JP2017207237A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a high performance heat exchange possible between exhaust gas and a heat recovery medium when a distribution/aggregation part having a compact structure.SOLUTION: A heat exchanger 1 comprises: a core part 21 for heat exchange between gas and liquid; a plate 20 having a distribution part 22 for distributing liquid to the core part 21 and an aggregation part 23 for collecting the liquid from the core part 21; a liquid introducing header 31 to the distribution part 22; and further a liquid discharge header 32 from the aggregation part 23. The distribution part 22 and the aggregation part 23 are overlapping with the core part 21 and the introducing header 31 and the discharge header 32 are not overlapping each other viewed in a predetermined direction. The introducing header 31 is located on the opposite side of the discharge header 32. With the distribution part 22/aggregation part 23, the cross sectional channel area has a monotonous decline/increment shape with respect to a liquid introducing/discharge direction; and the ratio between the maximum value and the minimum value of the cross-sectional area of the flow channel of the distribution part 22 and the aggregation part 23 is 0.1 or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat exchanger, and more particularly to a heat exchanger that performs heat exchange between a heat recovery medium such as a gas and a liquid.

As one of the countermeasures taken in recent years against global warming, development of a technique for separating and recovering CO ₂ from exhaust gas from factories such as steelworks is underway.
Typical examples of this separation and recovery technique include a physical adsorption method and a chemical absorption method.

In the physical adsorption method, a blower and a vacuum pump are required for adsorption and desorption of CO ₂ to the adsorbent, and a large amount of electric power is required.
Further, the chemical absorption method requires a large amount of steam for regenerating the absorbing solution that has absorbed CO ₂ .
However, using fossil fuels to supply these electric power and steam is not a countermeasure against global warming.

Therefore, a technique for further recovering heat from a low-temperature (for example, 400 ° C. or lower) exhaust gas that has been diffused into the atmosphere from a factory and using it for power generation or steam supply is being studied. Since the amount of heat required for CO ₂ recovery is large, it is expected that heat recovery will be performed with high efficiency.
A heat exchanger used for heat recovery is responsible for heat exchange between the exhaust gas and the heat recovery medium. For the CO ₂ recovery purposes mentioned above, the heat recovery medium is a liquid. In the following description, it is assumed that the heat recovery medium used in the heat exchanger is a liquid.

As a heat exchanger, a plate type or a plate fin type capable of highly efficient heat exchange is known. These heat exchangers generally include a heat exchange core portion, a distribution / aggregation portion, and a header portion. The heat exchange core unit is responsible for heat exchange, the distribution / collection unit distributes the fluid flowing into the heat exchange core unit, or collects the fluid flowing out of the heat exchange core unit, and the header unit distributes / distributes the fluid from the outside. Fluid is introduced into the collecting section, or fluid is discharged from the distributing / collecting section to the outside.
There are also heat exchangers in which two or three of these parts are integrated together.

When the fluid to be heat exchanged in the heat exchange core part flows evenly (when there is no drift), the heat exchanger exhibits maximum efficiency. That is, the amount of exchange heat becomes the largest, and highly efficient heat exchange can be achieved.
From such a background, all of Patent Documents 1 to 3 disclose a technique relating to a distribution / aggregation unit for reducing the drift and equalizing the flow rate.

In the heat transfer phenomenon related to heat exchange, there is generally a positive correlation between pressure loss and heat transfer capability.
Therefore, in the heat exchanger, the pressure loss at the heat exchange core is relatively largest compared to the pressure loss of the entire heat exchanger, and the contribution to the distribution / aggregation part and heat exchange that have a low contribution to heat exchange. However, in general, the pressure loss is relatively small in the header portion where there is no.
By adopting such a pressure loss balance, it can be expected that a uniform fluid flow rate distribution between the header portion and the distribution / collection portion and a uniform fluid flow rate distribution between the distribution / collection portion and the heat exchange core portion can be expected. .

JP 2007-139344 A JP 59-229193 A JP-A-1-102294

Here, when performing heat recovery from the exhaust gas as described above, since the exhaust gas has a large volume flow rate, the blower power for blowing is large, and there is a desire to reduce pressure loss on at least the exhaust gas side in the heat exchanger as much as possible. There is.
On the other hand, since the heat recovery medium (liquid) has an overwhelmingly large heat capacity with respect to the exhaust gas, its volume flow rate is small and the pump power is small and can be ignored.

Therefore, even if the pressure loss on the heat recovery medium side is high in the entire heat exchanger, minimizing the pressure loss on the exhaust gas side leads to overall power cost reduction.
In order to achieve this, it is desirable to install a heat exchanger so that the heat exchange core portion is disposed along the flue gas or chimney exhaust gas mainstream direction. This is because the header part and the distribution / aggregation part are almost unnecessary on the exhaust gas side, and no pressure loss occurs in these parts.

On the other hand, on the heat recovery medium side, a header part and a distribution / aggregation part are necessary. In particular, since the distribution / aggregation part also overlaps the exhaust gas flow, a compact structure is desirable.
When the distribution / gathering portion is made compact, the pressure loss in the distribution / gathering portion is relatively larger than the pressure loss in the heat exchange core portion. Therefore, there is a problem that the uniform distribution of the fluid flow rate required for the distribution / collection unit is not satisfied.

  In any of Patent Documents 1 to 3, there is no examination from such a viewpoint.

  The present invention has been made in view of such a point, and even when the distribution / aggregation portion has a compact structure, heat exchange between the exhaust gas and the heat recovery medium can be performed with high efficiency. The object is to provide a heat exchanger.

  To achieve the above object, the present invention provides a heat exchange core that performs heat exchange between a gas and a heat recovery medium, a distribution unit that distributes and introduces the heat recovery medium to the heat exchange core, and the heat exchange core. A heat collecting unit that collects the heat recovery medium discharged from the heat source, an introduction header that introduces the heat recovery medium from the outside to the distribution unit, and a discharge header that discharges the heat recovery medium from the collection unit to the outside. In the exchanger, the distribution unit and the gathering unit are located in a portion overlapping the heat exchange core when viewed from a predetermined direction, and the introduction header and the discharge header are the heat exchange core as viewed from the predetermined direction. The introduction header is located on the opposite side of the discharge header, with the introduction header sandwiching the heat exchange core as seen from the predetermined direction, and the distribution unit is configured to transfer heat recovery medium from the introduction header. Regarding the introduction direction, the introduction header The collecting section has a shape in which the cross-sectional area of the flow path monotonously increases toward the discharge header in the discharge direction of the heat recovery medium from the discharge header. The ratio between the maximum value and the minimum value of the cross-sectional area of the flow path of the distribution part and the collecting part is 0.1 or less.

  According to the present invention, the introduction header and the discharge header do not hinder the introduction / discharge of the gas to the heat exchange core on the gas side, and the distribution / collection part has a compact structure, and the distribution / collection part Even when the pressure loss at is high, the flow rate of the liquid in the heat exchange core on the liquid side becomes uniform. Therefore, even if the distribution / collection portion has a compact structure, heat exchange can be performed with high efficiency.

  The predetermined direction is, for example, a gas flowing direction.

  The total pressure loss of the distribution unit and the collection unit may be equal to or greater than the pressure loss related to the heat recovery medium of the heat exchange core.

  The heat recovery medium is, for example, a liquid.

  According to the present invention, even a compact distribution / aggregation part can exchange heat between exhaust gas and a heat recovery medium with high efficiency.

It is the perspective view which showed typically an example of the heat exchanger which concerns on this invention. It is a schematic diagram for demonstrating the principal part of the liquid side plate of the heat exchanger of FIG. It is a figure for demonstrating an example of the liquid side plate. It is a figure for demonstrating the other example of the liquid side plate. It is a figure for demonstrating another example of a liquid side plate. It is a figure for demonstrating another example of a liquid side plate. It is the figure which showed typically an example of the gas side plate of FIG. It is the figure which showed the other example of the gas side plate typically. It is the figure which showed the liquid side plate of the comparative example typically. It is the figure which showed typically the liquid side plate of the other comparative example. It is the figure which showed typically the liquid side plate of another comparative example. It is a figure for demonstrating the conditions of simulation. It is a figure which shows a simulation result. It is a figure for demonstrating the conditions of other simulation. It is a figure which shows another simulation result.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

FIG. 1 is a perspective view schematically showing an example of a heat exchanger according to the present invention.
The heat exchanger 1 in FIG. 1 is a plate-type or plate-fin type heat exchanger that performs heat exchange between a gas and a heat recovery medium. In the heat exchanger 1, a set of a plurality of gas side plates 10 and a heat recovery medium side plate 20 is laminated between end plates (not shown). By joining the outer peripheral portions of these plates by welding or the like, a high-temperature flow path through which high-temperature gas (for example, exhaust gas) flows inside the end plate and the plates 10 and 20, and a low-temperature heat recovery medium (for example, The low-temperature flow paths through which the liquid) flows are alternately stacked. In the following description, the heat recovery medium side plate 20 is omitted as the liquid side plate 20.

In FIG. 1, there is a gap between the gas side plate 10 and the liquid side plate 20, but the outer peripheral portions of the plates 10 and 20 are actually joined as described above. Even if the outer peripheral part is joined between the plates 10 and 20, there is a gap in the central part, and the above-described flow path is formed. The gas side plate 10 and the liquid side plate 20 are produced, for example, by pressing a metal plate.
The heat exchanger 1 further includes an introduction header 31 and a discharge header 32. These will be described later.

The heat exchanger 1 is used, for example, for heat exchange between exhaust gas and liquid from an ironworks or the like.
At the time of heat exchange, for example, the exhaust gas flowing in the positive direction of the X direction in the figure flows in the heat exchanger 1 in the positive direction of the X direction, and is discharged from the side opposite to the exhaust gas introduction side in the X direction.
On the other hand, the liquid is introduced into the heat exchanger 2 from the direction orthogonal to the X direction via the introduction header 31 and discharged from the heat exchanger 2 to the direction orthogonal to the X direction via the discharge header 32. However, the main direction of the flow of the liquid in the heat exchanger 2 is the X direction (negative direction) as shown by a dotted arrow in the figure.
In this example, in the heat exchanger 2, the main directions of the flow of exhaust gas and gas are opposite to each other, but they may be the same direction.

FIG. 2 is a schematic diagram for explaining a main part of the liquid side plate 20 of the heat exchanger 1.
As illustrated, the liquid side plate 20 includes a portion (hereinafter referred to as a heat exchange core portion) 21 that forms a heat exchange core that exchanges heat between exhaust gas and liquid. Further, the plate 20 includes a portion (hereinafter referred to as a distribution portion) 22 that forms a distribution portion that distributes and introduces the liquid to the heat exchange core portion 21 and a collecting portion that collects the liquid discharged from the heat exchange core portion 21. And a portion (hereinafter referred to as a gathering portion) 23 that forms the.

As shown in FIG. 1 described above, the heat exchanger 1 includes an introduction header 31 and a discharge header 32 that are common to the plurality of liquid-side plates 20. The introduction header 31 introduces liquid into the distribution unit 22 from the outside of the heat exchanger 1, and the discharge header 32 discharges liquid from the collection unit 23 to the outside.
The liquid introduced from the introduction header 31 to the liquid side plate 20 flows to the distribution unit 22, the heat exchange core unit 21, the assembly unit 23, and the discharge header 32, and is discharged to the outside through the discharge header 32.

  Hereinafter, a characteristic configuration of the heat exchanger 1 will be described.

  In the heat exchanger 1, the introduction header 31 and the discharge header 32 are located outside (hereinafter simply referred to as “outside”) when viewed from the direction in which the exhaust gas flows, that is, the X direction in the drawing, with respect to the heat exchange core portion 21. Assuming that the heat exchange core portion 21 is located on the inner side (location corresponding to A1 and A2 in the figure) when viewed from the X direction in which the exhaust gas flows, the heat exchange core portion 21 and the gas side, that is, the exhaust gas side. Since the heat exchange core overlaps with the heat exchange core, introduction of the exhaust gas into the heat exchange core on the exhaust gas side is hindered. Therefore, the introduction header 31 and the discharge header 32 are located outside the heat exchange. In the heat exchanger 1, since the liquid flow rate is small, the above-described arrangement configuration is possible.

Further, the introduction header 31 is located on the opposite side of the discharge header 32 with the heat exchange core portion 21 sandwiched between the introduction header 31 and the X direction in which the exhaust gas flows.
When the introduction header 31 and the discharge header 32 are located outside the heat exchange core portion 21 when viewed from the X direction, the discharge header 32 is located on the same side as the introduction header 31 with reference to the heat exchange core portion 21. It is assumed to be located at a location corresponding to A3 in the figure. In this case, if the pressure loss of the distribution unit 22 and the collection unit 23 is large, the flow rate of the heat exchange core unit 21 becomes uneven. Since the fluid (in this case, liquid) flows through a path with little pressure loss, it is expected that the flow rate will increase on the side close to the fluid inlet / outlet and the flow rate will decrease on the far side. Therefore, the heat exchanger 1 employs an arrangement configuration in which the introduction header 31 is located on the opposite side of the discharge header 32 with the heat exchange core portion 21 interposed therebetween as described above.

  Furthermore, the distribution part 22 of the liquid side plate 20 has a shape in which the cross-sectional area of the flow path monotonously decreases from the introduction header 31 in the liquid introduction direction (Y1 direction in the figure) to the distribution part 22. Further, the collective portion 23 has a shape in which the cross-sectional area of the flow path monotonously increases toward the discharge header 32 in the discharge direction from the collective portion 23 (Y2 direction in the figure). Each of the cross-sectional areas is an area of the distribution unit 22 / aggregation unit 23 in a cross section having a perpendicular extending in the Y1 direction or the Y2 direction. The reason for adopting the monotonically decreasing / increasing shape as described above is as follows.

That is, in general, in a branch pipe flow (a flow in which a large number of branch pipes with a small diameter are attached to the side surface of a main pipe with a large diameter, and the flow rate of fluid flowing through the main pipe decreases downstream) Since the pressure in the main pipe increases, the flow distribution of the branch pipe is not uniform, and it is known that the branch pipe flow increases as it goes downstream. This is a phenomenon that occurs because the average flow velocity in the main pipe decreases toward the downstream.
In the liquid side plate 20, the distribution part 22 corresponds to the above-mentioned main pipe, and the flow path in the heat exchange core part 21 can be considered to correspond to the above-mentioned branch pipe.

Therefore, in the liquid side plate 20 of this example, the distribution unit 22 is monotonously decreased as described above so that the average flow velocity is kept constant in the distribution unit 22.
On the other hand, on the discharge side, a phenomenon opposite to the above occurs, and thus the liquid side plate 20 has a shape in which the collecting portion 23 monotonously increases as described above.

  In the figure, the distribution unit 22 and the collection unit 23 have the same shape, but may have different shapes.

3-6 is a figure for demonstrating the example of a liquid side plate, and also shows the below-mentioned ear | edge part which abbreviate | omitted illustration in FIG.
Liquid-side plate 20 ₁ in FIG. 3 are those used in the plate-type or plate-fin heat exchanger, having ears 24 ₁ surrounding the periphery of the heat exchange core section 21, distributing section 22 and the collecting portion 23 .
Ears 24 _1, or used for bonding the plates to each other, or be used to sandwich the spacer or gasket between the ears of the gas-side plate side.

Liquid-side plate 20 ₂ of FIG. 4, the plate 20 ₁ in FIG. 3, the shape of the distribution unit 22 and the collecting portion 23 is different. In plate 20 _1, but the distribution part 22 had ears 24 ₁ is provided so as to be triangular, the plate 20 _2, ears 24 ₂ is provided so that the shape of the distribution section 22 is trapezoidal ing.
Since a portion viewed from the X direction to overlap with the heat exchange core section 21 may be a monotonically increasing / monotonically decreasing shape, the ears 24 ₂ may be provided as a plate 20 ₂ of FIG.

Moreover, the liquid side plates 20 ₃ and 20 _{4 in} FIGS. 5 and 6 have wide portions 25 ₃ and 25 ₄ in the ear portions 24 ₃ and 24 ₄ so that the outer shape thereof is a shape corresponding to the gas side plate.

FIG. 7 is a diagram schematically showing the gas side plate 10 of FIG. 1, and shows only the main part of the plate 10.
The gas side plate 10 has a portion (hereinafter referred to as a heat exchange core portion) 11 corresponding to a heat exchange core portion that performs heat exchange between exhaust gas and liquid, and an ear portion 12 surrounding the heat exchange core portion 11. .
Heat exchange core portion of the gas-side plate 10 11, as viewed from the flow direction X of the gas, such as substantially the same size as the heat exchange core section 21 of the gas-side plate 20 ₄ of FIG.
In the heat exchange core part 11 of the gas side plate 10 shown in the figure, the liquid side plate 20 extends to positions corresponding to the distribution part 22 and the gathering part 23, but the corresponding position is the heat exchange core part. It is good also as a cavity without the fin which has, and an unevenness | corrugation, and structures, such as a support | pillar for supporting the force added to the heat exchanger 1, may be formed.

FIG. 8 is a diagram schematically showing another example of the gas side plate.
Gas-side plate 10 ₁ in FIG. 8, in addition to the heat exchange core 11 and the ear portions 12, a distribution unit 13 which evenly distribute the exhaust gas to the heat exchange core 11, is discharged from the heat exchange core 11 And a discharge unit 14 for discharging the exhaust gas to the outside.
By providing the distribution unit 13, heat exchange can be performed efficiently even when the flow rate is small.

(Example)
When the liquid side plate 20 having the configuration shown in FIG. 2 is used as an example and the liquid side plate having the configuration shown in FIGS. 9 to 11 is used as a comparative example, the pressure loss of the heat exchange core unit 21, the distribution unit 22, and the collecting unit 23 is changed. The flow rate distribution in the heat exchange core portion 21 was simulated.

The liquid side plate 100 of Comparative Example 1 in FIG. 9 has the introduction header 102 and the discharge header 103 outside the heat exchange core 101 as in the liquid side plate 20 of Example 1, but the distribution unit 104 has the introduction header 102. This is a shape having a constant cross-sectional area of the flow path without monotonously decreasing with respect to the liquid introduction direction. The same applies to the gathering unit 105.
As shown in FIG. 10, the liquid side plate 110 of Comparative Example 2 in FIG. 10 includes the heat exchange core 101, the distribution unit 104, and the gathering unit 105 having the same shape as the liquid side plate 100 of Comparative Example 1, but is discharged. The header 111 is located on the same side as the introduction header 102 with respect to the heat exchange core 101 as viewed from the X direction in which the gas flows.
The liquid side plate 120 of Comparative Example 3 in FIG. 11 includes the liquid heat exchange core 101, the distribution unit 121, and the gathering unit 122 similar to those in Example 1, but the discharge header 123 extends from the X direction in which the gas flows. As seen, it is located on the same side as the introduction header 102 with respect to the heat exchange core 101.

FIG. 12 is a diagram for explaining simulation conditions and the like.
The dimensions of each part of the liquid side plate 20 in the simulation are as follows. The following values are those when the thickness D1 of the introduction header 31 and the discharge header 32 is 1.

Width W1: 5 of liquid side plate 20 (heat exchange core portion 21)
Length L1 of heat exchange core 21: 2-5
Distribution unit 22 width W2: 0.2 to 0.5
Width W3 of the gathering portion 23: 0.2 to 0.5

Further, the pressure P _din of the liquid at the time of introduction into the distribution unit 22 is an average value in a range corresponding to the broken line part B1 in the figure. Similarly, the liquid pressure P _cin at the time of introduction into the heat exchange core portion 21 is the broken line portion B2, and the liquid pressure P _cout at the time of discharge from the heat exchange core portion 21 is the broken line portion B3, the discharge from the collecting portion 23. The _hourly pressure _Pdout was an average value in a range corresponding to the broken line part B4.
The flow rate distribution was measured at the center of the heat exchange core 21 (broken line B5 in the figure).
The dimensions of the comparative example were the same as the dimensions of the example, and the pressure and flow rate distribution of the comparative example were respectively average values in the ranges corresponding to the above B1 to B5.

FIG. 13 is a diagram illustrating simulation results for Comparative Examples 1 to 3 and simulation results for Examples.
In the figure, the horizontal axis shows the ratio of the sum of the pressure loss when the liquid passes through the distributing portion 22 and the pressure loss when the liquid passes through the collecting portion 23 to the pressure loss when the liquid passes through the heat exchange core portion 21. (Hereinafter, the ratio of pressure loss), the vertical axis is the flow rate (flow velocity) deviation indicating the flow rate deviation in the heat exchange core 21.

The pressure loss ratio is given by (dPd−dPc) / dPc where dPd = P _din −P _dout and dPc = P _cin −P _cout under the following definitions.
P _din : Liquid pressure at the time of introduction to the distribution part P _cin : Liquid pressure at the time of introduction to the heat exchange core part 21 P _cout : Liquid pressure at the time of discharge from the heat exchange core part 21 P _dout : Assembly Pressure when discharging from the section 23

  The flow rate deviation in the heat exchange core 21 is given by “(maximum flow rate−minimum flow rate) / average flow rate” in the flow rate distribution measurement section. When the flow rate deviation is 0, the flow rate distribution is completely uniform. For example, when the flow rate deviation is 0.5, it indicates that there is a flow rate difference of 50% (± 25%) with respect to the average flow rate.

In Comparative Examples 1 to 3, as shown in FIGS. 13A to 13C, the flow rate deviation increases as the pressure loss ratio increases. Even in the configurations of Comparative Examples 1 to 3, if the pressure loss ratio is 0.1 or less, for example, the flow rate deviation can be maintained at approximately 10% or less, and sufficient heat exchange performance is exhibited. It is considered possible to adopt the configurations of Comparative Examples 1 to 3 for a heat exchanger having a small value of 0.1 or less.
However, in the heat exchangers in which the distribution unit / mixing unit is compact and the pressure loss in the distribution unit / mixing unit is larger than that in the heat exchange core unit, that is, the heat exchanger having a high pressure loss ratio, Since the deviation becomes large, these configurations cannot be adopted.

On the other hand, in the embodiment, even when the pressure loss ratio is large, the flow rate deviation is maintained at about 1%.
From this, it can be seen that the configuration as in the embodiment is suitable for a heat exchanger in which the distribution unit / mixing unit is compact and the pressure loss in the distribution unit / mixing unit is larger than that in the heat exchange core unit.

Next, a simulation was performed to determine how much the flow rate deviation can be suppressed by reducing / increasing the cross section of the flow path of the distributor / mixer.
FIG. 14 is a diagram for explaining simulation conditions. FIG. 15 is a diagram showing simulation results.

In the simulation, the width of the side where the liquid is introduced into the distribution unit 22 in the distribution unit 22 and the width of the side where the liquid is discharged from the collection unit 23 in the collection unit 23 is a. The width on the opposite side of the side was b, and b / a was changed from 0 to 1. At that time, the pressure loss ratio was also changed, and the flow rate deviation at that time was calculated.
Other simulation conditions are the same as those of the above-described simulation.
In addition, when b / a = 0, it corresponds to the shape of FIG. 2, and when b / a = 1, it corresponds to the shape of FIG.

As can be seen from FIG. 15, when the width ratio b / a is 0.1 or less, even if the pressure loss ratio is as large as 1, the flow rate deviation can be kept as small as 0.1, that is, about ± 5%. it can.
Therefore, it is desirable for the distribution unit 22 / collection unit 23 to have a side length ratio of 0.1 or less. In other words, the distribution unit 22 / collection unit 23 is the maximum and minimum of the cross-sectional area of the flow path in the cross section having a perpendicular line parallel to the liquid introduction direction to the distribution unit 22 or the liquid discharge direction from the collection unit 23. It is desirable that the value ratio is 0.1 or less.

DESCRIPTION OF SYMBOLS 1 ... Heat exchanger 10, 10 ₁ ... Gas side plate 11 ... Heat exchange core part 12 ... Ear | edge part 13 ... Distributing part 14 ... Discharge part 20, 20 ₁ , 20 ₂ , 20 ₃ , 20 ₄ ... Heat recovery medium side plate (Liquid side plate)
21 ... heat exchange core 22 ... distributor 23 ... collective part ₂₄ 1, ₂₄ 2, 24 3 _... ears ₂₅ 3, 25 4 _... wide portion 31 ... introduction header 32 ... discharge header

Claims (4)

A heat exchange core for exchanging heat between the gas and the heat recovery medium;
A distribution unit for distributing and introducing a heat recovery medium to the heat exchange core;
A collecting unit for collecting the heat recovery medium discharged from the heat exchange core;
An introduction header for introducing a heat recovery medium from the outside into the distribution unit;
A discharge header for discharging the heat recovery medium from the gathering portion to the outside;
A heat exchanger comprising:
The distribution part and the gathering part are located in a portion overlapping the heat exchange core as seen from a predetermined direction,
The introduction header and the discharge header are located outside the heat exchange core when viewed from the predetermined direction, and the introduction header sandwiches the heat exchange core when viewed from the predetermined direction and is opposite to the discharge header Located in
The distribution part has a shape in which the cross-sectional area of the flow path monotonously decreases from the introduction header side with respect to the introduction direction of the heat recovery medium from the introduction header,
The collecting portion has a shape in which the cross-sectional area of the flow path monotonously increases toward the discharge header side with respect to the discharge direction of the heat recovery medium from the discharge header.
The ratio of the maximum value and the minimum value of the cross-sectional area of the flow path of the distribution part and the collecting part is 0.1 or less, and the heat exchanger.   The heat exchanger according to claim 1, wherein the predetermined direction is a direction in which a gas flows.   3. The heat exchanger according to claim 1, wherein the total pressure loss of the distribution unit and the collecting unit is equal to or greater than the pressure loss related to the heat recovery medium of the heat exchange core.   The heat exchanger according to claim 1, wherein the heat recovery medium is a liquid.