JP2009052874A - Plate fin type heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact plate fin type heat exchanger with heat transfer fins formed in an etching technique, having reduced pressure drop, improved heat exchanging performance and reduced machining cost by optimizing the shape and array of the fins. <P>SOLUTION: In the plate fin type heat exchanger, metal thin plates 6 having the plurality of heat transfer fins 7 protruded on the surfaces are alternately layered to form a flow path 8 for heat exchanging fluid between the opposed thin plates 6. The cross section of each heat transfer fin 7 cut in a plane parallel to the thin plate 6 is blade-shaped with a combination of curves having no inflection point. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a plate fin heat exchanger, and more particularly to a heat transfer fin (hereinafter also referred to as a fin) of a plate fin heat exchanger.

  In recent years, plate fin heat exchangers having heat transfer fins on the surface of thin metal plates such as stainless steel plates and aluminum plates have been developed and put into practical use. In order to improve the heat exchange efficiency of the plate heat exchanger, a conventional example of such a plate fin heat exchanger in which fins are formed on the plate will be described below with reference to FIG. FIG. 14 is a diagram for explaining the arrangement of heat transfer fins formed on the surface of a thin metal plate plate in a conventional heat exchanger.

  The heat exchanger according to the conventional example shown in FIG. 14 is provided with a plurality of heat transfer fins on a thin metal plate using an etching technique or the like, and alternately stacking the thin metal plates so that the two opposing metal In the heat exchanger configured to form a heat exchange fluid flow path between the thin plate-like plates, the heat transfer fin 19 forms a substantially S-shaped curved cross-section from the front end 19a to the rear end 19b. The flow path area of the fluid flowing between the heat transfer fins 19 is made substantially constant (see Patent Document 1).

According to the heat exchanger according to the above-described conventional example, a plurality of heat transfer fins 19 are provided on a metal thin plate plate using an etching technique or the like, and the two metal thin plate plates are alternately stacked, thereby opposing the two metal plates. Since the flow path of the heat exchange fluid is formed between the thin plate-like plates, the flow loss between the heat transfer fins 19 is bent in an S shape in the flow direction of the heat exchange fluid. Although small, satisfactory heat transfer performance cannot be obtained.
JP 2006-170549 A

  Accordingly, an object of the present invention is to improve heat exchange performance with low pressure loss by optimizing the fin shape and arrangement in a plate fin heat exchanger having heat transfer fins formed by etching technology or the like. An object of the present invention is to provide a compact plate fin type heat exchanger which can be obtained and processed at a reduced cost.

  In order to achieve the above object, the means employed by the plate fin heat exchanger according to claim 1 of the present invention is to alternately laminate thin metal plates having a plurality of heat transfer fins formed on the surface in a convex shape. In the plate fin type heat exchanger configured to form a heat exchange fluid flow path between the opposed thin plates, the blades formed by combining the cross sections of the heat transfer fins with curves having no inflection points It is characterized by being a mold.

  The means employed by the plate fin heat exchanger according to claim 2 of the present invention is the plate fin heat exchanger according to claim 1, wherein the airfoil has a cross-sectional shape having no recess. To do.

  The means employed by the plate fin heat exchanger according to claim 3 of the present invention is the plate fin heat exchanger according to claim 1 or 2, wherein the airfoil is parallel to the flow direction of the heat exchange fluid. It is characterized by being substantially symmetric with respect to the center line.

  The means employed by the plate fin heat exchanger according to claim 4 of the present invention is the plate fin heat exchanger according to any one of claims 1 to 3, wherein the blade length in the airfoil is as follows. The ratio L / d between L and the blade width d is in the range of 1.8 ≦ L / d ≦ 7.

  The means employed by the plate fin heat exchanger according to claim 5 of the present invention is the plate fin heat exchanger according to any one of claims 1 to 4, wherein heat exchange in the airfoil is performed. The ratio b / d between the blade gap b and the blade width d perpendicular to the fluid flow direction is in the range of 0.3 ≦ b / d ≦ 3.

  The means employed by the plate fin heat exchanger according to claim 6 of the present invention is the plate fin heat exchanger according to any one of claims 1 to 5, wherein the airfoil includes the airfoil. It is formed by etching a metal thin plate.

  According to the plate fin heat exchanger according to claim 1 of the present invention, heat exchange is performed between the opposing thin plates by alternately laminating metal thin plates having a plurality of heat transfer fins formed on the surface in a convex shape. In a plate fin type heat exchanger designed to form a fluid flow path, the cross-sectional shape of the heat transfer fin is an airfoil formed by combining curves having no inflection points, so heat exchange behind the fin It is possible to improve heat exchange efficiency by preventing fluid separation and not generating a vortex region that becomes a dead water region.

  Further, according to the plate fin heat exchanger according to claim 2 of the present invention, the airfoil has a cross-sectional shape having no recess, so that the flow of the heat exchange fluid along the fin surface is not separated. , To suppress the generation of vortices that become dead water areas.

  Furthermore, according to the plate fin type heat exchanger according to claim 3 of the present invention, the airfoil is substantially symmetrical with respect to a center line parallel to the fluid flow direction. In this case, the flow of the heat exchange fluid is not disturbed, and no dead water area is generated.

  Furthermore, according to the plate fin type heat exchanger according to claim 4 of the present invention, the ratio L / d between the blade length L and the blade width d in the airfoil is 1.8 ≦ L / d ≦ 7. Since the vortex area is not formed behind the fin and the boundary layer at the rear end of the fin is not developed, the heat exchange efficiency is improved compared to the conventional technology, and the plate fin type heat exchanger is made compact. Can be planned.

  According to the plate fin heat exchanger according to claim 5 of the present invention, the ratio b / d between the blade gap b and the blade width d perpendicular to the flow direction of the heat exchange fluid in the airfoil is 0. .3 ≦ b / d ≦ 3, so that no vortex area is formed behind the fin and the boundary layer at the rear end of the fin is undeveloped as in the above. The plate fin type heat exchanger can be made more compact.

  On the other hand, according to the plate fin type heat exchanger according to claim 6 of the present invention, since the airfoil is formed by etching a thin metal plate, the plate fin of the plate fin type heat exchanger is provided. Can be manufactured at low cost with less steps and less labor.

  First, a plate fin heat exchanger according to Embodiment 1 of the present invention will be described below with reference to FIGS. FIG. 1 is a perspective view showing an appearance of a plate fin heat exchanger according to an embodiment of the present invention, and FIG. 2 is an explanatory view showing a state in which thin metal plates are laminated in the plate fin heat exchanger of FIG. 3 is a plan view showing a flat cross-sectional shape of the heat transfer fin formed convexly on the surface of the metal thin plate in FIG. 2, and FIG. 4 is an arrangement example of the plurality of heat transfer fins formed on the surface of the metal thin plate in FIG. FIG. 5 is a plan view showing another arrangement example of the plurality of heat transfer fins formed on the surface of the thin metal plate in FIG. 2, and FIG. 6 is an arrangement of the heat transfer fins shown in FIG. It is a figure which compares and shows the heat-transfer area per unit area of the shown heat-transfer fin arrangement | positioning.

  As shown in FIG. 2, the plate fin type heat exchanger 1 according to the embodiment of the present invention is formed by alternately laminating metal thin plates 6 having a plurality of heat transfer fins 7 formed on the surface in a convex shape. A heat exchange fluid flow path 8 is formed between the thin plates 6.

  In such a plate fin type heat exchanger 1, as shown in FIG. 1, one fluid A for heat exchange is supplied from a water supply pipe 2a by a pump (not shown), and between the thin plates 6 via a water supply header 4a. After passing through the formed flow path 8 and exchanging heat with the other fluid B, the water is drained from the drain pipe 2b through the drain header 4b. On the other hand, the other fluid B to be heat-exchanged is supplied from the water supply pipe 3a by a pump (not shown), passes through the flow path 8 formed between the thin plates 6 through the water supply header 5a, and exchanges heat with the one fluid A. Thereafter, the water is drained from the drain pipe 3b through the drain header 5b.

  Then, heat is transferred from the higher temperature fluid of the heat exchange fluid A or B to the lower temperature fluid through the thin metal plate 6. At that time, by forming a plurality of convex heat transfer fins 7 on the surface of the thin metal plate 6, the heat exchange area is increased and the heat exchange efficiency is improved. It is preferable from the viewpoint of heat exchange efficiency that the flow paths 8 of fluid A and fluid B formed between the thin metal plates 6 form parallel flow paths that are alternately stacked and orthogonal flow paths that are orthogonal to each other.

  The plate fin heat exchanger 1 according to the embodiment of the present invention has a flat cross-sectional shape obtained by cutting the heat transfer fin 7 formed on the metal thin plate 6 along a plane parallel to the thin plate 6 as shown in FIG. Thus, the airfoil is formed by combining curves having no inflection points. Here, the curve having no inflection point refers to a part of a circular arc, a quadratic curve, a hyperbola, or the like or an arbitrarily shaped curve having no inflection point. The airfoil preferably has a shape having no recess, and preferably has a shape that is substantially symmetrical with respect to a center line C parallel to the fluid flow direction 9.

  Such a wing fin 7 formed on the thin metal plate 6 may be formed on one side of the thin metal plate 6 or may be formed on both sides. Further, for use in the following description, as shown in FIG. 3, the blade length of such an airfoil fin 7 is represented by L and the blade width is represented by d.

  In the plate fin heat exchanger 1 according to the present invention, since the shape of the heat transfer fin 7 is an airfoil formed by combining curves having no inflection points, heat exchange behind the fin 7 is performed. It is possible to improve the heat exchange efficiency because the fluid is prevented from peeling and the vortex that becomes the dead water area is not generated. Further, since the airfoil is substantially symmetrical with respect to the center line C parallel to the fluid flow direction 9 without having a recess, the airfoil is easy to manufacture and does not disturb the fluid flow behind the fins 7. In addition, no dead water area is generated.

  A number of heat transfer fins 7 having such an airfoil shape are formed on the surface of the thin metal plate 6 in a staggered arrangement so as to be substantially parallel to the fluid flow direction 9 as shown in FIG. It is preferable. At the same time, it is preferable that the heat transfer fins 7 are arranged at substantially equal intervals in the fluid flow direction 9 and in the direction orthogonal to the flow direction 9. By forming the fins 7 in such a staggered arrangement, the heat exchange fluid flows across the flow direction 9 of the flow path 8 formed between the thin metal plates 6 and the width direction perpendicular to the flow direction 9. This is because a uniform flow can be formed. Here, for use in the following description, in such a blade row, as shown in FIG. 4, the space between the blades perpendicular to the flow direction 9 of the heat exchange fluid is represented by b.

  The wing-type fins 7 can also be arranged so that the projection surfaces of the fins 7 in the direction perpendicular to the fluid flow direction 9 overlap with each other in the fluid flow direction 9. For example, as shown in FIG. 5, the transmission per unit area when the projection surfaces of the fins 7 in the direction orthogonal to the fluid flow direction 9 overlap each other by 1/3 L before and after the fins 7. As shown in FIG. 6, the thermal area increases 1.1 times compared to the case where the thermal areas are arranged so as not to overlap (that is, arranged so that the overlapping amount corresponding to 1 / 3L becomes 0).

  Therefore, by disposing the projection surfaces of the fins 7 in the direction perpendicular to the fluid flow direction 9 so as to overlap before and after the fins 7, the heat transfer area per unit area increases, and the plate fin type It can be seen that the heat exchanger 1 is effective for downsizing.

  Next, the relationship between the blade length L and the blade width d (see FIG. 3) of the airfoil fin according to the present invention is such that the ratio L / d between the blade length L and the blade width d is 1.8 ≦ L / d. A range of ≦ 7 is preferable. The reason for this will be described below with reference to FIGS. FIG. 7 shows a streamline diagram at a Reynolds number Re = 500 around the airfoil fins 7 arranged in a staggered manner. FIG. 7A is an example of a streamline diagram when L / d <1.8. Shows an example of a streamline diagram when L / d ≧ 1.8. 8 is a diagram showing the change in w / L with respect to the change in L / d, FIG. 9 is a diagram showing the thickness of the boundary layer at the fin rear end with respect to the change in L / d, and FIG. It is the figure which showed the change of the heat transfer performance with respect to pump power with respect to a change compared with the prior art.

The Reynolds number Re is defined by the following equation (1).
Re = uD / ν (1)
Where u is the flow rate of the heat exchange fluid
D: Hydraulic diameter based on narrow channel width
ν: Kinematic viscosity coefficient of heat exchange fluid Further, w represents the maximum width of the vortex region 10 generated in the wake of the fin 7 as shown in FIG.

  That is, in FIG. 7, the streamline in the case of (a) L / d <1.8 peels after passing through the maximum width portion of the fin 7, and the vortex region 10 is formed behind the fin 7. Further, the stream line is sparse and the flow is low behind the vortex region 10. Therefore, the vortex region 10 having the maximum dimension w stays in the flow between the fin 7 and the fin 7 in the flow direction 9, and the sensible heat possessed by the heat exchange fluid is also confined in this region, and heat transfer is deteriorated. It is estimated that In general, the presence of such a vortex region 10 is disadvantageous from the viewpoint of pressure loss.

  On the other hand, in the streamline in the case of (b) L / d ≧ 1.8, separation or vortex region behind the fins 7 is not recognized, and it is considered that heat transfer and pressure loss are unlikely to occur. The size of such a vortex region is expressed as a ratio w / L of the blade length L to the maximum dimension w, and according to FIG. 8 shown with respect to the ratio L / d of the blade length L and the blade width d, The vortex region decreases as L / d increases, and disappears when L / d reaches 1.8 or more. Therefore, L / d ≧ 1.8 at which the vortex region does not occur is set as a lower limit at which effective heat exchange performance can be obtained by the airfoil fin according to the present invention.

  By the way, generally, the heat transfer coefficient on the fin surface decreases as the boundary layer develops. Therefore, in order to obtain effective heat transfer performance with this fin shape, it is a condition that the boundary layer formation until the flow reaches the rear end of the fin is suppressed. As shown in FIG. 9, the boundary layer thickness at the fin rear end with respect to L / d is effectively suppressed and undeveloped in the range of L / d ≦ 7. Therefore, the airfoil fin according to the present invention has an effective heat transfer performance in the range of 1.8 ≦ L / d ≦ 7 together with the L / d region where the vortex region is not generated. Preferred above.

  On the other hand, if the heat transfer performance with respect to L / d of the airfoil fin 7 according to the embodiment of the present invention is compared with the prior art, the heat transfer performance increases as L / d increases as shown in FIG. If L / d is 1.7 or more, heat transfer performance higher than that of the prior art can be obtained, and the range where L / d specified by the present invention is about 1.8 or more is a range in which this is satisfied. .

  Here, j in FIG. 10 indicates a factor representing the heat transfer characteristic, and f indicates a friction coefficient. The “prior art” refers to Patent Document 1. 7 to 10 show that the plate is made of aluminum at a temperature of 100 ° C. using FRUENT (flow analysis program manufactured by FRUENT) (that is, the heat exchange between the high-temperature fluid and the annemy plate is ignored, and the aluminum plate has a temperature of This is the result of a simulation of only the heat exchange between the plate and the cryogenic fluid under the condition that the inlet temperature of the fluid is 20 ° C. (assuming that the temperature is 100 ° C.).

  Next, the relationship between the blade gap b and the blade width d (see FIG. 4) of the airfoil fin according to the present invention is such that the ratio b / d between the blade gap b and the blade width d is 0.3 ≦ b. It is preferable that / d ≦ 3. The reason for this will be described below with reference to FIGS. FIG. 11 is a diagram showing a change in w / L with respect to a change in b / d, FIG. 12 is a diagram showing a thickness of a boundary layer at a fin rear end with respect to a change in L / d, and FIG. 13 is a change in L / d. It is the figure which showed the change of the heat-transfer performance with respect to pump power compared with the prior art.

  First, according to FIG. 11 which shows the change in the ratio w / L of the maximum dimension w of the vortex region and the blade length L to the change in the ratio b / d between the blade gap b and the blade width d, the vortex region is b / It becomes smaller as d becomes larger, and disappears when b / d reaches 0.3 or more. Therefore, b / d ≧ 0.3 at which the vortex region does not occur is set as a lower limit at which effective heat exchange performance can be obtained by the airfoil fin according to the present invention.

  Further, as shown in FIG. 12, the boundary layer thickness at the fin rear end with respect to b / d is effectively suppressed and undeveloped in the range of b / d ≦ 3. Therefore, in order to exhibit effective heat transfer performance in the inter-blade gap b of this fin, it is preferable to set the range of b / d ≦ 3.

  On the other hand, when Re / 500 and L / d = 1.8, j / f with respect to b / d of airfoil fin 7 according to the embodiment of the present invention is examined. In comparison, as b / d increases, it decreases as shown in FIG. If b / d is 3.5 or less, heat transfer performance higher than that of the prior art can be obtained, and the range of b / d ≦ 3 specified from the boundary layer thickness at the fin rear end is the above condition. It is the range that is satisfied. Therefore, the airfoil fin according to the present invention has an effective heat transfer performance in the range of 0.3 ≦ b / d ≦ 3 together with the b / d region where the vortex region is not generated. Preferred above.

  As described above, a plate fin type in which a heat exchange fluid flow path is formed between the opposed thin plates by alternately laminating metal thin plates having a plurality of heat transfer fins formed in a convex shape on the surface. In the heat exchanger, by making the airfoil formed by combining a curve in which the cross-sectional shape of the heat transfer fin does not have an inflection point, preventing separation of fluid behind the fin and preventing formation of a vortex region, Eliminate dead water areas where heat transfer is poor.

  Further, by setting the ratio L / d between the blade length L and the blade width d of this airfoil in the range of 1.8 ≦ L / d ≦ 7, a vortex region is not formed behind the fin and the fin Since the boundary layer at the rear end is also undeveloped, the heat exchange efficiency can be improved as compared with the prior art. Further, if the ratio b / d between the blade gap b and the blade width d in the airfoil is in the range of 0.3 ≦ b / d ≦ 3, the vortex region is not formed behind the fin as described above. In addition, since the boundary layer at the fin rear end is not yet developed, the heat exchange efficiency can be improved as compared with the prior art.

  By making such a configuration, the plate fin heat exchanger can be made compact, and the flow of such a heat exchange fluid suppresses flow resistance and reduces pump power. Furthermore, since the shape of the airfoil fin according to the present invention is simple, it is possible to easily change the conditions such as the blade length and the blade width and to evaluate the performance as required in comparison with the prior art. In addition, the airfoil fin according to the present invention may be formed on a thin metal plate by an etching process or the like.

It is a perspective view which shows the external appearance of the plate fin type heat exchanger which concerns on embodiment of this invention. It is explanatory drawing which shows the state by which the metal thin plate was laminated | stacked within the plate fin type heat exchanger of FIG. It is sectional drawing which shows the plane cross-sectional shape of the heat-transfer fin formed in convex shape on the metal thin plate surface of FIG. It is a top view which shows the example of arrangement | positioning of the several heat-transfer fin formed in the metal thin plate surface of FIG. It is a top view which shows the other example of arrangement | positioning of the several heat-transfer fin formed in the metal thin plate surface of FIG. It is a figure which compares and shows the heat-transfer area per unit area of arrangement | positioning of the heat-transfer fin shown in FIG. 4, and the heat-transfer fin arrangement | positioning shown in FIG. The streamline figure in Reynolds number Re = 500 around a staggered wing-type fin is shown, (a) is an example of a streamline figure in the case of L / d <1.8, (b) is L / d> = 1. .8 shows an example of a streamline diagram. It is a figure which shows the change of w / L with respect to the change of L / d. It is the figure which showed the thickness of the boundary layer in the fin rear end with respect to the change of L / d. It is the figure which showed the change of the heat transfer performance with respect to pump power with respect to the change of L / d compared with the prior art. It is a figure which shows the change of w / L with respect to the change of b / d. It is the figure which showed the thickness of the boundary layer in the fin rear end with respect to the change of L / d. It is the figure which showed the change of the heat transfer performance with respect to pump power with respect to the change of L / d compared with the prior art. It is a figure explaining the arrangement | positioning of the heat-transfer fin formed in the surface of a metal thin plate plate in connection with the heat exchanger of a prior art example.

Explanation of symbols

L: Blade length, d: Blade width, b: Spacing between blades C: Center line in the direction of flow of heat exchange fluid, w: Maximum dimension of vortex region 1: Plate fin heat exchanger 2a, 3a: Water supply pipe, 2b, 3b: Drain pipe 4a, 5a: Water supply header, 4b, 5b: Drain header 6: Metal thin plate, 7: Heat transfer fin (wing fin)
8: flow path, 9: flow direction of heat exchange fluid 10: vortex region

Claims (6)

  In a plate fin type heat exchanger in which a heat exchange fluid channel is formed between the opposed thin plates by alternately laminating metal thin plates having a plurality of heat transfer fins formed on the surface in a convex shape, The plate fin heat exchanger according to claim 1, wherein a cross-sectional shape of the heat transfer fin cut along a plane parallel to the thin plate is an airfoil formed by combining curves having no inflection point.   The plate fin heat exchanger according to claim 1, wherein a cross-sectional shape of the heat transfer fin has no recess.   The plate fin heat exchanger according to claim 1 or 2, wherein a cross-sectional shape of the heat transfer fin is substantially symmetric with respect to a center line parallel to a flow direction of the heat exchange fluid.   The ratio L / d between the blade length L and the blade width d in the airfoil is in a range of 1.8 ≦ L / d ≦ 7. The plate fin type heat exchanger as described in 1.   The ratio b / d between the blade gap b and the blade width d perpendicular to the flow direction of the heat exchange fluid in the airfoil is in the range of 0.3 ≦ b / d ≦ 3. 5. The plate fin heat exchanger according to any one of items 4 to 4.   The plate fin heat exchanger according to any one of claims 1 to 5, wherein the heat transfer fin is formed by etching the metal thin plate.

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