HEAT EXCHANGER FOR A MOTOR VEHICLE

Abstract

A heat exchanger for a motor vehicle may include an outer pipe through which hot gas may flow, the outer pipe extending along a longitudinal direction, defining an outer pipe interior, and including two outer pipe walls in a cross section perpendicular to the longitudinal direction. The heat exchanger may also include an inner pipe arranged in the outer pipe interior, the inner pipe extending along the longitudinal direction, being closed on a first longitudinal end, defining an inner pipe interior, and including two inner pipe walls in the cross section. The inner pipe walls may include a plurality of apertures by which the inner and outer pipe interiors may communicate fluidically. The heat exchanger may further have a plurality of thermoelectric modules arranged on an outer side of the outer pipe walls, each having a hot side facing the outer pipe and a cold side facing away from the outer pipe, and at least one coolant pipe through which a coolant may flow and which is arranged on the cold side of at least one thermoelectric module.

Claims

1. A heat exchanger for a motor vehicle, comprising: an outer pipe through which hot gas is flowable, the outer pipe extending along a longitudinal direction, defining an outer pipe interior, and including two outer pipe walls in a cross section perpendicular to the longitudinal direction; an inner pipe arranged in the outer pipe interior, extending along the longitudinal direction, being closed on a first longitudinal end, defining an inner pipe interior, and including two inner pipe walls in the cross section perpendicular to the longitudinal direction; a plurality of apertures in the inner pipe walls by which the inner pipe interior communicates fluidically with the outer pipe interior; a plurality of thermoelectric modules arranged on an outer side of the outer pipe walls, each thermoelectric module having a hot side, which faces the outer pipe, and a cold side, which faces away from the outer pipe; and at least one coolant pipe through which a coolant is flowable and which is arranged on the cold side of at least one thermoelectric module.

2. The heat exchanger according to claim 1, wherein: the outer pipe is a flat pipe; and in the cross section perpendicular to the longitudinal direction, the two outer pipe walls are located opposite one another and form two broad sides of the flat pipe.

3. The heat exchanger according to claim 1, wherein: the inner pipe is a flat pipe; in the cross section perpendicular to the longitudinal direction, the two inner pipe walls are located opposite one another and form two broad sides of the flat pipe; and the apertures are arranged in a first inner pipe wall and a second inner pipe wall of the two inner pipe walls.

4. The heat exchanger according to claim 3, wherein a first outer pipe wall of the two outer pipe walls faces the first inner pipe wall in the cross section perpendicular to the longitudinal direction, and a second outer pipe wall of the two outer pipe walls faces the second inner pipe wall.

5. The heat exchanger according to claim 1, wherein: the at least one coolant pipe includes at least a first coolant pipe and at least a second coolant pipe; and wherein the at least one first coolant pipe is arranged on the cold side of the at least a first thermoelectric module, and the at least one second coolant pipe is arranged on the cold side of at least a second thermoelectric module.

6. The heat exchanger according to claim 1, the outer pipe is arranged between a first coolant pipe and a second coolant pipe along a stack direction, which runs at right angles to the longitudinal direction of the outer pipe.

7. The heat exchanger according to claim 1, wherein the at least one coolant pipe is a flat pipe with a broad side, which in the cross section perpendicular to the longitudinal direction faces one of the thermoelectric modules.

8. The heat exchanger according to claim 5, wherein: at least one of the first coolant pipe and the second coolant pipe has a U-shaped geometry including a base, a first leg, and a second leg; and the first leg and the second leg extend along the longitudinal direction of the outer pipe.

9. The heat exchanger according to claim 8, further comprising: a coolant distributor on a first longitudinal end of the outer pipe, the coolant distributor communicating fluidically with a coolant inlet of the first coolant pipe and of the second coolant pipe, the coolant inlet being present on the first leg; and a coolant collector on the first longitudinal end of the outer pipe, the coolant collector communicating fluidically with a coolant outlet of the first coolant pipe and of the second coolant pipe, the coolant outlet being present on the second leg.

10. The heat exchanger according to claim 1, wherein the outer pipe is closed on two longitudinal ends located opposite one another along the longitudinal direction.

11. The heat exchanger according to claim 1, wherein the outer pipe closed on one longitudinal end and open on another longitudinal end for discharging the hot gas.

12. The heat exchanger according to claim 1, wherein on a second longitudinal end of the inner pipe, which is located opposite the first longitudinal end, a gas inlet for introducing the hot gas into the inner pipe connects to said second longitudinal end.

13. The heat exchanger according to claim 2, wherein: the flat pipe, which forms the outer pipe, has two narrow sides in the cross section perpendicular to the longitudinal direction; and a side ratio of a broad side to a narrow side is more than 1.

14. The heat exchanger according to claim 3, wherein the flat pipe, which forms the inner pipe, has two narrow sides in the cross section perpendicular to the longitudinal direction; and a side ratio of a broad side to a narrow side is more than 1.

15. A heat exchanger arrangement comprising at least two heat exchangers arranged on top of one another, each heat exchanger including: an outer pipe through which hot gas is flowable, the outer pipe extending along a longitudinal direction, defining an outer pipe interior, and including two outer pipe walls in a cross section perpendicular to the longitudinal direction; an inner pipe arranged in the outer pipe interior, extending along the longitudinal direction, being closed on a first longitudinal end, defining an inner pipe interior, and including two inner pipe walls in the cross section perpendicular to the longitudinal direction; a plurality of apertures in the inner pipe walls by which the inner pipe interior communicates fluidically with the outer pipe interior; a plurality of thermoelectric modules arranged on an outer side of the outer pipe walls, each thermoelectric module having a hot side, which faces the outer pipe, and a cold side, which faces away from the outer pipe; and at least one coolant pipe through which a coolant is flowable and which is arranged on the cold side of at least one thermoelectric module; wherein the at least two heat exchangers communicate fluidically with one another via at least one common gas outlet for discharging the hot gas from the heat exchanger arrangement.

16. A vehicle comprising: an internal combustion engine having an exhaust gas system; and one of a heat exchanger, which cooperates with the exhaust gas system, or a heat exchanger arrangement, which cooperates with the exhaust gas system; wherein the heat exchanger includes: an outer pipe through which hot gas is flowable, the outer pipe extending along a longitudinal direction, defining an outer pipe interior, and including two outer pipe walls in a cross section perpendicular to the longitudinal direction; an inner pipe arranged in the outer pipe interior, extending along the longitudinal direction, being closed on a first longitudinal end, defining an inner pipe interior, and including two inner pipe walls in the cross section perpendicular to the longitudinal direction; a plurality of apertures in the inner pipe walls by which the inner pipe interior communicates fluidically with the outer pipe interior; a plurality of thermoelectric modules arranged on an outer side of the outer pipe walls, each thermoelectric module having a hot side, which faces the outer pipe, and a cold side, which faces away from the outer pipe; and at least one coolant pipe through which a coolant is flowable and which is arranged on the cold side of at least one thermoelectric module: and wherein the heat exchanger arrangement includes at least two heat exchangers arranged on top of one another and communicating fluidically with one another via at least one common gas outlet for discharging the hot gas from the heat exchanger arrangement.

17. The heat exchanger arrangement according to claim 15, wherein: the outer pipe is a flat pipe; and in the cross section perpendicular to the longitudinal direction, the two outer pipe walls are located opposite one another and form two broad sides of the flat pipe.

18. The heat exchanger arrangement according to claim 17, wherein: the inner pipe is a flat pipe; in the cross section perpendicular to the longitudinal direction, the two inner pipe walls are located opposite one another and form two broad sides of the flat pipe; and the apertures are arranged in a first inner pipe wall and a second inner pipe wall of the two inner pipe walls.

19. The heat exchanger arrangement according to claim 18, wherein a first outer pipe wall of the two outer pipe walls faces the first inner pipe wall in the cross section perpendicular to the longitudinal direction, and a second outer pipe wall of the two outer pipe walls faces the second inner pipe wall.

20. The heat exchanger arrangement according to claim 15, wherein: the at least one coolant pipe includes at least a first coolant pipe and at least a second coolant pipe; and wherein the at least one first coolant pipe is arranged on the cold side of the at least a first thermoelectric module, and the at least one second coolant pipe is arranged on the cold side of at least a second thermoelectric module.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In each case schematically:

[0027] FIG. 1 shows an example of a heat exchanger embodied as exhaust gas heat exchanger in a longitudinal section,

[0028] FIG. 2 shows the heat exchanger of FIG. 1 in a cross section perpendicular to the longitudinal direction of the heat exchanger,

[0029] FIG. 3 shows a section through a U-shaped coolant pipe of the heat exchanger,

[0030] FIG. 4 shows an alternative of the heat exchanger according to FIGS. 1 and 2, in the case of which the coolant pipes do not extend in the longitudinal direction, as in the case of the example of FIG. 1, but at right angles.

DETAILED DESCRIPTION

[0031] FIG. 1 shows, schematically, an example of a heat exchanger 1, which is embodied as exhaust gas heat exchanger. According to FIG. 1, the heat exchanger 1 has an outer pipe 2 for a hot gas H to flow through, which extends along a longitudinal direction L and which defines an outer pipe interior 3. An inner pipe 4, through which the hot gas H can likewise flow, and which defines an inner pipe interior 5, is arranged in the outer pipe interior 3.

[0032] The outer pipe 2 is embodied as flat pipe 30 comprising a first outer pipe pipe wall 31a and a second outer pipe pipe wall 31b, which is located opposite the first outer pipe pipe wall 31a. According to FIGS. 1 and 2, a portion of the thermoelectric modules 10hereinafter referred to as first thermoelectric elements 10aare arranged on the outer side 8 of the first outer pipe pipe wall 31a. The remaining thermoelectric elements 10hereinafter referred to as second thermoelectric elements 10bare arranged on the outer side 8 of the second outer pipe pipe wall 31b. The inner pipe 4 is also embodied as flat pipe 32 comprising a first inner pipe pipe wall 33a and a second inner pipe pipe wall 33b located opposite the first inner pipe pipe wall 33a.

[0033] FIG. 2 shows the heat exchanger 1 from FIG. 1 in a cross section perpendicular to the longitudinal direction L along the sectional line II-II of FIG. 1. It can be seen that in the cross section perpendicular to the longitudinal direction L, the two outer pipe pipe walls 31a, 31b in each case form a broad side 34a, 34b of the outer pipe 2, which is realized as flat pipe 30. The flat pipe 30, which forms the outer pipe 2, furthermore has two narrow sides 34c, 34d in the cross section perpendicular to the longitudinal direction L. The side ratio of one of the two broad sides 34a, 34b to one of the two narrow sides 34c, 34d is more than 1, preferably at least 2, maximally preferably at least 4.

[0034] In the cross section perpendicular to the longitudinal direction L, the two inner pipe pipe walls 33a, 33b in each case form a broad side 35a, 35b of the inner pipe 4, which is realized as flat pipe 32. In the cross section perpendicular to the longitudinal direction L, the flat pipe 32, which forms the inner pipe 4, furthermore has two narrow sides 35c, 35d. The side ratio of one of the two broad sides 35a, 35b to one of the two narrow sides 35c, 35d is more than 1, preferably at least 2, maximally preferably at least 6.

[0035] According to FIG. 2, the first outer pipe pipe wall 31a faces the first inner pipe pipe wall 33a in the cross section perpendicular to the longitudinal direction L. Accordingly, the second outer pipe pipe wall 31b faces the second inner pipe pipe wall 33b.

[0036] In the example of FIGS. 1 and 2, the heat exchanger 1 furthermore comprises a first coolant pipe 13a and a second coolant pipe 13b for a coolant K to flow through, which has a lower temperature than the hot gas H. The coolant pipes 13a, 13b are thus arranged on the cold sides 12 of the thermoelectric modules 10, so that the coolant K, which flows through the coolant pipes 13, can thermally couple to the cold sides 12 of the thermoelectric modules 10.

[0037] The first coolant pipe 13a is arranged on the cold sides 12 of the first thermoelectric modules 10a. The second coolant pipe 13b is arranged on the cold sides 12 of the second thermoelectric modules 10b. The outer pipe 2 is thereby arranged between the first and the second coolant pipe 13a, 13b along a stack direction S, which runs at right angles to the longitudinal direction L of the outer pipe 2. The installation space required for the heat exchanger 1 in the stack direction S can be kept small in this way. The coolant pipes 13a, 13b can in each case also be embodied as flat pipes 36, the broad sides 37a of which face the first or second thermoelectric modules 10a, 10b, respectively, in the cross section perpendicular to the longitudinal direction L.

[0038] On a first longitudinal end 26a, the inner pipe 4 is embodied so as to be closed. For this purpose, the inner pipe has a front wall 16. On a second longitudinal end 26b of the inner pipe 4, which is located opposite the first longitudinal end 26a, however, a gas inlet 27 for introducing the hot gas H into the inner pipe 4 connects to the inner pipe 4. In other words, the inner pipe 4 is embodied so as to be open on the second longitudinal end 26b. In the first inner wall pipe wall 33a and in the second inner wall pipe wall 33b of the inner pipe 4, a plurality of apertures 7 is embodied in each case, by means of which the inner pipe interior 5 communicates fluidically with the outer pipe interior 3. The hot gas H, which flows through the outer pipe 2, can be thermally coupled to the hot sides 11 of the thermoelectric modules 10 in this way.

[0039] FIG. 3 shows a top view onto the coolant pipe 13a in a viewing direction B, which is suggested by means of an arrow in FIG. 1, which extends perpendicular to the longitudinal direction L and which runs opposite to the stack direction S. In the example of FIG. 3, the first coolant pipe 13a has a U-shaped geometry comprising a base 38 and a first and a second leg 39a, 39b. The two legs 39a, 39b extend along the longitudinal direction L of the outer pipe 2. On a first longitudinal end 24a (see FIG. 1) of the outer pipe 2, a coolant distributor 41 is present, which communicates fluidically with a coolant inlet 43 of the first coolant pipe 13, which is present on the first leg 39a. A coolant collector 42, which fluidically communicates with a coolant outlet 44 of the first coolant pipe 13a, which is present on the second leg 39b, is likewise present on the first longitudinal end 24a of the outer pipe 2. The two coolant pipes 13a, 13b can be embodied as identical parts. In this case, the second coolant pipe 13b is likewise embodied as shown in FIG. 3.

[0040] The flow-through of the heat exchanger 1 with hot gas H will be described below by means of FIG. 1. Via the gas inlet 27, the hot gas H is introduced into the inner pipe interior 5, which is defined by the inner pipe 4, and flows through said inner pipe interior along the longitudinal direction L (see arrows 21a). Due to the fact that the inner pipe interior 5 is defined by the front wall 16 of the inner pipe 4 in the longitudinal direction L, the hot gas H can only leave the inner pipe interior 5 along the stack direction S, thus at right angles to the longitudinal direction L, through the apertures 7, which are embodied in the first or second inner pipe pipe wall 33a, 33b, respectively (see arrows 21b). Due to the dynamic pressure, which forms in the inner pipe interior 5 in the hot gas H, the hot gas H is accelerated while flowing through the apertures 7 and in each case impacts the first or second outer pipe pipe wall 31a, 13b, respectively, of the outer pipe 2, in the form of an impact jet (see arrows 21c). Thermal energy is thereby emitted to the thermoelectric modules 10. The hot gas H, which bounces off the outer pipe pipe walls 31a, 31b, thus reflected hot gas, can leave the heat exchanger 1 (see arrows 21d) through two gas outlets 23a, 23b (see FIG. 2), which are present on the outer pipe 2 and which extend along the stack direction S. In the scenario of FIGS. 1 and 2, the outer pipe 2 is embodied so as to be closed on one of two longitudinal ends 24a, 24b, which are located opposite one another along the longitudinal direction. The outer pipe 2 is thereby closed by means of a front wall 25. This allows for an advantageous discharge of the hot gas H in the outer pipe 2 in two directions opposite one another (see arrows 21c, 21d in FIG. 2), which is known to the pertinent person of skill in the art as medium crossflow.

[0041] A heat exchanger arrangement comprising two heat exchangers 1, which are arranged on top of one another, can be formed from the above-described heat exchanger 1. The heat exchangers 1 can preferably be stacked on top of one another along the stack direction S (see FIG. 2) and can fluidically communicate with one another by means of the two gas outlets 23a, 23b. FIG. 2 thus shows a single heat exchanger 1 of such a heat exchanger arrangement.

[0042] FIG. 4 illustrates an alternative of the example of FIG. 1, in the case of which the outer pipe 2 is embodied so as to be open on the longitudinal end 24a for discharging the hot gas H. This allows for an advantageous discharge of the hot gas H in only one direction (see arrows 21d in FIG. 4) via a gas outlet 23c, which connects to the outer pipe 2 on the first longitudinal end 24a. This scenario is known to the pertinent person of skill in the art as maximum crossflow.

[0043] In an alternative, which is not shown in more detail in the figures, the alternatives maximum crossflow and medium crossflow can also be combined.

[0044] The heat exchanger 1 according to FIG. 4 has three first coolant pipes 13a and three second coolant pipes 13b. In alternatives, the number of first and second coolant pipes 13a, 13b can vary. According to FIG. 4, the first and second coolant pipes 13a, 13b are in each case arranged at a distance to one another along the longitudinal direction L and in each case extend along a transverse direction Q, which runs perpendicular to the longitudinal direction L as well as to the stack direction S.