid refrigerant is then throttled and depressurized by the main throttling device 3, becoming a low-temperature, low-pressure gas-liquid two-phase fluid. Most of the refrigerant enters the main evaporator 4, absorbing heat from the cabinet and evaporating into low-temperature, low-pressure superheated vapor, undertaking the main refrigeration task. A small portion of the refrigerant enters the auxiliary evaporator 6 through the flow-limiting bypass branch 400, maintaining its low-temperature state and providing auxiliary refrigeration. The two return gas streams mix in the gas-liquid separator 5, ensuring that pure gaseous refrigerant returns to compressor 1, completing the refrigeration cycle.

[0044] In this mode, most of the refrigerant enters the main evaporator 4, and the main refrigeration circuit 100, where the main evaporator 4 is located, undertakes the main refrigeration task of the system. At the same time, with the help of the capillary tube 7 and the one-way valve 8 in the flow-limiting bypass branch 400, a small portion of the refrigerant enters the auxiliary evaporator 6 through the flow-limiting bypass branch 400 to provide auxiliary refrigeration, while keeping the auxiliary evaporator 6 at a low temperature to ensure that the auxiliary evaporator 6 can be activated immediately when needed (that is, it needs to be activated quickly in the later defrosting mode), avoiding the delay and energy loss of starting from room temperature.

[0045] When the main evaporator 4 reaches the set thickness of frost, the system switches from the cooling mode to the defrosting mode. In the defrosting mode, the first on / off valve 9 is closed, while the second on / off valve 10 and the third on / off valve 1 are opened.

[0046] Reference Figure 3 In this mode, the workflow is as follows:

[0047] On the one hand, some of the high-temperature and high-pressure gas discharged from the compressor 1 enters the condenser 2 and is condensed into a high-pressure liquid. After the high-pressure liquid is throttled by the main throttling device 3, it becomes a low-temperature and low-pressure gas-liquid two-phase fluid. The refrigerant enters the auxiliary evaporator 6 through the second shut-off valve 10, absorbs heat in the cabinet and evaporates for cooling. The low-temperature and low-pressure superheated vapor after evaporation enters the gas-liquid separator 5. The separated gaseous refrigerant returns to the compressor 1 so that it can independently undertake the cooling task during defrosting.

[0048] On the other hand, part of the high-temperature and high-pressure refrigerant gas discharged from the compressor 1 enters the main evaporator 4 directly through the third shut-off valve 11. The high-temperature gas releases heat and condenses in the main evaporator 4, melting the frost layer. The defrosted gas-liquid mixed refrigerant enters the gas-liquid separator 5. The separated gaseous refrigerant returns to the compressor 1 to form a defrosting circuit 300 for defrosting the main evaporator 4.

[0049] At the same time, due to the pressure difference between the second shut-off valve 10 and the flow-limiting bypass branch 400, and combined with the one-way conduction principle of the check valve 8, the pressure difference is cut off, thereby closing the flow-limiting bypass branch 400 and preventing backflow.

[0050] In this mode:

[0051] Firstly, the auxiliary evaporator 6 independently undertakes the cooling task during defrosting, and the temperature fluctuation inside the cabinet is small during defrosting. Actual test data shows that its temperature fluctuation is ≤±1℃, which is far better than the 5-10℃ temperature rise of traditional technology, achieving true "unobtrusive defrosting" and achieving defrosting without temperature rise.

[0052] Secondly, the defrosting circuit 300 fully utilizes the waste heat generated by the auxiliary evaporator 6 during defrosting, which independently handles the refrigeration task, to perform defrosting, replacing the traditional electric heating method and resulting in significant energy savings. Testing has verified that it saves 60%-70% more energy than electric defrosting, with even more pronounced annual energy savings.

[0053] Thirdly, because the high-temperature refrigerant gas compressed by compressor 1 directly enters the main evaporator 4 through defrost circuit 300 for defrosting, the defrosting efficiency is greatly improved and the defrosting speed is fast. The actual defrosting time is only 5-8 minutes, which is more than 3 times more efficient than traditional technology.

[0054] Fourthly, in cooling mode, a small portion of the refrigerant enters the auxiliary evaporator 6 through the flow-limiting bypass branch 400, maintaining it at a low temperature. Therefore, when switching from cooling mode to defrost mode, the auxiliary evaporator 6 can be activated immediately, avoiding the delay and energy loss from starting at room temperature, while improving defrost efficiency.

[0055] In defrost mode, the flow rate ratio of most of the high-temperature, high-pressure refrigerant gas discharged from compressor 1 to condenser 2 and to main evaporator 4 can be adjusted as needed, for example, by controlling the flow rate ratio using a flow valve. In this application, in defrost mode, most of the high-temperature, high-pressure refrigerant gas discharged from compressor 1 flows to main evaporator 4 via third shut-off valve 11 for defrosting. A small portion of the high-temperature, high-pressure gas discharged from compressor 1 flows to condenser 2 to provide cooling during defrosting via auxiliary evaporator 6.

[0056] The working principle is as follows: This application has two modes: cooling and defrosting. In cooling mode, the first on-off valve 9 is opened, while the second on-off valve 10 and the third on-off valve 11 are closed. The main evaporator 4 operates to undertake the cooling task, while the auxiliary evaporator 6 maintains a low temperature through the bypass flow-limiting branch 400, ensuring that it can immediately start cooling operation when switching to defrosting mode, suppressing the temperature rise inside the cabinet. When the frost on the main evaporator 4 reaches the set thickness, it switches to defrosting mode, closes the first on-off valve 9, and opens the second on-off valve 10 and the third on-off valve 11. In this mode, the main evaporator 4 stops working, and the auxiliary evaporator 6 works. Through the defrosting circuit 300, the high-temperature refrigerant gas discharged from the compressor 1 (system waste heat) is used to defrost the main evaporator 4. At the same time, the auxiliary evaporator 6 independently cools to maintain the temperature inside the cabinet, replacing the traditional electric heating method, resulting in significant energy saving and a substantial improvement in defrosting efficiency.

[0057] This application also discloses an energy-saving defrosting method based on main and auxiliary evaporators.

[0058] Reference Figure 4An energy-saving defrosting method based on a main and auxiliary evaporator, and based on the aforementioned energy-saving defrosting system based on a main and auxiliary evaporator, includes the following steps:

[0059] S1. In the initial state, the system is in normal cooling mode. The first on-off valve 9 is open, the second on-off valve 10 is closed, and the third on-off valve 11 is closed. The main cooling circuit 100 and the flow-limiting bypass branch 400 work together, and the main evaporator 4 and the auxiliary evaporator 6 work together to achieve cabinet cooling.

[0060] When the main refrigeration circuit 100 and the flow-limiting bypass branch 400 operate in coordination, the high-temperature and high-pressure refrigerant gas discharged from the compressor 1 enters the condenser 2, releases heat to the environment, and condenses into a high-pressure liquid. The high-pressure liquid refrigerant is throttled and depressurized by the main throttling device 3, becoming a low-temperature and low-pressure gas-liquid two-phase fluid. Most of the refrigerant enters the main evaporator 4, absorbs heat from the cabinet, and evaporates into low-temperature and low-pressure superheated steam, undertaking the main refrigeration task. A small portion of the refrigerant enters the auxiliary evaporator 6 through the flow-limiting bypass branch 400 to maintain its low-temperature state and provide auxiliary refrigeration. The two return gases are mixed in the gas-liquid separator 5 to ensure that pure gaseous refrigerant returns to the compressor 1, completing the refrigeration cycle.

[0061] S2. After the refrigeration system has been running normally for 4 hours, the system switches to defrost mode;

[0062] S3. In defrost mode, the first shut-off valve 9 is closed, the second shut-off valve 10 and the third shut-off valve 11 are closed, the auxiliary refrigeration circuit 200 is running, and the defrost circuit 300 is running at the same time.

[0063] When the auxiliary refrigeration circuit 200 is running, part of the high-temperature and high-pressure gas discharged from the compressor 1 enters the condenser 2 and is condensed into a high-pressure liquid. After the high-pressure liquid is throttled by the main throttling device 3, it becomes a low-temperature and low-pressure gas-liquid two-phase fluid. The refrigerant enters the auxiliary evaporator 6 through the second on / off valve 10, absorbs heat in the cabinet and evaporates to maintain refrigeration. The low-temperature and low-pressure superheated vapor after evaporation enters the gas-liquid separator 5, and the separated gaseous refrigerant returns to the compressor 1.

[0064] When the defrosting circuit 300 is running, part of the high-temperature and high-pressure refrigerant gas discharged from the compressor 1 enters the main evaporator 4 directly through the third shut-off valve 11. The high-temperature gas releases heat and condenses in the main evaporator 4, melting the frost layer. The defrosted gas-liquid mixture enters the gas-liquid separator 5, and the separated gaseous refrigerant returns to the compressor 1.

[0065] S4. When the temperature of the main evaporator reaches the set defrosting termination temperature, the system switches back to normal cooling mode and repeats steps S1-S3.

[0066] The foregoing description of specific exemplary embodiments of this application is for illustrative and explanatory purposes. These descriptions are not intended to limit this application to the precise form disclosed, and it is obvious that many changes and variations can be made in accordance with the above teachings. Although embodiments of this application have been shown and described, these specific embodiments are merely explanations of this application and are not intended to limit the application. The specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. The purpose of selecting and describing exemplary embodiments is to explain the specific principles of this application and its practical application, so that those skilled in the art, after reading this specification, can make modifications, substitutions, variations, and various choices and changes to the embodiments as needed without departing from the principles and spirit of this application, provided that such modifications, substitutions, variations, and choices and changes are within the scope of the claims of this application and are protected by patent law.

Claims

1. An energy-saving defrosting method based on a main and auxiliary evaporator, and an energy-saving defrosting system based on a main and auxiliary evaporator, characterized in that: The system has two modes: refrigeration and defrosting. It includes a main refrigeration circuit (100) formed by a compressor (1), condenser (2), main throttling device (3), and main evaporator (4) connected in series. An auxiliary evaporator (6) is connected in parallel to the main evaporator (4), forming an auxiliary refrigeration circuit (200) between the auxiliary evaporator (6), the compressor (1), the condenser (2), and the main throttling device (3). A first on / off valve (9) is installed between the main throttling device (3) and the main evaporator (4), and a [missing information - likely a valve name] is installed between the main throttling device (3) and the auxiliary evaporator (6). The second shut-off valve (10) also includes a defrost circuit (300), which flows from the compressor (1) into the main evaporator (4) and then flows back from the main evaporator (4) to the compressor (1) circuit. The flow of high-temperature refrigerant in the defrost circuit (300) into the main evaporator (4) is controlled by the third shut-off valve (11). A flow-limiting bypass branch (400) is connected in parallel to the second shut-off valve (10). The flow-limiting bypass branch (400) is composed of a capillary tube (7) and a one-way valve (8) connected in series. The one-way valve (8) is directed from the main throttling device (3) to the auxiliary evaporator (6). The energy-saving defrosting method includes the following steps: S1. In the initial state, the system is in normal cooling mode. The first on-off valve (9) is open, the second on-off valve (10) and the third on-off valve (11) are closed, the main cooling circuit (100) and the flow-limiting bypass branch (400) work together, and the main evaporator (4) and the auxiliary evaporator (6) work together to achieve cabinet cooling. S2. After the refrigeration system has been running normally for 4 hours, the system switches to defrost mode; S3. In defrost mode, the first on / off valve (9) is closed, the second on / off valve (10) and the third on / off valve (11) are opened, the auxiliary refrigeration circuit (200) is running, and the defrost circuit (300) is running at the same time. S4. When the temperature of the main evaporator reaches the set defrosting termination temperature, the system switches back to normal cooling mode and repeats steps S1-S3.

2. The energy-saving defrosting method based on main and auxiliary evaporators according to claim 1, characterized in that: The system also includes a gas-liquid separator (5), which is installed on the return gas line of the compressor (1); after the self-evaporator (4) in the defrost circuit (300) flows out, it first flows into the gas-liquid separator (5) and then into the compressor (1) circuit.

3. The energy-saving defrosting method based on main and auxiliary evaporators according to claim 1, characterized in that: The heat exchange power of the auxiliary evaporator (6) is less than that of the main evaporator (4).

4. The energy-saving defrosting method based on main and auxiliary evaporators according to claim 2, characterized in that: In step S1, when the main refrigeration circuit (100) and the flow-limiting bypass branch (400) work together, the high-temperature and high-pressure refrigerant gas discharged from the compressor (1) enters the condenser (2), releases heat to the environment and condenses into a high-pressure liquid. The high-pressure liquid refrigerant is throttled and depressurized by the main throttling device (3), becoming a low-temperature and low-pressure gas-liquid two-phase fluid. Most of the refrigerant enters the main evaporator (4), absorbs heat from the cabinet and evaporates into low-temperature and low-pressure superheated steam, undertaking the main refrigeration task. A small portion of the refrigerant enters the auxiliary evaporator (6) through the flow-limiting bypass branch (400) to maintain its low-temperature state and provide auxiliary refrigeration. The two return gases are mixed in the gas-liquid separator (5) to ensure that pure gaseous refrigerant returns to the compressor (1) and completes the refrigeration cycle.

5. The energy-saving defrosting method based on main and auxiliary evaporators according to claim 2, characterized in that: In step S3, when the auxiliary refrigeration circuit (200) is running, part of the high-temperature and high-pressure gas discharged by the compressor (1) enters the condenser (2) and is condensed into a high-pressure liquid. After the high-pressure liquid is throttled by the main throttling device (3), it becomes a low-temperature and low-pressure gas-liquid two-phase fluid. The refrigerant enters the auxiliary evaporator (6) through the second on / off valve (10), absorbs heat in the cabinet, evaporates and refrigerates to maintain refrigeration. The low-temperature and low-pressure superheated vapor after evaporation enters the gas-liquid separator (5), and the separated gas phase refrigerant returns to the compressor (1).

6. The energy-saving defrosting method based on main and auxiliary evaporators according to claim 2, characterized in that: In step S3, when the defrosting circuit (300) is running, part of the high-temperature and high-pressure refrigerant gas discharged by the compressor (1) enters the main evaporator (4) directly through the third shut-off valve (11). The high-temperature gas releases heat and condenses in the main evaporator (4), melting the frost layer. The defrosted gas-liquid mixed refrigerant enters the gas-liquid separator (5), and the separated gas phase refrigerant returns to the compressor (1).

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