An arc-shaped manifold evaporator

Abstract

This invention provides an arc-shaped manifold evaporator, comprising an arc-shaped cover plate and an arc-shaped base plate. Microchannels are machined on the base plate. The cover plate includes a working fluid inlet, an inlet branching section, a manifold guide plate, an outlet confluence section, and a working fluid outlet. The microchannels are located in the middle of the base plate, with their length direction perpendicular to the length direction of the manifold guide plate. The manifold guide plate is located in the middle of the cover plate, corresponding to the position of the microchannels on the base plate. After the base plate and cover plate are assembled, the manifold guide plate is installed above the microchannels. A working fluid inlet and outlet are located diagonally at the top of the base plate, and the branching section is located between the manifold guide plate and the working fluid inlet and outlet. This invention designs an arc-shaped evaporator structure, which prolongs the working fluid flow time, increases the heat exchange area, and improves the heat transfer capacity. By adding a manifold guide plate structure to optimize the fluid flow path and shorten the working fluid flow path, pump power consumption can be reduced.

Description

Technical Field

[0001] This invention relates to heat exchanger technology, and more particularly to an arc-shaped flow equalization manifold evaporator used in a heat pipe heat exchanger. Background Technology

[0002] Heat exchangers are widely used in industries such as chemical, petroleum, refrigeration, nuclear power, and power. Due to the global energy crisis, the demand for heat exchangers in industrial production is increasing, and the quality requirements for heat exchangers are also becoming more stringent. In recent decades, compact heat exchangers (plate, plate-fin, and welded plate heat exchangers, etc.), heat pipe heat exchangers, and direct contact heat exchangers have developed rapidly. Heat exchangers are widely used in many fields. In fields such as electronics, petrochemicals, communications, and aerospace, due to their special working environments, there are special requirements for the size and weight of heat exchangers, as well as a need for stronger heat exchange capacity. In 1981, some scholars proposed using microchannels for heat dissipation, which can reduce the size of the heat exchanger and significantly improve its heat exchange capacity by utilizing the high specific surface area of ​​the microchannels. However, although the heat exchange capacity is strong, the overall pressure loss is also high due to the small hydraulic diameter of the microchannels.

[0003] Numerous studies have found that microchannel heat exchangers still suffer from uneven temperature distribution. In 1991, researchers proposed a manifold microchannel heat exchanger based on existing microchannel heat exchangers, significantly reducing its overall pressure loss. However, extensive research indicates that the fluid distribution within the manifold microchannels is not uniform, leading to uneven temperature distribution.

[0004] Patent CN202111291436.7 discloses a manifold shell-and-tube heat exchanger, a microchannel heat exchanger capable of exchanging heat between hot and cold fluids. It reduces overall pressure loss while also possessing the advantages of manifold impinging jets, enhancing fluid turbulence and heat exchange. Simultaneously, it ensures uniform fluid distribution and counter-current flow of hot and cold fluids, improving heat exchange efficiency. However, its flow distribution structure uses a conical channel, which still suffers from uneven fluid distribution; the design of the flow distribution section requires further optimization. It also exhibits problems such as low heat exchange efficiency and excessive flow resistance. Most existing evaporator structures are flat, making it difficult to dissipate heat from curved surfaces such as hydraulic cylinders and motors.

[0005] To address the aforementioned shortcomings, this invention improves upon existing evaporators by proposing a novel evaporator structure, an optimized scheme for a manifold microchannel structure in an arc-shaped evaporator, and an optimized design scheme for the evaporator flow divider section. These improvements enhance heat dissipation capacity, temperature uniformity, and enable heat dissipation for arc-shaped surfaces such as hydraulic cylinders and motors. Summary of the Invention

[0006] This invention provides a novel arc-shaped manifold evaporator, which improves the evaporator structure and thus solves the aforementioned technical problems.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] An arc-shaped manifold evaporator includes an arc-shaped cover plate and an arc-shaped base plate. Microchannels are machined on the base plate. The cover plate includes a working fluid inlet, an inlet branching section, a manifold guide plate, an outlet confluence section, and a working fluid outlet. The microchannels are located in the middle of the base plate, with their length direction perpendicular to the length direction of the manifold guide plate. The manifold guide plate is located in the middle of the cover plate, its position corresponding to the position of the microchannels on the base plate. After the base plate and cover plate are assembled, the manifold guide plate is installed above the microchannels. A working fluid inlet and outlet are located diagonally at the top of the cover plate, and the branching section is located between the manifold guide plate and the working fluid inlet and outlet.

[0009] An improvement is that the top of the cover plate is provided with a working medium inlet 1-1 and a working medium outlet 1-2, with the inlet and outlet of the working medium located at the diagonal position of the cover plate.

[0010] One improvement is that the manifold deflector is located in the middle of the bottom of the cover plate, and the deflector is obtained by a U-shaped periodic structure array.

[0011] One improvement is that the manifold guide plate has eight manifold inlets and manifold outlets, located at the openings of the U-shaped periodic units.

[0012] An improvement is made by providing an inlet diversion section 1-6 between the manifold inlet 1-4 and the working fluid inlet 1-1, and an outlet confluence section 1-7 between the manifold outlet 1-5 and the working fluid outlet 1-2, to ensure uniform distribution of the working fluid.

[0013] One improvement is that the inlet diversion section on the cover plate is obtained by constructing an equivalent flow resistance network model 5 and calculating the flow resistance of each segment of the inlet diversion section. The widths at the midpoints of each segment of the inlet diversion section are 9.5mm, 6.8mm, 4.3mm, 3.3mm, 2.6mm, 2.3mm, and 2.15mm.

[0014] An improved equivalent flow resistance network model has 7 individual loops. Analyzing at the diagonal nodes of each loop, the voltage drop across the two paths between nodes should be equal, satisfying the formula: [Formula omitted for brevity]

[0015] Formula 1

[0016] ,

[0017] In the formula This represents the flow resistance of the i-th inlet branch segment. The flow resistance of each segment is shown in Figure 2-5. The inlet branch segments closer to the working medium inlet have smaller numbers, while those farther from the working medium inlet have larger numbers. Similarly, ... This represents the flow resistance of the i-th outlet busbar, where the outlet busbars closer to the working medium outlet have smaller numbers, and the outlet busbars farther from the working medium outlet have larger numbers.

[0018] Preferably, the base plate has a microchannel structure, a thickness of 3.25 mm, a length of 80 mm, a width of 53.42 mm, and a bending angle of 60°.

[0019] Preferably, the evaporator bottom plate has 27 microchannels, each channel is 50.22mm long, 1mm wide, and 2mm high; the spacing between the microchannels is 1mm.

[0020] R134A is preferred as the working fluid.

[0021] Preferably, the working fluid flows into the evaporator working fluid inlet 1-1 through the pipeline and is evenly distributed into the 8 manifold inlets under the action of the inlet diversion section. The flow direction of the manifold guide plate is perpendicular to the extension direction of the microchannel. After the working fluid flows into the guide plate, it will flow into the microchannel below. The bottom of the microchannel is the heat source. The manifold microchannel structure increases the working fluid jet effect, enhances heat exchange, shortens the flow path of the working fluid in the microchannel, and reduces pressure loss.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] (1) The present invention is provided with an arc-shaped cover plate and an arc-shaped bottom plate. By setting the arc structure, the working fluid flow time is extended, the heat exchange area is increased, and the heat transfer capacity is improved.

[0024] (2) The arc-shaped structure can be directly fitted with motors, actuators, hydraulic cylinders, circular pipes, etc., reducing thermal resistance. The invention integrates manifold-type microchannels with an arc-shaped structure to obtain an arc-shaped evaporator. r arc length L radius of curvature R microchannel width in manifold microchannels Microchannel spacing Manifold deflector height Microchannel height , deflector plate and longboard The optimization formula for the length is proposed, and design specifications for different curvatures are put forward, which can guide the design of manifold microchannels under different curvature conditions.

[0025] , , ,

[0026] ,

[0027] ,

[0028] .

[0029] (3) Flow distribution is a critical issue in manifold microchannel structures, largely determining their heat transfer performance. The arc-shaped manifold evaporator proposed in this invention is equipped with an inlet branch section and an outlet merge section, and provides a design optimization method for the inlet branch section. This method constructs an equivalent flow resistance network model, uses nonlinear programming to calculate the width of the flow channels at each point in the inlet branch section, and obtains the design curve of the inlet branch section (outlet merge section).

[0030] ,

[0031] In the formula The length of the inlet branch section is 2-2 (the length is along the arc length of the evaporator). The width of the widest part of the inlet branch channel is 2-1. The distance from a certain point in the inlet diversion section to the working fluid inlet is 2-3. The distance between the inlet diversion section and the working medium inlet The width of the inlet branch channel is 2-4.

[0032] Compared to the conventional conical flow divider design, this method optimizes the working fluid flow path, improves temperature uniformity, and avoids local hot spots. It is also easy to calculate and has practical engineering significance. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the pump-driven two-phase circuit structure of the present invention.

[0034] Figure 2 This is a schematic diagram of a preferred evaporator cover structure of the present invention.

[0035] Figure 3 This is a schematic diagram of the preferred evaporator cover inlet diversion section structure of the present invention.

[0036] Figure 4 This is a schematic diagram of the preferred evaporator base plate structure of the present invention.

[0037] Figure 5 This is a preferred equivalent flow resistance network model diagram of the present invention.

[0038] Figure 6 This is a preferred structural diagram of the evaporator unit of the present invention. Detailed Implementation

[0039] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0040] Unless otherwise specified, in this article, " / " represents division, and "×" and "*" represent multiplication.

[0041] A mechanical pump drives a two-phase fluid circuit, such as Figure 1 As shown, the pump-driven two-phase circuit includes a mechanical pump 1, an evaporator 2, a condenser 3, a liquid receiver 4, a regenerator 5, a preheater 6, a sensor 7, and fuel oil 8. During operation, the subcooled single-phase working fluid, driven by the mechanical pump 1, is preheated by the regenerator 5 and preheater 6 until it reaches saturation temperature, then flows into the evaporator 2. The saturated working fluid undergoes a phase change in the evaporator 2, absorbing heat from the heat source. Subsequently, the two phases flow through the regenerator 5 again, exchanging heat with the subcooled working fluid, and then flow into the condenser 3, where heat is exchanged again and the heat is discharged. The condensed subcooled working fluid then enters the next working cycle. During system operation, the liquid receiver 4 can compensate for the working fluid in the main pipeline in real time, buffering system pressure fluctuations. The evaporator is the core heat transfer component of the pump-driven two-phase flow system. Currently, most pump-driven two-phase evaporators adopt a straight microchannel or ordinary manifold structure, and their heat transfer capacity, drag reduction effect, and temperature uniformity performance need to be improved.

[0042] As an improvement, such as Figure 2 , 3 As shown, the evaporator includes an arc-shaped cover plate and an arc-shaped base plate. Microchannels are machined on the base plate. The cover plate includes a working fluid inlet 1-1, an inlet branch section 1-6, a manifold guide plate, an outlet confluence section 1-7, and a working fluid outlet 1-2. The working fluid inlet connects to the inlet branch section, and the outlet confluence section connects to the working fluid outlet. The manifold guide plate includes a long plate and a bent plate, with the bent plate connecting adjacent long plates. The microchannels are located in the middle of the base plate, with their length direction perpendicular to the direction of the long plate of the manifold guide plate. The manifold guide plate is located in the middle of the cover plate, its position corresponding to the position of the microchannels on the base plate. After the base plate and cover plate are installed together, the manifold guide plate is installed above the microchannels. A working fluid outlet and a working fluid inlet are located diagonally at the top of the cover plate. The inlet branch section and the outlet confluence section are respectively located between the manifold guide plate and the working fluid outlet and inlet.

[0043] This invention provides an arc-shaped manifold evaporator, which features an arc-shaped cover plate and an arc-shaped bottom plate. By setting the arc-shaped structure, the flow time of the working fluid is extended, the heat exchange area is increased, and the heat transfer capacity is improved.

[0044] Preferably, the top of the cover plate is provided with a working fluid inlet 1-1 and a working fluid outlet 1-2, with the inlet and outlet located diagonally opposite each other at the top of the cover plate. Providing the inlet and outlet at the top eliminates the limitation imposed by thickness on the size of the inlet and outlet, buffers the working fluid flow rate, and improves flow uniformity.

[0045] The arc-shaped structure of this invention can directly fit with motors, actuators, hydraulic cylinders, circular pipes, etc., reducing thermal resistance. This invention integrates a manifold microchannel with an arc-shaped structure, obtaining optimized formulas for the arc radius of the arc-shaped evaporator and the width of the microchannel, the height of the manifold guide plate, and the lengths of the bent and long plates of the guide plate. Design specifications for different arc radii are proposed, guiding the design of manifold microchannels under various arc conditions. Simultaneously, a method for optimizing the design of the evaporator inlet flow branch section is proposed, and a formula for the flow channel width of the inlet flow branch section is given. This solves the problem of uneven flow in arc-shaped manifold evaporators, and the arc-shaped manifold microchannel can further increase the heat exchange area and extend the flow heat exchange time.

[0046] Preferably, the manifold guide vanes 1-3 are located in the middle of the bottom of the cover plate, and the guide vanes are formed by a U-shaped periodic structure array. Based on a series of simulation analyses, the length of the guide vane bending plates 1-9 is... Deflector plate length 1-10 and the height of the deflector It should meet the requirements of the evaporator arc length. L and evaporator curvature r Relationship:

[0047] , , .

[0048] Through the above optimizations, the problem of uneven flow in the arc-shaped manifold evaporator has been solved. The arc-shaped manifold microchannel can further increase the heat exchange area and extend the flow heat exchange time.

[0049] As a preferred option, the evaporator curvature r Preferably, the evaporator curvature radius is 60°-80°, and the curvature radius of the heat dissipation surface is consistent with that of the heat dissipation surface, which makes the arc-shaped manifold evaporator have stronger heat dissipation performance.

[0050] Further optimization yielded a manifold guide plate with a width of 0.8-1.2 mm, a length of 50-60 mm (preferably 56 mm), and a height of 1.8-2.2 mm. This size and structure satisfy the preferred dimensions for a manifold-type microchannel unit structure. This size also optimizes the working fluid flow path and reduces flow resistance.

[0051] Further optimization shows that the manifold guide plate has a width of 1mm, a length of 56mm, and a height of 2mm.

[0052] Preferably, the manifold guide plate has eight manifold inlets 1-4 and manifold outlets 1-5, located at the openings of the periodic units. Based on a series of simulation analyses, the widths of the manifold inlets and outlets 1-8 should satisfy the following relationship:

[0053] .

[0054] At this size, the optimization of the working fluid flow path is effective, and the flow resistance is lower.

[0055] As a preferred option, an inlet diversion section 1-6 is designed between the manifold inlet 1-4 and the working fluid inlet 1-1, and an outlet confluence section 1-7 is provided between the manifold outlet 1-5 and the working fluid outlet 1-2 to ensure uniform distribution of the working fluid.

[0056] As a preferred embodiment, the inlet diversion section on the cover plate is constructed by building an equivalent flow resistance network model ( Figure 5 The inlet flow divider is calculated by dividing the inlet flow divider into 7 segments by 8 manifold inlets 1-5. The i-th segment is the flow segment sandwiched between the i-th manifold inlet closest to the working fluid inlet 1-1 and the (i+1)-th manifold inlet. The width at the midpoint of the i-th segment is... The width direction is along the length direction of the manifold guide vane.

[0057] As a preferred option, the equivalent flow resistance network model has 8 loops. Analyzing at the diagonal nodes of each loop, the pressure drop of the two paths between the nodes should be equal and satisfy the formula:

[0058] ,

[0059] In the formula This represents the flow resistance of the i-th inlet branch segment, which is the flow resistance of the inlet branch segment sandwiched between the i-th manifold inlet and the (i+1)-th manifold inlet closest to the working fluid inlet 1-1. Similarly... This represents the flow resistance of the i-th outlet manifold, which is the flow resistance of the outlet manifold sandwiched between the i-th manifold outlet and the (i+1)-th manifold outlet, which are close to the working fluid outlets 1-2.

[0060] As a preferred method, nonlinear programming is used to solve the problem. This ensures that the inlet branch section satisfies the following conditions: monotonic rate of change of flow resistance, minimum amplitude of flow resistance change, and minimum overall average flow resistance. The final determination is...

[0061] , , .

[0062] As a preferred option, according to the flow resistance calculation formula

[0063] ,

[0064] The width at the midpoint of each segment of the inlet diversion section is calculated. In the formula... For dynamic viscosity, L For the flow channel length, H For the height of the flow channel, W This refers to the width of the flow channel.

[0065] The calculated width at the midpoint of the i-th inlet diversion segment is:

[0066] ,

[0067] In the formula, represents the ratio of flow resistance. .

[0068] Inlet diversion section (outlet merging section) design curve

[0069] ,

[0070] In the formula The length of the inlet branch section is 2-2 (the length is along the arc length of the evaporator). The width of the widest part of the inlet branch channel is 2-1. The distance from a certain point in the inlet diversion section to the working fluid inlet is 2-3. The distance between the inlet diversion section and the working medium inlet The width of the inlet branch channel is 2-4.

[0071] Theoretically, this ensures that the working fluid is evenly distributed to the inlet of each manifold guide plate after it flows in.

[0072] Further optimization revealed that the channel widths at the midpoints of each segment (2-4) were 9.5mm, 6.8mm, 4.3mm, 3.3mm, 2.6mm, 2.3mm, and 2.15mm, respectively.

[0073] Preferably, the base plate has a microchannel structure and a thickness of 2.5 mm. 3.5mm, length 80mm, width 52mm 54mm, bending angle 60°. This size structure meets the preferred dimensions for a manifold microchannel unit structure. This size optimizes the working fluid flow path and reduces flow resistance.

[0074] This structural dimension satisfies the following formula, representing the optimal dimensions for the arc-shaped manifold evaporator microchannel unit structure. It effectively increases the effective heat exchange area of ​​the arc-shaped manifold evaporator microchannel structure, prolongs the working fluid flow heat exchange time, enhances the jet impact effect, and improves heat transfer. It also avoids the occurrence of localized hot spots in the arc-shaped heat dissipation structure used in traditional manifold microchannel applications.

[0075] ,

[0076] ,

[0077] ,

[0078] In the formula For microchannel width, For microchannel spacing,R The radius of curvature of the arc-shaped evaporator. r In radians, For microchannel height, This refers to the thickness of the base plate.

[0079] R134A is preferred as the working fluid. R134A has a high latent heat of vaporization, low dynamic viscosity, a suitable operating temperature range, and is non-toxic, harmless, safe, and stable, making it a commonly used two-phase working fluid.

[0080] Further optimization shows that the number of microchannels 3-1 on the evaporator bottom plate is 27, with each channel being 50.22 mm long, 1 mm wide, and 2 mm high; the spacing between microchannels 3-2 is 1 mm, and the radius of curvature is 50.75 mm.

[0081] Preferably, the working fluid flows into the evaporator working fluid inlet 1-1 through the pipeline and is evenly distributed into the 8 manifold inlets under the action of the inlet diversion section. The flow direction of the manifold guide plate is perpendicular to the extension direction of the microchannel. After the working fluid flows into the guide plate, it will flow into the microchannel below. The bottom of the microchannel is the heat source. The manifold microchannel structure increases the working fluid jet effect, enhances heat exchange, shortens the flow path of the working fluid in the microchannel, and reduces pressure loss.

[0082] This patent provides a novel evaporator for a pump-driven two-phase system, with the following innovations: (1) An innovative design of the evaporator inlet branch section and outlet confluence section. By constructing an equivalent flow resistance network model, assuming that the flow rates at the inlet and outlet of each manifold are the same, the flow resistance of each flow segment corresponding to each inlet is calculated, thereby obtaining the width of the midpoint of each segment of the inlet branch section. The calculation process is achieved through nonlinear programming, ensuring uniform flow resistance variation and small overall flow resistance. (2) An innovative design of a manifold microchannel structure. The evaporator consists of a bottom plate and a cover plate. Microchannels are provided on the bottom plate, and manifold guide plates are provided on the cover plate. When the bottom plate and cover plate are installed, a manifold microchannel structure is formed. Through two-phase heat and mass transfer finite element analysis, the optimal microchannel width, thickness, spacing, and manifold guide plate width and height are selected to enhance the heat transfer and reduce flow resistance of the manifold microchannel. The optimal dimensions are as follows:

[0083] , , ,

[0084] ,

[0085] ,

[0086] .

[0087] While the present invention has been disclosed above with reference to preferred embodiments, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. An arc-shaped manifold evaporator, the evaporator comprising an arc-shaped cover plate and an arc-shaped base plate, the base plate having microchannels machined thereon, the bottom of the cover plate comprising a first working fluid inlet, an inlet branching section, a manifold guide plate, an outlet confluence section, and a first working fluid outlet; the first working fluid inlet connecting to the inlet branching section, and the outlet confluence section connecting to the first working fluid outlet; the manifold guide plate comprising a long plate and a bent plate, the bent plate connecting adjacent long plates, the microchannels being disposed in the middle of the base plate, the length direction of the microchannels being perpendicular to the length direction of the manifold guide plate; the manifold guide plate being disposed in the middle of the cover plate, the position of the manifold guide plate corresponding to the position of the microchannels on the base plate, the manifold guide plate being installed above the microchannels after the base plate and the cover plate are combined and installed; a second working fluid outlet and a second working fluid inlet are disposed at the diagonal of the top of the cover plate, the inlet branching section and the outlet confluence section being respectively disposed between the manifold guide plate and the first working fluid inlet and the second working fluid outlet, the length of the bent plate of the manifold guide plate being... Length of manifold guide plate and manifold guide plate height It should meet the requirements of the evaporator arc length. L and evaporator curvature r Relationship: , , 。 2. The arc-shaped manifold evaporator as described in claim 1, characterized in that, The manifold guide plate is equipped with 8 manifold inlets and manifold outlets. The inlet flow branch section on the cover plate is obtained by constructing an equivalent flow resistance network model and calculating the flow resistance of each section of the inlet flow branch section. The widths of the flow channels at the midpoints of each section of the inlet flow branch section are 9.5mm, 6.8mm, 4.3mm, 3.3mm, 2.6mm, 2.3mm, and 2.15mm.

3. The arc-shaped manifold evaporator as described in claim 2, characterized in that, The equivalent flow resistance network model has 7 individual loops. Analyzing at the diagonal nodes of each loop, the pressure drop of the two paths between nodes should be equal, and the outlet confluence and inlet branch sections should be structurally symmetrical. Satisfying the formula: Formula 1 ， In the formula This represents the flow resistance of the i-th inlet branch segment. Inlet branch segments closer to the first working fluid inlet have smaller numbers, while those farther from the first working fluid inlet have larger numbers. Similarly... This represents the flow resistance of the i-th outlet busbar, where the outlet busbars closer to the second working medium outlet have smaller numbers, and the outlet busbars farther from the second working medium outlet have larger numbers.

4. The arc-shaped manifold evaporator as described in claim 3, characterized in that, Solving through nonlinear programming To ensure that the inlet branch section satisfies the following conditions: monotonic rate of change of flow resistance, minimum amplitude of flow resistance change, and minimum overall average flow resistance, the following is ultimately established: , , 。 5. The arc-shaped manifold evaporator as described in claim 1, characterized in that, The base plate has a microchannel structure, a thickness of 3.25mm, a length of 80mm, a width of 53.42mm, and a bending angle of 60°.

6. The arc-shaped manifold evaporator as described in claim 1, characterized in that, The evaporator base plate has 27 microchannels, each channel is 50.22mm long, 1mm wide, and 2mm high; the spacing between the microchannels is 1mm.

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