Evaporator with secondary branch

Abstract

The utility model discloses a kind of evaporators with two-stage branch, belong to the heat exchange technical field of parking air conditioner, to solve the problem of wake interference, heat exchange efficiency is insufficient and temperature is uneven caused by coil full of traditional evaporator, indoor heat exchange unit body is equipped with first branch pipe and two-stage branch pipe, refrigerant first completes primary heat exchange by first, second inlet branch pipe, from gas-liquid mixed state conversion gas state, further absorb heat conversion superheated gas state by two-stage heat exchange of first to fourth branch pipe, realize the ladder type heat absorption process of " phase change+superheat", maximize utilization coil heat exchange area, improve the total amount of heat exchange in unit time, let parking air conditioner reduce indoor temperature under the scene of parking, shorten refrigeration response time.

Description

Technical Field

[0001] This utility model relates to the field of heat exchange technology for parking air conditioning, specifically to an optimized structure of the primary and secondary branch pipes of an evaporator for use in the cooling mode of a parking air conditioning system. Background Technology

[0002] A parking air conditioner is an air conditioner that operates on a battery while the vehicle is parked and waiting or resting. It is mainly used in large vehicles such as trucks and RVs. It does not rely on the vehicle's engine for power and can be directly connected to the vehicle's battery. It can work normally even when the engine is off.

[0003] The invention patent application 2025114222231, filed by the applicant, proposes a coil assembly for a parking air conditioning indoor heat exchange unit. This assembly features a parallel branch A with an upper inlet and lower outlet, and a branch B with a lower inlet and upper outlet, arranged in a cross pattern, along with a blank area on the windward side. This design aims to solve the problems of wake interference, insufficient air intake at the bottom, and uneven temperature caused by the full coverage of coils in traditional evaporators.

[0004] The technical solution in this application is a further improvement on the existing solution, with the aim of achieving higher heat exchange efficiency. Utility Model Content

[0005] To address the above issues, an evaporator with two-stage branches is proposed to solve the corresponding technical problems. The evaporator includes a main body, which comprises fins and coil assemblies inserted in the fins. The coil assembly includes at least two parallel refrigerant flow paths: a first intake branch pipe and a second intake branch pipe. The first intake branch pipe includes at least two parallel branch pipes: a third branch pipe and a fourth branch pipe. The second intake branch pipe includes at least two parallel branch pipes: a first branch pipe and a second branch pipe. The first, second, third, and fourth branch pipes all converge at the outlet pipe. The refrigerant enters the evaporator and undergoes primary heat exchange at the first and second intake manifolds, followed by secondary heat exchange at the first, second, third, and fourth manifolds.

[0006] The core structural innovation of "two-stage heat exchange + multi-stage parallel branch pipes" precisely matches the refrigerant phase change law with the evaporator heat exchange requirements, achieving multiple breakthroughs in heat exchange efficiency, system stability, oil film control, and scenario adaptability. Maximizing heat absorption capacity, the refrigerant first undergoes primary heat exchange through the first and second intake branch pipes, completing the basic phase change from a gas-liquid mixture to a gaseous state. Then, through secondary heat exchange in the first to fourth branch pipes, it further absorbs heat and transforms into a superheated gaseous state, forming a stepped heat absorption path of "phase change-superheating." This design allows the refrigerant to fully utilize the coil area at different heat exchange stages, significantly increasing the total heat exchange per unit time. This enables the parking air conditioner to quickly reduce the interior temperature in parked scenarios with the engine off, shortening the cooling response time.

[0007] Preferably, the main body is arranged vertically and has an upper region and a lower region; the first intake branch pipe guides the refrigerant through the upper region of the main body and then connects to the third branch pipe and the fourth branch pipe in parallel in the lower region of the main body; the second intake branch pipe guides the refrigerant through the lower region of the main body and then connects to the first branch pipe and the second branch pipe in parallel in the upper region of the main body.

[0008] After the first intake branch pipe covers the upper area of ​​the main body, it branches into the third and fourth branch pipes in the lower area; after the second intake branch pipe covers the lower area of ​​the main body, it branches into the first and second branch pipes in the upper area. This cross-branch layout allows the primary and secondary branch pipes to work together to cover the entire upper and lower areas of the main body, completely solving the problem of "dense flow channels in some areas and no flow channels in others" in traditional coils. This ensures that the air in the vehicle and the refrigerant flowing through the fins are in full contact, improving the overall cooling comfort.

[0009] Preferably, the main body is provided with a first column of tube holes, a second column of tube holes, and a third column of tube holes in the direction of the reverse airflow. The first and second air intake branches are located in the first column of tube holes and are divided into first, second, third, and fourth branches at the second column of tube holes. The first, second, third, and fourth branches converge at the air outlet after passing through the third column of tube holes.

[0010] This technical solution, through its core design of "orderly arrangement of three rows of tubes + precise matching of branch pipes for distribution and convergence," offers multiple advantages in heat exchange process optimization, airflow and refrigerant synergy, system stability, and production and maintenance. The primary branch pipes within the first row of tubes, namely the first and second inlet branch pipes, provide the initial heat exchange channel for the refrigerant's transformation from a gas-liquid mixture to a gaseous state, completing the basic phase change. The second row of tubes acts as a diversion node, allowing the refrigerant to smoothly enter the secondary branch pipes. The secondary branch pipes within the third row of tubes provide sufficient heat exchange for the refrigerant to further transform into a superheated gaseous state. The thermal space forms a stepped heat absorption path of phase change and superheating, ensuring that the refrigerant can fully contact the air at each heat exchange stage, increasing the total heat exchange per unit time, and enhancing the cooling response speed and cooling intensity of the parking air conditioner. The air flowing through the fins can form a counter-current heat exchange effect with the coil assembly. The air flow direction is opposite to the refrigerant heat exchange process, widening the temperature difference between the air and the refrigerant, increasing the heat transfer driving force, and avoiding the problem of temperature difference shrinkage and heat exchange efficiency reduction in the later stages of traditional co-current heat exchange, making heat exchange more thorough and reducing energy waste. At the same time, the fixed tube hole row serves as the installation positioning reference for the branch pipes, ensuring that the secondary branch pipes are evenly distributed in the third tube hole row without dead zones, effectively preventing refrigerant stagnation and congestion in local areas, and preventing the deposition of refrigeration oil due to uneven flow velocity. The high-speed flowing superheated gaseous refrigerant can more efficiently carry oil droplets back to the compressor, reducing oil residue in the coils and reducing the negative impact of oil film thermal resistance on heat exchange.

[0011] The arrangement of the coils optimizes the wind resistance distribution and reduces the energy consumption of the fan. The regular three-row tube hole layout makes the pipes on the fins more evenly blocked, and the wind resistance distribution when the airflow passes through the gap between the fins and the coil tends to be stable, avoiding the increase in fan load caused by excessive local wind resistance.

[0012] Preferably, the coiling dimension A of the first and second intake manifolds in the longitudinal height direction of the body is greater than the coiling dimension B of the first, second, third, and fourth manifolds.

[0013] This technical solution precisely matches the needs of staged heat exchange of refrigerant through the differentiated coiling dimensions of the primary and secondary branch pipes along the longitudinal height of the pipe body. This results in significant advantages in heat exchange efficiency, flow stability, space utilization, and system safety. When airflow passes through the indoor heat exchange unit, it first passes through the secondary branch pipe and then the primary branch pipe. The smaller windward area of ​​the secondary branch pipe does not obstruct the windward area of ​​the larger primary branch pipe, reducing wake interference. Furthermore, it ensures sufficient phase change in the primary heat exchange, achieving a foundation for efficient heat absorption. The primary branch pipe undertakes the core task of converting the refrigerant from a gas-liquid mixture to a gaseous state. Its larger longitudinal coiling dimension A means a more ample heat exchange area and a longer heat exchange path. This provides sufficient heat absorption time and space for the gas-liquid mixture refrigerant, ensuring that the refrigerant completes most of the phase change before entering the secondary branch pipe. This avoids uneven secondary heat exchange load due to insufficient phase change, thus improving the superheating efficiency of the secondary heat exchange and increasing the heat exchange intensity per unit area. The smaller coiling dimension B of the secondary branch pipe allows for a denser distribution in the longitudinal space. At this point, the refrigerant is already in a gaseous state, so there is no need for a large single branch coiling space. The densely distributed secondary branch pipes can increase the number of flow channels in a limited longitudinal area, increase the refrigerant flow rate, expand the frequency of contact with air, accelerate the conversion of gaseous refrigerant to superheated gas, significantly improve the heat exchange intensity per unit longitudinal height, and enhance the overall cooling capacity.

[0014] Preferably, on the windward side of the body, there are blank areas in the upper and lower regions of the third row of tube holes, and only fins are provided in the blank areas.

[0015] The third row of pipes corresponds to the secondary branch pipe area. The unobstructed areas above and below it provide a smoother airflow path, avoiding the airflow congestion caused by traditional full-area pipe layouts. This design effectively reduces overall wind resistance, lowering the power required by the fan for the same airflow output. The fins in the unobstructed areas guide airflow evenly across the entire windward surface, reducing localized eddies caused by wind speed differences between dense and sparse pipe areas. This allows airflow to flow more smoothly through the core heat exchange area containing the pipes, improving the contact efficiency between air and the coils and preventing heat waste caused by turbulent airflow.

[0016] Preferably, in the second row of tubes, the uppermost end is the first intake branch pipe, the lowermost end is the second intake branch pipe, and the first, second, third and fourth branch pipes are located between the first intake branch pipe and the second intake branch pipe.

[0017] This design achieves uniform flow distribution and reduces pressure loss. The second tube orifice is the transition area from the primary branch to the secondary branch. The first intake branch is located at the top of the second tube orifice, and the second intake branch is located at the bottom, forming a longitudinally symmetrical flow distribution starting point. The first to fourth branches in the middle area serve as the secondary branches after flow distribution, allowing the refrigerant in the primary branch to be distributed to each secondary branch along the shortest path, avoiding uneven flow distribution caused by branch intersections or chaotic layouts. This design reduces local eddies and pressure surges during refrigerant flow distribution, reduces system circulation resistance, and thus reduces the compressor operating load.

[0018] Preferably, the diameters of the first intake branch pipe, the second intake branch pipe, and the first, second, third, and fourth branch pipes are basically the same and are inserted into the pipe hole of the main body.

[0019] The branch pipes at all levels have essentially the same diameter, allowing for the use of standardized pipe materials for processing. This reduces differences in the procurement, cutting, and bending processes for different pipe specifications, lowering mold development and production management costs. Simultaneously, the standardized pipe diameter design facilitates mass production, improving efficiency and avoiding processing errors caused by diverse pipe diameters. The assembly process is simplified, and assembly accuracy is improved. The standardized pipe diameter of the branch pipes allows for precise matching with the main body's bore, eliminating the need for differentiated bore designs for different diameters and reducing the complexity of bore processing. During assembly, branch pipes at all levels can be inserted into the bores according to a unified standard, reducing installation difficulty and avoiding problems such as excessive gaps or insertion difficulties due to pipe diameter mismatches. This improves the assembly accuracy of the coil assembly and the main body, as well as product consistency.

[0020] The beneficial effects of this application will be further explained in specific embodiments. Attached Figure Description

[0021] Figure 1 The three-dimensional view of the parking air conditioner in this utility model after removing part of the upper cover; Figure 2 for Figure 1 The 3D view of the parking air conditioner after removing the evaporator has been further enhanced. Figure 3 This is a perspective view of the indoor heat exchange unit of the parking air conditioner in this utility model; Figure 4 for Figure 3 A diagram of the coil assembly after the fins have been removed; Figure 5 for Figure 4 A stereoscopic view from another perspective; Figure 6 for Figure 4 The left view; Figure 7 for Figure 4 Based on the colored diagrams of different pipelines.

[0022] In the diagram: 1. Base; 2. Indoor heat exchange unit; 3. Indoor fan; 4. Outdoor fan; 5. Outdoor heat exchange unit; 6. Compressor; 7. Controller; 8. Water tank windward baffle; 9. Water tank leeward baffle; 10. Support rib; 20. Inlet pipe; 21. First inlet branch pipe; 22. Second inlet branch pipe; 23. First branch pipe; 24. Second branch pipe; 25. Third branch pipe; 26. Fourth branch pipe; 27. First row of tube holes; 28. Second row of tube holes; 29. ​​Third row of tube holes; 30. Outlet pipe; 31. Blank area; A. Primary heat exchange area; B. Secondary heat exchange area Detailed Implementation

[0023] 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.

[0024] The parking air conditioner operates on the same principle as a conventional air conditioner. An indoor heat exchange unit 2, an indoor fan 3, a compressor 6, an outdoor heat exchange unit 5, an expansion valve, and a controller are installed on the base 1, forming a heat pump circulation system. The indoor heat exchange unit 2 and the outdoor heat exchange unit 5 can be selectively used as condensers or evaporators, respectively. When the indoor heat exchange unit 2 acts as a condenser, the parking air conditioner operates in heating mode; when the indoor heat exchange unit 2 acts as an evaporator, the parking air conditioner operates in cooling mode. On the outdoor side, due to the action of the outdoor fan 4, airflow from the outside environment is introduced through the outdoor air inlet, passes upwards through the outdoor heat exchange unit 5, and is further discharged upwards from the outdoor fan 4, completing the heat exchange between the outdoor air and the heat exchanger.

[0025] A water receiving trough is provided on the base 1. The water receiving trough has a windward baffle 8 and a leeward baffle 9, and a water guiding space between them. The water receiving trough is also provided with a support rib 10. The bottom of the indoor heat exchange unit 2 rests on the support rib 10 of the water receiving trough. When the indoor heat exchange unit 2 acts as an evaporator, the parking air conditioner operates in cooling mode. The refrigeration system of the parking air conditioner compresses the refrigerant into a high-temperature, high-pressure gas through the compressor. After being dissipated by the outdoor heat exchange unit 5, which acts as a condenser, it becomes a low-temperature, high-pressure liquid. The low-temperature, high-pressure liquid enters the indoor heat exchange unit 2, which acts as an evaporator, through the expansion valve or throttle valve and the air intake pipe 27. In the evaporator, it rapidly depressurizes and evaporates, absorbing a large amount of heat, causing the temperature of the evaporator fins and coils to drop below the air dew point, typically 5°C to 10°C. Water vapor in the air condenses upon contact with the condenser. During this process, the indoor fan 3 blows hot, humid air from the cab across the evaporator fins. When the humid air comes into contact with the low-temperature evaporator surface, the temperature of the water vapor in the air rapidly drops below the dew point temperature, and the water vapor loses heat and condenses into liquid water. As the indoor heat exchange unit 2, acting as the evaporator, operates, the condensed water droplets adhere to the fin surface of the indoor heat exchange unit 2, gradually accumulating into water droplets that flow down the fins and drip into the water collection tank of the base 1. The bottom of the water collection tank has a drain hole and a drain pipe to lead the condensate outside the vehicle for discharge, typically dripping onto the ground or under the vehicle.

[0026] In the entire unit, indoor heat exchange unit 2 is placed vertically. The condensate produced collects downwards due to gravity. However, the fin spacing is typically only 1.4-2.0 mm, making it easy for liquid water to form a "water film" or "water droplet bridge" between the fins. This reduces the cross-sectional area of ​​the airflow channel, significantly increasing airflow resistance. Ultimately, this results in a much lower actual airflow rate in the lower half of the fins compared to the upper half. Based on the heat calculation formula related to specific heat capacity: Q = cmΔt, where c is the specific heat capacity of air, m is the mass flow rate, and Δt is the temperature difference. Since the heat exchange rate is positively correlated with the air volume, the lower section cannot fully exchange heat with the low-temperature fins due to insufficient air volume, resulting in an uneven heat exchange phenomenon of "strong at the top and weak at the bottom". Because the fan power is usually lower when the vehicle is parked than when it is in motion, the air volume reserve is insufficient and it is more susceptible to the effects of condensate. This problem is particularly prominent in parking air conditioners.

[0027] Meanwhile, the applicant discovered that refrigerant oil negatively impacts the heat exchange efficiency of the coil assembly, forming an oil film with thermal resistance and hindering heat transfer. The compressor is the core component of the air conditioning refrigeration system, containing numerous high-speed moving parts, such as the piston and cylinder wall of a reciprocating compressor, and the rotor and vanes of a rotary compressor. These parts have precise clearances; without lubrication, severe friction occurs, leading to wear, overheating, and even seizure. Refrigerant oil forms a uniform oil film on the surface of the components, separating the metal contact surfaces and converting dry friction into liquid friction between the oil films, significantly reducing the coefficient of friction and wear, and extending the compressor's lifespan. The core purpose of mixing refrigerant oil into the air conditioning refrigerant is to provide crucial support for the stable operation of the compressor, while also ensuring the overall reliability of the air conditioning refrigeration system; its role permeates the core aspects of compressor operation. Therefore, in the air conditioning system, refrigerant oil enters the evaporator, condenser, and other coil assemblies along with the refrigerant, with some adhering to the inner wall of the coils, forming a continuous oil film. Because the thermal conductivity of refrigeration oil is much lower than that of the refrigerant and the metal of the coil, this oil film acts as a barrier to heat transfer. Therefore, in cooling mode, the low-temperature refrigerant in the evaporator coil needs to absorb heat from the air inside the vehicle. The oil film hinders the transfer of heat from the air to the refrigerant, resulting in decreased heat exchange efficiency and weakened air conditioning cooling capacity. If the refrigeration oil and refrigerant are not miscible, oil stratification may occur. That is, the denser refrigeration oil may deposit at the bottom of the coil or stagnate at bends or narrow points in the pipes, obstructing the flow path of the refrigerant within the coil and causing uneven flow distribution. In some areas, the refrigerant flow rate is too slow, failing to remove heat in time; in other areas, due to oil blockage, localized heat exchange failures, such as "empty coils," may even occur, further exacerbating the overall decrease in the heat exchange efficiency of the coil.

[0028] Experiments have shown that in refrigeration cycles, especially within the evaporator, increasing the flow rate of superheated gaseous refrigerant can, to some extent, reduce the thickness of the refrigerant oil film on the inner wall of the coil. The refrigerant oil film adheres to the inner wall of the coil through molecular adhesion and surface tension. Increased flow rate of the superheated gaseous refrigerant generates stronger fluid shear forces on the oil film. When the shear force exceeds the adhesion between the oil film and the coil wall, it will peel off part of the adhered oil film, reducing its thickness. This peeling effect is particularly significant for thicker oil films or locally deposited oil droplets. The high-speed flow of superheated gaseous refrigerant can also promote uniform flow of the oil film with the airflow, reducing the problem of excessively thick localized oil films and making the oil film thickness more uniform across the entire inner wall of the coil, thereby reducing the average oil film thermal resistance. Furthermore, increased flow rate of the superheated gaseous refrigerant enhances its ability to carry liquid oil droplets. The stripped oil film will mix into the refrigerant in the form of tiny oil droplets and flow back to the compressor with the high-speed airflow, reducing the amount of refrigeration oil remaining in the coil and further inhibiting the thickening of the oil film.

[0029] In this embodiment, the overall inventive concept is to comprehensively utilize the superheated refrigerant steam that accelerates flow to improve heat exchange performance while also ensuring the uniformity of coil arrangement.

[0030] Figures 3-6 As shown, the main body has a first row of tube holes 27, a second row of tube holes 28, and a third row of tube holes 29 sequentially arranged on the windward side along the direction of the airflow. Different branches of the coil assembly pass through each row of tube holes. The first intake branch pipe 21 and the second intake branch pipe 22 are located in the first row of tube holes 27. At the second row of tube holes 28, the flow splits to form the first branch pipe 23, the second branch pipe 24, the third branch pipe 25, and the fourth branch pipe 26. The above four branch pipes converge at the outlet pipe 30 after passing through the third row of tube holes 29. In addition, the windward side of the main body has blank areas in the upper and lower parts of the third row of tube holes 29. These blank areas are only equipped with fins, which can reduce the obstruction of airflow by the pipes, optimize the airflow path, reduce wind resistance, and improve the overall heat exchange utilization rate of the fins.

[0031] Specifically, the primary refrigeration branch consists of a first intake branch pipe 21 and a second intake branch pipe 22 arranged in parallel. The input ends of both branches are connected to the intake pipe to receive the low-temperature, low-pressure refrigerant after pressure reduction by the expansion valve. In terms of structural arrangement, the first intake branch pipe 21 guides the refrigerant through the upper region of the body, while the second intake branch pipe 22 guides the refrigerant through the lower region of the body. The two form an intersecting direction, which can fully cover the entire windward surface of the body, ensuring that the refrigerant has sufficient contact with the air flowing through the fins during the primary heat exchange stage and avoiding local heat exchange dead zones. In the second row of pipe holes 28, the uppermost end is the first intake branch pipe 21, and the lowermost end is the second intake branch pipe 22. This arrangement provides reasonable space for the subsequent secondary branches formed by diversion, and further optimizes the uniformity of refrigerant distribution along the longitudinal height of the body.

[0032] In addition, the coiling size A of the first intake branch pipe 21 and the second intake branch pipe 22 in the longitudinal height direction of the body is larger than the coiling size B of the subsequent secondary branch. The larger coiling size can ensure that the primary heat exchange stage has sufficient heat exchange area, providing the necessary heat exchange conditions for the refrigerant to change from a gas-liquid mixed state to a gaseous state, thus becoming the basis for efficient heat exchange.

[0033] The secondary refrigeration branch consists of the first branch pipe 23, the second branch pipe 24, the third branch pipe 25, and the fourth branch pipe 26. The third branch pipe 25 and the fourth branch pipe 26 are connected in parallel to the output end of the first intake branch pipe 21, and the first branch pipe 23 and the second branch pipe 24 are connected in parallel to the output end of the second intake branch pipe 22. The four branch pipes are parallel to each other and have the same upward direction. Their output ends converge at the outlet pipe 30.

[0034] In terms of structural design, the sum of the pipe diameters of the third branch pipe 25 and the fourth branch pipe 26 is greater than the sum of the pipe diameters of the first intake branch pipe 21, and the sum of the pipe diameters of the first branch pipe 23 and the second branch pipe 24 is greater than the sum of the pipe diameters of the second intake branch pipe 22. This design significantly increases the pipe volume after the refrigerant enters the secondary branch from the primary branch, which is conducive to the flow of superheated refrigerant vapor. On the other hand, it can make the refrigerant more evenly distributed in the secondary branch, avoiding the problem of local pipe refrigerant congestion or insufficient flow.

[0035] In terms of layout, the third branch pipe 25 and the fourth branch pipe 26 receive the refrigerant from the first intake branch pipe 21 and extend in the lower part of the body; the first branch pipe 23 and the second branch pipe 24 receive the refrigerant from the second intake branch pipe 22 and extend in the upper part of the body. Combined with the intersection of the primary branch pipes, this further improves the uniformity of refrigerant coverage on the entire windward side and vertical height of the body, ensuring all-round heat exchange with the air inside the vehicle.

[0036] When using the parking air conditioner: When the parking air conditioner is in cooling mode, the compressor starts and delivers high-temperature, high-pressure gaseous refrigerant to the condenser. The refrigerant releases heat in the condenser and condenses into a liquid state. After being depressurized by the expansion valve, it is transformed into a low-temperature, low-pressure gas-liquid mixture of refrigerant, which then enters the first-stage cooling branch of the indoor heat exchange unit through the intake pipe.

[0037] The gas-liquid mixture of refrigerant entering the first intake manifold 21 and the second intake manifold 22 exchanges heat with the air flowing through the fins during the first-stage heat exchange process. After absorbing heat from the air, the refrigerant gradually evaporates, changing from a gas-liquid mixture to a gaseous state. The gaseous refrigerant that has completed the first-stage heat exchange enters the corresponding second-stage refrigeration branches at the second row of tube holes 28. Specifically, the refrigerant from the first intake manifold 21 is diverted to the third manifold 25 and the fourth manifold 26, while the refrigerant from the second intake manifold 22 is diverted to the first manifold 23 and the second manifold 24.

[0038] During the secondary heat exchange process, the gaseous refrigerant continues to absorb heat from the vehicle's interior air in the larger and more evenly distributed secondary branch, further transforming into superheated gaseous refrigerant. Because the pipe diameter and area of ​​the secondary branch are larger than those of the primary branch, the refrigerant flow space is expanded, resulting in a more stable flow state. Simultaneously, the high-speed flow of the superheated gaseous refrigerant can flush away the refrigerant oil adhering to the inner wall of the coil, effectively reducing the thickness of the refrigerant oil film and minimizing its obstruction to heat exchange, thus significantly improving the heat exchange efficiency of the interior heat exchange unit. After completing the secondary heat exchange, the superheated gaseous refrigerant returns to the compressor via the outlet pipe 30, entering the next cycle and continuously providing cooling for the vehicle interior.

[0039] Refrigeration test: The refrigeration test was conducted in accordance with GB / T21361-2017 "Standard for Automotive Air Conditioners". As shown in the table above, the 2-inlet, 4-outlet evaporator of this application has a greater cooling capacity than the 2-inlet, 2-outlet evaporator, and also consumes less energy and has a higher energy efficiency ratio (EER / COP). This embodiment, through a staged heat exchange design of primary and secondary refrigeration branches, combined with the coordinated optimization of pipe diameter, layout, and orifice distribution, effectively improves heat exchange efficiency while ensuring heat exchange uniformity, reduces refrigerant flow resistance and the negative impact of refrigeration oil, and features a compact and reasonable structural layout that adapts to the installation space requirements of parking air conditioners, significantly improving the cooling performance and operational stability of parking air conditioners.

[0040] Furthermore, there is no need to reconstruct the core structure of the existing evaporator. The original horizontal pipe routing channels can still be used, and the original horizontal pipe routing channels of the evaporator can still be used. Only the selection of whether to use a certain pipe channel and the connection relationship between the coils needs to be made. There is no need to adjust the channel size or add new fixing structures. The original evaporator has reserved space for pipe turning in the vertical direction. The turning of the primary branch, secondary branch and the associated bend can be directly adjusted without adding new turning structures or changing the fin arrangement.

[0041] Compared to reconstructing the evaporator frame, this technical solution allows for maximum reuse of core components such as the fin forming mold and the frame stamping mold. Only the hole positions for primary and secondary supports need to be marked on the fin mold without altering the mold cavity. The production line adjustment cycle is short, and it can be directly integrated into existing mass production lines without requiring production shutdowns. Furthermore, the optimized solution's evaporator dimensions, refrigerant inlet / outlet, and fixing hole positions are completely identical to the original evaporator, allowing for direct replacement of existing parking air conditioner evaporators. Aftermarket modifications require no changes to the air conditioning unit, fan, or other peripheral components, facilitating widespread adoption.

[0042] It should be noted that the specific parameter values ​​given in this embodiment should not be construed as limiting the claims, but are used to illustrate the feasibility of the technical solution given in this embodiment.

[0043] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0044] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An evaporator with two-stage branches, comprising a body, the body including fins and coil assemblies inserted in the fins; characterized in that: The coil assembly includes at least a first intake branch pipe (21) and a second intake branch pipe (22) connected in parallel for refrigerant flow. The first intake branch pipe (21) includes at least a third branch pipe (25) and a fourth branch pipe (26) connected in parallel. The second intake branch pipe includes at least a first branch pipe (23) and a second branch pipe (24) connected in parallel. The first, second, third, and fourth branch pipes all converge at the outlet pipe (30). The refrigerant enters the evaporator and undergoes primary heat exchange at the first intake branch pipe (21) and the second intake branch pipe (22), followed by secondary heat exchange at the first, second, third and fourth branch pipes.

2. The evaporator with two-stage branches according to claim 1, characterized in that: The combined pipe diameter area of ​​the third branch pipe (25) and the fourth branch pipe (26) is greater than the pipe diameter area of ​​the first intake branch pipe (21); The pipe diameter area of ​​the first branch pipe (23) and the second branch pipe (24) is greater than the pipe diameter area of ​​the second intake branch pipe (22).

3. The evaporator with two-stage branches according to claim 1, characterized in that: The main body is vertically arranged and has an upper area and a lower area; The first intake branch pipe (21) guides the refrigerant through the upper part of the body and then connects to the third branch pipe (25) and the fourth branch pipe (26) in the lower part of the body. The second intake branch pipe (22) guides the refrigerant from the lower part of the body to the upper part of the body, where it is connected in parallel with the first branch pipe (23) and the second branch pipe (24).

4. The evaporator with two-stage branches according to claim 1, characterized in that: The main body is provided with a first row of tube holes (27), a second row of tube holes (28), and a third row of tube holes (29) in the direction of the reverse airflow. The first intake branch pipe (21) and the second intake branch pipe (22) are located in the first row of tube holes (27) and split into the first, second, third, and fourth branch pipes at the second row of tube holes (28). The first, second, third, and fourth branch pipes converge at the outlet pipe (30) after passing through the third row of tube holes (29).

5. The evaporator with two-stage branches according to claim 4, characterized in that: The coiling dimension A of the first intake branch pipe (21) and the second intake branch pipe (22) in the longitudinal height direction of the body is greater than the coiling dimension B of the first, second, third and fourth branch pipes.

6. The evaporator with two-stage branches according to claim 4, characterized in that: On the windward side of the main body, there are blank areas in the upper and lower parts of the third column of tube holes (29), and only fins are set in the blank areas.

7. The evaporator with two-stage branches according to claim 1, characterized in that: In the second row of pipe holes (28), the uppermost end is the first intake branch pipe (21) and the lowermost end is the second intake branch pipe (22). The first, second, third and fourth branch pipes are located between the first intake branch pipe (21) and the second intake branch pipe (22).

8. The evaporator with two-stage branches according to claim 1, characterized in that: The diameters of the first intake branch pipe (21), the second intake branch pipe (22), and the first, second, third, and fourth branch pipes are basically the same and are inserted into the pipe hole of the main body.

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