Hot gas bypass defrosting system and method

Abstract

The present invention discloses a hot gas bypass defrosting system and method, the system includes a compressor, a condenser, a condensing fan, a condensing temperature sensor, a condensing temperature relay, a defrosting temperature relay, a drying filter, a capillary tube, an evaporator, an evaporating fan, a defrosting temperature sensor, a defrosting solenoid valve and a controller, the compressor, the condenser, the drying filter, the capillary tube, and the evaporator are sequentially connected through a refrigeration pipeline, an exhaust bypass pipeline is connected between the compressor and the evaporator, the defrosting solenoid valve is arranged on the exhaust bypass pipeline, the output end of the controller is respectively connected to the compressor, the defrosting solenoid valve, the condensing fan, and the evaporating fan, the condensing temperature relay is connected in series between the output end of the controller and the condensing fan, and the defrosting temperature relay is connected in series between the other output end of the controller and the defrosting solenoid valve. The present invention adds an exhaust bypass pipeline, and adds a heat accumulation process before defrosting, greatly shortens the defrosting time, and solves the problem of insufficient heat in the hot gas bypass defrosting structure.

Description

[0001] This application is a divisional application of the "Hot gas bypass defrost system and method", the original application number is 202210464163X, and the application date is April 29, 2022. Technical Field

[0002] The present invention relates to the field of refrigeration, and in particular to a hot gas bypass defrosting system and method, which can be used for commercial refrigeration equipment, commercial cold storage refrigerators and freezers, household refrigerators and freezers, etc. Background Art

[0003] The current defrosting structure design of refrigeration equipment mostly adopts the scheme design of heating wire by electricity to generate heat to melt the evaporator and its auxiliary structures, and draining water after defrosting is completed (such as patent CN 113959161 A). This scheme belongs to the external heating of the evaporation device, which only conducts heat through convection and radiation, takes a long time and has low efficiency, which often seriously affects the storage temperature of food in the effective area of ​​the cabinet. A small number of current refrigeration equipment defrosting also adopts the structure design of hot gas defrosting, which is carried out through the four-way valve like the cooling and heating switching mode of the air conditioner. This scheme belongs to the evaporation device heated by the internal hot refrigerant above 50℃ through conduction, which takes a short time (only 10% of the time of the former), has high efficiency and complete defrosting, but the process of hot-cold mode conversion takes a long time. Considering the time of hot-cold conversion, the time used for one defrosting process is more than the former, so the defrosting affects the storage temperature of food in the effective area of ​​the cabinet; in addition, the hot-cold conversion requires additional power consumption and the implementation cost is also high. At present, there are very few structural designs for defrosting refrigeration equipment that use compressor exhaust bypass to the evaporator and its components for defrosting; this solution is that the evaporator is heated by internal hot refrigerant above 50°C through conduction, which is short in time, high in efficiency, and thorough in defrosting, and there is no complicated hot-cold conversion mode. However, the internal temperature cannot be above 50°C every time during the defrosting process, and the management process cannot meet the requirements; the defrosting process is not thorough, and even dripping water and ice accumulation occur, causing the refrigeration equipment to lose its refrigeration capacity. In reality, the actual starting time of defrosting is often during the shutdown process, especially when the ambient temperature is low and humid. The defrosting process is usually ineffective, and even some frost flowers melt into water and accumulate at local low temperatures to form ice accumulation; in reality, when the defrosting process is cut into the refrigeration process, the compressor power is often sharply increased in order to completely defrost, causing overload or even coil burnout. Summary of the invention

[0004] In order to solve the defects of the prior art, the present invention provides a hot gas bypass defrost system and method, which adds an exhaust bypass pipeline and increases a heat accumulation process before defrosting, greatly shortening the defrost time and solving the problem of insufficient heat in the hot gas bypass defrost structure.

[0005] In order to solve the technical problem, the technical solution adopted by the present invention is: a hot gas bypass defrosting system, including a compressor, a condenser, a condensing fan, a condensing temperature sensor, a condensing temperature relay, a defrosting temperature relay, a drying filter, a capillary tube, an evaporator, an evaporating fan, a defrosting temperature sensor, a defrosting solenoid valve and a controller, the compressor, the condenser, the drying filter, the capillary tube, and the evaporator are connected in sequence through a refrigeration pipeline, the compressor and the condenser are connected to form an exhaust part, the condenser, the drying filter, and the capillary tube are connected to form a condensation part, an exhaust bypass pipeline is connected between the compressor and the evaporator, the defrosting solenoid valve is arranged on the exhaust bypass pipeline, the condensing temperature sensor collects the temperature of the condenser, the defrosting temperature sensor collects the temperature of the evaporator return air pipe, and the temperature signals collected by the condensing temperature sensor and the defrosting temperature sensor are transmitted to the controller, the output end of the controller is respectively connected to the compressor, the defrosting solenoid valve, the condensing fan, and the evaporating fan, the condensing temperature relay and the defrosting temperature relay are used to sense the temperature on the condensing pipeline, the defrosting temperature relay is connected in series between the output end of the controller and the defrosting solenoid valve, and the condensing temperature relay is connected in series between the other output end of the controller and the condensing fan.

[0006] Furthermore, the gas outlet end of the exhaust bypass pipeline passes through the drain pipe, the water receiving pan and the fin heat exchanger of the evaporator in sequence.

[0007] Furthermore, a defrost temperature sensor is arranged on the return air duct of the evaporator to collect the temperature of the set point, thereby controlling the hot gas bypass defrosting progress and the operation of the evaporating fan during the refrigeration process after defrosting and dripping water drainage.

[0008] Furthermore, a condensing temperature sensor is arranged on the liquid supply pipe of the condenser to collect the temperature of the set point, thereby controlling the degree of heat accumulation before the hot gas bypass defrosting.

[0009] The present invention also discloses a hot gas bypass defrosting method, which defrosts by bypassing the compressor exhaust to the evaporator, and adds a heat accumulation process before defrosting to make the defrosting more thorough. During the defrosting process, the defrosting process is controlled based on signals collected by the defrost temperature sensor, the condensation temperature sensor and the defrost temperature relay.

[0010] Furthermore, the method includes five processes: heat accumulation, bypass defrosting, drip drainage, local refrigeration, and full-cycle refrigeration, specifically: S01) In the low-temperature refrigeration system, the surface temperature of the evaporator is lower than the cabinet temperature. While the evaporator is radiating cold, the water vapor in the air gradually exists on its surface in the form of frost. With the long-term refrigeration process, the invading water vapor also accumulates on the evaporator and its accessories in the form of frost. As the accumulation increases, it will affect the ventilation and cold dissipation capabilities, and enter the defrosting process by time judgment or temperature judgment; S02) Heat accumulation process: When the refrigeration system enters the defrosting process, the output end of the controller is continuously connected to the compressor to ensure the normal operation of the compressor. At the same time, the output power connected to the condensing fan is cut off to stop the condensing fan from working, so that the condenser enters the process of accumulating heat. At the same time, the condensing temperature sensor collects the temperature of the condenser in real time and feeds it back to the controller. The controller makes a logical judgment on whether the preset temperature parameter is reached. At the same time, the defrosting temperature relay senses the temperature on the condensing pipe. S03), defrosting process: when the defrost temperature relay senses that the temperature on the condensation pipeline reaches the set value, the temperature relay closes and turns on the defrost solenoid valve. When the condenser temperature detected by the condensation temperature sensor reaches the preset temperature parameter, the controller disconnects the output power supply connected to the evaporation fan, so that the evaporation fan enters the stop state, and at the same time connects the output end of the defrost solenoid valve to provide power. The defrost solenoid valve opens, and the high-temperature refrigerant with heat accumulation bypasses the capillary tube and directly enters the drain pipe, water tray, and fin heat exchanger of the evaporator through the exhaust bypass pipeline. Finally, the refrigerant after heat consumption returns to the compressor through the return air pipeline; the output end connected to the compressor still provides power, and the compressor continues to work. The defrost temperature sensor collects the temperature of the evaporation chamber and continuously feeds it back to the controller. The controller performs logical judgment whether the preset temperature parameter is reached. S04), dripping and drainage process: the high-temperature refrigerant first melts the ice particles in the drainage pipeline and raises the temperature in the pipeline to above 30°C, and then melts the ice particles in the evaporator water tray and raises the temperature in the pipeline to above 30°C. When the frost on the fin heat exchanger of the evaporator is heated and melted into water and flows down, it will not freeze again, and then dripping and drainage will be smooth; when the signal collected by the defrost temperature sensor reaches the preset temperature parameter, the controller disconnects the power supply of the output end connected to the defrost solenoid valve, the defrost solenoid valve is closed, the exhaust bypass pipeline is closed, and the power supply of the output end connected to the compressor is disconnected at the same time, the compressor stops working, and the power supply of the output end connected to the evaporator fan is still disconnected, and the evaporator fan is in a stopped state. According to the preset time parameters of the controller, the system enters a timed dripping and drainage process. During this period, the temperatures of the drainage pipe, water tray, and fin heat exchanger of the evaporator are all above 30°C, ensuring smooth dripping and drainage; S05), return to the refrigeration cycle process, after the dripping and drainage process is completed, the controller automatically switches to the cooling mode, at this time, the controller is connected to the output end of the condensing fan to provide power, the condensing fan is turned on, and at the same time, the condensing temperature sensor collects the temperature of the condenser and continuously feeds it back to the controller. The controller performs a logical judgment on whether the preset temperature parameters are reached. After reaching the preset temperature parameters, the controller output end connected to the compressor provides power, and the compressor starts working. At the same time, the defrost temperature sensor collects the evaporation chamber temperature in real time and feeds it back to the controller. The controller performs a logical judgment on whether the preset temperature parameters are reached. When the preset temperature parameters are reached, the controller output end connected to the evaporator provides power, and the evaporation fan starts working. At this time, the effective volume in the cabinet and the space where the evaporator is located are ventilated.

[0011] Furthermore, after step S05), according to the temperature signal collected by the defrost temperature sensor, the evaporating fan is turned on and off to prevent the residual heat of the defrost from invading the effective volume in the cabinet, and gradually returns to the refrigeration cycle, and the defrost process is completely ended.

[0012] Beneficial effects of the present invention: The present invention adopts a method of bypassing the compressor exhaust to the evaporator and its components to perform defrosting, dripping, and drainage, and adopts signal acquisition and logic control to manage each process. Defrosting is performed regularly according to a preset time or switched when it is intelligently determined that frosting is serious, thereby solving the problem of timely defrosting of the evaporator.

[0013] Add a heat accumulation process to improve the hot gas bypass defrost, which includes five processes: heat accumulation, bypass defrost, drip drainage, local refrigeration, and full-cycle refrigeration. Before bypass defrost is realized, the exhaust and condensing parts of the compressor reach the preset temperature, which is not affected by the environment and the cycle process. The heat is sufficient, the compressor power is stable, the time is short, and the defrost is thorough, which fundamentally solves the problem of insufficient heat in hot gas bypass defrost.

[0014] Temperature sensors, temperature relays, defrost solenoid valves and controllers are set up, and signal acquisition and logic control methods are used to achieve control and management of each process. This can greatly shorten the defrost time (equivalent to only 8% of the time required for electric heating) while flexibly managing the defrost start time and the refrigerant temperature during the defrost process.

[0015] The defrost and ice melting sequence is designed from the drainage pipeline, water receiving tray to the fin heat exchanger, so as to realize the gradual and sequential drainage, ice melting and defrost. Each process is executed thoroughly without water accumulation, ice accumulation and frost accumulation, thus solving the problem of incomplete defrost.

[0016] A defrost temperature sensor is set on the return air pipe of the evaporator (300 mm out of the evaporator) to control the progress of hot gas bypass defrosting and the operation of the evaporator fan during the refrigeration process after defrosting and dripping drainage, so as to solve the problem of the impact of defrost heat on the food storage temperature in the effective range of the cabinet during the entire defrosting process. It also solves the problem of unstable compressor power, avoids overload and even coil burnout due to a sharp increase in electric power, and solves the problem of stable compressor power during the re-refrigeration process after defrosting.

[0017] A condensing temperature sensor is set on the liquid supply pipe of the condenser (100 mm from the condenser) to control the degree of heat accumulation before hot gas bypass defrosting, ensuring that the defrost is started after a reasonable enough heat judgment is obtained during the heat accumulation process, and the start and stop of the condensing fan are controlled at a corresponding lower ambient temperature, so as to quantitatively manage the heat accumulation during the defrosting process, and also ensure that the refrigeration equipment can operate well in a wider environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the composition of the present invention; Figure 2 It is a schematic diagram of the control principle of the present invention; In the figure: 1. compressor, 2. condenser, 3. condensing fan, 4. condensing temperature sensor, 5. defrost temperature relay, 6. condensing temperature relay, 7. drying filter, 8. capillary tube, 9. evaporator, 10. evaporating fan, 11. defrost temperature sensor, 12. defrost solenoid valve, 13. controller, 14. cabinet door opening and closing sensor, 15. cabinet temperature sensor. DETAILED DESCRIPTION

[0019] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0020] Example 1 This embodiment discloses a hot gas bypass defrost system, such as Figure 1 As shown, it includes a compressor 1, a condenser 2, a condensing fan 3, a condensing temperature sensor 4, a defrost temperature relay 5, a condensing temperature relay 6, a drying filter 7, a capillary tube 8, an evaporator 9, an evaporating fan 10, a defrost temperature sensor 11, a defrost solenoid valve 12 and a controller 13. The compressor 1, the condenser 2, the drying filter 7, the capillary tube 8 and the evaporator 9 are connected in sequence through a refrigeration pipeline. The compressor 1 is connected to the condenser 2 to form an exhaust part, the condenser 2, the drying filter 7 and the capillary tube 8 are connected to form a condensation part, the capillary tube 8 is connected to the evaporator 9, and the evaporator 9 is connected back to the compressor 1 through a return air pipe.

[0021] In order to realize bypass exhaust, an exhaust bypass pipeline is connected between the compressor 1 and the evaporator 9, and the defrost solenoid valve 12 is arranged on the exhaust bypass pipeline.

[0022] The condensing temperature sensor 4 is arranged on the liquid supply pipe of the condenser 2, 100 mm away from the condenser. The condensing temperature sensor 4 is used to collect the temperature of the condenser 2 and transmit it to the controller 13, so as to control the heat accumulation degree before the hot gas bypass defrosting.

[0023] The defrost temperature sensor 11 is arranged on the return air pipe of the evaporator, 300 mm away from the evaporator. The defrost temperature sensor 11 is used to collect the temperature of the return air pipe of the evaporator and transmit it to the controller 13, so as to control the hot gas bypass defrosting progress and the operation of the evaporating fan in the refrigeration process after defrosting and dripping drainage.

[0024] The control principle of this embodiment is as follows Figure 2 As shown, the temperature signals collected by the condensing temperature sensor 4 and the defrost temperature sensor 11 are transmitted to the controller 13, and the signals collected by the cabinet temperature sensor 15 and the cabinet door opening signal sensor 14 are also transmitted to the controller 13, but they are irrelevant to the purpose of the present invention and will not be repeated here. The output ends of the controller 13 are respectively connected to the compressor 1, the defrost solenoid valve 12, the condensing fan 3, and the evaporating fan 10. Specifically, the output end C of the controller 13 is connected to the compressor 1, the output end R is connected to the defrost solenoid valve 12, the output end C2 is connected to the condensing fan 3, and the output end C1 is connected to the evaporating fan. In order to sense the temperature of the condensing pipeline in real time, the condensing temperature relay 6 and the defrost temperature relay 5 are set on the condensing pipeline. At the same time, in order to manage the condensing fan 3 and the defrost solenoid valve 12 based on the condensing temperature sensor 4, the defrost temperature relay 5, and the condensing temperature relay 6. It is reflected in Figure 2 In the embodiment, the defrost temperature relay 5 is connected in series between the output terminal R of the controller 13 and the defrost solenoid valve 12, and the condensation temperature relay 6 is connected in series between the output terminal C2 of the controller and the condensation fan 3.

[0025] In this embodiment, the outlet end of the exhaust bypass pipeline passes through the drain pipe, the water receiving pan and the fin heat exchanger of the evaporator in sequence. With such a design, the hot air (after heat accumulation) in the exhaust bypass pipeline can pass through the drain pipe, the water receiving pan and the fin heat exchanger in sequence, first melting the frost on the drain pipe and the water receiving pan, and then melting the frost on the fin heat exchanger. In this way, the water generated by the defrosting can be smoothly drained through the drain pipe and the water receiving pan, avoiding the re-frosting phenomenon caused by poor drainage.

[0026] Example 2 The present embodiment discloses a hot gas bypass defrosting method, which defrosts by bypassing the compressor exhaust to the evaporator, and adds a heat accumulation process before defrosting to make the defrosting more thorough. During the defrosting process, the defrosting process is controlled based on signals collected by the defrost temperature sensor and the condensing temperature sensor.

[0027] Specifically, the method includes five processes: heat accumulation, bypass defrosting, drip drainage, local refrigeration, and full-cycle refrigeration, specifically: S01), before defrosting, in the low-temperature (cabinet temperature below -10℃) refrigeration system, the surface temperature of evaporator 9 is 4℃ lower than the cabinet temperature. While evaporator 9 dissipates cold air, water vapor in the air gradually exists on its surface in the form of frost. With the long-term refrigeration process, the invading water vapor also accumulates on evaporator 9 and its accessories (water tray, drain pipe) in the form of frost. With the increase of defrost accumulation, it will affect the ventilation and cold dissipation capabilities, and enter the defrost process by time judgment or temperature judgment.

[0028] In this embodiment, two methods are used to determine whether to start the defrosting process. One is the time interval parameter preset in the controller 13, and the controller 13 determines the time point to start the defrosting. The other is temperature judgment. The temperature signal collected by the defrosting temperature sensor 11 is transmitted to the controller. After logical judgment, the temperature reaches the preset value and the defrosting is started.

[0029] S02), heat accumulation process: when the refrigeration system enters the defrosting process, the output terminal C of the controller 13 is continuously connected to the compressor 1 to ensure the normal operation of the compressor 1, and at the same time, the power supply of the output terminal C2 connected to the condensing fan is cut off to stop the condensing fan 3, so that the condenser 2 enters the process of accumulating heat. At the same time, the condensing temperature sensor 4 collects the temperature of the condenser 2 in real time and feeds it back to the controller 13. The controller 13 performs a logical judgment on whether the preset temperature parameters are reached. At the same time, the defrosting temperature relay 5 senses the temperature on the condensing pipeline.

[0030] S03), defrosting process: when the defrost temperature relay 5 senses that the temperature on the condensation pipeline reaches the set value, the defrost temperature relay 5 is closed to connect the defrost solenoid valve 12. When the condenser temperature detected by the condensation temperature sensor 4 reaches the preset temperature parameter, the power supply of the output terminal C1 of the controller 13 causes the evaporation fan 10 to enter the stop state. At the same time, the output terminal R provides power, and the defrost solenoid valve 12 is opened. The high-temperature (greater than 55°C) refrigerant with heat accumulation avoids the capillary tube 8 and directly enters the drain pipe, water tray, and fin heat exchanger of the evaporator 10 through the exhaust bypass pipeline. Finally, the refrigerant after heat consumption returns to the compressor 1 through the return air pipeline; the output terminal C connected to the compressor 1 still provides power, and the compressor 1 continues to work. The defrost temperature sensor 11 collects the temperature of the evaporation chamber and continuously feeds it back to the controller 13. The controller 13 performs a logical judgment on whether the preset temperature parameter is reached.

[0031] S04), dripping and drainage process: the high-temperature refrigerant first melts the ice particles in the drainage pipeline and raises the temperature in the pipeline to above 30°C, and then melts the ice particles in the evaporator water tray and raises the temperature in the pipeline to above 30°C. When the frost on the fin heat exchanger of the evaporator is heated and melted into water and flows down, it will not freeze again, and then dripping and drainage will be smooth; when the signal collected by the defrost temperature sensor 11 reaches the preset temperature parameter, the controller 13 disconnects the power supply of the output terminal R, the defrost solenoid valve 12 is closed, the exhaust bypass pipeline is closed, and the output terminal C is disconnected from the power supply at the same time, the compressor 1 stops working, the output terminal C1 is still disconnected from the power supply, and the evaporating fan 10 is in a stopped state. According to the time parameters preset by the controller, the system enters a timed dripping and drainage process. During this period, the temperatures of the drainage pipe, water tray, and fin heat exchanger of the evaporator are all above 30°C, ensuring smooth dripping and drainage.

[0032] S05), return to the refrigeration cycle process, after the dripping and drainage process is completed, the controller 13 automatically switches to the refrigeration mode, at this time, the output terminal C2 of the controller 13 provides power, the condensing fan 3 is turned on, and at the same time, the condensing temperature sensor 4 collects the temperature of the condenser 2 and continuously feeds it back to the controller 13, the controller 13 performs a logical judgment whether the preset temperature parameter is reached, after the preset temperature parameter is reached, the output terminal C provides power, the compressor 1 starts working, and at the same time, the defrost temperature sensor 11 collects the evaporation chamber temperature in real time and feeds it back to the controller 13, the controller 13 performs a logical judgment whether the preset temperature parameter is reached, when the preset temperature parameter is reached, the output terminal C1 provides power, the evaporation fan 10 starts working, and at this time, the effective volume in the cabinet and the space where the evaporator is located are ventilated.

[0033] After step S05), according to the temperature signal collected by the defrost temperature sensor 11, the evaporator fan 10 is turned on and off to prevent the residual heat of defrosting from invading the effective volume in the cabinet, gradually returning to the refrigeration cycle, and the defrosting process is completely ended. Specifically, when the temperature signal collected by the defrost temperature sensor 11 is high, the evaporator fan 10 is stopped, and when the temperature signal is low, the evaporator fan is turned on. The temperature signal is judged by setting a temperature threshold.

[0034] The above description is only the basic principle and preferred embodiments of the present invention. Improvements and substitutions made by those skilled in the art based on the present invention belong to the protection scope of the present invention.

Claims

1. A hot gas bypass defrost system, characterized in that: It includes a compressor, a condenser, a condensing fan, a condensing temperature sensor, a condensing temperature relay, a defrost temperature relay, a drying filter, a capillary tube, an evaporator, an evaporating fan, a defrost temperature sensor, a defrost solenoid valve and a controller. The compressor, the condenser, the drying filter, the capillary tube and the evaporator are connected in sequence through a refrigeration pipeline. The compressor and the condenser are connected to form an exhaust part. The condenser, the drying filter and the capillary tube are connected to form a condensation part. An exhaust bypass pipeline is connected between the compressor and the evaporator. The defrost solenoid valve is arranged on the exhaust bypass pipeline. The condensing temperature sensor collects the temperature of the condenser. The defrost temperature sensor collects the temperature of the evaporator return air pipe. The temperature signals collected by the condensing temperature sensor and the defrost temperature sensor are transmitted to the controller. The output end of the controller is respectively connected to the compressor, the defrost solenoid valve, the condensing fan and the evaporating fan. The condensing temperature relay and the defrost temperature relay are used to sense the temperature on the condensing pipeline. The condensing temperature relay is connected in series between the output end of the controller and the condensing fan. The defrost temperature relay is connected in series between the other output end of the controller and the defrost solenoid valve.

2. The hot gas bypass defrost system according to claim 1, characterized in that: The outlet end of the exhaust bypass pipeline passes through the drain pipe, water receiving tray and fin heat exchanger of the evaporator in sequence.

3. The hot gas bypass defrost system according to claim 1, characterized in that: The defrost temperature sensor is installed on the evaporator return air pipe to collect the temperature of the set point, so as to control the hot gas bypass defrost progress and the operation of the evaporator fan in the refrigeration process after defrosting and dripping water drainage.

4. The hot gas bypass defrost system according to claim 1, characterized in that: The condensing temperature sensor is set on the liquid supply pipe of the condenser to collect the temperature of the set point, so as to control the heat accumulation degree before the hot gas bypass defrost.

5. A hot gas bypass defrosting method, characterized in that: The method uses the compressor exhaust gas bypassing to the evaporator to defrost, and adds a heat accumulation process before defrosting to make the defrosting more thorough. During the defrosting process, the defrosting process is controlled based on the signals collected by the defrost temperature sensor, the condensing temperature sensor and the defrost temperature relay.

6. The hot gas bypass defrosting method according to claim 5, characterized in that: This method includes five processes: heat accumulation, bypass defrosting, drip drainage, local refrigeration, and full-cycle refrigeration, specifically: S01) In the low-temperature refrigeration system, the surface temperature of the evaporator is lower than the cabinet temperature. While the evaporator is radiating cold, the water vapor in the air gradually exists on its surface in the form of frost. With the long-term refrigeration process, the invading water vapor also accumulates on the evaporator and its accessories in the form of frost. As the accumulation increases, it will affect the ventilation and cold dissipation capabilities, and enter the defrosting process by time judgment or temperature judgment; S02) Heat accumulation process: When the refrigeration system enters the defrosting process, the output end of the controller is continuously connected to the compressor to ensure the normal operation of the compressor. At the same time, the output power connected to the condensing fan is cut off to stop the condensing fan from working, so that the condenser enters the process of accumulating heat. At the same time, the condensing temperature sensor collects the temperature of the condenser in real time and feeds it back to the controller. The controller makes a logical judgment on whether the preset temperature parameter is reached. At the same time, the defrosting temperature relay senses the temperature on the condensing pipe. S03), defrosting process: when the defrost temperature relay senses that the temperature on the condensation pipeline reaches the set value, the temperature relay closes and turns on the defrost solenoid valve. When the condenser temperature detected by the condensation temperature sensor reaches the preset temperature parameter, the controller disconnects the output power supply connected to the evaporator fan, so that the evaporator fan enters the stop state, and at the same time connects the output end of the defrost solenoid valve to provide power. The defrost solenoid valve opens, and the high-temperature refrigerant with heat accumulation bypasses the capillary tube and directly enters the drain pipe, water tray, and fin heat exchanger of the evaporator through the exhaust bypass pipeline. Finally, the refrigerant after heat consumption returns to the compressor through the return air pipeline; the output end connected to the compressor still provides power, and the compressor continues to work. The defrost temperature sensor collects the temperature of the evaporator return air pipe and continuously feeds it back to the controller. The controller performs logical judgment whether the preset temperature parameter is reached. S04), dripping and drainage process: the high-temperature refrigerant first melts the ice particles in the drainage pipeline and raises the temperature in the pipeline to above 30°C, and then melts the ice particles in the evaporator water tray and raises the temperature in the pipeline to above 30°C. When the frost on the fin heat exchanger of the evaporator is heated and melted into water and flows down, it will not freeze again, and then dripping and drainage will be smooth; when the signal collected by the defrost temperature sensor reaches the preset temperature parameter, the controller disconnects the power supply of the output end connected to the defrost solenoid valve, the defrost solenoid valve is closed, the exhaust bypass pipeline is closed, and the power supply of the output end connected to the compressor is disconnected at the same time, the compressor stops working, and the power supply of the output end connected to the evaporator fan is still disconnected, and the evaporator fan is in a stopped state. According to the preset time parameters of the controller, the system enters a timed dripping and drainage process. During this period, the temperatures of the drainage pipe, water tray, and fin heat exchanger of the evaporator are all above 30°C, ensuring smooth dripping and drainage; S05), return to the refrigeration cycle process, after the dripping drainage process is completed, the controller automatically switches to the cooling mode, at this time, the controller is connected to the output end of the condensing fan to provide power, the condensing fan is turned on, and at the same time, the condensing temperature sensor collects the temperature of the condenser and continuously feeds it back to the controller. The controller performs a logical judgment on whether the preset temperature parameters are reached. After reaching the preset temperature parameters, the controller output end connected to the compressor provides power, and the compressor starts working. At the same time, the defrost temperature sensor collects the evaporator return air pipe temperature in real time and feeds it back to the controller. The controller performs a logical judgment on whether the preset temperature parameters are reached. When the preset temperature parameters are reached, the controller output end connected to the evaporator provides power, and the evaporating fan starts working. At this time, the effective volume in the cabinet and the space where the evaporator is located are ventilated.

7. The hot gas bypass defrosting method according to claim 6, characterized in that: After step S05), according to the temperature signal collected by the defrost temperature sensor, the evaporating fan is turned on and off to prevent the residual heat of the defrost from invading the effective volume in the cabinet, and gradually returns to the refrigeration cycle to ensure that the temperature in the effective volume is not affected by the defrost heat.

Images