CN215832535U

CN215832535U - Mixed rib heat exchanger core and heat exchanger

Info

Publication number: CN215832535U
Application number: CN202122241327.6U
Authority: CN
Inventors: 李利昂; 邓宏武; 李华
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2021-09-16
Filing date: 2021-09-16
Publication date: 2022-02-15
Anticipated expiration: 2031-09-16

Abstract

The utility model discloses a mixed rib row heat exchanger core and a heat exchanger, which comprise a heat exchange unit, wherein the heat exchange unit comprises an upper layer rib row plate, a lower layer rib row plate and an inner partition plate, ribs of the upper layer rib row plate and ribs of the lower layer rib row plate are mutually staggered, the upper rib and the lower rib are intersected at the boundary of the heat exchange unit, two opposite sides of the heat exchange unit are provided with side baffles, and the other two opposite sides of the heat exchange unit are provided with an inlet and an outlet; an in-layer partition plate is arranged between the upper rib row plate piece and the lower rib row plate piece, through holes are formed in the positions of the partition plate in the layer, projected from the area enclosed by the ribs of the upper rib row plate piece, the ribs of the lower rib row plate piece and the side baffle plate, and cold medium fluid and heat medium fluid are respectively introduced into adjacent inter-rib flow channels of the lower rib row plate piece. The utility model reduces the heat exchange distance of cold and hot fluid, effectively improves the specific surface area of the heat exchanger, strengthens the heat exchange performance, and has high strength and high reliability.

Description

Mixed rib heat exchanger core and heat exchanger

Technical Field

The utility model belongs to the technical field of heat exchangers, and relates to a core body of a mixed rib heat exchanger and a heat exchanger.

Background

The volume of an early shell-and-tube Heat Exchanger is too large and designed coarsely, as shown in fig. 1-2, so that the Heat Exchanger has to be developed towards miniaturization and refinement of an internal structure under the design constraints of cost and efficiency, a plate-fin Heat Exchanger which appears later has higher Heat transfer efficiency and tends to replace a traditional shell-and-tube Heat Exchanger, but the weak points in the aspects of pressure resistance and corrosion resistance brought by processes such as brazing and the like always limit the application occasions, so that a more advanced diffusion welding process and a Printed Circuit plate Heat Exchanger (PCHE), or called a diffusion welding Compact Heat Exchanger (Diffusion-bonded Compact Heat Exchanger, DCHE) are generated, and plate welding is realized by utilizing intermolecular diffusion, and the strength is extremely high (close to the strength of a base material). The most common heat exchanger is a single-phase dividing wall type heat exchanger because of its stable heat exchange and high reliability.

From the basic formula of heat transfer science: q = hA delta T, and the heat exchange strengthening measures are generally three, namely, the heat exchange temperature difference delta T is increased, the heat exchange area A is increased, and the total heat exchange coefficient h is increased. However, for a single-phase dividing wall type heat exchanger which determines working conditions and uses simple working media, the heat transfer temperature difference is improved by adopting a scheme of counter-flow and cross-flow arrangement of cold and hot fluids, and the temperature difference can be changed almost without other modes; therefore, the increase of the heat exchange area and the heat transfer coefficient become two main enhanced heat exchange means. The increase of the heat exchange area is usually realized by adding turbulence structures such as fins and the like and secondary heat exchange surfaces, and the increase of the heat transfer coefficient is mainly realized by disturbance such as jet flow, impact, rotation and the like of fluid. These designs are all embodied in designs such as corrugated plate heat exchangers, spiral baffle shell and tube heat exchangers, and the like.

However, the heat exchange capacity of these heat exchangers is still limited, and since the hydraulic diameter of the channel is usually near the conventional dimension and above the micro dimension, and the cold and hot fluids are not disturbed sufficiently, and the cold and hot fluids are relatively independent, the specific surface area of the heat exchanger is small, the heat exchange effect is not good, and further the volume and weight of the heat exchanger are large. The existing plate heat exchanger is mostly sealed by a sealing ring, plates are fastened and connected through bolts, the pressure resistance is limited, and special medium fluid cannot be adopted.

Disclosure of Invention

In order to solve the problems, the utility model provides a core body of a mixed rib heat exchanger, which reduces the heat exchange distance of cold and hot fluids, effectively improves the specific surface area of the heat exchanger, strengthens the heat exchange performance, and has high compressive strength, high reliability and easy processing.

Another object of the present invention is to provide a heat exchanger.

The utility model adopts the technical scheme that the core body of the hybrid rib row heat exchanger comprises a heat exchange unit, wherein the heat exchange unit comprises an upper layer rib row plate, a lower layer rib row plate and an inner partition plate, ribs of the upper layer rib row plate and ribs of the lower layer rib row plate are mutually staggered, the upper rib and the lower rib are intersected at the boundary of the heat exchange unit, two opposite sides of the heat exchange unit are provided with side baffles, and the other two opposite sides of the heat exchange unit are provided with an inlet and an outlet; an in-layer partition plate is arranged between the upper rib row plate piece and the lower rib row plate piece, through holes are formed in the positions of the partition plate in the layer, projected from the area enclosed by the ribs of the upper rib row plate piece, the ribs of the lower rib row plate piece and the side baffle plate, and cold medium fluid and heat medium fluid are respectively introduced into adjacent inter-rib flow channels of the lower rib row plate piece.

Furthermore, the cold fluid flows to the side baffle plate along the intercostal flow channel of the lower rib row plate and then turns to the intercostal flow channel of the upper rib row plate through the through hole, and continues to flow to the other side baffle plate and then enters the intercostal flow channel of the lower rib row plate through the through hole, and the process is repeated until the cold fluid flows out from the outlet of the heat exchange unit, and the flowing mode of the hot fluid is the same as that of the cold fluid.

Furthermore, the through holes are triangular.

Furthermore, interlayer clapboards are arranged at the upper part of the upper rib row plate and the bottom of the lower rib row plate.

Furthermore, a plurality of heat exchange units are stacked up and down, an interlayer partition plate is arranged at the bottom of the lower rib row plate of each heat exchange unit, and the upper part of the upper rib row plate and the bottom of the upper heat exchange unit share one interlayer partition plate.

Furthermore, every N heat exchange units are provided with through holes on one interlayer partition plate, the arrangement mode of the through holes is the same as that of the interlayer partition plates, and N is not less than 1 and is less than the total number of the heat exchange units.

Furthermore, the thickness of the layer spacing plate is 0.1 mm-4 mm.

Further, the thickness of the upper rib row plate and the thickness of the lower rib row plate are both 0.2 mm-6 mm.

Further, the cross sections of the adjacent intercostal flow channels of the upper rib row plate sheet and the adjacent intercostal flow channels of the lower rib row plate sheet are all in width-to-height ratio (0.2-5): 1, in a rectangular shape.

A heat exchanger comprises the mixed rib row heat exchanger core.

The utility model has the beneficial effects that:

1. the heat exchange core body realizes two-dimensional flow distribution of cold and hot fluid in the rib rows on the same layer through the arrangement of the mixed rib rows; compared with the existing heat exchanger, the utility model reduces the heat exchange distance of the cold fluid and the hot fluid, increases the specific surface area of the heat exchanger, realizes heat exchange reinforcement, is a high heat flow density heat exchange structure, and is particularly suitable for products such as aircraft engines needing high-strength heat exchange.

2. The heat exchange core body of the utility model adopts the straight ribs to form the turning channels, forces the fluid to periodically turn up and down, and the pressure difference at the staggered positions inside the heat exchange core body causes series flow and shearing flow, and can self-coordinately strengthen the longitudinal vortex caused by the turning, so that the disturbance increases the turbulence intensity and strengthens the heat exchange.

3. The heat exchange core body can be realized by adopting the processes of laser cutting/water cutting/corrosion carving, surface grinding, diffusion welding and the like, and has high overall strength, high precision and high reliability; the requirements of high-efficiency heat exchange such as aerospace and the like are met.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a first structure of a conventional heat exchanger.

In FIG. 1, 1 is a separator, 2 is a seal, and 3 is a fin;

fig. 2 shows a second structure of a conventional heat exchanger.

In figure 2, 1 is a seal head, 2 is a shell, 3 is a heat exchange tube, 4 is a baffle plate, and 5 is a tube plate.

Fig. 3 is a schematic view of a core structure according to an embodiment of the present invention.

FIG. 4 is a top view of the sheets of example 1 of the present invention.

Fig. 5a-5b are schematic views of the distribution of fluid in the core structure of example 1 of the present invention.

Fig. 6 is a simulation diagram of embodiment 1 of the present invention.

In fig. 3-6, 1 is an upper rib row plate, 2 is an inner partition, 3 is a lower rib row plate, 4 is an interlayer partition, 5 is a through hole, 6 is a side baffle, 7 is a cooling medium fluid, and 8 is a heating medium fluid.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the case of the example 1, the following examples are given,

a mixed rib row heat exchanger core body is structurally shown in figures 3-4 and comprises a heat exchange unit, wherein the heat exchange unit comprises upper-layer rib row plate pieces 1, lower-layer rib row plate pieces 3 and an inner partition plate 2, the upper-layer rib row plate pieces 1 and the lower-layer rib row plate pieces 3 are mutually staggered, ribs of the upper-layer rib row plate pieces 1 and ribs of the lower-layer rib row plate pieces 3 are intersected at the boundary of the heat exchange unit, side baffles 6 are arranged on two opposite sides of the heat exchange unit, and an inlet and an outlet are arranged on the other two opposite sides of the heat exchange unit; an in-layer partition plate 2 is arranged between the upper-layer rib row plate piece 1 and the lower-layer rib row plate piece 3, a through hole 5 is formed in the position of the in-layer partition plate 2 in a projection manner of a region enclosed by the ribs of the upper-layer rib row plate piece 1 and the side baffle 6 of the lower-layer rib row plate piece 3, a cold medium fluid 7 and a hot medium fluid 8 are respectively introduced into adjacent intercostal channels of the lower-layer rib row plate piece 3, the cold medium fluid 7 flows to the position of the side baffle 6 along the intercostal channels of the lower-layer rib row plate piece 3 and is inverted to the intercostal channels of the upper-layer rib row plate piece 1 through the through hole 5, the cold medium fluid continues to flow to the position of the other side baffle 6 and enters the intercostal channels of the lower-layer rib row plate piece 3 through the through hole 5, the operation is repeated until the cold fluid flows out from an outlet of the heat exchange unit, and the flowing mode of the hot fluid is the same as that of the cold fluid.

The through holes 5 are triangular, and the size of the through holes 5 is required to be as large as possible, but the two fluids in the upper layer and the lower layer cannot be mixed. The upper part of the upper rib row plate 1 and the bottom of the lower rib row plate 3 are both provided with an interlayer clapboard 4.

As shown in fig. 5a-5b, the front and rear sides of the heat exchange unit are respectively provided with an inlet and an outlet, the left and right sides of the heat exchange unit are both provided with side baffles 6, and the inlets of the cold medium fluid 7 and the hot medium fluid 8 are arranged at intervals at the front side of the heat exchange unit and are symmetrical with respect to the width direction of the heat exchange unit, so as to ensure that the cold medium fluid 7 and the hot medium fluid 8 independently and closely surround flow in the heat exchange unit. The simulation figure is shown in fig. 6, and it can be seen from fig. 6 that the cold and hot fluids are tightly interlaced together, and the distance between the cold and hot fluids is extremely short, so that the heat exchange is enhanced.

In some embodiments, the sheets are arranged in a circle or other shape.

In some embodiments, a mixed rib heat exchanger core is formed by stacking a plurality of heat exchange units up and down, wherein an interlayer partition plate 4 is arranged at the bottom of a lower rib plate 3 of each heat exchange unit, and the upper part of an upper rib plate 1 and the bottom of an upper heat exchange unit share one interlayer partition plate 4; every N heat exchange units are provided with through holes 5 on one interlayer partition plate 4, the arrangement mode of the through holes 5 is the same as that of the interlayer partition plates 2, and N is not less than 1 and is less than the total number of the heat exchange units.

In some embodiments, the flow area ratios of the cold and hot fluids are different, the projection length a1 of the flow channel width of the first fluid in the inlet direction, the projection length a2 of the flow channel width of the second fluid in the inlet direction, a1 ≠ a2, therefore, the flow channel area ratio of the two fluids is a1/a2, the ratio range depends on the flow rate and the flow resistance design value of the two fluids, the flow resistance design requirement should be satisfied as a first principle, and when the fluid on one side cannot satisfy the resistance requirement, the flow channel area on the side is appropriately increased.

In some embodiments, the cross section of the flow channel between adjacent ribs has an aspect ratio (0.2-5): 1, when the cross section of the flow channel between adjacent ribs in the prior art (patent of invention publication No. CN 101100951A) is square, the influence of the limitation of the ribs on the heat exchange efficiency is very large, while the influence of the limitation of the ribs is very small in the embodiment 1 of the application, and the average heat exchange coefficient is improved. Of course, the heat exchange is promoted in various ways, and the cross section shape of the channel is optimized to be in an aspect ratio (0.2-5) under the condition of fixed hydraulic diameter: 1, including square, but preferably if the hydraulic diameter can be reduced. In practical application, the pressure drop can be obviously increased by reducing the hydraulic diameter, the pressure drop requirement cannot be met, and meanwhile, the machining cost is increased linearly by further reducing the hydraulic diameter and touching a machining boundary (with a precision problem).

In some embodiments, the rib width is as small as possible and the spacer is as thin as possible. The thickness of the interlayer partition plate 4 is 0.1 mm-4 mm, and the thickness of the upper rib row plate sheet 1 and the thickness of the lower rib row plate sheet 3 are both 0.2 mm-6 mm; the width of the flow channel between adjacent ribs is 0.2-6 mm, and the rib width of the upper rib row plate sheet 1 and the lower rib row plate sheet 3 is 0.2-4 mm.

In the case of the example 2, the following examples are given,

a heat exchanger comprising the heat exchange core of embodiment 1.

In the prior art (patent publication No. CN 101100951A), the cooling cavity is divided into a plurality of small secondary fluid channels by two sets of staggered ribs inclined at angles β and- β; the inner parts of the two groups of staggered ribs are filled with cooling medium fluid to exchange heat with the outer parts of the two groups of staggered ribs, so that the full heat exchange between cold and hot fluids is obviously limited, and particularly, the heat transfer of the heat exchange enhancement area on the side surface of the rib needs to be transferred through the thermal resistance of the rib (namely, the rib efficiency exists), thereby causing the attenuation of the thermal efficiency. In practical applications, in order to obtain lower core weight (increased porosity), lower pressure drop and relatively larger flow area, the rib height is usually larger than the rib width and the partition thickness, and this design has the disadvantage that the heat exchange distance between the two fluids is twice the rib height plus the partition thickness, the horizontal distance is infinite, the rib height enables the rib efficiency to exist, the higher the rib height, the lower the rib efficiency, and the narrower the rib width, the lower the rib efficiency.

In example 1, the cold and hot fluids flow alternately and crossly in the same layer, and the heat exchange distance is one channel width + rib width (horizontal direction), or one channel height + partition thickness (Z direction), and most of the secondary heat exchange surface is converted into the direct heat exchange surface. The fluid is still guided to two sides by the ribbed plates and is folded at the side, but the through hole 5 (namely the mixed flow section) between two layers of flow channels formed by the upper ribbed plate and the lower ribbed plate is blocked by the inner partition plate 2, and only the mixed flow sections at two sides are reserved. The effect of rib efficiency is greatly reduced, and the advantage of this structure is more pronounced as the higher the Re, the lower the solid thermal conductivity.

The solid thermal conductivity has a significant effect on the rib efficiency of a micro-channel heat exchange core in the form of staggered ribs. When Re =100, the theoretical calculated rib efficiency value of the model with the rib width coefficient of 0.2 is 35-90% (thermal conductivity is 10-200); and along with the rising of Re, the rib efficiency is reduced along with the rising of the surface heat exchange coefficient, because the temperature of the surface of the rib is closer to the fluid temperature relative to the rib root after the fluid side heat exchange is promoted, and the reduction of the temperature difference weakens the heat exchange on the rib. When Re reaches 1000, the rib efficiency is only 19% to 75%. For common materials (except aluminum alloy) such as titanium alloy and stainless steel, the rib efficiency is expected to be between 28% and 50% at Re of 100-1000. The Knoop number Nu of the secondary heat exchange surface of the rib is relatively high, and the area of the rib accounts for about half of the total area of the core body, so that the heat exchange on the rib is an important component of the core body of the LHE (straight rib row), and the existing solid heat resistance becomes an important factor for weakening the performance of the core body of the LHE. In one document of flow-solid conjugated Heat Transfer (Wang Y., Wang L. -C., Lin Z. -M., Yao Y. -H., Wang L. -B., The condition requirement coupling numerical method in student of Heat Transfer characteristics of tube bank and Heat exchanger, International Journal of Heat and Mass Transfer, 55 (2012) 2353-. In the actual three-dimensional numerical simulation calculations that have been performed, it was found that the actual rib efficiency is lower than the values provided above, and therefore the original structure is severely restricted.

In summary, the structure disclosed in the prior art is severely restricted by the rib efficiency, while the staggered ribs disclosed in embodiment 1 of the present application are hardly affected by the rib efficiency, so that higher heat exchange performance can be achieved under the condition that various design parameters are the same and the internal flow structure is similar.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.

Claims

1. A mixed rib row heat exchanger core is characterized by comprising a heat exchange unit, wherein the heat exchange unit comprises an upper layer rib row plate (1), a lower layer rib row plate (3) and an inner partition plate (2), ribs of the upper layer rib row plate (1) and ribs of the lower layer rib row plate (3) are mutually staggered, the upper and lower ribs are intersected at the boundary of the heat exchange unit, side baffles (6) are arranged on two opposite sides of the heat exchange unit, and an inlet and an outlet are arranged on the other two opposite sides of the heat exchange unit; an in-layer partition plate (2) is arranged between the upper-layer rib row plate piece (1) and the lower-layer rib row plate piece (3), through holes (5) are formed in the positions, surrounded by the ribs of the upper-layer rib row plate piece (1), the ribs of the lower-layer rib row plate piece (3) and the side baffle (6), of the partition plate (2) in the projection mode, and cold medium fluid (7) and heat medium fluid (8) are respectively introduced into adjacent inter-rib flow channels of the lower-layer rib row plate piece (3).

2. A hybrid ribbed heat exchanger core as claimed in claim 1, wherein the coolant fluid (7) flows along the intercostal flow channels of the lower ribbed plate (3), reverses to the intercostal flow channels of the upper ribbed plate (1) through the through holes (5) at the side baffle (6), continues to flow through the through holes (5) at the other side baffle (6) into the intercostal flow channels of the lower ribbed plate (3), and repeats until the coolant fluid (7) flows out from the outlet of the heat exchange unit, and the heat medium fluid (8) flows in the same manner as the coolant fluid (7).

3. A hybrid rib heat exchanger core according to claim 1, wherein the through-holes (5) are triangular.

4. A hybrid ribbed heat exchanger core according to claim 1, characterised in that the upper ribbed plate (1) and the lower ribbed plate (3) are provided with an interlayer partition (4) at both the upper and lower ends.

5. A hybrid ribbed heat exchanger core as claimed in claim 1, wherein a plurality of heat exchange units are stacked one on top of the other, an interlayer partition (4) is provided at the bottom of the lower ribbed plate (3) of each heat exchange unit, and the upper part of the upper ribbed plate (1) and the bottom of the upper heat exchange unit share one interlayer partition (4).

6. A hybrid ribbed heat exchanger core as claimed in claim 1, wherein through holes (5) are provided in one inter-layer partition (4) for every N heat exchange units, the through holes (5) being provided in the same manner as the inter-layer partitions (2), 1 ≦ N and less than the total number of heat exchange units.

7. A hybrid ribbed heat exchanger core according to claim 4, characterised in that the thickness of the interlayer separator (4) is between 0.1mm and 4 mm.

8. A hybrid rib heat exchanger core according to claim 1, wherein the upper and lower rib plates (1, 3) each have a thickness of 0.2mm to 6 mm.

9. A hybrid rib row heat exchanger core according to claim 1, wherein the cross-sections of the adjacent inter-rib flow channels of the upper rib row plate (1) and the adjacent inter-rib flow channels of the lower rib row plate (3) are all width-to-height ratios (0.2-5): 1, in a rectangular shape.

10. A heat exchanger comprising a hybrid rib row heat exchanger core according to any of claims 1 to 9.