JP2002181467A - Multitube heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multitube heat exchanger wherefrom decrease of the number of manufacturing processes and increase of heat exchange efficiency can be expected. SOLUTION: The multitube heat exchanger has a plurality of inner tubes (heat transfer tubes) 114 through which a first fluid such as high-temperature gas passes and an outer tube (trunk) 116 through which a second fluid such as cooling water passes. Groups 114, 114... of the heat transfer tubes in a plurality are fitted in such a manner that the opposite ends thereof are retained by introduction-side and discharge-side retaining plates 118 and 120 positioned on the first fluid introduction side and the first fluid discharge side respectively. The groups 114, 114... of the heat transfer tubes are so bent and bundled (converged) as to face an introduction port 126 of the first fluid, at the portions retained by the introduction-side retaining plate 118, and are retained by the plates 118.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention comprises an inner tube (heat transfer tube) group through which a first fluid passes, and an outer tube (body) through which a second fluid passes,
The present invention relates to a multi-pipe heat exchanger in which a plurality of heat transfer tube groups are arranged with their both ends held on an inlet / outlet holding plate located on a first fluid inlet side and a first fluid outlet side, respectively. . In particular, a multi-tube heat exchanger that exchanges heat by passing high-speed high-temperature gas (gas) through a heat transfer tube group and cooling water (liquid) through a body, for example, cooling exhaust gas of an internal combustion engine with cooling water. The present invention is suitable for an exhaust gas cooler (which requires a high heat exchange capability).

Here, a multi-tube heat exchanger that exchanges heat by passing high-speed high-temperature gas (gas) through a straight heat transfer tube group and cooling water (liquid) through a body will be described as an example.

[0003]

2. Description of the Related Art As described above, a multi-tube heat exchanger 12 as shown in FIGS.

That is, a plurality of inner tubes (heat transfer tubes) 14 through which a first fluid (high-temperature gas) passes, and a second fluid (cooling water)
And a plurality of heat transfer tubes 14 (a group of heat transfer tubes) having both ends located on a first fluid introduction side and a first fluid discharge side, respectively. It is arranged to be held by holding plates 18 and 20. In the illustrated example, a large number of heat transfer tube groups 14, 14,...
Are provided via introduction and discharge side holding plates (tube sheets) 18 and 20 at both ends of the body 16. Both ends of the body 16 have a truncated conical rectifying cylinder portion (rectifying portion).
Are provided with inlet / outlet ports (connection pipes) 26, 28 having flanges 26a, 28a via 22, 24 so that the first fluid (high-temperature gas) can pass through the inside of the heat transfer tube groups 14, 14,. . In addition, introduction / discharge nozzles 30 and 32 are provided above and below the body 16, and the second fluid (cooling water) can pass outside the heat transfer tube 14.

However, the multi-tube heat exchanger 12 shown in FIGS. 1 and 2 has the following problems when the number of heat transfer tube groups 14, 14,... Is increased in order to increase the heat exchange efficiency. It was easy to occur.

[0006] As the flow resistance of the cooling water increases,
As a result, it is difficult to increase the heat exchange efficiency due to problems such as a decrease in the gas flow velocity and a decrease in the heat transfer coefficient and the like.

[0007] The multi-tubular heat exchanger 12 requires a large number of manufacturing steps and tends to increase in weight.

[0008] In view of the above, the inventors of the present invention aim to provide a multi-tube heat exchanger in which the heat exchange efficiency can be easily increased and the number of manufacturing steps can be reduced. A tubular heat exchanger was proposed earlier (Japanese Patent Application No. 2000-06).
No. 1541: not disclosed at the time of filing).

[0009] In a multi-tube heat exchanger having a plurality of heat transfer tubes disposed inside a body, each heat transfer tube is formed between a heat transfer tube main body having a flat cross section and a longitudinally opposed surface of the heat transfer tube main body. The present invention mainly relates to the improvement of the multi-tube heat exchanger having the above-described structure, and can expect further increase in the number of manufacturing steps and heat exchange efficiency. It is an object of the present invention to provide a multitubular heat exchanger.

[0010]

DISCLOSURE OF THE INVENTION The present inventors have made intensive efforts to solve the above-mentioned problems, and as a result, have conceived of a multitubular heat exchanger having the following structure.

[0011] A plurality of inner tubes (heat transfer tubes) through which the first fluid passes and an outer tube (body) through which the second fluid passes are provided. In a multi-tube heat exchanger that is arranged to be held on the introduction-side and discharge-side holding plates respectively located on the first fluid discharge side, the heat transfer tube group is configured such that the first fluid is held at the holding portion of the introduction-side holding plate. Characterized by being bent and bundled (converged) so as to face the introduction port of the above and held by the introduction side holding plate.

With the above configuration, the following operations and effects can be obtained.

[0013] The spread of the heat transfer tube group facing the inlet of the first fluid is smaller than in the past, and the flow rate difference (expansion of the flow velocity distribution) in each heat transfer tube is relatively small. Therefore, a decrease in the heat exchange efficiency based on the spread of the flow velocity distribution in each heat transfer tube is reduced, and as a result, the heat exchange efficiency is increased.

The opening ratio of the portion of the introduction-side holding plate facing the introduction port relatively increases. Accordingly, the resistance of the introduction-side holding plate to the flow of the first fluid (high-speed gas) is reduced, and the reduction of the flow velocity is reduced. From this point, the heat exchange efficiency is also increased.

Since it is bundled and held on the introduction-side holding plate, it is not necessary to set it on the introduction-holding plate and braze one by one. Therefore, man-hours for manufacturing the heat exchanger can be reduced.

The circumference (outer diameter) of the holding plate connecting portion of the rectifying cylinder portion connected to the introduction-side holding plate can be relatively reduced. Therefore, it is easy to make the heat exchanger compact (small) and lightweight.

In the above configuration, it is desirable that the center of the heat transfer tube group substantially coincides with the center of the inlet of the first fluid. The spread of the flow velocity distribution in each heat transfer tube becomes relatively small, and it is possible to ensure that the opening ratio of the portion facing the inlet is relatively increased, and the above-mentioned increase in the heat exchange efficiency is expected more reliably. This is because it can be done.

In the above configuration, it is desirable that the heat transfer tube group be bent and bundled (converged) and held on the discharge side holding plate also at the holding portion of the discharge side holding plate. The reduction in the number of manufacturing steps and the reduction in size and weight become easier.

In the above configuration, it is desirable that the outer cross section of each heat transfer tube be a flat cross section. When converging on the introduction holding plate side, there is no gap between the heat transfer tubes,
This is because the heat exchange efficiency can be expected to increase more reliably. Further, the number of heat transfer tubes can be relatively reduced, and further, it is not necessary to fill gaps (in the case of round pipes) generated between the heat transfer tubes, and the number of manufacturing steps of the heat exchanger does not increase.

In the above construction, each of the heat transfer tubes is connected between a heat transfer tube main body composed of a flat tube and a longitudinally opposed surface of the heat transfer tube main body, or a plurality of heat transfer tubes protruding from both or one of the opposed surfaces. It is desirable to use a configuration including fins. As described above, a small number of heat transfer tubes is required to secure a heat transfer area for the first fluid passing through the inside of the heat transfer tubes, and the number of welds for holding the holding plate is also reduced. Therefore, the number of parts and the number of manufacturing steps can be reduced. Also,
The outside of the heat transfer tube becomes substantially flat, the flow of the second fluid flowing outside the heat transfer tube becomes smooth, and an increase in heat exchange efficiency can be expected. The reason why the flow of the second fluid is smooth is that the flow path (gap) formed in the cross-sectional direction of the second fluid is linear (conventionally, meandering).

In the above configuration, it is desirable that the outer cross section of the body be square or rectangular and that the widths of the heat transfer tubes be all equal. This is because the heat transfer tubes having the same dimensions can be used, and as a result, the number of parts and, consequently, the number of manufacturing steps are reduced.

In each of the above structures, it is desirable to use the present invention when heat exchange is performed by passing high-speed high-temperature gas through the heat transfer tube group and passing cooling water through the body. This is because, in the case of a high-speed high-temperature gas, the flow velocity distribution in the central part and the peripheral part tends to widen, and the effect of the present invention relating to the increase in the heat exchange efficiency becomes remarkable.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. For the parts corresponding to the above-described examples, the last two digits are given as the same numerals.

FIGS. 3 to 5 show the multitubular heat exchanger 112 according to the present embodiment. FIG. 3 is a horizontal vertical sectional view of the present embodiment (a sectional view of the heat transfer tube is omitted), FIG. 4 is an end view taken along line 4-4 in FIG. 3, and FIG. 5 is an end view taken along line 5-5 in FIG.

That is, the rectangular cylinder body 1 having the introduction side / outlet side holding plates (tube sheets) 118 and 120 at both ends.
16, a plurality of heat transfer tubes 114 are provided with fixed tube sheets 118, 1.
20 are provided. At both ends of the rectangular cylinder body 116, a truncated quadrangular pyramid-shaped rectifying cylinder portion (rectifying portion) 12 on the introduction side and the exit side is provided.
First fluid inlet / outlet (connecting pipe) 126, 128 with flange 126a, 128a via 2, 124
And the first fluid (high-temperature gas) is
14... Can be conducted.

In addition, the upper and lower sides of the
Discharge side nozzles 130 and 132 are provided, and the second fluid (cooling water) can be conducted outside the heat transfer tube 114. Up to this point, it is the same as the above-described example, except that the body is changed from a cylindrical shape to a rectangular cylindrical shape.

As shown in FIG. 6 (corresponding to the portion taken along line 6-6 in FIG. 5), the body may be a cylindrical body 116A. The number of types of parts can be reduced. That is, when it is cylindrical, heat transfer tubes 114, 114A,
114B must be prepared.

Each of the heat transfer tubes may be a square pipe or a conventional round pipe, as shown in the drawing, without having to have a flat outer cross section. When the square pipes are bent and bundled, a gap is not formed between the heat transfer tubes, which is preferable.

In the heat exchanger of the present embodiment, the heat transfer tube groups 114 are bent and bundled (converged) so as to face the first fluid inlet 126 at the holding portion of the inlet side holding plate 118. It is held on the introduction-side holding plate 118.

More specifically, the introduction side holding plate (tube sheet) 118 holds a rectangular introduction end portion having upper and lower sides corresponding to a shape in which the heat transfer tube groups 114, 114. A hole 119 is formed, and the introduction-side end of the heat transfer tube group 114 is held in the holding hole 119 in a bent state (see FIG. 7). On the other hand, heat transfer tube groups 114, 114 ...
Are straight without bending (ie, not converging), that is, with a gap between each other. Therefore, a number of discharge end holding holes (heat transfer tube holding holes) 121, 121... Corresponding to the number of heat transfer tubes 114 are formed in the discharge side holding plate (tube sheet) 120.
Are held on the discharge side of the heat tube groups 114, 114,.

Usually, the center of the heat transfer tube groups 114, 114...
, But may be unevenly distributed. In the case of uneven distribution, the spread of the relative flow velocity distribution is larger than in the case where the centers are coincident, but since the opening ratio of the inlet to the facing surface of the heat transfer tube group is high, the first fluid is The flow resistance at the time of flowing into the heat transfer tube is reduced (especially in the case of a high-speed and high-temperature gas), and an increase in heat exchange efficiency can be expected. Further, even if it is unevenly distributed with respect to the center (axial line) of the inlet 126, the number of manufacturing (manufacturing) steps is naturally reduced as described below. The flow rate of the exhaust gas from the automobile is usually from 0 to 50 m / min at the inlet 126 and from 120 to 700 ° C.

When the discharge-side ends of the heat transfer tube groups 114, 114,...
The number of joints is reduced, leading to a further reduction in the number of manufacturing steps.

Next, a method for manufacturing the heat exchanger of the present embodiment will be described.

First, as shown in FIG. 7, a flat tube (a rectangular cross section in the figure) 134 serving as a main body of the heat transfer tube 114, a metal corrugated plate 136 serving as a heat transfer fin, and holding the inlet and outlet sides. Plates 118 and 120 are prepared. Here, the flat tube 13
The cross section of 4 may be a rectangular cylinder or an ellipse. Also,
The corrugated plate 136 has a rectangular wave shape in the illustrated example, but may have a triangular wave shape, a trapezoidal wave shape, or a circular wave shape.

At this time, the flat tube (heat transfer tube main body) 134,
The thickness of the corrugated plate 136 and the thicknesses of the holding plates 118 and 120 vary depending on the material used and the service life. For example, in the case of stainless steel, the first member is 0.1 to 1.0 mm (preferably 0.1 to 1.0 mm).
3 to 0.8 mm), the former second: 0.01 to 0.8 mm (preferably 0.05 to 0.5 mm), and the latter: 0.5 to 3 mm (preferably 1 to 2 mm).

The method for preparing the corrugated plate 136 is not particularly limited, and can be prepared by a conventional method. For example, pull out,
A gear-shaped punch may be rolled on a corrugated die to perform corrugating molding (pressing).

Then, a wax is attached to each top of the corrugated plate 136.
After the flat tube 134 is inserted into the flat tube 134 in a state where the brazing material is adhered, and the flat tube 134 is in a state where the brazing material is adhered between the adjacent surfaces of the inlet-side end, the flat tube 134 is compression-molded to form a wave. At the same time as the plate 136 is temporarily fixed, the plate 136 is bent so as to be joined (converged) in the longitudinal direction at the introduction port side end.

Next, both ends of the heat transfer tubes 114 are inserted and joined (brazed) to the heat transfer tube holding holes 119 and the discharge side holding plate 120 of the introduction side holding plate 118, respectively. A unit 138 is prepared.

At this time, when the material of the heat exchanger is stainless steel, for example, copper brazing or Ni brazing is usually used. The heating and cooling conditions at the time of brazing are set in consideration of the type and heat capacity of the brazing material.

The inlet / discharge side holding plates 118, 12
No. 0 has annular joining lips (joining flanges) 118a and 120a around the periphery thereof, and the inlet side holding plate 11
8 is provided with an engagement step portion 118b formed on both sides in the width direction as shown in the drawing. The engagement step serves as a positioning step when joining with the introduction-side rectifying cylinder 122.

After the heat transfer tube unit 138 thus prepared is partially inserted into the outer periphery of the holding plates 118 and 120 of the heat transfer tube unit 138 and inserted into the rectangular tube 116 forming the body, the large-diameter side of the truncated pyramid tube forming the straightening tube portions 122 and 124 is formed. And, on the other hand, the flange 1
The inlet (inlet-side connecting pipe) 126 and the outlet (outlet-side connecting pipe) 128 into which the 18a and 120a are integrated are inserted into the small-diameter side, and are joined (fixed).

As the joining (main fixing) means, for example, TIG welding or laser welding, in which the steel material is less likely to be oxidized and deteriorated and the joining strength is easily ensured, is desirable. It may be.

In the above description, it is also possible to divide the rectangular cylinder 116 in half and attach it later. In this case, after the parts other than the square cylinder 116 are integrated by resistance welding / brazing, etc., the square cylinder 116 is integrated by resistance welding in another step. For this reason, although the number of manufacturing steps is large, it is desirable that the problem of metal cracking due to the difference in heat contact efficiency between the brazing surface and the cooling rate between the surface side and the inside after brazing hardly occurs.

As described above, the structure of the heat transfer tube is such that the heat transfer tube main body 134 having a flat cross section and the heat transfer fins 136 connecting the longitudinally opposed surfaces of the heat transfer tube main body 134 are formed of separate corrugated plates. The configuration does not need to be.

The heat transfer tubes 214, 214A, 21 shown in FIG.
4B is a multi-stage press working (compression and
Necking etc.) so that the heat transfer tube main bodies 234, 234A, 2
Heat transfer fins 236, 236A, 236B with 34B
Are integrally formed.

FIG. 8B shows a plurality (two in the illustrated example) of heat transfer tube elements 214A ', 214A' joined in the width direction.

FIG. 8 (c) shows the heat transfer fins 236B protruding alternately.

In the illustrated example, the heat transfer fins 236 and 236A projecting from both sides are joined to each other, but there may be a gap. When projecting the heat transfer fin from one side, the heat transfer fin is normally brought into contact with the other facing surface, but may be separated from the viewpoint of formability.

In these heat transfer tubes, the heat transfer tubes 214C are processed by press working in the order shown in FIG.

Large-diameter round pipe (drawn or ERW) P
Is manufactured through a flattening compression process → a required number of grooving (necking) processes → a compression process from the lateral direction. At this time, the wall thickness of the round pipe is 0.1 to 1.0 mm (preferably 0.3 to 0.8 mm), similar to the wall thickness of the heat transfer tube body described above.
And

The heat transfer tubes 314 and 314A shown in FIG.
Heat transfer tube bodies 334, 33 from one metal plate (hoop material: steel strip) by multi-stage roll forming or multi-stage press
The heat transfer fins 336 and 336A are integrally formed with 4A. Naturally, similarly to the above, a configuration in which a plurality of pieces are joined in the width direction is also possible.

Specifically, from one plate (hoop material),
An annular body having fins projecting from both walls in order from the one end S is joined together at the center and the end E to manufacture. At this time, a brazing material is applied in the middle of joining the terminal end E.

The material thickness of the heat transfer tube of both embodiments is 0.1%, similarly to the thickness of the heat transfer tube main body (flat tube) described above.
To 1.0 mm (preferably 0.3 to 0.8 mm).

In the case where the heat transfer tube is manufactured in this manner, there is no possibility of occurrence of poor soldering (variation in soldering) when the heat transfer fin is formed by a separate corrugated plate.

In the above description, the high-speed high-temperature gas (gas) is supplied to the straight heat transfer tube (inner tube) group by the body (outer tube).
A heat exchanger that performs heat exchange by passing cooling water (liquid) through the fluid is taken as an example, but the combination of the first fluid and the second fluid is arbitrary as long as there is a temperature difference at which heat exchange is possible.

However, usually, it is desirable to select the first fluid (passing through the inner pipe) and the second fluid (passing through the outer pipe) based on the following criteria. (Chemical Engineering Dictionary, Chemical Engineering Dictionary)
(May 30, 1974) Maruzen, p. 365-366) Fluid to be passed through the inner pipe (inside the pipe): corrosive fluid, fluid with large stains on the pipe wall, high-pressure fluid, high-temperature fluid requiring special materials .

Fluid to be passed through the outer pipe (outside the pipe): a fluid having a small flow rate, a fluid having a large viscosity, and a fluid having a small allowable pressure loss.

The present invention is also applicable to a heat transfer tube group that is bent (bent) in the middle, and is further bent in a U-shape and has both ends on the same side.

Naturally, the present invention can be applied to all types of multi-tube heat exchangers, such as a heat exchanger in which a rectifying section (rectifying chamber) is provided only at one end and partitioned by a partition plate and the inlet and outlet are on the same side. You can do it.

[Brief description of the drawings]

FIG. 1 is a vertical longitudinal sectional view showing an example of a conventional multi-tube heat exchanger.

FIG. 2 is a sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a horizontal longitudinal sectional view showing one embodiment of the multi-tube heat exchanger of the present invention (a sectional view of a heat transfer tube is omitted).

FIG. 4 is an end view taken along the line 4-4 in FIG. 3;

FIG. 5 is an end view taken along line 5 (6) -5 (6) in FIG. 3;

FIG. 6 shows a case where the body is a cylindrical body in FIG.
(6) -5 (6) End view at line section

FIG. 7 is a schematic explanatory view showing a manufacturing process of the heat transfer tube unit of the present embodiment.

FIG. 8 is a cross-sectional view showing each form of a heat transfer tube formed from a pipe material.

FIG. 9 is an explanatory view of a manufacturing process of a heat transfer tube formed from a pipe material.

FIG. 10 is a cross-sectional view showing each form of a heat transfer tube formed from a hoop material.

[Explanation of symbols]

 12, 112 Multi-tube heat exchanger 16, 116 Body (outer tube) 114, 114, 214, 314 Heat transfer tube (inner tube) 18, 118 Inlet-side holding plate (tube sheet) 119 Heat transfer tube holding hole 120 Discharge side holding Plate (tube sheet) 121 Heat transfer tube holding hole 138 Heat transfer tube unit 22, 122 Inlet-side rectifying tube portion (rectifying portion) 24, 124 Discharge-side rectifying tube portion (rectifying portion) 134, 234, 334 Heat transfer tube main body (flat tube) 136, 236, 336 heat transfer fins

Claims (8)

[Claims] 1. A heat exchanger comprising a plurality of inner tubes (heat transfer tubes) through which a first fluid passes, and an outer tube (body) through which a second fluid passes. The heat transfer tubes are arranged in such a manner that both ends thereof are held by the inlet / outlet holding plates located on the first fluid inlet side and the first fluid outlet side, respectively. Multi-tubes wherein a group is bent and bundled (converged) so as to face the inlet of the first fluid at a holding portion of the introduction-side holding plate and held by the introduction-side holding plate. Type heat exchanger. 2. The heat transfer tube group according to claim 1, wherein the center of the heat transfer tube group substantially coincides with the center of the first fluid inlet.
The multi-tubular heat exchanger as described. 3. The heat transfer tube group is also bent and bundled (converged) and held on the discharge side holding plate at a holding portion of the discharge side holding plate.
The multi-tubular heat exchanger as described. 4. The multi-tube heat exchanger according to claim 1, wherein the outer cross section of each of the heat transfer tubes is a flat cross section. 5. A plurality of heat transfer fins, wherein each heat transfer tube connects a heat transfer tube main body made of a flat tube and a longitudinally opposed surface of the heat transfer tube main body, or protrudes from both or one of the opposed surfaces. The multi-tube heat exchanger according to claim 4, comprising: 6. The heat transfer tube according to claim 1, wherein each of the heat transfer tubes has a structure in which a heat transfer fin is formed by inserting and joining a corrugated sheet separate from the heat transfer tube body to a heat transfer tube body formed of a flat tube. Item 5
The multi-tubular heat exchanger as described. 7. The multi-tube type as claimed in claim 1, wherein the outer cross section of the body is square or rectangular, and the width of each heat transfer tube is all equal. Heat exchanger. 8. The method according to claim 1, wherein the heat exchange tube group is used when a high-speed high-temperature gas is passed through the heat transfer tube group and cooling water is passed through the body to perform heat exchange. ,
The multitubular heat exchanger according to 5, 6, or 7.