CN116772513A - A hot gas defrost system for a refrigerator and its control method - Google Patents

Abstract

The invention discloses a hot air defrosting system of a refrigerator and a control method thereof, wherein the hot air defrosting system comprises: the normal cooling branch is sequentially connected with a compressor, a total flow regulating valve, a condenser, an anti-condensation pipe, a drying filter, a gas-liquid separator, a cold room cooling branch and a liquid collector; the cold supply branches of each cold room are connected in parallel after being connected in sequence by a capillary tube, an evaporator and a pressure regulating valve respectively; the hot gas defrosting branch is sequentially connected with the anti-blocking pipe, the freezing evaporator, the defrosting capillary tube, the gas-liquid separator and the liquid collector by the drainage groove, and gaseous refrigerant in the gas-liquid separator is converged with the cooling branch at the liquid collector through the pressure regulating valve and returns to the compressor. The invention shortens the time required by the defrosting process by the design of the hot gas defrosting system, prevents secondary freezing and blockage at the water discharge groove, avoids wet compression and liquid impact of the compressor, effectively controls the temperature rise of the box chamber, and is suitable for air-cooled refrigerators.

Description

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

Technical field

The invention belongs to the technical field of refrigerator defrosting, and more specifically, relates to a hot gas defrosting system of a refrigerator and a control method thereof.

Background technique

Air-cooled refrigerators, also known as frost-free refrigerators, use fans in the air duct to force cold air to flow between the box chamber and the evaporator, thereby sending the cold energy generated by the evaporator into the box chamber to cool the food. Compared with direct-cooling refrigerators, air-cooled refrigerators have advantages such as automatic defrost, multiple temperature zones, and large capacity, and are increasingly favored by consumers.

The water vapor in the box chamber circulates with the air and condenses into frost when encountering the low-temperature evaporator surface. In the early stages of frost formation on the air-cooled refrigerator evaporator, the frost crystals attached to the surface of the fins act as micro-ribs, which is beneficial to enhancing heat transfer. As the thickness and densification of the frost layer increases, the heat transfer resistance and air flow resistance of the frost layer continue to increase, and the heat transfer performance of the evaporator decreases, resulting in a decrease in the cooling efficiency of the refrigerator and an increase in power consumption. Therefore, it is particularly important to develop efficient defrosting methods and control strategies.

Refrigerator defrost methods include electric heating defrost, hot gas defrost, ultrasonic defrost, etc. Among them, electric heating defrost is the most widely used. It melts the frost layer on the evaporator surface through the thermal radiation generated by the heating element. It is an outside-in defrosting method.

Relevant studies have shown that the electric heating defrosting efficiency of air-cooled refrigerators is low, and the heat used for effective defrosting is only 15-20% of the total power consumption of the electric heating element; during the defrosting process, the circulating air duct and the internal temperature of the box rise. The amplitude is large, and the impact on temperature-sensitive foods cannot be ignored; affected by the layout and control strategy of electric heaters, there are often problems such as long defrost cycles, untimely defrost, and excessive defrost; currently, refrigerator refrigeration systems generally use R600a, etc. For flammable and explosive working fluids, when the defrost heater continues to heat, there is a risk of burning the plastic liner of the refrigerator and causing leakage of flammable working fluids, which poses certain safety risks.

Chinese patent CN 104613688A discloses a refrigeration system with hot gas defrosting and cold recovery for a dual-temperature refrigerator. In theory, the refrigerated evaporator can be used as a condenser to bypass the hot air to defrost it according to the refrigeration needs of the refrigerator room. According to engineering practice and operating experience, hot gas bypass defrost systems often have the following problems: (1) Affected by the needs of different temperature zones, the temperature of the refrigerator compartment is usually 10-20°C higher than the temperature of the freezer compartment, and the refrigerant at the evaporator outlet of both The pressure difference is large. When the dual/three-temperature zone parallel refrigerants are mixed and returned to the compressor, there is a phenomenon that the low-temperature evaporator pipeline cannot return air; (2) The heat bypass flow of the refrigeration evaporator is adjusted according to the cooling capacity of the refrigerator, which is prone to defrost. The problems of incomplete and excessive defrosting lead to poor defrosting effect of the refrigerated evaporator, temperature rise and other problems; (3) hot air defrost causes the frost layer on the tube fins to peel off partially/wholly, resulting in frost/ice that cannot be completely melted. Gathering in the drainage channel can easily cause blockage of the drainage channel and large area of ice; at the same time, the condensed water in the water tray cannot be discharged, and flows back to the freezer, affecting the normal use of the refrigerator; (4) There is a hidden danger of liquid shock in the compressor suction.

Contents of the invention

In view of the problems of existing air-cooled refrigerators with low electric heating defrosting efficiency, large indoor temperature rise, potential safety hazards, and inability to defrost on demand, the present invention proposes a hot gas defrosting system and a control method for the refrigerator. The design of the hot gas defrost system shortens the time required for the defrost process, prevents secondary freezing and clogging of the drainage channel, avoids wet compression and liquid shock of the compressor, and effectively controls the temperature rise in the box chamber; through optimized control strategies, The amount of frost on the fin surface dynamically adjusts the refrigerant flow rate of the hot gas defrost branch to truly achieve on-demand defrost and improve the overall performance of the refrigerator.

The object of the present invention can be achieved through the following technical solutions.

The hot gas defrosting system of the refrigerator of the present invention includes a compressor. Between the outlet and the inlet of the compressor, a total flow regulating valve, a condenser, an anti-condensation pipe, and a dry filter are connected in series through pipelines along the flow direction of the refrigerant. device, a gas-liquid separator, a liquid distributor, a cold room cooling branch, and a liquid collector; the cold room cooling branch includes a parallel-connected cold room cooling branch, a variable temperature greenhouse cooling branch, and a freezer. The cooling branch of the cold room is provided with a refrigeration capillary tube, a refrigeration evaporator, and a second pressure regulating valve in sequence. The cooling branch of the variable room is provided with a variable temperature capillary tube, a variable temperature evaporator, and a third pressure regulator. Regulating valve, the cooling branch of the freezing chamber is provided with a No. 1 solenoid valve, a freezing capillary tube, a freezing evaporator, a No. 2 solenoid valve, and a fourth pressure regulating valve in sequence;

A section A hot gas defrost branch is connected between one of the ports of the refrigeration evaporator and the outlet of the total flow regulating valve, and a drainage tank anti-clogging pipe and a No. 3 solenoid valve are provided on the A section hot gas defrost branch; A section B hot gas defrost branch is connected between the other port of the refrigeration evaporator and the gas-liquid separator. The section B hot gas defrost branch is provided with a defrost capillary tube and a No. 4 solenoid valve; the gas-liquid separator A section C hot gas defrost branch is connected to the liquid collector, and a first pressure regulating valve is provided on the section C hot gas defrost branch.

The tube side inlet of the gas-liquid separator is connected to the outlet of the drying filter, the tube side outlet of the gas-liquid separator is connected to the liquid separator inlet, and the shell side inlet of the gas-liquid separator is connected to the hot gas defrost branch of section B. , the shell side outlet of the gas-liquid separator is connected to the hot gas defrost branch of section C.

In normal cooling mode, the No. 3 solenoid valve, No. 4 solenoid valve, and the first pressure regulating valve are closed, and the No. 1 solenoid valve, the No. 2 solenoid valve, the second pressure regulating valve, the third pressure regulating valve, and the fourth pressure regulating valve are closed. Open; the liquid refrigerant absorbs the heat in the cooling room through the evaporator of each cooling branch and vaporizes into a saturated gas. After being regulated by the pressure regulating valve of each cooling branch, it is compressed into a high-temperature and high-pressure gas by the compressor; it is adjusted by the total flow regulating valve. Afterwards, it is liquefied in the condenser and the anti-condensation pipe is supercooled. It then passes through the drying filter and gas-liquid separator, and is divided at the liquid distributor. The flow rate of the cooling branch of each cold room is adjusted according to the heat load demand of each cold room. ; The saturated liquid working fluid passes through capillary throttling in each cooling branch, evaporates and absorbs heat at the evaporator of the cooling branch, and returns to the compressor after adjusting the pressure with the pressure regulating valve to complete the cooling cycle.

In the hot gas defrost mode, the No. 1 solenoid valve and the No. 2 solenoid valve are closed, and the No. 3 solenoid valve, the No. 4 solenoid valve, the first pressure regulating valve, the second pressure regulating valve, and the third pressure regulating valve are opened; the compressor discharges The high-temperature and high-pressure gaseous refrigerant is divided into two paths through the total flow regulating valve, one of which is condensed into a saturated liquid through the condenser and anti-condensation pipe in sequence. After filtering through the drying filter, it is heat exchanged in the gas-liquid separator to achieve subcooling, and then The flow is adjusted at the liquid distributor to provide cooling for the cold room of the cold room and variable room; the other path is the hot gas defrost branch. The high-temperature and high-pressure defrost gas heats the drainage tank through the anti-clogging pipe of the drainage tank, and then enters The frozen evaporator releases heat through condensation to melt the frost layer of the frozen evaporator. After condensation, the liquid refrigerant passes through the No. 4 solenoid valve, is throttled and depressurized in the defrost capillary, and then enters the gas-liquid separator. Cool the liquid refrigerant in the cooling branch to increase its degree of subcooling; in addition, the gaseous refrigerant in the gas-liquid separator is regulated by the first pressure regulating valve and communicates with the cold room cooling branch and the greenhouse cooling branch. The return air passes through the liquid collector and returns to the compressor.

The object of the present invention can also be achieved through the following technical solutions.

The control method of the hot gas defrost system of the refrigerator of the present invention includes the following processes:

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

Step 2: The refrigerator system controller determines whether the preset defrosting conditions of the refrigerator are met; if so, perform step three and enter the hot gas defrost mode; if not, return to step one and continue to collect system operating parameters;

Step 3: The refrigerator system controller issues a command to enter the hot gas defrost mode, the compressor reduces the frequency to the hot gas defrost mode, and the No. 1 solenoid valve and the No. 2 solenoid valve are closed; after a delay of 30 seconds, the No. 3 solenoid valve and the No. 4 solenoid valve are opened. The first pressure regulating valve opens, the system enters the hot gas defrost mode, and the defrost time is accumulated at the same time;

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 hot gas defrost branch refrigerant flow through the total flow regulating valve;

Step 5: The refrigerator system controller determines whether the preset defrost exit conditions of the refrigerator are met; if so, perform step 6; if not, continue hot gas defrost and accumulate the defrost time;

Step 6: The refrigerator system controller issues a command to exit hot gas defrost, the compressor speeds up to normal cooling mode, solenoid valves No. 3 and 4 are closed, and the first pressure regulating valve is closed; after a delay of 30 seconds, the freezer supply is turned on. Solenoid valve No. 1 and solenoid valve No. 2 on the cold branch road;

Step 7: 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 and the liquid distributor to effectively control the temperature fluctuation of the freezing evaporator; repeat From the above steps one to seven, the refrigerator system is running and continues to collect system operating parameters, entering a new defrost judgment cycle.

Compared with the existing technology, the beneficial effects brought by the technical solution of the present invention are:

(1) In addition to the normal cooling branch, the present invention also includes a hot gas defrosting branch. The hot gas defrosts the refrigeration evaporator through the high-temperature exhaust of the compressor, and exchanges heat with the cooling branch to make it supercooled. Return to the compressor after pressure adjustment. The invention uses the high-temperature exhaust gas of the compressor to heat the frost layer of the refrigeration evaporator from the inside out, causing the frost layer to melt and fall off, which is beneficial to shortening the time required for defrosting, reducing defrosting heat loss, and improving the safe operation of the air-cooled refrigerator. Efficiency and system performance.

(2) The present invention uses the high-temperature exhaust of the compressor to prevent clogging of the drainage channel, so that large pieces of ice and frost that fall off during the defrosting process can quickly melt again at the drainage channel and be discharged in time to avoid secondary freezing and ice blockage.

(3) The hot gas defrosting process of the present invention avoids wet compression of the compressor through the gas-liquid separator, and at the same time increases the degree of subcooling of the refrigeration and variable room cooling branches, which is beneficial to improving the performance of the entire machine.

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

The hot air defrosting system and control method of an air-cooled refrigerator according to the present invention can realize independent temperature control of each cold room, and can perform independent hot air defrosting according to the amount of frost in the freezing chamber. During the defrosting process of the freezer evaporator, the high-temperature exhaust gas of the compressor is effectively utilized. On the one hand, it improves the defrosting efficiency and reduces the system energy consumption; on the other hand, it increases the subcooling degree of the cooling branch, which is beneficial to the cooling capacity. improvement. The setting of the gas-liquid separator can ensure 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.

Description of drawings

Figure 1 is a schematic diagram of the hot gas defrosting system of the refrigerator of the present invention.

Figure 2 is a flow chart of the control method of the hot gas defrost system of the refrigerator of the present invention.

Reference signs: 1-Compressor; 2-Total flow regulating valve; 3-Condenser; 4-Anti-condensation pipe; 5-Drying filter; 6-Gas-liquid separator; 7-Liquid separator; 8-Refrigeration Capillary tube; 9-variable temperature capillary tube; 10-freezing capillary tube; 11-refrigeration evaporator; 12-variable temperature evaporator; 13-freezing evaporator; 14-liquid collector; 15-drainage tank anti-clogging tube; 16-defrost capillary tube; 17-No.1 solenoid valve; 18-No.2 solenoid valve; 19-No.3 solenoid valve; 20-No.4 solenoid valve; 21-First pressure regulating valve; 22-Second pressure regulating valve; 23-Third pressure regulating valve Valve; 23-fourth pressure regulating valve.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figure 1, the hot gas defrosting system of the refrigerator of the present invention includes a compressor 1. Between the outlet and the inlet of the compressor 1, there are a total flow regulating valve 2, a condensation valve 2 and a condensation valve 2 connected in series through pipelines along the refrigerant flow direction. 3, anti-condensation pipe 4, filter dryer 5, gas-liquid separator 6, liquid distributor 7, cold room cooling branch, liquid collector 14. Since the anti-condensation pipe 4 is provided, condensation heat can be used to prevent condensation from occurring outside the refrigerator. The filter dryer 5 is used to filter out moisture in the refrigeration system and impurities that may cause pipeline blockage to prevent "ice blockage" and "dirty blockage" in the refrigeration system.

The cold room cooling branch includes a first cooling branch, a second cooling branch, and a third cooling branch connected in parallel, and the first cooling branch serves as the cold room cooling branch, so The second cooling branch is used as a cooling branch for the variable room, and the third cooling branch is used as a cooling branch for the freezing room. The cooling branch of the cold room is provided with a refrigeration capillary 8, a refrigeration evaporator 11, and a second pressure regulating valve 22 in sequence. The cooling branch of the variable room is provided with a temperature-changing capillary 9, a temperature-changing evaporator 12, and a third pressure regulating valve. Regulating valve 23, the cooling branch of the freezing chamber is provided with a No. 1 solenoid valve 17, a freezing capillary tube 10, a freezing evaporator 13, a No. 2 solenoid valve 18, and a fourth pressure regulating valve 24 in sequence.

A section A hot gas defrost branch is connected between one of the ports of the refrigeration evaporator 13 (the port close to the side of the No. 2 solenoid valve 18) and the outlet of the total flow regulating valve 2, and a drainage tank is provided on the branch to prevent The clogging pipe 15 and No. 3 solenoid valve 19 first melt and discharge the peeling frost quickly through the anti-clogging pipe 15 of the drainage tank. The high-temperature exhaust of the compressor can be used to prevent secondary freezing and blocking of ice and frost at the drainage tank. A section B hot gas defrost branch is connected between the other port of the refrigeration evaporator 13 (the port close to the side of the refrigeration capillary 10) and the gas-liquid separator 6, and a defrost capillary 16, No. 4 is provided on this branch. Solenoid valve 20. A section C hot gas defrost branch is connected between the gas-liquid separator 6 and the liquid collector 14, and a first pressure regulating valve 21 is provided on this branch. The hot gas defrost branch of section A, the hot gas defrost branch of section B, and the hot gas defrost branch of section C can be regarded as being connected in series with each other. The hot gas defrost branch exchanges heat with the cooling branch in the gas-liquid separator 6 to increase the subcooling degree of the cooling branch and the superheating degree of the defrosting branch, prevent the compressor from being compressed with liquid, and improve the refrigeration performance of the system. The hot gas defrost branch can be controlled independently, and the flow rate of the defrost branch can be adjusted according to the defrosting process to achieve on-demand heating and defrosting.

In the above hot gas defrost 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 channels: one channel is connected to the condenser inlet through a pipeline , the other is connected to the anti-clogging pipe inlet of the drainage tank through a pipeline.

In the above hot gas defrosting system, the tube-side inlet of the gas-liquid separator 6 is connected to the outlet of the drying filter 5 through a pipeline, and the tube-side outlet of the gas-liquid separator 6 is connected to the inlet of the liquid separator 7 through a pipeline. The outlet of the liquid separator 7 is divided into three channels, 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 hot gas defrost branch of section B is connected. The shell side outlet of the gas-liquid separator 6 is connected with the hot gas defrost branch of section C. The gaseous refrigerant in the gas-liquid separator 6 passes through the first pressure regulating valve 21 and is connected to the cooling supply. The branches merge at the liquid collector 14 and return to the compressor 1 .

In the above hot gas defrost system, the inlet of the liquid collector 14 is divided into four channels, which are connected with the first cooling branch, the second cooling branch, the third cooling branch, and the C section hot gas defrosting branch. The outlet end of the liquid collector 14 is connected to the inlet of the compressor 1 through a pipeline.

When the cold room is being cooled normally, the hot gas defrosting branches of each section do not work and are in an open circuit state; when defrosting the freezing evaporator, the hot gas defrosting branches of each section are working and the cooling branch of the freezer compartment is in an open circuit state. The cooling branch of the cold room and the cooling branch of the variable room can be independently adjusted according to their own cooling capacity needs. The cooling branches of each cold room are independent of each other and can provide on-demand cooling according to different temperature requirements. There is a pressure regulating valve between the outlet of each cold room evaporator and the liquid collector 14 to ensure the smooth convergence and air return of the cooling branches with different return air pressures in different temperature zones.

The hot gas defrost system of the refrigerator of the present invention enters the normal cooling mode. When the dual/multi-temperature zone cooling room is normally supplied with cooling, the No. 3 solenoid valve 19, the No. 4 solenoid valve 20, and the first pressure regulating valve 21 are closed, and the first pressure regulating valve 21 is closed. The No. 1 solenoid valve 17, the No. 2 solenoid 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 absorbs the heat in the cold room through the evaporators of each cooling branch (refrigeration evaporator 11, variable temperature evaporator 12, and refrigeration evaporator 13) and vaporizes into saturated gas. It passes through the pressure regulating valve (second pressure) of each cooling branch. The regulating valve 22, the third pressure regulating valve 23, the fourth pressure regulating valve 24) are compressed into high temperature and high pressure gas by the compressor 1 after the pressure is regulated. After being adjusted by the total flow regulating valve 2, it is liquefied through the condenser 3, and the anti-condensation pipe 4 is supercooled, liquefying and cooling while avoiding condensation in the refrigerator; then it passes through the drying filter 5, the gas-liquid separator 6, and the liquid separator 7 The flow is divided at each cold room, and the flow rate of the cooling branch of each cold room is adjusted according to the heat load demand of each cold room. The saturated liquid working medium is throttled through capillary tubes (refrigeration capillary 8, variable temperature capillary 9, freezing capillary 10) in each cooling branch, and is evaporated in the cooling branch evaporator (refrigeration evaporator 11, variable temperature evaporator 12, freezing The evaporation heat is absorbed at the evaporator 13), and the pressure is adjusted through each branch pressure regulating valve (the second pressure regulating valve 22, the third pressure regulating valve 23, the fourth pressure regulating valve 24) and then collected at the liquid collector 14, and is saturated. The gaseous/superheated refrigerant returns to the compressor 1 to complete the cold room cooling cycle.

The hot gas defrosting system of the refrigerator of the present invention enters the hot gas defrosting mode. When defrosting the freezing evaporator 13, the No. 1 solenoid valve 17 and the No. 2 solenoid valve 18 are closed, and the No. 3 solenoid valve 19 and the No. 4 solenoid valve are opened. 20. The first pressure regulating valve 21, the second pressure regulating valve 22 and the third pressure regulating valve 23 remain open. The high-temperature and high-pressure gaseous refrigerant discharged from the compressor 1 is divided into two paths through the total flow regulating valve 2: one of them is condensed into a saturated liquid through the condenser 3 and the anti-condensation pipe 4. After being filtered by the drying filter 5, the gas-liquid refrigerant is The separator 6 exchanges heat to achieve subcooling, and then adjusts the flow at the liquid distributor 7 to provide cooling for the cold rooms of the cold storage room and the variable room. The other path is a hot gas defrost branch. The high-temperature and high-pressure defrost gas heats the drainage channel through the drainage channel anti-clogging pipe 15 to prevent secondary freezing and frost accumulation; then it enters the freezing evaporator 13 to condense and release heat, melting the frozen gas. The frost layer of the evaporator 13; after condensation, the liquid refrigerant passes through the No. 4 solenoid valve 20, is throttled and depressurized in the defrost capillary 16, and then enters the gas-liquid separator 6, where it passes through the cooling branch The liquid refrigerant cools down and increases its degree of subcooling. In addition, the gaseous refrigerant in the gas-liquid separator 6 is pressure-regulated through the first pressure regulating valve 21 and merges with the return air from the refrigeration room cooling branch and the variable room cooling branch at the liquid collector 14, and returns to the compression chamber. Machine 1.

As shown in Figure 2, the control method of the hot gas defrost system of the refrigerator of the present invention includes the following processes:

Step 1: When the refrigerator is running normally for cooling, at time τ, the return air temperature T _in,τ , return air relative humidity RH _in,τ , and supply air temperature T _out,τ of the freezing evaporator 13 are monitored in real time through preset sensors. , supply air relative humidity RH _out,τ , surface temperature T _s , air volume V _air,τ , compressor exhaust temperature T _p,τ and other system operating parameters. The preset sensor uploads the collected system operating parameter data to the refrigerator system. The controller, the refrigerator system controller calculates the frost amount Mi of the freezing evaporator ₁₃ and the heat required for defrosting Q _i based on the above-mentioned monitored system operating parameter data. Wherein, the preset sensors are a plurality of different temperature sensors, humidity sensors, and air volume sensors.

Step 2: The refrigerator system controller determines whether the preset defrosting conditions of the refrigerator are met; if so, perform step three and enter the hot gas defrost mode; if not, return to step one and continue collecting system operating parameters.

Step 3: The refrigerator system controller issues a command to enter hot gas defrost, controls compressor 1 to reduce the frequency to hot gas defrost mode, and closes solenoid valves 17 and 18. After a delay of 30 seconds, solenoid valves 19 and 18 close. The solenoid valve 20 opens, the first pressure regulating valve 21 opens, the system enters the hot gas defrost mode, and the current defrost time T is accumulated.

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 hot gas defrost branch refrigerant flow through the total flow regulating valve 2.

Step 5: The refrigerator system controller determines whether the preset defrost exit conditions of the refrigerator are met; if so, perform step 6; if not, continue hot gas defrost and accumulate the defrost time T.

Step 6: The refrigerator system controller issues a command to exit the hot gas defrost and controls the compressor to increase frequency to the normal cooling mode. The No. 3 solenoid valve 19 and the No. 4 solenoid valve 20 are closed, and the first pressure regulating valve 21 is closed. After a delay of 30 seconds, Turn on the No. 1 solenoid valve 17 and No. 2 solenoid valve 18 on the cooling branch of the freezer.

Step 7: 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 liquid distributor 7 to effectively control the temperature of the freezing evaporator 13 fluctuation. Repeat the above steps one to seven, the refrigerator system will run and continue to collect system operating parameters, entering a new defrost judgment cycle.

The invention discloses a hot gas defrosting system and control method for an air-cooled refrigerator, which relates to the field of air-cooled refrigerator defrosting. It is mainly used to solve the problem of low efficiency, high energy consumption of existing defrosting methods and possible induction of working fluids by electric heating tubes. Leakage may cause problems such as combustion and explosion. The invention uses the high-temperature exhaust gas of the compressor to heat the anti-clogging pipe of the drainage channel and performs independent hot gas defrosting on the evaporator of the freezing chamber to improve the defrosting effect of the refrigerator. The hot air defrosting system of the above-mentioned air-cooled refrigerator can achieve independent cooling according to different greenhouse needs during normal cooling. When it is necessary to defrost the freezer evaporator, independent hot air defrost can be used to peel off the frost layer as a whole and improve defrosting. Frost efficiency, and can effectively control the temperature fluctuations in the box room. At the same time, the anti-clogging heating design of the drainage tank is conducive to the timely removal of defrost water, ensuring safe, stable and efficient operation of the system.

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 above-mentioned specific functions and working processes. The above-mentioned specific implementations are only illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill can also make many forms without departing from the spirit of the present invention and the scope protected by the claims, and these all fall within the protection of the present invention.

Claims (5)

1. The hot gas defrosting system of the refrigerator comprises a compressor (1), and is characterized in that a total flow regulating valve (2), a condenser (3), an anti-condensation pipe (4), a drying filter (5), a gas-liquid separator (6), a liquid separator (7), a cold-room cooling branch and a liquid collector (14) are sequentially connected in series between an outlet and an inlet of the compressor (1) along the flowing direction of a refrigerating medium through pipelines; the cold room cooling branch comprises a refrigerating room cooling branch, a temperature changing room cooling branch and a freezing room cooling branch which are connected in parallel, wherein a refrigerating capillary tube (8), a refrigerating evaporator (11) and a second pressure regulating valve (22) are sequentially arranged on the refrigerating room cooling branch, a temperature changing capillary tube (9), a temperature changing evaporator (12) and a third pressure regulating valve (23) are sequentially arranged on the temperature changing room cooling branch, and a first electromagnetic valve (17), a freezing capillary tube (10), a freezing evaporator (13), a second electromagnetic valve (18) and a fourth pressure regulating valve (24) are sequentially arranged on the freezing room cooling branch;

an A-section hot gas defrosting branch is connected between one port of the freezing evaporator (13) and the outlet of the total flow regulating valve (2), and a drain tank anti-blocking pipe (15) and a third electromagnetic valve (19) are arranged on the A-section hot gas defrosting branch; a B-section hot gas defrosting branch is connected between the other port of the freezing evaporator (13) and the gas-liquid separator (6), and a defrosting capillary tube (16) and a fourth electromagnetic valve (20) are arranged on the B-section hot gas defrosting branch; c section hot gas defrosting branch road is connected with between gas-liquid separator (6) and liquid trap (14), be provided with first pressure regulating valve (21) on the C section hot gas defrosting branch road.

2. The hot gas defrosting system of a refrigerator according to claim 1, wherein a tube side inlet of the gas-liquid separator (6) is connected with an outlet of the drying filter (5), a tube side outlet of the gas-liquid separator (6) is connected with an inlet of the knockout drum (7), a shell side inlet of the gas-liquid separator (6) is connected with a B-section hot gas defrosting branch, and a shell side outlet of the gas-liquid separator (6) is connected with a C-section hot gas defrosting branch.

3. The hot air defrosting system of a refrigerator according to claim 1, wherein in a normal cooling mode, the solenoid valve No. 19, the solenoid valve No. 20, the first pressure regulating valve (21) are closed, and the solenoid valve No. 17, the solenoid valve No. 18, the second pressure regulating valve (22), the third pressure regulating valve (23), the fourth pressure regulating valve (24) are opened; the liquid refrigeration working medium is vaporized into saturated gas by absorbing heat between cold through each cold supply branch evaporator, and is compressed into high-temperature high-pressure gas by a compressor (1) after pressure regulation of each cold supply branch pressure regulating valve; after the total flow is regulated by a total flow regulating valve (2), the total flow is liquefied by a condenser (3), an anti-condensation pipe (4) is supercooled, and then the total flow is split at a liquid separator (7) through a drying filter (5) and a gas-liquid separator (6), so that the flow of each cold-to-cold cooling branch is regulated according to the heat load requirement of each cold-to-cold cooling branch; the saturated liquid working medium is throttled by capillary tubes in each cooling branch, evaporated and absorbed at the evaporator of the cooling branch between the cooling branches, and returned to the compressor (1) after pressure regulation by the pressure regulating valve, so as to complete cooling circulation between the cooling branches.

4. The hot air defrosting system of a refrigerator according to claim 1, wherein in the hot air defrosting mode, the first solenoid valve (17), 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 high-pressure gaseous refrigerant discharged by the compressor (1) is divided into two paths through a total flow regulating valve (2), one path is condensed into saturated liquid through a condenser (3) and an anti-condensation pipe (4) in sequence, the saturated liquid is filtered through a drying filter (5), heat exchange is realized in a gas-liquid separator (6) to realize supercooling, and then flow regulation is carried out at a liquid separator (7) to supply cold for cold rooms of a refrigerating chamber and a temperature-changing chamber; the other path is a hot gas defrosting branch, high-temperature high-pressure defrosting gas heats a drainage tank through a drainage tank anti-blocking pipe (15), then enters a freezing evaporator (13), melts a frost layer of the freezing evaporator (13) through condensation release heat, throttles and reduces pressure in a defrosting capillary tube (16) through a fourth electromagnetic valve (20), then enters a gas-liquid separator (6), and cools the liquid refrigerant of the cooling branch in the gas-liquid separator (6) to improve the supercooling degree of the liquid refrigerant; in addition, the gaseous refrigerant in the gas-liquid separator (6) is regulated in pressure through the first pressure regulating valve (21), and returns to the compressor (1) together with the return air of the refrigerating chamber cooling branch and the temperature changing chamber cooling branch through the liquid trap (14).

5. A control method of a hot air defrosting system of a refrigerator according to any one of the preceding claims 1 to 4, comprising the steps of:

step one: when the refrigerator is in normal cold supply operation, at tau moment, respectively monitoring the return air temperature, the return air relative humidity, the supply air temperature, the supply air relative humidity, the surface temperature, the air quantity and the compressor exhaust temperature of the freezing evaporator (13) in real time through a preset sensor, and calculating the frosting quantity and the heat required by defrosting of the freezing evaporator (13) by a refrigerator system controller according to the monitored system operation parameter data;

step two: the refrigerator system controller judges whether a preset defrosting condition of the refrigerator is met or not; if yes, executing a step three, and entering a hot gas defrosting mode; if not, returning to the first step, and continuously collecting the system operation parameters;

step three: the refrigerator system controller gives a hot air defrosting command, the compressor (1) is reduced in frequency to a hot air defrosting mode, and the first electromagnetic valve (17) and the second electromagnetic valve (18) are closed; after delaying for 30 seconds, opening a third electromagnetic valve (19) and a fourth electromagnetic valve (20), opening a first pressure regulating valve (21), enabling the system to enter a hot gas defrosting mode, and accumulating the defrosting time;

step four: the method comprises the steps that a preset sensor monitors system operation parameters in real time, a refrigerator system controller calculates residual frost quantity and required defrosting heat according to monitored system operation parameter data, and the total flow regulating valve (2) is used for regulating the flow of a hot gas defrosting branch refrigerant;

step five: the refrigerator system controller judges whether a defrosting exit condition preset by the refrigerator is met or not; if yes, executing the step six; if not, continuing hot gas defrosting and accumulating defrosting time;

step six: the refrigerator system controller gives out a hot gas defrosting instruction, the compressor is increased in frequency to a normal cooling mode, a third electromagnetic valve (19) and a fourth electromagnetic valve (20) are closed, and a first pressure regulating valve (21) is closed; after delay for 30s, opening a first electromagnetic valve (17) and a second electromagnetic valve (18) on a cold supply branch of the freezing chamber;

step seven: the refrigerator system enters a normal cooling stage, and the flow of the refrigerant of each cooling branch is regulated through a total flow regulating valve (2) and a liquid distributor (7) according to the system operation parameters acquired by a preset sensor, so that the temperature fluctuation of a freezing evaporator (13) is effectively controlled; repeating the first step to the seventh step, running the refrigerator system and continuously collecting the system running parameters, and entering a new defrosting judging period.