Rib for supercritical working medium printed circuit board heat exchanger

Abstract

The invention provides a fin for a supercritical working medium printed circuit board heat exchanger, which comprises a plurality of fins arranged on a supercritical working medium heat exchange plate I, the fins are diamond-like, and through holes are formed in the fins. According to the fin structure, the negative pressure gradient before and after incoming flow of the fins is reduced, incoming flow resistance is reduced, stagnation generated when a fluid working medium impacts the front edges of the fins and fluid separation at the tails of the fins are weakened, and the speed, pressure and temperature distribution of the whole fluid is more uniform; therefore, the purposes of improving the stability and efficiency of flow heat exchange of the supercritical fluid with drastic thermophysical property changes, remarkably reducing flow resistance and pressure loss and improving the comprehensive heat exchange capacity of the supercritical working medium printed circuit board heat exchanger are achieved, and the comprehensive heat exchange capacity of the supercritical working medium printed circuit board heat exchanger is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of microchannel heat exchanger fins, in particular to a fin used for a supercritical working medium printed circuit board heat exchanger. Background Art

[0002] Printed Circuit Heat Exchanger (PCHE) is a micro-channel plate heat exchanger. Tiny hot and cold fluid channels with a diameter of 0.5 to 2 mm are etched on the heat exchange plate by chemical etching, and then the alternately stacked hot and cold fluid channels are welded into one body using vacuum diffusion technology. It has the characteristics of compact structure and resistance to high temperature and high pressure. It is widely used in supercritical carbon dioxide Brayton power generation cycle system, solar thermal power generation cycle system, ultra-high temperature gas-cooled reactor and other fields.

[0003] At present, the common forms of channel structures of printed circuit board heat exchangers include continuous zigzag channels such as Z-shaped channels and discontinuous channels such as wing-shaped ribs. The study of heat transfer and resistance characteristics of printed circuit board heat exchangers with different channel structures found that when the fluid flows through the discontinuous ribs, the fluids in adjacent channels mix with each other, and the collision of the downstream ribs produces turbulence, which is conducive to destroying the boundary layer. The wall thermal resistance is small, thus making the heat transfer performance stronger, but at the same time it also increases the flow resistance. In addition, when the heat exchange medium of the printed circuit board heat exchanger is a supercritical fluid, due to the extremely poor stability of the thermal properties of the supercritical fluid near the critical point, the thermal conductivity, density, and dynamic viscosity decrease rapidly with increasing temperature, and the constant pressure specific heat capacity will rapidly increase first and then decrease.

[0004] In order to adapt to the changing characteristics of the thermal properties of supercritical fluid heat exchangers, improve the heat exchange efficiency of the heat exchanger, reduce the resistance pressure drop of the heat exchanger, and improve the overall performance of the heat exchanger, it is necessary to further optimize the channel structure of the printed circuit board heat exchanger. For example, the Chinese invention patent with an authorization announcement date of 2023.08.29 and an authorization announcement number of CN114111393B discloses a heat exchange plate, a core and a printed circuit board type heat exchanger based on supercritical working fluid. The technical solution is: according to the supercritical working fluid property change curve, the wing-shaped fin area, the S-shaped fin area and the diamond fin area are arranged in sequence, and the fins in each fin area are arranged in a staggered manner; or, according to the supercritical working fluid property change curve, the basic fin area, the dense fin area and the sparse fin area are arranged in sequence, and the fins in each fin area are arranged in a staggered manner.

[0005] In the above-mentioned prior art, the comprehensive heat exchanger performance of the heat exchanger is improved by arranging fins of different shapes in different heat exchange sections of the supercritical fluid working medium. However, there are many types of fins, and the arrangement of the fins on the heat exchange plate is relatively complicated. Summary of the invention

[0006] In view of the deficiencies in the above-mentioned background technology, the present invention proposes a fin for a supercritical working fluid printed circuit board heat exchanger, which has the advantages of simple structure, improving the flow and heat exchange stability and efficiency of the supercritical working fluid, significantly reducing the flow resistance and pressure loss, and improving the comprehensive heat exchange capacity of the supercritical working fluid printed circuit board heat exchanger.

[0007] The technical solution of this application is:

[0008] A fin for a supercritical working fluid printed circuit board heat exchanger, comprising a plurality of fins arranged on a supercritical working fluid heat exchange plate, wherein the fins are in a rhombus shape and are provided with through holes. Compared with a supercritical working fluid printed circuit board heat exchanger having a conventional continuous fin structure such as a Z-shaped rib and a discontinuous fin structure such as a wing-shaped rib, the fin structure of the present invention reduces the negative pressure gradient before and after the fin incoming flow, reduces the incoming flow resistance, weakens the stagnation of the fluid working fluid when impacting the leading edge of the fin and the fluid separation at the tail of the fin, and makes the velocity, pressure and temperature distribution of the overall fluid more uniform, thereby achieving the purpose of improving the stability and efficiency of the flow heat exchange of a supercritical fluid with drastic changes in thermal properties, significantly reducing the flow resistance and pressure loss, and improving the comprehensive heat exchange capacity of the supercritical working fluid printed circuit board heat exchanger, thereby improving the comprehensive heat exchange capacity of the supercritical working fluid printed circuit board heat exchanger.

[0009] Furthermore, the rib includes a symmetrically arranged isosceles triangle structure 1 and a symmetrically arranged isosceles triangle structure 2, the bases of the isosceles triangle structure 1 and the isosceles triangle structure 2 are connected, and the through hole connects the isosceles triangle structure 1 and the isosceles triangle structure 2.

[0010] Furthermore, two or more through holes are provided along the length direction of the rib.

[0011] Furthermore, the through holes are symmetrically arranged with respect to the long axis of the rib.

[0012] Furthermore, when two through holes are provided, the ports of the through holes are provided at the center of the side surface of the fin, so that the flow heat exchange effect is better.

[0013] Furthermore, the aperture d of the through hole is 0.08 mm to 0.16 mm.

[0014] Furthermore, the length L of the rib c is 4.0 to 16.0 mm, and the width L of the ribs w is 0.89 to 3.56 mm, and the height L of the ribs h 0.5~2.0mm.

[0015] Furthermore, the fins on each layer of the supercritical working medium heat exchange plate 1 are arranged in a plurality of rows or columns, and the fins in adjacent rows or columns are arranged in a staggered manner.

[0016] Furthermore, the vertical spacing L between adjacent fins t The horizontal spacing between adjacent fins is 2.11 to 5.11 mm. z The staggered spacing between adjacent ribs is 4.0 to 16.0 mm. k 4.0~16.0mm.

[0017] Furthermore, a second supercritical working fluid heat exchange plate is disposed on the upper surface of the fin, and a supercritical fluid channel is formed between the lower portion of the second supercritical working fluid heat exchange plate and the upper portion of the first supercritical working fluid heat exchange plate.

[0018] The specific beneficial effects of the present invention include:

[0019] 1. The fin structure of the present invention reduces the negative pressure gradient before and after the fin flow, reduces the flow resistance, weakens the stagnation of the fluid working medium when it impacts the leading edge of the fin and the fluid separation at the tail of the fin, and makes the velocity, pressure and temperature distribution of the overall fluid more uniform, thereby achieving the purpose of improving the stability and efficiency of the flow heat exchange of the supercritical fluid with drastic changes in thermal properties, significantly reducing the flow resistance and pressure loss, and improving the comprehensive heat exchange capacity of the supercritical working medium printed circuit board heat exchanger, thereby improving the comprehensive heat exchange capacity of the supercritical working medium printed circuit board heat exchanger;

[0020] 2. The fin structure of the present invention is simple, and the processing of complex curves is avoided during production, thus saving materials and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0022] Figure 1 It is a plane view of the fin of the present invention;

[0023] Figure 2 It is a schematic diagram of the formation of the fins of the present invention;

[0024] Figure 3 This is a three-dimensional diagram of the fins in Example 1 of the present invention;

[0025] Figure 4 It is a schematic diagram of the arrangement of adjacent fins of the present invention;

[0026] Figure 5 It is a schematic diagram of the arrangement of the fins on the supercritical working medium heat exchange plate 1 of the present invention;

[0027] Figure 6A three-dimensional diagram of the core structure of a printed circuit board heat exchanger using the fins of the present invention on the supercritical working medium side;

[0028] Figure 7 A side view of the core structure of a printed circuit board heat exchanger using the fins of the present invention on the supercritical working medium side;

[0029] Figure 8 A three-dimensional diagram of the fins in Example 2 of the present invention;

[0030] Fig. 9 This is a plan view of the fins in Example 2 of the present invention.

[0031] Description of Figure Numbers:

[0032] 1. Ribs;

[0033] 2. Through hole;

[0034] 3. Supercritical working fluid heat exchange plate 1;

[0035] 4. Supercritical working fluid heat exchange plate 2;

[0036] 5. Supercritical fluid channel;

[0037] 11. Isosceles triangle structure 1;

[0038] 12. Isosceles triangle structure 2. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Embodiment 1, a fin for a supercritical working fluid printed circuit board heat exchanger, comprising a plurality of fins 1 arranged on a supercritical working fluid heat exchange plate 3, wherein the fins 1 are rhombus-shaped fins 1, and the fins 1 are provided with through holes 2. The fin structure of the present invention reduces the negative pressure gradient before and after the fin incoming flow, reduces the incoming flow resistance, weakens the stagnation of the fluid working medium when it impacts the front edge of the fin and the fluid separation at the tail of the fin, and makes the velocity, pressure and temperature distribution of the overall fluid more uniform, thereby achieving the purpose of improving the stability and efficiency of the flow heat exchange of the supercritical fluid with drastic changes in thermal properties, significantly reducing the flow resistance and pressure loss, and improving the comprehensive heat exchange capacity of the supercritical working fluid printed circuit board heat exchanger, thereby improving the comprehensive heat exchange capacity of the supercritical working fluid printed circuit board heat exchanger; the fin structure in the present invention is simple, and the processing of complex curves is avoided during production and manufacturing, saving materials and reducing costs.

[0041] Based on the above embodiment, the rib 1 includes a symmetrically arranged isosceles triangle structure 1 11 and an isosceles triangle structure 2 12, the base of the isosceles triangle structure 1 11 is connected to the base of the isosceles triangle structure 2 12, and the through hole 2 connects the isosceles triangle structure 1 11 and the isosceles triangle structure 2 12.

[0042] Specifically, Figure 1 , Figure 2 As shown, the fin 1 adopts two NACA00 series standard symmetrical wing-shaped fins of the same size, and the tail parts are cross-connected along the direction of their symmetry axis to form a fin with a rhombus-like cross-section. The outer edge of the cross-connection is smooth, forming two symmetrical vertices A of the new rhombus-like fin, and the two vertices retained at the tail of the original wing-shaped fin constitute the other two vertices of the new rhombus-like fin.

[0043] On the basis of the above embodiment, two through holes 2 are provided along the length direction of the fin 1 and are symmetrical with respect to the long axis of the fin 1 .

[0044] Preferably, the port of the through hole 2 is arranged at the center of the side of the fin 1 to achieve a better flow heat exchange effect. The fin 1 has four sides, and a through hole 2 is opened at the center of each side. Figure 3 As shown, the through hole 2 is connected from the left side to the right side along the length direction of the rib 1.

[0045] On the basis of the above-mentioned embodiment, the diameter d of the through hole 2 is 0.08 mm to 0.16 mm.

[0046] Based on the above embodiment, the length L of the fin 1 is c is 4.0 to 16.0 mm, and the width L of the fin 1 is w is 0.89-3.56 mm, and the height L of the fin 1 h 0.5~2.0mm.

[0047] On the basis of the above implementation mode, the fins 1 on each layer of supercritical working fluid heat exchange plate 3 are arranged in a plurality of rows or columns, and the fins 1 in adjacent rows or columns are arranged in a staggered manner.

[0048] Based on the above embodiment, the vertical distance L between adjacent fins 1 is t The horizontal spacing L between adjacent fins 1 is 2.11 to 5.11 mm. z is 4.0~16.0mm, and the staggered spacing L between adjacent ribs 1 k 4.0~16.0mm.

[0049] Specifically, the symmetrical wing-shaped fins adopt NACA0025. Table 1 lists three diamond-shaped perforated fins No. 1 to No. 3 of different structural sizes formed by the NACA0025 standard symmetrical wing-shaped fins.

[0050] Table 1 Structural dimensions of fins No. 1 to No. 3 of the present invention and their distribution dimensions on a supercritical working fluid heat exchange plate 1

[0051]

[0052]

[0053] On the basis of the above embodiment, a second supercritical working fluid heat exchange plate 4 is provided on the upper surface of the fin 1 , and the lower part of the second supercritical working fluid heat exchange plate 4 and the upper part of the first supercritical working fluid heat exchange plate 3 form a supercritical fluid channel 5 .

[0054] Specifically, a tiny supercritical fluid channel 5 and a fluid channel on the other side for heat exchange with the supercritical working fluid heat exchange plate 1 3 and the supercritical working fluid heat exchange plate 2 4 are etched by chemical etching method, and the channels are alternately stacked and welded together by vacuum diffusion welding technology. A plurality of non-continuously staggered fins 1 are etched between the supercritical working fluid heat exchange plate 1 3 and the supercritical working fluid heat exchange plate 2 4 by chemical etching method. The heat exchange plate on the side of the supercritical fluid channel on the other side for heat exchange with the supercritical working fluid can select a suitable channel structure according to the type of fluid and heat exchange conditions.

[0055] The ANSYS FLUENT flow heat transfer numerical simulation software was used to numerically calculate the pressure loss ΔP, friction factor f, heat transfer factor j, and the ratio j / f of the heat transfer factor to the friction factor (reflecting the comprehensive heat transfer performance of the fluid channel) on the supercritical working medium side of the printed circuit board type heat exchanger under the three different structures and distribution characteristic sizes of the fins No. 1 to No. 3 of the present invention in Table 1 of the present invention, and the calculation results were compared with the corresponding calculation results on the supercritical working medium side of the NACA0025 wing-shaped rib printed circuit board type heat exchanger under the condition of equal proportional size.

[0056] Table 2 Numerical model and parameter settings

[0057]

[0058]

[0059] Tables 3, 4 and 5 respectively list the simulation calculation results of the pressure loss ΔP, friction factor f, and ratio of heat transfer factor to friction factor j / f (reflecting the comprehensive heat transfer performance of the fluid channel) on the supercritical working medium side of the printed circuit board type heat exchanger under fins No. 1 to No. 3 of the present invention in Table 1 when the inlet Reynolds number Re increases uniformly at an increase of 1 / 6 in the range of 12477 to 71705, and the comparison of the corresponding calculation results on the supercritical working medium side of the NACA0025 wing-shaped rib printed circuit board type heat exchanger under the condition of equal proportional size.

[0060] It can be seen that when the inlet Reynolds number Re increases uniformly with an increase of 1 / 6 in the range of 12477 to 71705, compared with the NACA0025 wing-shaped fins of equal proportion, the pressure loss △P on the supercritical working medium side of the printed circuit board type heat exchanger under the fins of No. 1 of the present invention in Table 1 is reduced by 10.07% to 15.49%, the friction factor f is reduced by 6.26% to 15.58%, and the ratio j / f of the heat transfer factor to the friction factor representing the comprehensive heat transfer performance is increased by 2.80% to 11.27% (see Table 3), and the pressure loss △P on the supercritical working medium side of the printed circuit board type heat exchanger under the fins of No. 2 of the present invention is reduced by 10.07% to 15.49%, and the friction factor f is reduced by 6.26% to 15.58%. The pressure loss △P is reduced by 24.07% to 30.96%, the friction factor f is reduced by 8.74% to 17.80%, and the ratio j / f of the heat transfer factor to the friction factor representing the comprehensive heat exchange performance of the channel is increased by 3.70% to 10.75% (see Table 4). The pressure loss △P on the supercritical working fluid side of the printed circuit board type heat exchanger under the fins of No.3 of the present invention is reduced by 8.58% to 19.27%, the friction factor f is reduced by 7.08% to 17.47%, and the ratio j / f of the heat transfer factor to the friction factor representing the comprehensive heat exchange performance of the channel is increased by 3.33% to 9.29% (see Table 5).

[0061] The above data show that the heat transfer stability and efficiency of the supercritical working fluid side of the printed circuit board type heat exchanger using the fin structure of the present invention are effectively improved, the flow resistance and pressure loss are significantly reduced, and the comprehensive heat transfer capacity of the heat exchanger is significantly improved.

[0062] Table 3 Comparison of heat transfer performance of supercritical fluid side flow of NACA0025 wing-shaped fin printed circuit board heat exchanger with fin No. 1 in Table 1 of the present invention and fin No. 1 in Table 1 of the same proportion

[0063]

[0064] Table 4 Comparison of heat transfer performance of supercritical fluid side flow of No. 2 fins of the present invention and NACA0025 wing-shaped fins of equal size printed circuit board heat exchanger

[0065]

[0066] Table 5 Comparison of heat transfer performance of supercritical fluid side flow of No. 3 fins of the present invention and NACA0025 wing-shaped fins of equal size printed circuit board heat exchanger

[0067]

[0068] Example 2, as a preferred embodiment, is different from Example 1 in that Figure 8 , Fig. 9 As shown, four through holes 2 are arranged along the length direction of the fin 1, the through holes 2 are symmetrical about the long axis of the fin 1, two through holes 2 are arranged on both sides of the long axis of the fin 1, and the spacing between the through holes 2 is arranged equidistantly. According to the numerical simulation method of Example 1, numerical calculations are performed to obtain the corresponding pressure loss △P, friction factor f, and ratio of heat transfer factor to friction factor j / f (reflecting the comprehensive heat transfer performance of the fluid channel) calculation results of the supercritical working medium side of the printed circuit board type heat exchanger, and the comparison of the calculation results of the supercritical working medium side of the NACA0025 wing-shaped rib printed circuit board type heat exchanger under the condition of equal scale size, see Table 6. It can be seen that when the inlet Reynolds number Re increases in the range of 12477 to 71705, compared with the NACA0025 wing-shaped fin of equal proportion, the pressure loss △P of the fin No. 2 of the present invention having four through holes 2 arranged along the length direction of the fin 1 is reduced by 21.18% to 33.75%, the friction factor f is reduced by 6.64% to 15.65%, and the ratio j / f of the heat transfer factor to the friction factor representing the comprehensive heat exchange performance is increased by 3.55% to 6.99%.

[0069] Table 6 Comparison of heat transfer performance of No.2 fins of the present invention with 4 through holes and NACA0025 wing-shaped fins of the same size on the supercritical working medium side of the printed circuit board heat exchanger

[0070]

[0071] The above data show that the heat exchange stability and efficiency of the supercritical fluid side of the printed circuit board heat exchanger using the fin structure of the present invention are effectively improved, the flow resistance and pressure loss are significantly reduced, and the comprehensive heat exchange capacity of the heat exchanger is significantly improved. Compared with the supercritical fluid printed circuit board heat exchanger with traditional Z-shaped continuous and wing-shaped ribs and other discontinuous fin structures, the fin structure of the present invention reduces the negative pressure gradient before and after the fin flow, reduces the flow resistance, weakens the stagnation of the fluid working medium when it impacts the leading edge of the fin and the fluid separation at the tail of the fin, and makes the velocity, pressure and temperature distribution of the overall fluid more uniform, thereby achieving the purpose of improving the stability and efficiency of the flow heat exchange of supercritical fluids with drastic changes in thermal properties, significantly reducing the flow resistance and pressure loss, and improving the comprehensive heat exchange capacity of the supercritical fluid printed circuit board heat exchanger, thereby improving the comprehensive heat exchange capacity of the supercritical fluid printed circuit board heat exchanger.

[0072] The details not described in detail in the present invention are all conventional technical means known to those skilled in the art.

[0073] The above content shows and describes the basic principles, main features and beneficial effects of the present invention. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fin for a supercritical printed circuit board heat exchanger, characterized in that: It comprises a plurality of fins (1) arranged on a supercritical working medium heat exchange plate (3), wherein the fins (1) are in a rhombus shape and through holes (2) are arranged on the fins (1).

2. The fin for a supercritical medium printed circuit board heat exchanger according to claim 1, characterized in that: The rib (1) comprises a symmetrically arranged quasi-isosceles triangle structure one (11) and a quasi-isosceles triangle structure two (12); the bases of the quasi-isosceles triangle structure one (11) and the quasi-isosceles triangle structure two (12) are connected; and the through hole (2) connects the quasi-isosceles triangle structure one (11) and the quasi-isosceles triangle structure two (12).

3. The fin for a supercritical medium printed circuit board heat exchanger according to claim 1 or 2, characterized in that: Two or more through holes (2) are arranged along the length direction of the rib (1).

4. The fin for a supercritical medium printed circuit board heat exchanger according to claim 3, characterized in that: The through holes (2) are arranged symmetrically with respect to the long axis of the fin (1).

5. The fin for a supercritical medium printed circuit board heat exchanger according to claim 4, characterized in that: When two through holes (2) are provided, the ends of the through holes (2) are provided at the center of the side surface of the fin (1).

6. The fin for a supercritical medium printed circuit board heat exchanger according to any one of claims 1-2, 4-5, characterized in that: The aperture d of the through hole (2) is 0.08 mm to 0.16 mm.

7. The fin for a supercritical medium printed circuit board heat exchanger according to any one of claims 1-2, 4-5, characterized in that: The length L of the rib (1) c is 4.0 to 16.0 mm, the width L of the rib (1) w is 0.89 to 3.56 mm, and the height L of the fin (1) h 0.5~2.0mm.

8. A heat exchanger for a supercritical working medium printed circuit board, characterized in that: The fins (1) on each layer of supercritical working fluid heat exchange plate (3) are arranged in a plurality of rows or columns, and the fins (1) in adjacent rows or columns are arranged in a staggered manner.

9. The heat exchanger for a supercritical printed circuit board according to claim 8, characterized in that: The vertical distance L between adjacent fins (1) t The horizontal spacing L between adjacent fins (1) is 2.11 to 5.11 mm. z is 4.0 to 16.0 mm, and the staggered spacing L between adjacent ribs (1) is k 4.0~16.0mm.

10. The heat exchanger for a supercritical printed circuit board according to claim 8 or 9, characterized in that: A second supercritical working fluid heat exchange plate (4) is provided on the upper surface of the fin (1), and a supercritical fluid channel (5) is formed between the lower portion of the second supercritical working fluid heat exchange plate (4) and the upper portion of the first supercritical working fluid heat exchange plate (3).

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