JP2012137251A - Multitubular heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multitubular heat exchanger free from formation of a recessed part forming a condensed water pool in the heat exchanger when used, between a thick tube part and a tapered tube part.SOLUTION: This heat exchanger includes a plurality of inner tubes 114, 114, ..., through which a first fluid passes, and an outer tube 117 through which a second fluid passes, and the inner tubes 114 include the thick tube parts 114a at both ends, a thin tube part 114b at the middle, and the tapered tube part 114c between the thin tube part 114b and the thick tube part 114a. In this multitubular heat exchanger, the inner tubes 114, 114, ..., are in sealed contact at the thick tube parts 114a and integrally held by the outer tube 117, so that a second fluid pass-through gap S is formed between the outside of each inner tube 114 and the inside of the outer tube 117. The inner tube 114 is tapered at one side in the vertical direction of the tapered tube part 114c, and its surface (bottom surface) to be on the downside when the inner tube 114 is used, is provided as a longitudinal flat surface.

Description

  The present invention includes an inner tube (heat transfer tube) group through which a first fluid passes and an outer tube (fuselage) through which a second fluid passes, and a plurality of heat transfer tube groups held in the outer tube. The present invention relates to a heat exchanger.

  In particular, a multi-tube heat exchanger for exchanging heat by passing high-speed high-temperature gas (gas) through the heat transfer tube group and cooling water (liquid) through the fuselage, for example, an exhaust gas recirculation device (hereinafter referred to as “EGR device”) The invention is suitable for an exhaust cooler (which requires a high degree of heat exchange capability) that cools the exhaust gas of the internal combustion engine with cooling water.

  As described above, for example, a multi-tubular heat exchanger having an outer shape as shown in FIGS. And this heat exchanger had an internal structure as shown in FIGS.

  A plurality of inner tube groups (heat transfer tubes) 14, 14... Through which the first fluid (hot gas) passes, and the second fluid (cooling water) that holds the heat transfer tube groups and forms a passage gap. A tube (body) 17 and rectifying cylinders 20 and 21 attached to both ends of the outer tube 17 are provided. The inner tube 14 includes a thick tube portion 14a at both ends, a thin tube portion 14b in the middle, and a tapered tube portion 14c between the thin tube portion 14b and the thick tube portion 14a. Each inner tube 14 is tightly held and integrated with the outer tube 17 by the thick tube portion 14 a, and a second fluid passage gap S is formed between the outer side of the inner tube 14 and the inner side of the outer tube 17. Yes. Usually, heat transfer fins 22 are inserted into the inner tube 14 from the viewpoint of heat transfer.

  Here, the heat exchanger is usually manufactured by assembling each member and then integrating them by brazing or welding.

  From the viewpoint of assembly workability, the inner tube 14 is divided into a receiving inner tube portion 15 and a covered inner tube portion 16, and the outer tube 17 is divided into a receiving outer tube portion 18 and a covered outer tube portion 19.

  That is, after setting the heat transfer fins 22 in the covered inner tube portion 16, the receiving inner tube portion 15 is fitted. After the inner tube groups 14, 14... Thus prepared are fitted to the receiving outer tube portion 18 and the covered outer tube portion 19, respectively, the covered outer tube portion 19 is inverted to receive the outer tube portion. 18 (see FIG. 5).

  Thereafter, the flow straightening cylinders 20 and 21 are fitted to both ends of the outer tube 17 to be integrated as a heat exchanger assembly through a brazing furnace. At this time, the receiving outer pipe portion 18 and the covering outer pipe portion 19 may be integrated in advance by spot welding or the like.

  When the heat exchanger thus prepared is used as an exhaust cooler in an EGR device, when the inclination angle is smaller than the taper angle, a concave portion with respect to the horizontal plane is formed at the boundary between the tapered tube portion 14c and the thick tube portion 14a of the inner tube 14. C is formed. Condensed water tends to accumulate in the recess C. This condensate pool promotes corrosion when exhaust gas or the like contains sulfide or the like (see FIG. 7 and paragraph 0002 of Patent Document 1).

  In order not to generate the condensate pool, it is necessary to incline the heat exchanger to an angle (for example, 15 °) α or more of the slope portion as shown in FIG. However, from the viewpoint of effective use of space in the engine room, there are cases where it is difficult to set the heat exchanger to be tilted beyond an angle at which no condensed water pool is generated.

  In addition, although it does not affect the patentability of this invention, patent documents 1-3 etc. can be mentioned as prior art literature relevant to the condensed water countermeasure of a heat exchanger.

  Patent Document 1 describes a technique related to brazing when an EGR gas heat exchanger or the like is manufactured by brazing using stainless steel.

  Patent Documents 2 and 3 describe a technique for ensuring drainage of condensed water in a heat exchanger composed of flat tubes and corrugated fins, which is used in an outdoor unit of an air conditioner that also serves as an air conditioner.

JP 2002-28775 A JP 2005-37002 A JP 2004-317002 A

  In view of the above, an object of the present invention is to provide a multi-tube heat exchanger that does not form a concave portion that forms a condensate pool in the heat exchanger between the thick tube portion and the taper tube portion in use. To do.

  In order to solve the above-mentioned problems, the present inventors have made extensive efforts to develop them, and as a result, have arrived at a multi-tube heat exchanger having the following configuration. For reference, a figure symbol is attached with parentheses.

A plurality of inner tube groups (114, 114 ...) through which the first fluid passes, and an outer tube (117) through which the second fluid passes,
The inner tube (114) has a thick tube portion (114a) at both ends, a thin tube portion (114b) in the middle, and a tapered tube portion (114c) between the thin tube portion (114b) and the thick tube portion (114a). With
The inner pipe (114) is held and integrated with the outer pipe (117) in intimate contact with the thick pipe section (114a), so that it is between the outer side of the inner pipe (114) and the inner side of the outer pipe (117). In the multi-tube heat exchanger having a configuration in which the second fluid passage gap (S) is formed in
The inner tube (114) has a single taper in the vertical direction of the tapered tube portion (114c), and the lower surface (bottom surface) when the inner tube (114) is used is a flat surface in the longitudinal direction. It is characterized by that.

  Since the lower surface (bottom surface) when using the inner pipe is a flat surface, the boundary between the tapered pipe portion and the thick pipe portion of the inner pipe can be used regardless of the taper angle of the single taper during use. A concave portion with respect to a horizontal plane is not formed in the portion. Therefore, no condensate (condensate) pool is generated, and as a result, a high degree of rust prevention measures due to the condensate pool are not required. In addition, when applied to a refrigerator or the like, it is possible to prevent a decrease in heat exchange performance due to condensed water that freezes and hinders the flow of the first fluid.

  The said structure WHEREIN: The said outer pipe | tube (117) is a division | segmentation structure which consists of a receiving outer pipe part (118) and a covering outer pipe part (119), Comprising: The said receiving outer pipe part (118) is said inner pipe group (114). , 114... Are all stacked and held, and are closed and integrated by the covered outer tube portion (119).

  Compared to the case where the outer tube portion is inverted and assembled with respect to the conventional receiving outer tube portion, the assembly workability of the heat exchanger is improved. This is because, after all of the inner tube group is stacked and held on the receiving outer tube portion, the covering outer tube portion is fitted and closed, and the inner tube group can be assembled to the outer tube (see FIGS. 5 and 12). .

It is a front view which shows an example of the conventional multitubular heat exchanger. It is a side view similarly. FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 1. FIG. 4 is a sectional view taken along line 4-4 in FIG. 3. FIG. 5 is a sectional view taken along line 5-5 in FIG. 1 and an assembly explanatory diagram of a heat exchanger using the sectional view. FIG. 6 is a cross-sectional view taken along line 6-6 in FIG. Explanatory drawing for eliminating and eliminating condensate pool in the inner pipe of a conventional heat exchanger It is a front view which shows an example of the multitubular heat exchanger of this invention. It is a side view similarly. FIG. 10 is a cross-sectional view taken along line 10-10 in FIG. 8. It is an 11-11 line arrow directional cross-sectional view of FIG. FIG. 12 is a cross-sectional view taken along line 12-12 in FIG. 8 and an assembly explanatory diagram of a heat exchanger using the cross-sectional view. It is a 13-13 line arrow directional cross-sectional view of FIG. It is explanatory drawing of condensate water pool elimination in the inner tube | pipe of the heat exchanger in one Embodiment of this invention.

  Next, an embodiment of the multi-tube heat exchanger according to the present invention will be described based on the drawings. Here, a heat exchanger applied to EGR gas (exhaust gas) will be described as an example. In addition, as for the figure code | symbol of the part corresponding to a prior art example, the hundreds place was made into "1", the last two digits were made the same number, and those description was abbreviate | omitted all or one part.

  A plurality of inner tube groups 114, 114... Through which exhaust gas (first fluid) passes and an outer tube 117 through which cooling water (second fluid) passes are provided.

  The inner tube 114 includes a thick tube portion 114a at both ends, a thin tube portion 114b in the middle, and a tapered tube portion 114c between the thin tube portion 114b and the thick tube portion 114a. Then, the inner tube 114 is closely held and integrated with the outer tube 117 by the thick tube portion 114a, and a second fluid passage gap S is formed between the outer side of the inner tube 114 and the inner side of the outer tube 117. Yes.

  In the above description, the inner tube 114 has a divided configuration including a receiving inner tube portion 115 and a covered inner tube portion 116, and heat transfer fins 122 are inserted and integrated into the inner tube 114. In the case of a configuration that does not include heat transfer fins, the configuration of the inner tube may be formed of a drawing formed body or a seamless tube. In that case, it is good also as a structure which forms the protrusion part which a longitudinal vortex generate | occur | produces inside for the heat-transfer efficiency improvement (refer the summary etc. of Unexamined-Japanese-Patent No. 2002-350081 / 181468).

  Up to this point, it is substantially the same as the conventional example.

  And in the said structure, the inner pipe | tube 114 is made into one taper in the up-down direction of the taper pipe part 114c, and the surface (bottom face) used as the lower side at the time of use of the said inner pipe | tube 114 is made into the flat surface in a longitudinal direction.

  And it is the same that the outer tube | pipe 117 is a division body of the receiving outer tube | pipe part 118 and the covering outer tube | pipe part 119, However, A cross-sectional shape differs. That is, the receiving outer pipe portion 118 has a U-shaped cross section having a depth capable of holding all of the inner tube groups 114, 114..., And all of the inner tube groups 114, 114. Are stacked and held, and are closed and integrated by the covering outer tube portion.

  The rectifying cylinders 120 and 121 are connected and integrated at both ends of the outer tube 117. In consideration of drainability when condensed water is generated, the flow straightening cylinder is formed with the circular connection ports 120a and 121a unevenly distributed so that the side which becomes the lower side surface (bottom surface) in use has a linear cross section. . In the illustrated example, reference numeral 117a denotes a positioning convex portion for fitting and assembling the rectifying cylinders 120 and 121 to the outer tube 117.

  Next, the manufacturing method of the heat exchanger of the said structure is demonstrated.

  The material of each member of the heat exchanger is usually stainless steel, and the plate thickness is 0.5 to 3 mm (preferably 1 to 2 mm) for the outer tube and the rectifying cylinder, and 0.05 to 3 mm for the inner tube and the heat transfer fin. 1 mm (preferably 0.1 to 0.8 mm).

  First, after setting (inserting and assembling) the heat transfer fins 122 in the covered inner tube portion 116, the receiving inner tube portion 115 is fitted and assembled. At this time, the joining mode of each member is brazing. When these materials are made of stainless steel as described above, copper brazing or nickel brazing is usually used.

  A plurality of inner tube groups 114, 114... Thus prepared are all set on the receiving outer tube portion 118, and then the covered outer tube portion 119 is covered. The inner tube groups 114, 114... And the joint between the inner tube 114 and the outer tube 117 are brazed in the same manner as described above.

  In addition, joining of the receiving outer pipe part 115 and the covering outer pipe part 116 is also normally brazed similarly to the above.

  Further, the rectifying cylinders 120 and 121 are inserted into the outer tube 117 and brazed as described above.

  And the said heat exchanger assembly passes a brazing furnace (vacuum furnace), and each member is brazed and integrated. The heating and cooling conditions during brazing are set in consideration of the type of brazing material and the heat capacity.

  Thus, the manufactured multi-tube heat exchanger is assembled to the piping system of the EGR apparatus with the flat surface side facing down.

  In the heat exchanger of this embodiment, a concavity is not formed at the boundary between the thick tube portion 114a and the tapered tube portion 114c as in the prior art on the lower side (bottom side) of the inner tube, and a condensate pool is generated. There is no (FIG. 14). Accordingly, the degree of freedom in setting the assembly angle of the heat exchanger is expanded.

14, 114 Inner pipe (heat transfer pipe)
14a, 114a Thick tube portion 14b, 114b Narrow tube portion 14c, 114c Tapered tube portion 15, 115 Receiving inner tube portion 16, 116 Covered inner tube portion 17, 117 Outer tube 18, 118 Receiving outer tube portion 19, 119 Covered outer tube portion 20, 120 Rectifier cylinder 21, 121 Rectifier cylinder 22, 122 Heat transfer fin S Second fluid passage gap C Concavity (condensate pool)

Claims (4)

A plurality of inner pipes through which the first fluid passes (hereinafter referred to as “inner pipe group”) and an outer pipe through which the second fluid passes;
The inner tube includes a thick tube portion at both ends, a thin tube portion in the middle, and a tapered tube portion between the thin tube portion and the thick tube portion,
The inner pipe is closely held and integrated with the outer pipe in close contact with the thick pipe portion, and a second fluid passage gap is formed between the outer side of the inner pipe and the inner side of the outer pipe. In tube heat exchangers,
A multi-tubular heat characterized in that the inner pipe has a single taper in the vertical direction of the taper pipe portion, and the lower surface (bottom surface) when the inner pipe is used is a flat surface in the longitudinal direction. Exchanger.   The outer tube has a divided configuration including a receiving outer tube portion and a covering outer tube portion, and the receiving outer tube portion is stacked and held by the entire outer tube group, and is closed and integrated with the covering outer tube portion. The multitubular heat exchanger according to claim 1, wherein   The multi-tube according to claim 1 or 2, wherein the inner tube has a divided structure including a receiving inner tube portion and a covered inner tube portion, and heat transfer fins are held and integrated with the inner tube. Type heat exchanger.   4. The method of assembling a multi-tube heat exchanger according to claim 2 or 3, wherein all of the inner tube group is stacked and held on the receiving outer tube portion, and then the covered outer tube portion is fitted and closed. A method for assembling a multi-tubular heat exchanger.

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