A hot gas defrosting system for a refrigerator and its control method

Abstract

This invention discloses a hot gas defrosting system for a refrigerator and its control method: the normal cooling supply branch is connected sequentially to the compressor, the main flow regulating valve, the condenser, the anti-condensation pipe, the dryer filter, the gas-liquid separator, the liquid distributor, the cold compartment cooling supply branch, and the liquid collector; each cold compartment cooling supply branch is connected in parallel by a capillary tube, an evaporator, and a pressure regulating valve; the hot gas defrosting branch is connected sequentially to the drain anti-clogging pipe, the freezing evaporator, the defrosting capillary tube, the gas-liquid separator, and the liquid collector. The gaseous refrigerant in the gas-liquid separator merges with the cooling supply branch at the liquid collector through the pressure regulating valve and returns to the compressor. This invention, through its hot gas defrosting system design, shortens the defrosting time, prevents secondary freezing and blockage at the drain, avoids wet compression and liquid slugging in the compressor, and effectively controls the temperature rise in the refrigerator compartment, making it suitable for air-cooled refrigerators.

Description

Technical Field

[0001] This invention belongs to the field of refrigerator defrosting technology, and more specifically, relates to a hot air defrosting system for refrigerators and its control method. Background Technology

[0002] Frost-free refrigerators, also known as air-cooled refrigerators, use a fan in the air duct to force cold air to circulate between the compartment and the evaporator, thereby delivering the cooling energy generated by the evaporator into the compartment to cool food. Compared to direct-cooling refrigerators, air-cooled refrigerators have advantages such as automatic defrosting, multiple temperature zones, and larger capacity, making them increasingly popular with consumers.

[0003] Water vapor inside the refrigerator circulates with the air and condenses into frost on the surface of the low-temperature evaporator. In the early stages of frost formation, the frost crystals adhering to the fins of the evaporator in a frost-cooled refrigerator act as micro-ribs, enhancing heat exchange. However, as the frost layer thickens and becomes denser, the thermal resistance of the frost layer and the airflow resistance increase, leading to a decrease in the evaporator's heat exchange performance, resulting in reduced refrigerator cooling efficiency and increased power consumption. Therefore, developing efficient defrosting methods and control strategies is crucial.

[0004] Refrigerators can be defrosted in several ways, including electric defrosting, hot air defrosting, and ultrasonic defrosting. Among these, electric defrosting is the most widely used. It uses heat radiation generated by a heating element to melt the frost layer on the evaporator surface, and it is a defrosting method that works from the outside in.

[0005] Related studies have shown that the defrosting efficiency of electric heating in air-cooled refrigerators is relatively low, with the heat used for effective defrosting accounting for only 15-20% of the total power consumption of the electric heating element. The temperature rise in the circulating air duct and inside the refrigerator is significant during defrosting, which has a considerable impact on temperature-sensitive foods. Due to the influence of the electric heater's placement and control strategy, problems such as long defrosting cycles, untimely defrosting, and over-defrosting often occur. Currently, refrigerator refrigeration systems generally use flammable and explosive refrigerants such as R600a. With continuous heating by the defrosting heater, there is a risk of burning the refrigerator's plastic liner and causing leaked flammable refrigerant to ignite and explode, posing certain safety hazards.

[0006] Chinese patent CN 104613688A discloses a refrigeration system for a dual-temperature refrigerator with hot gas defrosting and cold energy recovery. Theoretically, the evaporator can be used as a condenser for hot gas bypass defrosting according to the refrigeration needs of the refrigerator compartment. According to engineering practice and operational experience, the hot gas bypass defrosting system often has the following problems: (1) Due to the influence of different temperature zone requirements, the temperature of the refrigerator compartment is usually 10-20°C higher than that of the freezer compartment, and the refrigerant pressure difference at the outlet of the evaporator of the two compartments is large. When the refrigerant in the dual / triple temperature zone is mixed and returned to the compressor, there is a phenomenon that the low-temperature evaporator pipeline cannot return gas; (2) Adjusting the heat bypass flow of the evaporator according to the cooling capacity of the refrigerator compartment can easily lead to incomplete defrosting and over-defrosting, resulting in poor defrosting effect of the evaporator and temperature rise; (3) Hot gas defrosting causes the frost layer on the tube fins to peel off partially or entirely, causing the frost / ice that cannot be completely melted to accumulate in the drain pan, which can easily cause blockage of the drain pan and large-area freezing; at the same time, the condensed water in the drip tray cannot be discharged and flows back to the freezer compartment, affecting the normal use of the refrigerator; (4) There is a risk of liquid slugging when the compressor sucks in air. Summary of the Invention

[0007] To address the problems of low defrosting efficiency, large temperature rebound in the refrigerator compartment, safety hazards, and inability to defrost on demand in existing air-cooled refrigerators, this invention proposes a hot gas defrosting system and its control method. Through the design of the hot gas defrosting system, the defrosting process time is shortened, secondary freezing and blockage at the drain pan are prevented, wet compression and liquid slugging of the compressor are avoided, and the temperature rebound in the refrigerator compartment is effectively controlled. By optimizing the control strategy, the refrigerant flow rate in the hot gas defrosting branch is dynamically adjusted based on the amount of frost on the fin surface, truly achieving on-demand defrosting and improving the overall performance of the refrigerator.

[0008] The objective of this invention can be achieved through the following technical solutions.

[0009] The hot gas defrosting system of the refrigerator of the present invention includes a compressor. A total flow regulating valve, a condenser, an anti-condensation pipe, a dryer filter, a gas-liquid separator, a liquid distributor, a cold room cooling branch, and a liquid collector are connected in series via pipelines between the compressor outlet and inlet along the refrigerant flow direction. The cold room cooling branch includes a refrigerator compartment cooling branch, a variable temperature compartment cooling branch, and a freezer compartment cooling branch connected in parallel. A refrigerator compartment cooling branch is sequentially equipped with a refrigerator capillary tube, a refrigerator evaporator, and a second pressure regulating valve. A variable temperature compartment cooling branch is sequentially equipped with a variable temperature capillary tube, a variable temperature evaporator, and a third pressure regulating valve. A freezer compartment cooling branch is sequentially equipped with a first solenoid valve, a freezing capillary tube, a freezing evaporator, a second solenoid valve, and a fourth pressure regulating valve.

[0010] One port of the refrigerated evaporator is connected to the outlet of the total flow regulating valve via a hot gas defrosting branch A, which is equipped with a drain anti-clogging pipe and a No. 3 solenoid valve. The other port of the refrigerated evaporator is connected to the gas-liquid separator via a hot gas defrosting branch B, which is equipped with a defrosting capillary tube and a No. 4 solenoid valve. The gas-liquid separator and the liquid collector are connected via a hot gas defrosting branch C, which is equipped with a first pressure regulating valve.

[0011] The inlet of the gas-liquid separator tube side is connected to the outlet of the dryer filter, the outlet of the gas-liquid separator tube side is connected to the inlet of the separator, the inlet of the gas-liquid separator shell side is connected to the B-section hot gas defrosting branch, and the outlet of the gas-liquid separator shell side is connected to the C-section hot gas defrosting branch.

[0012] In normal cooling mode, solenoid valves No. 3 and No. 4, and the first pressure regulating valve are closed, while solenoid valves No. 1, No. 2, the second pressure regulating valve, the third pressure regulating valve, and the fourth pressure regulating valve are open. The liquid refrigerant absorbs heat from the cold room and vaporizes into saturated gas through the evaporators of each cooling branch. After being pressurized by the pressure regulating valves of each cooling branch, it is compressed into a high-temperature, high-pressure gas by the compressor. After being regulated by the total flow regulating valve, it is liquefied by the condenser, and the anti-condensation pipe is overcooled. Then, it passes through the dryer filter and the gas-liquid separator, and is split at the distributor. The flow rate of each cooling branch is adjusted according to the heat load demand of each cold room. The saturated liquid refrigerant is throttled through the capillary tube in each cooling branch, evaporates and absorbs heat at the evaporator of the cold room cooling branch, and returns to the compressor after being pressurized by the pressure regulating valve to complete the cold room cooling cycle.

[0013] In hot gas defrosting mode, solenoid valves 1 and 2 are closed, while solenoid valves 3 and 4, the first pressure regulating valve, the second pressure regulating valve, and the third pressure regulating valve are open. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor is divided into two paths by the total flow regulating valve. One path sequentially passes through the condenser and anti-condensation pipe to condense into a saturated liquid, then passes through the dryer filter, undergoes heat exchange in the gas-liquid separator for subcooling, and finally has its flow regulated at the distributor to provide cooling for the cold storage and variable temperature compartments. The other path is the hot gas defrosting branch, where the high-temperature, high-pressure refrigerant... The defrosting gas is heated by the anti-clogging pipe of the drain tank, and then enters the refrigeration evaporator. It releases heat through condensation to melt the frost layer on the refrigeration evaporator. After condensation, the liquid refrigerant passes through the No. 4 solenoid valve and is throttled and depressurized in the defrosting capillary tube. Then it enters the gas-liquid separator, where the liquid refrigerant in the cooling branch is cooled to increase its subcooling. In addition, the gaseous refrigerant in the gas-liquid separator is regulated by the first pressure regulating valve and, together with the return gas from the refrigeration branch of the cold storage compartment and the cooling branch of the variable temperature compartment, returns to the compressor through the liquid collector.

[0014] The objective of this invention can also be achieved through the following technical solutions.

[0015] The control method for the hot gas defrosting system of a refrigerator of the present invention includes the following process:

[0016] Step 1: When the refrigerator is running normally, at time τ, the return air temperature, return air relative humidity, supply air temperature, supply air relative humidity, surface temperature, air volume, and compressor exhaust temperature of the freezer evaporator are monitored in real time by preset sensors. The refrigerator system controller calculates the amount of frost on the freezer evaporator and the heat required for defrosting based on the above-mentioned monitored system operating parameter data.

[0017] Step 2: The refrigerator system controller determines whether the refrigerator's preset defrosting conditions are met; if yes, proceed to Step 3 and enter the hot air defrosting mode; if no, return to Step 1 and continue collecting system operating parameters.

[0018] Step 3: The refrigerator system controller issues a command to enter hot gas defrosting mode. The compressor frequency is reduced to hot gas defrosting mode, and solenoid valves 1 and 2 are closed. After a 30-second delay, solenoid valves 3 and 4 are opened, the first pressure regulating valve is opened, and the system enters hot gas defrosting mode. At the same time, the defrosting time is accumulated.

[0019] Step 4: The preset sensor monitors the system operating parameters in real time. The refrigerator system controller calculates the remaining frost amount and the required defrosting heat based on the monitored system operating parameter data, and adjusts the refrigerant flow rate of the hot gas defrosting branch through the total flow regulating valve.

[0020] Step 5: The refrigerator system controller determines whether the refrigerator's preset defrost exit conditions are met; if yes, proceed to step 6; if no, continue hot defrosting and accumulate the defrosting time.

[0021] Step Six: The refrigerator system controller issues a command to exit hot defrosting, the compressor frequency increases to normal cooling mode, solenoid valves No. 3 and No. 4 close, and the first pressure regulating valve closes; after a 30-second delay, solenoid valves No. 1 and No. 2 on the freezer cooling branch are opened.

[0022] Step 7: The refrigerator system enters the normal cooling stage. Based on the system operating parameters collected by the preset sensors, the refrigerant flow of each cooling branch is adjusted through the total flow regulating valve and the distributor to effectively control the temperature fluctuation of the freezer evaporator. Repeat steps 1 to 7 above, the refrigerator system runs and continues to collect system operating parameters, and enters a new defrost judgment cycle.

[0023] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0024] (1) In addition to the normal cooling supply branch, this invention also includes a hot gas defrosting branch, which uses high-temperature exhaust gas from the compressor to defrost the evaporator and exchange heat with the cooling supply branch to make it subcooled. After pressure regulation, the gas returns to the compressor. This invention utilizes the high-temperature exhaust gas from the compressor to heat the frost layer on the evaporator from the inside out, causing the frost layer to melt and fall off. This helps to shorten the defrosting time, reduce defrosting heat loss, and improve the safe operation efficiency and system performance of the air-cooled refrigerator.

[0025] (2) The present invention utilizes the high-temperature exhaust of the compressor to design the drainage channel to prevent blockage, which allows large pieces of frost that fall off during the defrosting process to melt quickly again at the drainage channel and be discharged in time, avoiding secondary freezing and ice blockage.

[0026] (3) In the hot gas defrosting process of the present invention, the wet compression of the compressor is avoided by the gas-liquid separator, and the subcooling degree of the cooling branch of the refrigeration and variable temperature room is improved, which is beneficial to the overall performance improvement.

[0027] (4) The cooling branch and the hot defrosting branch of the present invention are independently controlled, and the refrigerant flow rate of the defrosting branch can be adjusted according to the defrosting process to achieve on-demand heating and defrosting.

[0028] The hot gas defrosting system and control method for an air-cooled refrigerator described in this invention can achieve independent temperature control for each cold compartment and can perform independent hot gas defrosting based on the amount of frost buildup in the freezer compartment. During the defrosting process of the freezer compartment evaporator, the high-temperature exhaust gas from the compressor is effectively utilized, which improves defrosting efficiency and reduces system energy consumption on the one hand; on the other hand, it increases the subcooling degree of the cooling supply branch, which is beneficial to increasing the cooling capacity. The gas-liquid separator ensures that the compressor suction is saturated / overheated, effectively avoiding potential dangers such as liquid compression in the system, and improving system operating efficiency and safety. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the hot air defrosting system of the refrigerator of the present invention.

[0030] Figure 2 This is a flowchart of the control method for the hot air defrosting system of the refrigerator of the present invention.

[0031] Figure reference numerals: 1-Compressor; 2-Total flow regulating valve; 3-Condenser; 4-Anti-condensation pipe; 5-Drier filter; 6-Gas-liquid separator; 7-Distributor; 8-Refrigeration capillary tube; 9-Variable temperature capillary tube; 10-Refrigeration capillary tube; 11-Refrigeration evaporator; 12-Variable temperature evaporator; 13-Refrigeration evaporator; 14-Collector; 15-Drainage trough anti-clogging pipe; 16-Defrosting capillary tube; 17-Solenoid valve No. 1; 18-Solenoid valve No. 2; 19-Solenoid valve No. 3; 20-Solenoid valve No. 4; 21-First pressure regulating valve; 22-Second pressure regulating valve; 23-Third pressure regulating valve; 24-Fourth pressure regulating valve. Detailed Implementation

[0032] The present invention will now be further described with reference to the accompanying drawings.

[0033] like Figure 1 As shown, the hot gas defrosting system of the refrigerator of the present invention includes a compressor 1. A total flow regulating valve 2, a condenser 3, an anti-condensation pipe 4, a dryer filter 5, a gas-liquid separator 6, a liquid distributor 7, a cold room cooling branch, and a liquid collector 14 are connected in series via pipes between the outlet and inlet of the compressor 1 along the refrigerant flow direction. Due to the anti-condensation pipe 4, condensation heat can be used to prevent condensation from forming on the outside of the refrigerator. The dryer filter 5 is used to filter out moisture and impurities that may cause pipe blockage in the refrigeration system, preventing "ice blockage" and "dirt blockage" in the refrigeration system.

[0034] The cold room cooling supply branch includes a first cooling supply branch, a second cooling supply branch, and a third cooling supply branch connected in parallel. The first cooling supply branch serves as the cooling supply branch for the refrigerator compartment, the second cooling supply branch serves as the cooling supply branch for the variable temperature compartment, and the third cooling supply branch serves as the cooling supply branch for the freezer compartment. The refrigerator compartment cooling supply branch is sequentially equipped with a refrigeration capillary tube 8, a refrigeration evaporator 11, and a second pressure regulating valve 22. The variable temperature compartment cooling supply branch is sequentially equipped with a variable temperature capillary tube 9, a variable temperature evaporator 12, and a third pressure regulating valve 23. The freezer compartment cooling supply branch is sequentially equipped with a first solenoid valve 17, a freezing capillary tube 10, a freezing evaporator 13, a second solenoid valve 18, and a fourth pressure regulating valve 24.

[0035] One port of the evaporator 13 (the port near the second solenoid valve 18) is connected to the outlet of the total flow regulating valve 2 via a hot gas defrosting branch (section A). This branch is equipped with a drain anti-clogging pipe 15 and a third solenoid valve 19. The frost is quickly melted and discharged through the drain anti-clogging pipe 15, and the high-temperature exhaust from the compressor prevents secondary freezing and clogging of the frost in the drain. The other port of the evaporator 13 (the port near the freezing capillary tube 10) is connected to the gas-liquid separator 6 via a hot gas defrosting branch (section B). This branch is equipped with a defrosting capillary tube 16 and a fourth solenoid valve 20. The gas-liquid separator 6 and the liquid collector 14 are connected via a hot gas defrosting branch (section C), which is equipped with a first pressure regulating valve 21. The hot gas defrosting branches (sections A, B, and C) can be considered to be connected in series. The hot gas defrosting branch exchanges heat with the cooling branch in the gas-liquid separator 6, increasing the subcooling of the cooling branch and the superheat of the defrosting branch, preventing liquid from being carried in the compressor, and improving the system's cooling performance. The hot gas defrosting branch can be controlled independently, and its flow rate can be adjusted according to the defrosting progress to achieve on-demand heating and defrosting.

[0036] In the above-mentioned hot gas defrosting system, the inlet of the total flow regulating valve 2 is connected to the outlet of the compressor 1 through a pipeline, and the outlet of the total flow regulating valve 2 is divided into two paths: one path is connected to the inlet of the condenser through a pipeline, and the other path is connected to the inlet of the anti-clogging pipe of the drain trough through a pipeline.

[0037] In the above-mentioned hot gas defrosting system, the inlet of the gas-liquid separator 6 is connected to the outlet of the dryer filter 5 via a pipeline, and the outlet of the gas-liquid separator 6 is connected to the inlet of the distributor 7 via a pipeline. The outlet of the distributor 7 is divided into three paths, which are respectively connected to the inlet ends of the first cooling branch, the second cooling branch, and the third cooling branch. The shell-side inlet of the gas-liquid separator 6 is connected to the B-section hot gas defrosting branch, and the shell-side outlet of the gas-liquid separator 6 is connected to the C-section hot gas defrosting branch. The gaseous refrigerant in the gas-liquid separator 6 merges with the cooling branch at the liquid collector 14 through the first pressure regulating valve 21 and returns to the compressor 1.

[0038] In the above-mentioned hot gas defrosting system, the inlet of the liquid collector 14 is divided into four paths, which are respectively connected to the outlets of the first cooling branch, the second cooling branch, the third cooling branch, and the C-section hot gas defrosting branch. The outlet of the liquid collector 14 is connected to the inlet of the compressor 1 through a pipeline.

[0039] During normal cooling of the cold rooms, the hot gas defrosting branches are inactive and disconnected. When defrosting the evaporator, the hot gas defrosting branches operate, the cooling branches for the freezer compartment are disconnected, and the cooling branches for the refrigerator compartment and the variable temperature compartment can be independently controlled according to their own cooling needs. Each cold room's cooling branch is independent, allowing for on-demand cooling based on different temperature requirements. Pressure regulating valves are installed between the evaporator outlet and the liquid collector 14 in each cold room to ensure smooth convergence and return of cooling branches with different return gas pressures in different temperature zones.

[0040] In the hot defrosting system of the refrigerator of this invention, when entering normal cooling mode and providing normal cooling to the dual / multi-temperature zone cold room, solenoid valves 19 (number 3), 20 (number 4), and 21 (number 1 pressure regulating valve) are closed, while solenoid valves 17 (number 1), 18 (number 2), 22 (number 3 pressure regulating valve), 23 (number 4 pressure regulating valve), and 24 (number 5 pressure regulating valve) are open. The liquid refrigerant absorbs heat from the cold room and vaporizes into saturated gas through the evaporators of each cooling branch (refrigeration evaporator 11, variable temperature evaporator 12, and freezing evaporator 13). After pressure regulation by the pressure regulating valves of each cooling branch (number 22, 23, and 24), it is compressed into a high-temperature, high-pressure gas by the compressor 1. After being regulated by the total flow regulating valve 2, the refrigerant is liquefied by the condenser 3 and subcooled by the anti-condensation pipe 4, thus preventing condensation in the refrigerator while liquefying and cooling. It then passes through the dryer filter 5 and the gas-liquid separator 6, and is split at the distributor 7. The flow rate of each cold room's cooling branch is adjusted according to the heat load requirements of each cold room. The saturated liquid working fluid is throttled in each cooling branch through capillary tubes (refrigeration capillary tube 8, variable temperature capillary tube 9, and freezing capillary tube 10), and evaporates and absorbs heat at the evaporators (refrigeration evaporator 11, variable temperature evaporator 12, and freezing evaporator 13) in the cold room cooling branch. After pressure regulation by the pressure regulating valves (second pressure regulating valve 22, third pressure regulating valve 23, and fourth pressure regulating valve 24) of each branch, it is collected at the collector 14. The saturated gaseous / superheated refrigerant returns to the compressor 1 to complete the cold room cooling cycle.

[0041] The hot gas defrosting system of this invention refrigerator, when entering hot gas defrosting mode, closes solenoid valve 17 and solenoid valve 18 while defrosting the evaporator 13, and opens solenoid valves 19, 20, and the first pressure regulating valve 21, while the second and third pressure regulating valves 22 and 23 remain open. The high-temperature, high-pressure gaseous refrigerant discharged from compressor 1 is divided into two paths by the total flow regulating valve 2: one path sequentially passes through condenser 3 and anti-condensation pipe 4 to condense into a saturated liquid, which is then filtered by dryer filter 5, undergoes heat exchange in gas-liquid separator 6 for subcooling, and then has its flow regulated at distributor 7 to supply cooling to the cold storage compartment and variable temperature compartment. The other path is the hot gas defrosting branch. High-temperature, high-pressure defrosting gas heats the drain tank through the anti-clogging pipe 15 to prevent secondary freezing and frost accumulation. It then enters the evaporator 13 to condense and release heat, melting the frost layer. After condensation, the liquid refrigerant passes through the fourth solenoid valve 20, undergoes throttling and pressure reduction in the defrosting capillary tube 16, and then enters the gas-liquid separator 6. In the gas-liquid separator 6, the liquid refrigerant in the cooling branch is cooled, increasing its subcooling. Furthermore, the gaseous refrigerant in the gas-liquid separator 6, after being pressurized by the first pressure regulating valve 21, merges with the return gas from the cold storage cooling branch and the variable temperature compartment cooling branch at the liquid collector 14 and returns to the compressor 1.

[0042] like Figure 2As shown, the control method of the hot gas defrosting system of the refrigerator of the present invention includes the following process:

[0043] Step 1: During normal cooling operation of the refrigerator, at time τ, the return air temperature T of the evaporator 13 is monitored in real time by a preset sensor. in,τ RH of return air in,τ Supply air temperature T out,τ Supply air relative humidity (RH) out,τ Surface temperature T s Air volume V air,τ Compressor discharge temperature T p,τ The system operating parameters are collected by preset sensors and uploaded to the refrigerator system controller. The refrigerator system controller then calculates the frost amount M of the evaporator 13 based on the monitored system operating parameter data. i And the heat required for defrosting Q i The preset sensors include multiple different temperature sensors, humidity sensors, and airflow sensors.

[0044] Step 2: The refrigerator system controller determines whether the refrigerator's preset defrosting conditions are met; if yes, proceed to Step 3 and enter the hot air defrosting mode; if no, return to Step 1 and continue collecting system operating parameters.

[0045] Step 3: The refrigerator system controller issues a command to enter hot gas defrosting mode, controlling the compressor 1 to reduce its frequency to hot gas defrosting mode, and closing solenoid valves 17 and 18. After a 30-second delay, solenoid valves 19 and 20 open, and the first pressure regulating valve 21 opens, and the system enters hot gas defrosting mode, while accumulating the defrosting time T.

[0046] Step 4: The preset sensor monitors the system operating parameters in real time. The refrigerator system controller calculates the remaining frost amount and the required defrosting heat based on the monitored system operating parameter data, and adjusts the refrigerant flow rate of the hot gas defrosting branch through the total flow regulating valve 2.

[0047] Step 5: The refrigerator system controller determines whether the refrigerator's preset defrost exit conditions are met; if yes, proceed to step 6; if no, continue hot defrosting and accumulate the defrosting time T.

[0048] Step Six: The refrigerator system controller issues a command to exit hot defrosting, controls the compressor to increase its frequency to normal cooling mode, closes solenoid valves 19 and 20, and closes the first pressure regulating valve 21; after a 30-second delay, opens solenoid valves 17 and 18 on the freezer cooling branch.

[0049] Step 7: The refrigerator system enters the normal cooling phase. Based on the system operating parameters collected by the preset sensors, the refrigerant flow in each cooling branch is adjusted through the total flow regulating valve 2 and the distributor 7 to effectively control the temperature fluctuation of the evaporator 13. Steps 1 to 7 are repeated, the refrigerator system continues to operate and collect system operating parameters, and a new defrosting judgment cycle begins.

[0050] This invention discloses a hot gas defrosting system and control method for air-cooled refrigerators, relating to the field of defrosting in air-cooled refrigerators. It primarily addresses the problems of low efficiency, high energy consumption, and the potential for refrigerant leakage and combustion / explosion caused by electric heating elements in existing defrosting methods. This invention improves the defrosting effect by heating the drain trough with high-temperature exhaust from the compressor to prevent blockage, and by performing independent hot gas defrosting on the freezer compartment evaporator. The aforementioned hot gas defrosting system for air-cooled refrigerators can provide independent cooling according to different temperature requirements during normal cooling operation. When defrosting of the freezer compartment evaporator is required, independent hot gas defrosting is performed, which not only removes the frost layer as a whole, improving defrosting efficiency, but also effectively controls temperature fluctuations within the refrigerator compartment. Simultaneously, the anti-blockage heating design of the drain trough facilitates the timely removal of defrost water, ensuring the safe, stable, and efficient operation of the system.

[0051] Although the functions and working processes of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific functions and working processes described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these are within the protection scope of the present invention.

Claims

1. A hot gas defrosting system of a refrigerator comprising a compressor (1), characterized in that, The compressor (1) outlet and the inlet are connected in series through a pipeline in the direction of refrigerant flow, and a total flow regulating valve (2), a condenser (3), an anti-condensation pipe (4), a drying filter (5), a gas-liquid separator (6), a distributor (7), a cold room cooling branch, and a liquid collector (14) are sequentially connected in series. One port of the freezing evaporator (13) and the outlet of the total flow regulating valve (2) are connected through an A-section hot gas defrosting branch, and a drainage groove anti-blocking pipe (15) and a third electromagnetic valve (19) are arranged on the A-section hot gas defrosting branch; the other port of the freezing evaporator (13) and the gas-liquid separator (6) are connected through a B-section hot gas defrosting branch, and a defrosting capillary tube (16) and a fourth electromagnetic valve (20) are arranged on the B-section hot gas defrosting branch; the gas-liquid separator (6) and the liquid collector (14) are connected through a C-section hot gas defrosting branch, and a first pressure regulating valve (21) is arranged on the C-section hot gas defrosting branch; the gas-liquid separator (6) pipeline inlet is connected with the outlet of the drying filter (5), the gas-liquid separator (6) pipeline outlet is connected with the inlet of the distributor (7), the gas-liquid separator (6) shell inlet is connected with the B-section hot gas defrosting branch, and the gas-liquid separator (6) shell outlet is connected with the C-section hot gas defrosting branch.

2. The hot gas defrosting system of the refrigerator according to claim 1, characterized in that, In the normal cooling mode, the third electromagnetic valve (19), the fourth electromagnetic valve (20), and the first pressure regulating valve (21) are closed, and the first electromagnetic valve (17), the second electromagnetic valve (18), the second pressure regulating valve (22), the third pressure regulating valve (23), and the fourth pressure regulating valve (24) are opened; the liquid refrigerant is vaporized into saturated gas by absorbing the heat of the cold room through the evaporators of each cooling branch, and is compressed into high-temperature and high-pressure gas by the compressor (1) after being regulated by the pressure regulating valves of each cooling branch; after being regulated by the total flow regulating valve (2), the refrigerant is liquefied by the condenser (3) and subcooled by the anti-condensation pipe (4), and then passes through the drying filter (5) and the gas-liquid separator (6), is distributed at the distributor (7), and is adjusted according to the heat load demand of each cold room; the saturated liquid refrigerant is throttled by the capillary tube in each cooling branch, is evaporated and absorbs heat at the evaporator of the cold room cooling branch, and returns to the compressor (1) after being regulated by the pressure regulating valve to complete the cooling cycle of the cold room.

3. The hot gas defrosting system of the refrigerator according to claim 1, characterized in that, In hot gas defrosting mode, the first solenoid valve (17) and the second solenoid valve (18) are closed, and the third solenoid valve (19), the fourth solenoid valve (20), the first pressure regulating valve (21), the second pressure regulating valve (22) and the third pressure regulating valve (23) are opened. The high-temperature and high-pressure gaseous refrigerant discharged by the compressor (1) is divided into two paths through the total flow regulating valve (2). One path is condensed into saturated liquid through the condenser (3) and the anti-condensation pipe (4) in sequence, filtered through the drying filter (5), and then overcooled in the gas-liquid separator (6) through heat exchange, and then the flow is adjusted in the distributor (7) to supply cold air to the cold room and the variable temperature room. The other path is the hot gas defrosting branch. The high-temperature and high-pressure defrosting gas heats the drain pan through the drain pan anti-clogging pipe (15), and then enters the freezer evaporator (13) to melt the frost layer of the freezer evaporator (13) by releasing heat through condensation. The liquid refrigerant after condensation passes through the fourth solenoid valve (20), is throttled and depressurized in the defrosting capillary (16), and then enters the gas-liquid separator (6) to cool the liquid refrigerant of the cooling branch and improve its supercooling degree. In addition, the gaseous refrigerant in the gas-liquid separator (6) is adjusted in pressure through the first pressure regulating valve (21), and then returns to the compressor (1) together with the return gas of the cold room cooling branch and the variable temperature room cooling branch through the liquid collector (14).

4. A method of controlling a hot gas defrosting system of a refrigerator according to any one of the preceding claims 1 to 3, characterized in that, The process includes the following steps: Step one: when the refrigerator is running normally, at time τ, the return air temperature, return air relative humidity, supply air temperature, supply air relative humidity, surface temperature, air volume and compressor discharge temperature of the freezer evaporator (13) are monitored in real time by the preset sensor, and the refrigerator system controller calculates the frost amount and defrosting heat required for the freezer evaporator (13) according to the monitored system operating parameter data. Step two: the refrigerator system controller determines whether the preset defrosting condition of the refrigerator is met. If yes, step three is performed to enter the hot gas defrosting mode. If not, step one is returned to continue collecting system operating parameters. Step three: the refrigerator system controller issues an instruction to enter the hot gas defrosting mode, and the compressor (1) is reduced to the hot gas defrosting mode, and the first solenoid valve (17) and the second solenoid valve (18) are closed. After a delay of 30 seconds, the third solenoid valve (19) and the fourth solenoid valve (20) are opened, and the first pressure regulating valve (21) is opened. The system enters the hot gas defrosting mode, and the defrosting time is accumulated at the same time. Step four: the preset sensor monitors the system operating parameters in real time, and the refrigerator system controller calculates the remaining frost amount and the required defrosting heat according to the monitored system operating parameter data, and adjusts the refrigerant flow of the hot gas defrosting branch through the total flow regulating valve (2). Step five: the refrigerator system controller determines whether the preset defrosting exit condition of the refrigerator is met. If yes, step six is performed. If not, the hot gas defrosting continues, and the defrosting time is accumulated. Step six: the refrigerator system controller issues an instruction to exit the hot gas defrosting mode, and the third solenoid valve (19) and the fourth solenoid valve (20) are closed. Step six: the refrigerator system controller issues a hot gas defrost exit instruction, the compressor is frequency-converted to normal cooling mode, the third solenoid valve (19) and the fourth solenoid valve (20) are closed, and the first pressure regulating valve (21) is closed; after a delay of 30 s, the first solenoid valve (17) and the second solenoid valve (18) on the freezer cooling branch are opened; Step seven: the refrigerator system enters the normal cooling stage, according to the system operating parameters collected by the preset sensor, the refrigerant flow of each cooling branch is adjusted through the total flow regulating valve (2) and the distributor (7), and the temperature fluctuation of the freezer evaporator (13) is effectively controlled; the above steps one to seven are repeated, the refrigerator system runs and continues to collect system operating parameters, and enters a new defrost judgment period.

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