A refrigeration system for vehicles that requires freezing and refrigeration

Abstract

This utility model discloses a refrigeration system for refrigerated vehicles, solving the problems of poor refrigeration efficiency and low defrosting efficiency in existing technologies. The utility model includes a compressor, a condenser, an expansion valve, and an evaporator, as well as a recooler, a three-way diverter valve, and an ejector. The compressor outlet is connected to the inlet I of the three-way diverter valve; the defrost outlet II of the three-way diverter valve is connected to the inlet IV of a gas-liquid separator; and the main outlet III of the three-way diverter valve is connected to the inlet of the condenser. In the ejector-pressurized intermediate gas-fueled refrigeration mode of this utility model, the ejector ejects a low-speed or low-pressure cooling medium through high-speed, high-pressure gas. The ejected low-temperature refrigerant is injected into the intermediate-pressure chamber, directly cooling the working fluid during the compression process. This avoids the problem of a sharp rise in exhaust temperature due to excessive compressor pressure ratio during low-temperature heating, and increases the total refrigerant circulation volume of the system, enhancing the refrigeration capacity under high-temperature environments. Hot gas bypass defrosting is used to improve defrosting efficiency.

Description

Technical Field

[0001] This utility model relates to the field of refrigeration technology for refrigerated vehicles, and in particular to a refrigeration system for refrigerated vehicles. Background Technology

[0002] Currently, vapor compression refrigeration technology is widely used to extract heat from cold storage compartments to control their temperature, thereby maintaining food quality during transportation. However, as the required refrigeration temperature for refrigerated trucks decreases, the cooling effect of conventional refrigeration units deteriorates. After throttling, the refrigerant produces more gas than liquid, resulting in insufficient utilization of the evaporator area.

[0003] When refrigerated trucks are in operation, the temperature inside the refrigerated compartment needs to be maintained within the operating range. This leads to problems such as poor refrigeration efficiency under large temperature differences, rapid evaporator frosting, and low defrosting efficiency. This is because when the ambient temperature outside the refrigerated truck is high, the condensing pressure increases accordingly. An excessively high system pressure ratio results in significant throttling losses, with more gas and less liquid refrigerant after throttling, causing the evaporator area to be underutilized. When the temperature inside the refrigerated compartment is too low (below the frosting condition), water molecules in the air form ice nuclei on the evaporator surface, and the frost layer thickness increases with refrigeration time, leading to decreased heat exchange efficiency and poorer refrigeration effect. This, in turn, affects the stability of the temperature inside the refrigerated truck and the preservation quality of the goods. To ensure the efficiency and stability of the refrigeration system, regular manual defrosting or electric defrosting is usually required. However, these methods are not only cumbersome and time-consuming, but may also damage the goods, while increasing energy consumption and operating costs. Utility Model Content

[0004] To address the shortcomings of the aforementioned background technology, this utility model proposes a refrigeration system for vehicles that is designed for freezing and refrigeration, which solves the problems of poor refrigeration efficiency, rapid evaporator frosting, and low defrosting efficiency in the prior art.

[0005] The technical solution of this utility model is implemented as follows: A refrigeration system for vehicles, including a compressor, a condenser, an expansion valve, and an evaporator, further including a recooler, a three-way diverter valve, and an ejector. The outlet of the compressor is connected to the inlet I of the three-way diverter valve; the defrost outlet II of the three-way diverter valve is connected to the inlet IV of a gas-liquid separator; the main outlet III of the three-way diverter valve is connected to the inlet of the condenser; the auxiliary outlet IV of the three-way diverter valve is connected to the high-pressure inlet I of the ejector; the outlet of the condenser is connected to the high-pressure inlet I of the recooler; the high-pressure outlet II of the recooler is connected to the inlet of the expansion valve; the outlet of the expansion valve is connected to the inlet I of the gas-liquid separator; the main outlet II of the gas-liquid separator is connected to the inlet of the evaporator; the auxiliary outlet III of the gas-liquid separator is connected to the low-pressure inlet III of the recooler; the low-pressure gas outlet IV of the recooler is connected to the low-pressure gas inlet II of the ejector; the outlet of the evaporator is connected to the inlet of the gas-liquid separator; the outlet of the gas-liquid separator is connected to the low-pressure inlet of the compressor; and the outlet III of the ejector is connected to the medium-pressure inlet of the compressor. This invention provides a novel refrigeration system for refrigerated trucks that improves the utilization area of ​​the evaporator and employs a hot gas bypass defrosting strategy, thus solving the problems of poor refrigeration efficiency, rapid evaporator frosting, and low defrosting efficiency.

[0006] Further optimization reveals that the refrigeration system for refrigerated vehicles also includes a liquid receiver tank, with the condenser outlet connected to the liquid receiver tank inlet; the liquid receiver tank outlet is connected to the high-pressure inlet I of the recooler. The liquid receiver tank, located at the condenser outlet, stores and regulates excess liquid refrigerant in the system, ensuring a continuous, bubble-free high-pressure liquid flow to the expansion valve under any operating condition, while also accommodating refrigerant migration caused by changes in operating conditions.

[0007] Further optimization reveals that the refrigeration system for refrigerated vehicles also includes an oil separator. The compressor outlet is connected to the oil separator inlet, and the oil separator outlet is connected to the inlet I of a three-way diverter valve. The oil separator is positioned between the compressor discharge port and the condenser inlet, quickly separating the lubricating oil flushed out with the high-pressure exhaust and returning it to the compressor crankcase. This ensures efficient heat exchange between the condenser and evaporator while preventing oil shortage in the compressor.

[0008] Further optimization reveals that the refrigeration system for refrigerated vehicles also includes a filter dryer and a sight glass. The high-pressure outlet II of the recooler is connected sequentially to the filter dryer, the sight glass, and then to the inlet of the expansion valve. The filter dryer is used to dry the high-pressure refrigerant exiting the recooler, while the sight glass is used to observe the refrigerant's condition, detect its moisture content, and identify system malfunctions.

[0009] Further optimization involves connecting the auxiliary outlet III of the gas-liquid separator to the low-pressure inlet III of the recooler via a check valve; and connecting the outlet III of the ejector to the medium-pressure inlet of the compressor via a vapor pressure regulating valve. The vapor pressure regulating valve maintains a constant evaporation pressure (i.e., evaporation temperature) to prevent excessively low pressure from causing icing or excessively high pressure from causing a decrease in cooling capacity.

[0010] Further preferably, the steam pressure regulating valve is any one of a proportional regulating valve, a proportional-integral regulating valve, a proportional-derivative regulating valve, or a proportional-integral-derivative regulating valve.

[0011] Further optimization is made by selecting any one of the following: a fixed-frequency refrigeration compressor, a variable-speed refrigeration compressor, a digital scroll refrigeration compressor, or a two-stage refrigeration compressor.

[0012] Further preferred, the condenser and evaporator are any one of finned tube heat exchangers, stacked heat exchangers, and parallel flow heat exchangers.

[0013] Further preferably, the ejector is any one of the following: an equal-area mixing chamber ejector, an equal-pressure mixing chamber ejector, a single-stage ejector ejector, or a two-stage ejector ejector.

[0014] Further optimization is made by selecting any one of plate heat exchangers, shell-and-tube heat exchangers, or flash heat exchangers.

[0015] The beneficial effects of this invention are as follows: The refrigeration system of this invention introduces an ejector. In the ejector-pressurized intermediate gas-fueled refrigeration mode, the ejector uses high-speed, high-pressure gas to eject a low-speed or low-pressure cooling medium. The ejected low-temperature refrigerant is then injected into the intermediate-pressure chamber to cool the working fluid during the compression process, avoiding the problem of a sharp rise in exhaust temperature due to an excessively high compressor pressure ratio during low-temperature heating. This mode of cooling system increases the flow rate and mass flow rate of the cooling medium, enhancing the cooling capacity under high-temperature conditions and overcoming the performance degradation of traditional single-stage compression systems under extreme conditions. Utilizing the existing high-pressure fluid energy of the system, no additional drive equipment is required, resulting in energy saving and high efficiency.

[0016] This invention employs a hot gas bypass defrosting system, optimizing the defrosting mode control strategy. First, the high pressure of the condenser is used to transfer the condensing heat to the evaporator, increasing the mass flow rate of the defrosting loop. Then, the compressor introduces high-temperature, high-pressure refrigerant gas into the evaporator for defrosting. This high-mass flow of refrigerant gas provides more heat, quickly melting the frost layer on the evaporator surface and improving defrosting efficiency. Hot gas bypass defrosting evenly distributes heat to all parts of the evaporator, including the fins and pipes, thoroughly removing the frost layer. This solves the problems of rapid evaporation and low defrosting efficiency in evaporators.

[0017] This utility model relates to a gas-liquid separation type distributor head. It separates the refrigerant into gas and liquid components using a gas-liquid separation baffle, storing the liquid and gas components separately in the distributor head's liquid collection chamber and gas collection chamber, respectively. The gas is then bypassed, increasing the refrigerant dryness. This distributor head structure improves refrigerant dryness and distribution efficiency, solving prominent problems in refrigerated trucks during high-temperature refrigeration operation, such as excessively high condensing pressure, excessively high compressor compression ratio, excessively high exhaust temperature, and frequent compressor protective shutdowns. It also addresses the issues of excessively low evaporation temperature, severe frost formation on the evaporator surface, excessively high compressor compression ratio, excessively high exhaust temperature, and a sharp decline in heating capacity and energy efficiency ratio during low-temperature heating operation. This has significant implications for the development of the cold chain industry.

[0018] This invention provides a novel refrigeration system for refrigerated trucks with an improved evaporator utilization area and a hot gas bypass defrosting strategy. Its concept is novel and its system design is ingeniously optimized. It can be widely used in various refrigerated trucks, cold storage facilities, and various scenarios for low-temperature refrigeration. Attached Figure Description

[0019] To more clearly illustrate the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the refrigeration system of this utility model;

[0021] Figure 2 This is a flowchart of the conventional refrigeration operating mode;

[0022] Figure 3 Flowchart of the ejector pressurization intermediate gas supply and cooling working mode;

[0023] Figure 4 Flowchart for conventional hot gas bypass defrosting operation mode;

[0024] Figure 5 Flowchart for the defrosting operation mode of condensation heat utilization + hot gas bypass. Detailed Implementation

[0025] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0026] Example 1, such as Figure 1 As shown, a refrigeration system for vehicles includes a compressor 1, a condenser 3, an expansion valve 8, and an evaporator 10. These four components are essential to a basic refrigeration system. The compressor compresses low-temperature, low-pressure gas into high-temperature, high-pressure gas, providing the power for circulation. The condenser dissipates the heat from the high-pressure gas to the outside, condensing it into a high-pressure liquid. The expansion valve instantly reduces the pressure, turning the high-pressure liquid into low-temperature, low-pressure wet vapor. The evaporator allows the low-temperature, low-pressure liquid to absorb heat and evaporate, completing the refrigeration process. With these four components, a functional basic refrigeration system can be formed. This embodiment of the refrigeration system for vehicles also includes a recooler 5, a three-way diverter valve 14, and an ejector 12. The recooler further subcools the high-pressure refrigerant that has already been liquefied in the condenser, lowering its temperature below the condensation saturation temperature. This increases the heat absorption capacity per unit mass of refrigerant, reduces flash gas, and improves the system's cooling capacity and energy efficiency ratio. The ejector 12 ejects a low-speed or low-pressure cooling medium through a high-speed mainstream (such as high-pressure steam, compressed gas or liquid). The ejected low-temperature refrigerant is then injected into the medium-pressure chamber to cool the working fluid during the compression process, thus avoiding the problem of a sharp rise in exhaust temperature due to an excessively high compressor pressure ratio when heating at low temperatures.

[0027] In this embodiment, the outlet of compressor 1 is connected to the inlet I of three-way diverter valve 14; the defrost outlet II of three-way diverter valve 14 is connected to the inlet IV of gas-liquid separator head 9; the main outlet III of three-way diverter valve 14 is connected to the inlet of condenser 3; the auxiliary outlet IV of three-way diverter valve 14 is connected to the high-pressure inlet I of ejector 12; the outlet of condenser 3 is connected to the high-pressure inlet I of recooler 5; the high-pressure outlet II of recooler 5 is connected to the inlet of expansion valve 8; the outlet of expansion valve 8 is connected to the gas-liquid separator head 9. The inlet I of the gas-liquid separator 9 is connected to the main outlet II of the gas-liquid separator 9, which is connected to the inlet of the evaporator 10. The auxiliary outlet III of the gas-liquid separator 9 is connected to the low-pressure inlet III of the recooler 5. The low-pressure gas outlet IV of the recooler 5 is connected to the low-pressure gas inlet II of the ejector 12. The outlet of the evaporator 10 is connected to the inlet of the gas-liquid separator 11, and the outlet of the gas-liquid separator 11 is connected to the low-pressure inlet of the compressor 1. The outlet III of the ejector 12 is connected to the medium-pressure inlet of the compressor 1. This embodiment provides a novel refrigeration system for refrigerated trucks with improved evaporator utilization area and a hot gas bypass defrosting strategy, solving the problems of poor refrigeration efficiency, rapid evaporator frosting, and low defrosting efficiency under high pressure ratio conditions. In addition, in this embodiment, the gas-liquid separator separates the refrigerant into gas and liquid components through a gas-liquid separation baffle, storing the liquid in the separator's liquid collection chamber and the gas in the separator's gas collection chamber, respectively, and then bypasses the gas to improve the refrigerant dryness. The change in the structure of the distributor head can improve the refrigerant dryness and increase the distribution efficiency of the distributor head. It solves the prominent problems of excessively high condensing pressure, excessively high compressor compression ratio, excessively high exhaust temperature, and frequent protective shutdown of the compressor in the high-temperature refrigeration mode of refrigerated trucks. It can also solve the prominent problems of excessively low evaporation temperature, severe frost on the evaporator surface, excessively high compressor compression ratio, excessively high exhaust temperature, and sharp decline in heating capacity and energy efficiency ratio in the low-temperature refrigeration mode. It is of great significance to the development of the cold chain industry.

[0028] In this embodiment, the evaporator 10 is any one of a finned tube heat exchanger, a stacked heat exchanger, or a parallel flow heat exchanger; it can be adapted to different operating conditions. The evaporator allows the low-temperature, low-pressure liquid refrigerant to boil and evaporate under low pressure, absorbing heat from the medium being cooled (air, water, or object), thus cooling it down, and sending the evaporated gas back to the compressor, completing the heat transfer on the refrigeration side.

[0029] In this embodiment, the refrigerated vehicle refrigeration system also includes a liquid storage tank 4, and the outlet of the condenser 3 is connected to the inlet of the liquid storage tank 4; the outlet of the liquid storage tank 4 is connected to the high-pressure inlet I of the recooler 5. The condenser 3 is any one of a finned tube heat exchanger, a stacked heat exchanger, or a parallel flow heat exchanger.

[0030] Example 2: A refrigerated vehicle refrigeration system, further optimized from Example 1. This example includes an oil separator 2, with the outlet of compressor 1 connected to the inlet of oil separator 2, and the outlet of oil separator 2 connected to the inlet I of three-way diverter valve 14. Compressor 1 is any one of a fixed-frequency refrigeration compressor, a variable-speed refrigeration compressor, a digital scroll compressor, or a two-stage refrigeration compressor.

[0031] The refrigeration system for refrigerated vehicles also includes a filter dryer 6 and a sight glass 7. The high-pressure outlet II of the recooler 5 is connected sequentially to the filter dryer 6 and the sight glass 7, and then connected to the inlet of the expansion valve 8. The recooler 5 can be any one of a plate heat exchanger, a shell-and-tube heat exchanger, or a flash heat exchanger. The expansion valve 8 can be any one of a manual expansion valve, a flow-restricted expansion valve, a float expansion valve, a thermostatic expansion valve, or an electronic expansion valve with a throttling mechanism.

[0032] The auxiliary outlet III of the gas-liquid separator 9 is connected to the low-pressure inlet III of the recooler 5 via a one-way valve 15; the outlet III of the ejector 12 is connected to the medium-pressure inlet of the compressor 1 via a steam pressure regulating valve 13. The steam pressure regulating valve 13 is any one of a proportional regulating valve, a proportional-integral regulating valve, a proportional-derivative regulating valve, or a proportional-integral-derivative regulating valve controlled by the upstream pressure. The ejector 12 is any one of an equal-area mixing chamber ejector, an equal-pressure mixing chamber ejector, a single-stage ejector ejector, or a two-stage ejector ejector.

[0033] Specifically: the outlet of compressor 1 is connected to the inlet of oil separator 2, and the outlet of oil separator 2 is connected to the inlet I of three-way diverter valve 14; the defrost outlet II of three-way diverter valve 14 is connected to the inlet IV of gas-liquid separator head 9; the main outlet III of three-way diverter valve 14 is connected to the inlet of condenser 3; the auxiliary outlet IV of three-way diverter valve 14 is connected to the high-pressure inlet I of ejector 12; the outlet of condenser 3 is connected to the inlet of liquid receiver 4; the outlet of liquid receiver 4 is connected to the high-pressure inlet I of recooler 5; the high-pressure outlet II of recooler 5 is connected in sequence to dryer filter 6 and sight glass 7 and then connected to the inlet of expansion valve 8; the outlet of expansion valve 8 is connected to the inlet I of gas-liquid separator head 9; the main outlet II of gas-liquid separator head 9 is connected to the inlet of evaporator 10; the auxiliary outlet III of gas-liquid separator head 9 is connected to the low-pressure inlet III of recooler 5 through check valve 15. The low-pressure gas outlet IV of the recooler 5 is connected to the low-pressure gas inlet II of the ejector 12; the outlet of the evaporator 10 is connected to the inlet of the gas-liquid separator 11, and the outlet of the gas-liquid separator 11 is connected to the low-pressure inlet of the compressor 1; the outlet III of the ejector 12 is connected to the medium-pressure inlet of the compressor 1 through the evaporation pressure regulating valve 13.

[0034] Through the optimized matching and combination of the above-mentioned refrigeration system and the intelligent adjustment of the programmable logic controller (PLC), this utility model can realize four working modes:

[0035] 1. Conventional refrigeration operating mode

[0036] like Figure 2 The diagram shown is a flowchart of the conventional refrigeration operating mode. This operating mode can be used when the outside temperature is approximately between 15℃ and 35℃, the inside temperature is approximately between 0℃ and 10℃, and the refrigerated truck has just started operating, with a small system load and a small pressure difference. At this time, the pump or fan installed in conjunction with the compressor 1, condenser 2, and evaporator 10 starts, the inlet I of the expansion valve 8 and the main outlet III of the three-way diverter valve 14 starts, and the defrost outlet II and auxiliary outlet IV of the three-way diverter valve 14 are closed. Conventional refrigeration process: The high-temperature, high-pressure gaseous refrigerant discharged from compressor 1 enters inlet I of three-way diverter valve 14 through oil separator 2. After valve adjustment, it enters condenser 3 through main outlet III of three-way diverter valve 14, releasing heat and condensing into subcooled or saturated liquid refrigerant, which enters receiver tank 4. Then, it sequentially passes through recooler 5, dryer filter 6, and sight glass 7 into expansion valve 8. After throttling and pressure reduction in expansion valve 8, it becomes a low-temperature, low-pressure gas-liquid two-phase refrigerant. Then, it passes through gas-liquid separator type distributor 9 to send the low-temperature, low-pressure gas-liquid two-phase refrigerant into evaporator to absorb heat in the refrigeration chamber, becoming a vapor-liquid two-phase refrigerant or superheated refrigerant vapor. The refrigerant returns to gas-liquid separator 11 for gas-liquid separation and then enters the suction port of compressor 1. After compression by compressor 1, the high-temperature, high-pressure gaseous refrigerant is discharged, and the next cycle begins. The conventional refrigeration mode ensures refrigeration effect for refrigerated trucks while meeting normal driving needs.

[0037] 2. Ejector-pressurized intermediate gas injection cooling working mode

[0038] like Figure 3The diagram shown is a flowchart of the ejector-pressurized intermediate gas injection refrigeration working mode. This working mode can be used when the outside temperature is approximately 35℃~45℃, the inside temperature is approximately 0℃~10℃, the outside temperature is approximately 15℃~35℃, and the inside temperature is approximately −10℃~0℃, and the refrigerated truck has a large load and a large pressure difference. At this time, the pump or fan installed in conjunction with the compressor 1, condenser 2, and evaporator 10 starts, the expansion valve 8, the inlet I of the three-way diverter valve 14, the main outlet III of the three-way diverter valve 14, and the auxiliary outlet IV of the three-way diverter valve 14 start, and the defrost outlet II of the three-way diverter valve 14 closes. The ejector-pressurized intermediate gas-fueled refrigeration process is as follows: The high-temperature, high-pressure gaseous refrigerant discharged from compressor 1 is divided into two paths after passing through oil separator 2. The main refrigerant enters condenser 3 through the main outlet III of three-way diverter valve 14, releasing heat and condensing into subcooled or saturated liquid refrigerant, which then enters liquid receiver 4. It then enters recooler 5, dryer filter 6, and sight glass 7 before entering expansion valve 8. In expansion valve 8, it is throttled and depressurized, becoming a low-temperature, low-pressure gas-liquid two-phase refrigerant. Gas-liquid separator 9 further divides the low-temperature, low-pressure refrigerant into two paths. The high-dryness gas-liquid two-phase refrigerant from the main path is sent to evaporator to absorb heat from the refrigeration chamber, becoming a vapor-liquid two-phase refrigerant or superheated refrigerant vapor. It then undergoes gas-liquid separation through low-pressure gas-liquid separator 11. The refrigerant enters the suction port of compressor 1, and after being compressed by compressor 1, it is discharged as a high-temperature, high-pressure gaseous refrigerant, and begins the next cycle. The auxiliary refrigerant enters the high-pressure inlet of ejector 12 through the auxiliary outlet IV of the three-way diverter valve 14. The gaseous refrigerant bypassed by the gas-liquid separator 9 enters the low-pressure inlet of recooler 5 through check valve 15 to recool the main refrigerant. Then it enters the low-pressure inlet of ejector 12 and is ejected by the high-pressure gas from compressor 1. After passing through the mixing section of ejector 12, it becomes a medium-temperature, medium-pressure gaseous refrigerant. After being regulated by evaporation pressure regulating valve 13, it enters the medium-pressure inlet of compressor 1. After being compressed by compressor 1, it is discharged as a high-temperature, high-pressure gaseous refrigerant, and begins the next cycle. In the ejector-pressurized intermediate-gas-supplement refrigeration mode, the ejector ejects a low-speed or low-pressure cooling medium through a high-speed mainstream (such as high-pressure steam, compressed gas, or liquid). The ejected cryogenic refrigerant is then injected into the intermediate-pressure chamber to cool the working fluid during the compression process, avoiding the problem of a sharp rise in exhaust temperature caused by an excessively high compressor pressure ratio during low-temperature heating. This system increases the flow rate and mass flow rate of the cooling medium, enhances the cooling capacity under high-temperature environments, and overcomes the performance degradation of traditional single-stage compression systems under extreme conditions. Utilizing the existing high-pressure fluid energy of the system, no additional drive equipment is required, resulting in energy efficiency and high performance.

[0039] 3. Conventional hot gas bypass defrosting mode

[0040] like Figure 4The diagram shows the flow chart for the conventional hot gas bypass defrosting operation mode. When the outside temperature is approximately 15℃~35℃ and the inside temperature is approximately 2℃~7℃, the low temperature and high humidity environment causes frost to condense on the evaporator surface, which grows over time. This operation mode can be used when the frost layer is thin. At this time, the compressor 1, the inlet I of the three-way diverter valve 14, and the defrost outlet II of the three-way diverter valve 14 are started. The pump or fan installed on the condenser 2 and evaporator 10 are turned on after being turned off according to the control logic. The expansion valve 8, the main outlet III of the three-way diverter valve 14, and the auxiliary outlet IV of the three-way diverter valve 14 are closed. Conventional hot gas bypass defrosting process: The high-temperature and high-pressure gaseous refrigerant discharged from compressor 1 first passes through oil separator 2, then through the defrost outlet II of three-way diverter valve 14 into the defrost inlet IV of gas-liquid separation type distributor head 9. Then, the high-temperature and high-pressure gaseous refrigerant releases heat in evaporator 10 and condenses into low-temperature and low-pressure gaseous or gas-liquid two-phase refrigerant. Finally, it passes through gas-liquid separator 11 and enters the low-pressure suction port of compressor 1. After being compressed by compressor 1, the high-temperature and high-pressure gaseous refrigerant is discharged and begins the next cycle.

[0041] 4. Condensation heat utilization + hot gas bypass defrosting working mode

[0042] like Figure 5The diagram shows the working mode of condensation heat utilization + hot gas bypass defrosting. When the outside temperature is approximately 15℃~35℃ and the inside temperature is approximately -7℃~2℃, the low temperature and high humidity environment causes frost to condense rapidly on the surface of the evaporator. The frost layer thickens rapidly. When the temperature and humidity inside the refrigerator fluctuate frequently, this working mode can be used. The condensing heat utilization + hot gas bypass defrosting mode is divided into two stages: During the condensing heat utilization stage: the expansion valve 8 is open, and the pump or fan installed in the compressor 1, condenser 2, and evaporator 10, the inlet I of the three-way diverter valve 14, the main outlet III of the three-way diverter valve 14, and the auxiliary outlet IV of the three-way diverter valve 14 are all closed. The medium-temperature and high-pressure gas-liquid two-phase refrigerant in the condenser 3 and the liquid receiver 4 passes through the recooler 5, the dryer filter 6, the sight glass 7, and the expansion valve 8 in sequence. After passing through the throttling mechanism, it becomes a medium-temperature and low-pressure gas-liquid two-phase refrigerant. Then, after passing through the gas-liquid separation type liquid separator 9, it enters the evaporator 10 to condense and release heat, and is finally stored in the evaporator and the gas-liquid separator. During the hot gas bypass defrosting stage: Compressor 1, inlet I of the three-way diverter valve 14, and defrost outlet II of the three-way diverter valve 14 are activated. The pumps or fans installed on condenser 2 and evaporator 10 are turned on after being shut down according to the control logic. The main outlet III and auxiliary outlet IV of the three-way diverter valve 14 are closed. The high-temperature, high-pressure gaseous refrigerant discharged from compressor 1 first passes through oil separator 2, then through defrost outlet II of the three-way diverter valve 14, and enters the defrost inlet IV of the gas-liquid separator head 9. Then, the high-temperature, high-pressure gaseous refrigerant releases heat in the evaporator 10, condensing into a low-temperature, low-pressure gaseous or gas-liquid two-phase refrigerant. Finally, it passes through gas-liquid separator 11 and enters the low-pressure suction port of compressor 1. After compression by compressor 1, the high-temperature, high-pressure gaseous refrigerant is discharged, and the next cycle begins. The condensation heat utilization + hot gas bypass defrosting mode recovers the condensation heat that was originally discharged during defrosting, reducing defrosting energy consumption and improving the overall energy efficiency ratio.

[0043] This invention employs a hot gas bypass defrosting system, optimizing the defrosting mode control strategy. First, the high pressure of the condenser draws heat to the evaporator, increasing the mass flow rate of the defrosting loop. Then, the compressor introduces high-temperature, high-pressure refrigerant gas into the evaporator for defrosting. This high-mass-flow refrigerant gas provides more heat, quickly melting the frost layer on the evaporator surface and improving defrosting efficiency. Hot gas bypass defrosting evenly distributes heat to all parts of the evaporator, including the fins and pipes, thoroughly removing frost. This novel refrigeration system for refrigerated trucks, with its increased evaporator utilization area and hot gas bypass defrosting strategy, can be widely applied to various refrigerated trucks, cold storage facilities, and other low-temperature refrigeration scenarios.

[0044] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A refrigeration system for vehicles, comprising a compressor (1), a condenser (3), an expansion valve (8), and an evaporator (10), characterized in that: It also includes a recooler (5), a three-way diverter valve (14), and an ejector (12). The outlet of the compressor (1) is connected to the inlet I of the three-way diverter valve (14); the defrost outlet II of the three-way diverter valve (14) is connected to the inlet IV of the gas-liquid separator head (9); the main outlet III of the three-way diverter valve (14) is connected to the inlet of the condenser (3); the auxiliary outlet IV of the three-way diverter valve (14) is connected to the high-pressure inlet I of the ejector (12); the outlet of the condenser (3) is connected to the high-pressure inlet I of the recooler (5); and the high-pressure outlet II of the recooler (5) is connected to the inlet of the expansion valve (8). The outlet of valve (8) is connected to the inlet I of gas-liquid separator (9); the main outlet II of gas-liquid separator (9) is connected to the inlet of evaporator (10); the auxiliary outlet III of gas-liquid separator (9) is connected to the low-pressure inlet III of recooler (5); the low-pressure gas outlet IV of recooler (5) is connected to the low-pressure gas inlet II of ejector (12); the outlet of evaporator (10) is connected to the inlet of gas-liquid separator (11); the outlet of gas-liquid separator (11) is connected to the low-pressure inlet of compressor (1); the outlet III of ejector (12) is connected to the medium-pressure inlet of compressor (1).

2. The refrigeration system for vehicles according to claim 1, characterized in that: It also includes a liquid storage tank (4), the outlet of the condenser (3) is connected to the inlet of the liquid storage tank (4); the outlet of the liquid storage tank (4) is connected to the high-pressure inlet I of the recooler (5).

3. The refrigeration system for vehicles according to claim 1 or 2, characterized in that: It also includes an oil separator (2), the outlet of the compressor (1) is connected to the inlet of the oil separator (2), and the outlet of the oil separator (2) is connected to the inlet I of the three-way diverter valve (14).

4. The refrigeration system for vehicles according to claim 1, characterized in that: It also includes a dryer filter (6) and a sight glass (7). The high pressure outlet II of the recooler (5) is connected in sequence to the dryer filter (6), the sight glass (7), and then connected to the inlet of the expansion valve (8).

5. The refrigeration system for vehicles according to claim 1 or 4, characterized in that: The auxiliary outlet Ⅲ of the gas-liquid separation type distributor (9) is connected to the low-pressure inlet Ⅲ of the recooler (5) through a one-way valve (15); the outlet Ⅲ of the ejector (12) is connected to the medium-pressure inlet of the compressor (1) through a steam pressure regulating valve (13).

6. The refrigeration system for vehicles according to claim 5, characterized in that: The steam pressure regulating valve (13) is any one of the following: proportional regulating valve, proportional integral regulating valve, proportional derivative regulating valve, and proportional integral derivative regulating valve.

7. The refrigeration system for vehicles according to claim 1 or 5, characterized in that: The compressor (1) is any one of the following: fixed frequency refrigeration compressor, variable speed refrigeration compressor, digital scroll refrigeration compressor, and two-stage refrigeration compressor.

8. The refrigeration system for vehicles according to claim 1, characterized in that: The condenser (3) and the evaporator (10) are any one of the following: finned tube heat exchanger, stacked heat exchanger, and parallel flow heat exchanger.

9. The refrigeration system for vehicles according to claim 1, characterized in that: The ejector (12) is any one of the following: equal area mixing chamber ejector, equal pressure mixing chamber ejector, single-stage ejector ejector, and double-stage ejector ejector.

10. The refrigeration system for vehicles according to claim 1, characterized in that: The recooler (5) is any one of the plate heat exchanger, shell-and-tube heat exchanger, or flash heat exchanger.

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