Periodic staggered fins for plate heat exchangers

Abstract

The application discloses a periodic staggered fin for a plate heat exchanger, which is composed of multiple rows of periodically arranged sawtooth units, each sawtooth unit being a circular-angled trapezoidal structure; the sawtooth units are repeatedly arranged in cycles, and each cycle contains N rows of sawteeth, wherein N is an integer of 3-6; in the same cycle, there is a lateral offset between two adjacent rows of sawteeth, and the offset amounts of at least two pairs of adjacent rows are different; the asymmetric offset of the adjacent rows of sawteeth in the same cycle causes a direction mutation when fluid flows through the sawteeth, and induces the formation of high-strength secondary flow and separation vortex; the vortex continuously erodes the surface of the fin, reduces the thickness of the thermal boundary layer, and at the same time, the mixing of hot and cold fluids is more sufficient, which significantly improves the convective heat transfer coefficient; each cycle (N=3-6 rows) forms a complete disturbance unit, and vortexes are repeatedly excited in the flow direction, avoiding the re-development of fluid into laminar flow (maintaining high turbulence).

Description

TECHNICAL FIELD

[0001] The present application relates to a fin of a plate heat exchanger, in particular to a periodically staggered fin for a plate heat exchanger. BACKGROUND

[0002] Electric vehicles are gradually replacing traditional fuel vehicles to become a new trend in the development of the automobile industry. Batteries replace the engines of traditional fuel vehicles and become the core components of automobiles. As an important part of the battery cooling module of new energy vehicles, the battery cooler provides sufficient cold capacity for the heat dissipation of the battery to ensure that the heat generated by the battery is released in time, guarantees the efficient operation of the battery at a reasonable working temperature, and ensures the safety of the battery. The battery cooler is usually a plate heat exchanger, which needs to dissipate the heat of the battery while reducing the volume and weight of the heat exchanger as much as possible. Therefore, the requirements for the fin of the plate heat exchanger are also increasing, and the demand for developing new types of fins is becoming more and more urgent.

[0003] In the prior art, such as patent CN207779210U, a plurality of sawtooth-shaped windowing fins arranged in a staggered manner are disclosed, which are formed by stamping a thin plate; the sawtooth-shaped windowing fin includes a plurality of orderly arranged tooth-shaped structures, the tooth-shaped structure includes a top plate and a first side plate and a second side plate connected with the top plate; on the same sawtooth-shaped windowing fin, the first side plate of one of the two adjacent tooth-shaped structures is connected with the second side plate of the other tooth-shaped structure through a bottom plate; the first side plate and the second side plate are both provided with a hollow reinforcing rib, however, the protrusion of the reinforcing rib causes local flow separation and increased pressure loss, and the reinforcing rib increases the material usage, which violates the lightweight demand of the battery cooler of the electric vehicle.

[0004] In the prior art, such as patent CN207866082U, a sawtooth-shaped staggered fin with varying window width in the technical field of heat exchangers and a heat exchanger having the same are disclosed, which includes a plurality of groups of sawtooth-shaped windowing fins arranged in a staggered manner, which are formed by stamping a thin plate; the number of sawtooth-shaped windowing fins in the same group is not less than 1, and the widths of the sawtooth-shaped windowing fins in adjacent two groups are different, however, the width variation only changes the flow distribution, but does not enhance the fluid disturbance, the boundary layer is still thick, the flow field homogenization slightly improves the heat exchange efficiency, and the multiple groups of different width windowing fins require customized molds, which is difficult to mass-produce. SUMMARY

[0005] Therefore, the present application provides a periodically staggered fin which can improve the heat exchange capacity while saving materials and reducing costs.

[0006] The application discloses a periodic staggered fin for plate heat exchangers, which is composed of multiple rows of periodically arranged sawtooth units, each sawtooth unit being a rounded trapezoidal structure; the sawtooth units are repeatedly arranged in cycles, and each cycle contains N rows of sawteeth, wherein N is an integer of 3-6; in the same cycle, there is a lateral offset between two adjacent rows of sawteeth, and the offset amounts of at least two pairs of adjacent rows are different, which forces the fluid to experience asymmetric direction mutation in a short distance, generates high-intensity secondary flow and separation vortex, and the disorder of vortex space distribution continuously destroys the thermal boundary layer, avoiding the re-development of the fluid into laminar flow.

[0007] In some embodiments, the sawtooth inclination angle α of the sawtooth unit satisfies When , the fluid does not produce significant flow separation when flowing along the sawtooth inclined surface, and if , the fluid generates large-scale separation vortex on the sawtooth leeward surface, resulting in a sharp increase in resistance and a decrease in effective heat exchange area.

[0008] Further, the pitch s between the two adjacent rows of sawteeth satisfies ; the pitch is the only balance point of heat transfer performance, resistance control and lightweight; the lower limit is 2mm, which blocks vortex interference and maintains effective flushing; the upper limit is 8mm, which suppresses the regeneration of the boundary layer and avoids heat transfer attenuation; more preferably, the core interval is 4-6mm, which expands the flow area to offset the staggered resistance, and realizes a 20-30% heat transfer improvement while keeping the overall resistance flat.

[0009] Further, the pitch s and the fin thickness δ satisfy: to expand the flow area to offset the staggered resistance.

[0010] Further, the cycle contains 3 rows of sawteeth, the lateral offset of the 2nd row of sawteeth relative to the 1st row of sawteeth is 1 / 3s, and the lateral offset of the 3rd row of sawteeth relative to the 1st row of sawteeth is 2 / 3s.

[0011] Further, the cycle contains 4 rows of sawteeth, wherein: the lateral offset of the 2nd row of sawteeth relative to the 1st row of sawteeth is 1 / 4s, the lateral offset of the 3rd row of sawteeth relative to the 1st row of sawteeth is 3 / 4s, and the lateral offset of the 4th row of sawteeth relative to the 1st row of sawteeth is 1 / 2s.

[0012] Further, the cycle contains 4 rows of sawteeth, wherein: the lateral offset of the 2nd row of sawteeth relative to the 1st row of sawteeth is 1 / 3s, the lateral offset of the 3rd row of sawteeth relative to the 1st row of sawteeth is 2 / 3s, and the lateral offset of the 4th row of sawteeth relative to the 1st row of sawteeth is 1 / 3s.

[0013] Further, the period contains 4 rows of sawteeth, wherein: the second row of sawteeth is laterally offset from the first row of sawteeth by 1 / 2s, the third row of sawteeth is laterally offset from the first row of sawteeth by s, and the fourth row of sawteeth is laterally offset from the first row of sawteeth by 1 / 2s.

[0014] Further, the period contains 5 rows of sawteeth, wherein: the second row of sawteeth is laterally offset from the first row of sawteeth by 1 / 5s, the third row of sawteeth is laterally offset from the first row of sawteeth by 3 / 5s, the fourth row of sawteeth is laterally offset from the first row of sawteeth by 4 / 5s, and the fifth row of sawteeth is laterally offset from the first row of sawteeth by 2 / 5s.

[0015] Further, the period contains 5 rows of sawteeth, wherein: the second row of sawteeth is laterally offset from the first row of sawteeth by 1 / 4s, the third row of sawteeth is laterally offset from the first row of sawteeth by 3 / 4s, the fourth row of sawteeth is laterally offset from the first row of sawteeth by s, and the fifth row of sawteeth is laterally offset from the first row of sawteeth by 1 / 2s.

[0016] Further, the period contains 5 rows of sawteeth, wherein: the second row of sawteeth is laterally offset from the first row of sawteeth by 1 / 3s, the third row of sawteeth is laterally offset from the first row of sawteeth by 2 / 3s, the fourth row of sawteeth is laterally offset from the first row of sawteeth by s, and the fifth row of sawteeth is laterally offset from the first row of sawteeth by 1 / 2s.

[0017] Further, the period contains 6 rows of sawteeth, wherein: the second row of sawteeth is laterally offset from the first row of sawteeth by 1 / 6s, the third row of sawteeth is laterally offset from the first row of sawteeth by 2 / 3s, the fourth row of sawteeth is laterally offset from the first row of sawteeth by 1 / 3s, the fifth row of sawteeth is laterally offset from the first row of sawteeth by 5 / 6s, and the sixth row of sawteeth is laterally offset from the first row of sawteeth by 1 / 2s.

[0018] Further, the period contains 6 rows of sawteeth, wherein: the second row of sawteeth is laterally offset from the first row of sawteeth by 1 / 6s, the third row of sawteeth is laterally offset from the first row of sawteeth by 1 / 2s, the fourth row of sawteeth is laterally offset from the first row of sawteeth by 5 / 6s, the fifth row of sawteeth is laterally offset from the first row of sawteeth by 2 / 3s, and the sixth row of sawteeth is laterally offset from the first row of sawteeth by 1 / 3s.

[0019] Further, the period contains 6 rows of sawtooth, wherein: the transverse offset of the 2nd row of sawtooth relative to the 1st row of sawtooth is 1 / 3s, the transverse offset of the 3rd row of sawtooth relative to the 1st row of sawtooth is 2 / 3s, the transverse offset of the 4th row of sawtooth relative to the 1st row of sawtooth is s, the transverse offset of the 5th row of sawtooth relative to the 1st row of sawtooth is 2 / 3s, and the transverse offset of the 6th row of sawtooth relative to the 1st row of sawtooth is 1 / 3s.

[0020] Further, the period contains 6 rows of sawtooth, wherein: the transverse offset of the 2nd row of sawtooth relative to the 1st row of sawtooth is 1 / 5s, the transverse offset of the 3rd row of sawtooth relative to the 1st row of sawtooth is 3 / 5s, the transverse offset of the 4th row of sawtooth relative to the 1st row of sawtooth is s, the transverse offset of the 5th row of sawtooth relative to the 1st row of sawtooth is 4 / 5s, and the transverse offset of the 6th row of sawtooth relative to the 1st row of sawtooth is 2 / 5s.

[0021] Further, the period contains 6 rows of sawtooth, wherein: the transverse offset of the 2nd row of sawtooth relative to the 1st row of sawtooth is 1 / 4s, the transverse offset of the 3rd row of sawtooth relative to the 1st row of sawtooth is 1 / 2s, the transverse offset of the 4th row of sawtooth relative to the 1st row of sawtooth is 3 / 4s, the transverse offset of the 5th row of sawtooth relative to the 1st row of sawtooth is 1 / 2s, and the transverse offset of the 6th row of sawtooth relative to the 1st row of sawtooth is 1 / 4s.

[0022] As can be seen from the technical solutions provided by the present application, compared with the prior art, the present application provides a periodically staggered fin, in terms of heat exchange performance, according to the boundary layer theory, the asymmetric offset of adjacent rows of sawtooth in the same period causes a sudden change in direction when the fluid flows through the sawtooth, inducing the formation of high-intensity secondary flow and separation vortex, the vortex continuously erodes the fin surface, thins the thermal boundary layer, and the cold and hot fluids are mixed more fully, significantly improving the convective heat transfer coefficient, each period (N=3~6 rows) forms a complete disturbance unit, repeatedly exciting vortex in the flow direction, avoiding the re-development of fluid into laminar flow (maintaining high turbulence); In terms of resistance, according to Bernoulli's equation, the resistance compensation mechanism of the increased pitch s includes the expansion of the flow area and the offset of the increased resistance of the staggered arrangement, wherein the expansion of the flow area is that the increased pitch s reduces the number of sawtooth rows per unit length, the fluid channel is widened, the flow rate is reduced, and the pressure loss ΔP is reduced (ΔP∝flow rate²), and the offset of the increased resistance of the staggered arrangement includes that although the staggered arrangement of the sawtooth will cause additional pressure loss due to the vortex, the decreasing effect of the increased pitch s on the resistance > the increasing effect of the staggered arrangement on the resistance, and the comprehensive resistance is flat; The contribution of the thinned fin thickness δ, the thickness δ is reduced, the actual width of the flow channel is increased, and under the same pitch s, the thinned δ further expands the effective flow area (especially for micro-channel plate heat exchangers), further reducing the flow rate; Material stiffness compensation, trapezoidal sawtooth structure with rounded corners (non-flat) still maintains mechanical strength at small δ, avoids deformation.

[0023] In terms of cost, cost and lightweight: systematic optimization of geometric parameters BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A schematic diagram of a periodic staggered fin provided by the present application has 3 rows of sawteeth in a period.

[0025] Figure 2 A schematic diagram of a periodic staggered fin provided by the present application has 3 rows of sawteeth in a period.

[0026] Figure 3 A schematic diagram of a periodic staggered fin provided by the present application has 4 rows of sawteeth in a period.

[0027] Figure 4 A schematic diagram of a periodic staggered fin provided by the present application has 4 rows of sawteeth in a period.

[0028] Figure 5 A schematic diagram of a periodic staggered fin provided by the present application has 4 rows of sawteeth in a period.

[0029] Figure 6 A schematic diagram of a periodic staggered fin provided by the present application has 4 rows of sawteeth in a period.

[0030] Figure 7 A schematic diagram of a periodic staggered fin provided by the present application has 4 rows of sawteeth in a period.

[0031] Figure 8 A schematic diagram of a periodic staggered fin provided by the present application has 4 rows of sawteeth in a period.

[0032] Figure 9 A schematic diagram of a periodic staggered fin provided by the present application has 5 rows of sawteeth in a period.

[0033] Figure 10 A schematic diagram of a periodic staggered fin provided by the present application has 5 rows of sawteeth in a period.

[0034] Figure 11 A schematic diagram of a periodic staggered fin provided by the present application has 5 rows of sawteeth in a period.

[0035] Figure 12 A schematic diagram of a periodic staggered fin provided by the present application has 5 rows of sawteeth in a period.

[0036] Figure 13 A schematic view of a c version of a periodic staggered fin with 5 rows of sawteeth in a period.

[0037] Figure 14 A schematic view of a c version of a periodic staggered fin with 5 rows of sawteeth in a period.

[0038] Figure 15 A schematic view of a c version of a periodic staggered fin with 5 rows of sawteeth in a period.

[0039] Figure 16 A schematic view of a c version of a periodic staggered fin with 5 rows of sawteeth in a period.

[0040] Figure 17 A schematic view of a c version of a periodic staggered fin with 5 rows of sawteeth in a period.

[0041] Figure 18 A schematic view of a c version of a periodic staggered fin with 5 rows of sawteeth in a period.

[0042] Figure 19 A schematic view of a c version of a periodic staggered fin with 5 rows of sawteeth in a period.

[0043] Figure 20 A schematic view of a c version of a periodic staggered fin with 5 rows of sawteeth in a period.

[0044] Figure 21 A schematic view of a c version of a periodic staggered fin with 5 rows of sawteeth in a period.

[0045] Figure 22 A schematic view of a c version of a periodic staggered fin with 5 rows of sawteeth in a period.

[0046] Figure 23 A schematic view of a c version of a periodic staggered fin with 5 rows of sawteeth in a period.

[0047] Figure 24 A schematic view of a c version of a periodic staggered fin with 5 rows of sawteeth in a period. DETAILED DESCRIPTION

[0048] The application will be further described below with reference to the drawings.

[0049] Comparative Example: Example 1: As Figures 1-2The diagram shows a periodically staggered fin with three rows of serrations within a period. The period contains three rows of serrations, with the second row of serrations offset laterally by 1 / 3s relative to the first row, and the third row of serrations offset laterally by 2 / 3s relative to the first row.

[0050] The sawtooth tilt angle α of the sawtooth unit satisfies The pitch s between two adjacent rows of saw teeth satisfies The pitch s and fin thickness δ satisfy the following: This expands the circulation area to offset the resistance of misalignment.

[0051] Example 2: like Figures 3-4 The diagram shows a periodically staggered fin with four rows of serrations within a period. The period contains four rows of serrations, wherein: the lateral offset of the second row of serrations relative to the first row of serrations is 1 / 4s, the lateral offset of the third row of serrations relative to the first row of serrations is 3 / 4s, and the lateral offset of the fourth row of serrations relative to the first row of serrations is 1 / 2s.

[0052] The sawtooth tilt angle α of the sawtooth unit satisfies The pitch s between two adjacent rows of saw teeth satisfies The pitch s and fin thickness δ satisfy the following: This expands the circulation area to offset the resistance of misalignment.

[0053] Example 3: like Figures 5-6 The diagram shows a periodically staggered fin with four rows of serrations within a period. The period contains four rows of serrations, wherein: the lateral offset of the second row of serrations relative to the first row of serrations is 1 / 3s, the lateral offset of the third row of serrations relative to the first row of serrations is 2 / 3s, and the lateral offset of the fourth row of serrations relative to the first row of serrations is 1 / 3s.

[0054] The sawtooth tilt angle α of the sawtooth unit satisfies The pitch s between two adjacent rows of saw teeth satisfies The pitch s and fin thickness δ satisfy the following: This expands the circulation area to offset the resistance of misalignment.

[0055] Example 4: like Figures 7-8 The diagram shows a periodically staggered fin with four rows of serrations within a period. The period contains four rows of serrations, wherein: the lateral offset of the second row of serrations relative to the first row of serrations is 1 / 2s, the lateral offset of the third row of serrations relative to the first row of serrations is s, and the lateral offset of the fourth row of serrations relative to the first row of serrations is 1 / 2s.

[0056] The sawtooth tilt angle α of the sawtooth unit satisfies The pitch s between two adjacent rows of saw teeth satisfies The pitch s and fin thickness δ satisfy the following: This is to expand the circulation area and offset the resistance of misalignment.

[0057] Example 5: like Figures 9-10 The diagram shows a periodically staggered fin with 5 rows of serrations within a period. The period contains 5 rows of serrations, wherein: the lateral offset of the 2nd row of serrations relative to the 1st row is 1 / 5s, the lateral offset of the 3rd row of serrations relative to the 1st row is 3 / 5s, the lateral offset of the 4th row of serrations relative to the 1st row is 4 / 5s, and the lateral offset of the 5th row of serrations relative to the 1st row is 2 / 5s.

[0058] The sawtooth tilt angle α of the sawtooth unit satisfies The pitch s between two adjacent rows of saw teeth satisfies The pitch s and fin thickness δ satisfy the following: This expands the circulation area to offset the resistance of misalignment.

[0059] Example 6: like Figures 11-12 The diagram shows a periodically staggered fin with 5 rows of serrations within a period. The period contains 5 rows of serrations, wherein: the lateral offset of the 2nd row of serrations relative to the 1st row is 1 / 4 s, the lateral offset of the 3rd row of serrations relative to the 1st row is 3 / 4 s, the lateral offset of the 4th row of serrations relative to the 1st row is s, and the lateral offset of the 5th row of serrations relative to the 1st row is 1 / 2 s.

[0060] The sawtooth tilt angle α of the sawtooth unit satisfies The pitch s between two adjacent rows of saw teeth satisfies The pitch s and fin thickness δ satisfy the following: This is to expand the circulation area and offset the resistance of misalignment.

[0061] Example 7: like Figures 13-14 The diagram shows a periodically staggered fin with 5 rows of serrations within a period. The period contains 5 rows of serrations, wherein: the lateral offset of the 2nd row of serrations relative to the 1st row is 1 / 3s, the lateral offset of the 3rd row of serrations relative to the 1st row is 2 / 3s, the lateral offset of the 4th row of serrations relative to the 1st row is s, and the lateral offset of the 5th row of serrations relative to the 1st row is 1 / 2s.

[0062] The sawtooth tilt angle α of the sawtooth unit satisfies The pitch s between two adjacent rows of saw teeth satisfies The pitch s and fin thickness δ satisfy the following: This expands the circulation area to offset the resistance of misalignment.

[0063] Example 8: like Figures 15-16 The diagram shows a periodically staggered fin with six rows of serrations within a period. The period contains six rows of serrations, wherein: the lateral offset of the second row of serrations relative to the first row is 1 / 6 s; the lateral offset of the third row of serrations relative to the first row is 2 / 3 s; the lateral offset of the fourth row of serrations relative to the first row is 1 / 3 s; the lateral offset of the fifth row of serrations relative to the first row is 5 / 6 s; and the lateral offset of the sixth row of serrations relative to the first row is 1 / 2 s.

[0064] The sawtooth tilt angle α of the sawtooth unit satisfies The pitch s between two adjacent rows of saw teeth satisfies The pitch s and fin thickness δ satisfy the following: This is to expand the circulation area and offset the resistance of misalignment.

[0065] Example 9: like Figures 17-18 The diagram shows a periodically staggered fin with six rows of serrations within a period. The period contains six rows of serrations, wherein: the lateral offset of the second row of serrations relative to the first row is 1 / 6 s; the lateral offset of the third row of serrations relative to the first row is 1 / 2 s; the lateral offset of the fourth row of serrations relative to the first row is 5 / 6 s; the lateral offset of the fifth row of serrations relative to the first row is 2 / 3 s; and the lateral offset of the sixth row of serrations relative to the first row is 1 / 3 s.

[0066] The sawtooth tilt angle α of the sawtooth unit satisfies The pitch s between two adjacent rows of saw teeth satisfies The pitch s and fin thickness δ satisfy the following: This expands the circulation area to offset the resistance of misalignment.

[0067] Example 10: like Figures 19-20The diagram shows a periodically staggered fin with six rows of serrations within a period. The period contains six rows of serrations, wherein: the lateral offset of the second row of serrations relative to the first row is 1 / 3 s; the lateral offset of the third row of serrations relative to the first row is 2 / 3 s; the lateral offset of the fourth row of serrations relative to the first row is s; the lateral offset of the fifth row of serrations relative to the first row is 2 / 3 s; and the lateral offset of the sixth row of serrations relative to the first row is 1 / 3 s.

[0068] The sawtooth tilt angle α of the sawtooth unit satisfies The pitch s between two adjacent rows of saw teeth satisfies The pitch s and fin thickness δ satisfy the following: This is to expand the circulation area and offset the resistance of misalignment.

[0069] Example 11: like Figures 21-22 The diagram shows a periodically staggered fin with 6 rows of serrations within each period. Within each period, the lateral offset of the 2nd row of serrations relative to the 1st row is 1 / 5 s, the lateral offset of the 3rd row is 3 / 5 s, the lateral offset of the 4th row is s, the lateral offset of the 5th row is 4 / 5 s, and the lateral offset of the 6th row is 2 / 5 s.

[0070] The sawtooth tilt angle α of the sawtooth unit satisfies The pitch s between two adjacent rows of saw teeth satisfies The pitch s and fin thickness δ satisfy the following: This is to expand the circulation area and offset the resistance of misalignment.

[0071] Example 12: like Figures 23-24 The diagram shows a periodically staggered fin with six rows of serrations within a period. The period contains six rows of serrations, wherein: the lateral offset of the second row of serrations relative to the first row is 1 / 4 s; the lateral offset of the third row of serrations relative to the first row is 1 / 2 s; the lateral offset of the fourth row of serrations relative to the first row is 3 / 4 s; the lateral offset of the fifth row of serrations relative to the first row is 1 / 2 s; and the lateral offset of the sixth row of serrations relative to the first row is 1 / 4 s.

[0072] The sawtooth tilt angle α of the sawtooth unit satisfies The pitch s between two adjacent rows of saw teeth satisfies The pitch s and fin thickness δ satisfy the following: This is to expand the circulation area and offset the resistance of misalignment.

[0073] The above embodiments only express several implementation manners of the present application, which are described in a more specific and detailed manner, but cannot be understood as a limitation on the patent scope of the present application. It should be noted that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, which all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A periodic staggered fin for plate heat exchangers, characterized in that: The fin is composed of multiple rows of periodically arranged sawtooth units, each sawtooth unit being a circularly-angled trapezoidal structure; the sawtooth units are repeatedly arranged in cycles, each cycle containing N rows of sawteeth, wherein N is an integer from 3 to 6; in the same cycle, there is a lateral offset between two adjacent rows of sawteeth, and the offset amounts of at least two pairs of adjacent rows are different.

2. The periodically staggered fin for plate heat exchangers according to claim 1, characterized in that: The saw tooth unit has a saw tooth inclination angle a satisfying .

3. The periodically staggered fin for plate heat exchangers according to claim 1, characterized in that: The pitch s between two adjacent rows of sawteeth satisfies .

4. The periodically staggered fin for a plate heat exchanger according to claim 1, characterized in that: The pitch s and the fin thickness δ satisfy: .

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