WO2019120980A1

WO2019120980A1 - Counter-current heat exchanger

Info

Publication number: WO2019120980A1
Application number: PCT/EP2018/083463
Authority: WO
Inventors: Andreas Janker; Andreas Reuter; Stephan Buckl; Daniel Eckert; Fritz Wegener
Original assignee: Webasto SE
Priority date: 2017-12-18
Filing date: 2018-12-04
Publication date: 2019-06-27
Also published as: DE102017130354A1

Abstract

The invention relates to a counter-current heat exchanger (10) for an electric vehicle heating system (12), comprising an inner pipe (14) with an axial direction of extent (16), an outer pipe (18) which surrounds the inner pipe (14) in the axial direction of extent (16), an electrical heating element (20) which is arranged on an outer jacket surface (22) of the outer pipe (18); a first connection region (24) with a first connector (26), wherein the first connection region (24) permits a transition of a fluid (28) between the first connector (26) and a jacket flow space (32), and wherein the jacket flow space (32) ends at a first end region (30) of the inner pipe (14) and of the outer pipe (18) and is formed between the inner pipe (14) and the outer pipe (18), at a second end region (34) opposite the first end region (30), a redirection region (36) by means of which the fluid (28) can be redirected between the jacket flow space (32) and a pipe flow space (38) in the inner pipe (14), and a second connection region (40) with a second connector (42), wherein the second connection region (40) permits a transition of the fluid (28) between the pipe flow space (32) and the second connector (42) at the first end region (30).

Description

Gegenstromwärmetäuscher

The present invention relates to a countercurrent heat exchanger for an electric vehicle heater.

Modern vehicles, in particular vehicles that do without a fuel-powered internal combustion engine, usually generate too little waste heat to be sufficient for heating the vehicle interior. Examples of such vehicles are in particular all-electric motor vehicles. To solve this problem, it is already known to provide an electric vehicle heater instead of a hitherto conventionally provided heat-based heating device. However, in connection with the transfer of heat to a fluid to be heated, there is still a considerable potential for improvement in connection with electric vehicle heaters.

The object of the present invention is to provide a countercurrent heat exchanger optimized for electric vehicle heating.

Described is a countercurrent heat exchanger for an electric vehicle heater. The described countercurrent heat exchanger includes an inner tube having an axial extension direction, an outer tube sheathing the inner tube in the axial extension direction, an electric heating element disposed on an outer circumferential surface of the outer tube, a first connection portion first port, wherein the first port region allows passage of a fluid between the first port and a jacket flow space, and wherein the jacket flow space terminates at a first end portion of the inner tube and the outer tube and is formed between the inner tube and the outer tube, at a second end region opposite the first end region, a deflection region through which the fluid flows between the jacket flow space and a pipe flow space in the inner tube is deflectable, and a second connection region with a second connection, wherein the second connection region allows a transition of the fluid between the tube flow space and the second connection at the first end region. The deflection region can be formed, for example, as a cap closing off the outer tube, so that the fluid in the second end region between the jacket flow space and the tube flow space is redirected in the radial direction and then flows back in the axial direction to the first end region, so that a "Countercurrent" arises in the heat exchanger. The inner tube and the outer tube may be concentric with each other. The first connection region with the first connection, which can be designed, for example, as a simple connection piece, can be designed in particular as an annular transition space, through which the fluid is uniformly distributed on all sides of the inner tube between the jacket flow space, that of the inner tube and the outer Pipe is formed, and can even exceed the first connection area. The second connection region with the second connection, which can be designed as a simple connection piece, can be surrounded in an annular manner, for example, by the first connection region. It is conceivable, for example, that the second connection region represents an extension of the inner tube in the axial extension direction. Due to the design of the heat exchanger in the manner of a Gegenstromwärmetäuschers a particularly compact design of the heat exchanger can be achieved. In addition, the second port and the first port can be arranged together at an end portion of the heat exchanger, which allows particularly compact electric vehicle heaters, since the fluid circuit can be formed with small spatial dimensions. Optionally, the first port or the second port may be the inlet port, with the respective other port then being the outlet port. The flow direction of the fluid within the Gegenstromwärmetäuschers changes depending on the port selected as the inlet port. The electrical heating element arranged on the outer jacket surface of the outer tube can be, for example, a non-intrinsic heat conductor track, which can be applied to the outer jacket surface. For example, the electrical heating element can be applied to the outer circumferential surface by means of a plasma spraying method or by a thermal spraying method. Alternatively, it is also possible for the electrical heating element to be applied to the outer jacket surface with the aid of a resistor paste. An electrically insulating separating layer can be applied between the electrical heating element and the outer jacket surface. The electrical heating element may consist of a plurality of mutually independently controllable heating resistors, for example, a fine gradation to realize the registered in the heat exchanger heat output. The electrical heating element can be covered to the outside to further improve the efficiency of the genstromstromwärmetauschers thermally insulating.

Each of the inner tube and the outer tube may be manufactured independently or together with the aid of an extrusion process.

Usefully, it may be provided that the jacket flow space is subdivided by at least two partition walls, wherein the at least two partition walls connect the inner tube and the outer tube perpendicular to the axial extension direction. In this way, for example, a uniform heat input into the fluid flowing in the jacket flow space can be promoted. The at least two partition walls delimit flow components of the fluid flowing in the jacket flow space, which do not run parallel to the axial extension direction. Furthermore, the at least two partitions also directly improve the heat input into the fluid, since they represent additional heat transfer surfaces and furthermore also produce a direct thermal bridge between the inner tube and the outer tube. The at least two partitions may, for example, be produced together with the inner tube and the outer tube as a common and continuous extruded profile.

Furthermore, it can be provided that the inner tube and / or the outer tube are composed of at least two axial sections, which are rotated in the axial direction of extension against each other. By rotating the at least two axial sections, the at least two partitions interconnecting the inner tube and the outer tube perpendicular to the axial extension direction can form turbulence-promoting leading and trailing edges which promote mixing of the fluid within the heat exchanger.

Advantageously, it can be provided that the first connection is oriented perpendicular to the second connection. Due to the orientation of the second connection and the first connection, which is perpendicular to one another, the installation of the heat exchanger can be simplified, since the two connections are easier to reach with tools during assembly from different directions.

Furthermore, it can be provided that the outer circumferential surface of the outer tube has an at least partially planar surface. This way, in a through the fluid to the outside cool area of the heat exchanger can be provided an easily accessible flat cooling surface. The at least sectionally planar surface can lie, for example, in the first end region or in the second end region. On the at least partially planar surface, for example, a control or power electronics can be arranged, which controls the electric heating element. It is also conceivable that the control or power electronics is not arranged directly on the at least partially planar surface, but spaced therefrom is arranged and is coupled instead using a material thermal bridge directly thermally conductive with the at least partially planar surface.

It can be provided that the inner circumferential surface of the outer tube has a turbulence-promoting surface structure. Regardless of this, it can also be provided that the outer circumferential surface of the inner tube has a turbulence-promoting surface structure. Furthermore, it can be provided independently that the inner circumferential surface of the inner tube has a turbulence-promoting surface structure. A turbulence-promoting surface structure may, for example, be a groove structure which reduces the thickness of the lamina boundary layer of the fluid flowing into the heat exchanger in the immediate vicinity of the respective surfaces of the inner or outer tube and, in particular, a vortex formation and / or promotes replacement. By promoting turbulent flows within the jacket flow space and the pipe flow space, the heat input into the fluid is improved because the formation of a wide laminar flowing warmer boundary layer and cool fluid flow farther away from the surface is at least reduced by the continuous mixing.

Usefully, it can be provided that the inner tube has ribs pointing radially inwards on an inner tube lateral surface. Ribs pointing radially inward on the inner tube lateral surface perform a similar function as the dividing walls between the outer tube and the inner tube.

Furthermore, a displacement body can be arranged in the interior of the inner tube. The displacer in the interior of the inner tube may be hollow or solid, for example, with a hollow design being preferred because of the weight saved and the amount of inert thermal mass saved. The displacer can ensure that the fluid flow in the tube flow space is only close to the inner tube surface of the inner tube can take place, which can for example improve the heat input into the fluid.

It can be provided that the electrical heating element is arranged by thermal spraying as a thermally sprayed layer on the outer circumferential surface of the outer tube. In this way, a uniform layer thickness of the heating element can be achieved. Furthermore, there is no need to fasten the electrical heating element with the aid of additional components, since even in the case of applications, a planar cohesive connection between the electrical heating element and the outer jacket surface of the outer tube results from the process. The application of the electrical heating element may also include the application of an electrically insulating layer between the outer surface of the outer tube and the actual electrically conductive heating layer of the electric heating element.

The invention is explained below by way of example with reference to preferred embodiments.

Show it:

Figure 1 is a schematic representation of a vehicle with an electrically operated vehicle heating;

Figure 2 is a three-dimensional external view of a heat exchanger;

FIG. 3 is a sectional view of a heat exchanger;

FIG. 4 shows a further sectional view of a heat exchanger;

Figure 5 is a three-dimensional exterior view of a heat exchanger without first

Terminal area;

Figure 6 is a three-dimensional view of heat exchanger components; and

FIG. 7 shows a further three-dimensional view of heat exchanger components. In the following drawings, like reference characters designate like or similar parts.

FIG. 1 shows a schematic representation of a vehicle 64 with an electrically operated vehicle heating system 12. The indicated vehicle 64 comprises as primary energy source a current source 66, which is connected to the electrically operated vehicle heating system 12 with the aid of connection lines 68. The electric vehicle heater 12 includes a countercurrent heat exchanger 10 that is heated with the electrical energy provided by the power source 66 and heats fluid flowing therethrough. The fluid may be, for example, water, air or a water-alcohol mixture.

FIG. 2 shows a three-dimensional external view of a countercurrent heat exchanger 10. The countercurrent heat exchanger 10 shown in FIG. 2 has a first connection region 24 with a first connection 26. The first port 26 is formed as a simple pipe socket. In the present example, the first port 26 is the inlet port of a fluid 28. The further description of the fluid flow in the countercurrent heat exchanger 10 is based thereon. However, it is also possible for the flow of fluid in the countercurrent heat exchanger 10 to take place in exactly the opposite way. In the example, fluid 28 enters countercurrent heat exchanger 10 at first port 26. The first connection region 24 diverts the entering fluid 28 in an axial extension direction 16, so that the fluid 28 in the interior of the outer tube 18 initially flows in the axial extension direction 16 as far as a deflection region 36. At the deflection region 36, the fluid 28 is deflected in the interior of the outer tube 18 and, contrary to the previous flow direction, flows back parallel to the axial extension direction 16 to a second connection region 40 with a second connection 42. The second connection 42 can likewise be designed as a simple pipe socket, just like the first connection 26. The fluid 28 leaves the countercurrent heat exchanger 10 at the second connection 42. Between the first connection region 24 and the outer tube 18 there is arranged an unspecified optional collar plate, which can serve, for example, for easier installation of the countercurrent heat exchanger 10. On an outer circumferential surface 22 of the outer tube 18, an electrical heating element 20 is indicated in the form of a conductor track. The electrical heating element 20 may be applied to the outer circumferential surface 22, for example by means of a coating method. The coating process may be, for example, a plasma spraying process. It is also possible for the electrical heating element 20 to be in the form of a resistor. Standpaste is applied to the outer surface 22. The outer lateral surface 22 may be electrically insulating or may be coated with a corresponding electrically insulating layer before the electrical heating element 20 is applied to the outer circumferential surface 22. At the first terminal region 24 facing the end of the outer tube 18 is a flat surface 50 can be seen, with other flat surfaces are at least partially hidden by the unspecified collar plate. The recognizable in Figure 2 flat surface 50 can be used to dissipate unwanted thermal waste heat of the electrical heating element driving electronic control circuit. For this purpose, such an electronic control circuit may either be arranged directly on the flat surface 50 or spaced from the flat surface 50, providing a direct thermal connection between the flat surface 50 and the electronic control not shown in FIG ,

FIG. 3 shows a sectional view of a countercurrent heat exchanger 10. The countercurrent heat exchanger 10 shown in FIG. 3 may be a sectional view of the countercurrent heat exchanger 10 illustrated in three dimensions in an external view in FIG. The countercurrent heat exchanger 10 shown in FIG. 3 has the first connection region 24 with the first connection 26 for the fluid 28. Again, in the present example, the first port 26 is the inlet port of the fluid 28. The further description of the fluid flow in the countercurrent heat exchanger 10 is also based on this flow direction. However, it is again possible that the fluid flow in the countercurrent heat exchanger 10 takes place exactly opposite. The fluid 28 that has entered the first port 26 is deflected in the first connection region 24 and guided in the axial extension direction 16 through an annular gap into a jacket flow space 32 between the outer tube 18 and an inner tube 14. The outer tube 18 and the inner tube 14 may be arranged in the axial extension direction 16 in particular concentric with each other. The first connection region 24 thus adjoins the inner tube 14 and the outer tube 18 at a first end region 30. A deflection region 36, in which a closure lid 70 is arranged, is located on a second end region 34 opposite the first end region 30. The closure lid 70 initially directs the fluid 28 inward in the radial direction in a direction perpendicular to the axial extension direction 16. Subsequently, the fluid 28 flows back against the axial extension direction 16 in the interior of the inner tube 14 in a tube flow space 38 to the first end region 30. There it enters the second extension region 40 opposite to the axial extension direction 16 and finally against the axial extension direction 16 at the second connection 42 from the countercurrent heat exchanger 10 out. The flat surface 50 can still be seen on the first end region 30 facing the first connection region 24. In the region of the flat surface 50, the temperature of the fluid that has just entered the outer tube is lowest, so that the flat surface 50 is particularly suitable for cooling electronic components of the electronic heating device, which are kept at the lowest possible temperature should.

FIG. 4 shows a further sectional view of a countercurrent heat exchanger 10. A shell-like structure of the countercurrent heat exchanger 10 can be seen. The outermost shell forms the outer tube 18 with the outer shell surface 22 and an inner shell surface 52. Concentric with the outer tube 18 is the inner tube 14 and connected via optional partitions 44, 46, 48 connected to the outer tube 18. The partition walls 44, 46, 48 can in particular be thermally highly conductive, so that the electrical heating power introduced on the outer lateral surface 22 of the outer tube 18 can still heat the inner tube 14 well. The partition walls 44, 46, 48 continue to serve as enlarged heat transfer surfaces and thus also contribute to the heating of the fluid. Furthermore, the dividing walls 44, 46, 48 define undesirable flow components of the fluid perpendicular to the axial extent direction 16 of the inner tube and the outer tube and contribute to an average uniform flow distribution in the interior of the counterflow heat exchanger 10. The partitions 44, 46, 48 may be distributed uniformly or non-uniformly along the jacket flow space 32.

The inner tube 14 also has an inner tube outer surface 54 and an inner tube inner lateral surface 60 at which, just as on the inner surface 52 of the outer tube 18, heat is transferred to the passing fluid. Inside the inner tube 14, a displacer 62 may be arranged, which transforms the pipe flow space 38 located in the interior of the inner tube 14 into an inner jacket flow space. The displacer 62 may be hollow or solid. The displacer 62 may be connected via ribs 74, 76 with the inner tube. The entire multi-shell construction of the countercurrent heat exchange 10 shown in FIG. 4 can be produced simultaneously, for example, by means of an extrusion process in its entirety. However, it is also possible that several parts of the multi-skin structure are produced independently of each other and then pushed into each other in the axial extension direction. FIG. 5 shows a three-dimensional external view of a counter flow heat exchanger 10 without a first connection area. In the case of the countercurrent heat exchanger 10 shown in FIG. 5, the representation of the first connection region and of the collar plate was dispensed with in order to be able to better recognize the multiplicity of flat surfaces 50. Instead of the first connection region, an annular gap 78 can now be seen in FIG. 5, at which the fluid between the jacket flow space, which is formed between the outer tube and the inner tube, and the first connection region, not shown, cross over.

FIG. 6 shows a three-dimensional view of heat exchanger components. In FIG. 6, the flat surfaces 50 are initially recognizable at one end of the illustrated heat exchanger components. Adjacent thereto extend in the axial extension direction, a first axial portion 56 and a second axial portion 58 of the outer tube 18, wherein on the outer tube 18 in the radial direction, the partitions 44, 46, 48 both at the first axial portion 56 as can also be seen on the second axial section 58. As can be seen in FIG. 6, the second axial section 58 is rotated about the axial extension direction 16 with respect to the first axial section 56, so that the respective partition walls 44, 46, 48 have an offset 80 and in the following manner after insertion Form the sheath flow space formed by the inner tube 14 inflow and demolition edges, which promote turbulence formation in the Mantelströ- mung space.

FIG. 7 shows a further view of heat exchanger components. The components illustrated in FIG. 7 can be inserted, for example, into the heat exchanger components shown in FIG. 6 in the axial extension direction 16 or, alternatively, can also be produced together with them. FIG. 7 shows the inner tube 14 with ribs 74, 76, which may have the same properties and effects as the partitions 44, 46, 48 between the outer tube 18 and the inner tube 14. Inside the inner tube, concentric Displacer 62 is arranged, which makes from the tube flow space in the interior of the inner tube 14 an inner jacket flow space.

The features of the invention disclosed in the foregoing description, in the drawings and in the claims may be essential to the realization of the invention both individually and in any combination with one another. LIST OF REFERENCE NUMBERS

10 countercurrent heat exchangers

12 electric vehicle heating

14 inner tube

16 axial extension direction

18 outer tube

20 electric heating element

22 outer surface

24 first connection area

26 first connection

28 fluid

30 first end area

32 sheath flow space

34 second end region

36 deflection area

38 tube flow space

40 second connection area

42 second connection

44 partition

46 partition

48 partition

50 level surface

52 inner lateral surface

54 inner tube outside surface

56 axial section

58 axial section

60 inner tube inside lateral surface

62 displacer

64 vehicle

66 power source

68 connection cable

70 closure lid

74 rib Rib annular gap offset

Claims

claims

1. Countercurrent heat exchanger (10) for an electric vehicle heater (12), comprising

an inner tube (14) having an axial extension direction (16);

an outer tube (18) which sheaths the inner tube (14) in the axial extension direction (16);

an electric heating element (20) disposed on an outer surface (22) of the outer tube (18);

a first connection region (24) having a first connection (26), wherein the first connection region (24) permits a transition of a fluid (28) between the first connection (26) and a jacket flow space (32), and wherein the jacket flow space ( 32) terminates at a first end portion (30) of the inner tube (14) and the outer tube (18) and is formed between the inner tube (14) and the outer tube (18);

at a second end region (34) opposite the first end region (30), a deflection region (36) through which the fluid (28) can be deflected between the jacket flow space (32) and a tube flow space (38) in the inner tube (14) is; and

a second connection region (40) having a second connection (42), wherein the second connection region (40) forms a transition of the fluid (28) between the tube flow chamber (38) and the second connection (42) to the first end region (30) allows.

2. Countercurrent heat exchanger (10) according to claim 1, wherein the jacket flow space (32) is subdivided by at least two partition walls (44, 46, 48), wherein the at least two partition walls (44, 46, 48) cover the inner tube (10). 14) and the outer tube (18) perpendicular to the axial extension direction (16) connect.

3. Gegenstromwärmeäuscher (10) according to claim 2, wherein the inner tube (14) and / or the outer tube (18) from at least two axial sections (56, 58) are put together set in the axial direction (16) against each other are twisted.

The countercurrent heat exchanger (10) according to any one of claims 1 to 3, wherein the first port (26) is oriented perpendicular to the second port (42).

5. Gegenstromwärmeäuscher (10) according to one of claims 1 to 4, wherein the outer outer surface (22) of the outer tube (18) has at least one partially planar surface (50).

6. Gegenstromwärmeäuscher (10) according to any one of claims 1 to 5, wherein an inner circumferential surface (52) of the outer tube (18) has a turbulence-promoting surface structure.

7. The countercurrent heat exchanger (10) according to any one of claims 1 to 6, wherein an inner tube outer surface (54) of the inner tube (14) has a turbulence-promoting surface structure.

8. Gegenstromwärmeäuscher (10) according to any one of claims 1 to 7, wherein the inner tube (14) on an inner tube inner circumferential surface (60) radially inwardly facing ribs (74, 76).

9. Gegenstromwärmeäuscher (10) according to any one of claims 1 to 8, wherein in the interior of the inner tube (14) a displacement body (62) is arranged.

10. Gegenstromwärmeäuscher (10) according to any one of claims 1 to 9, wherein the electrical heating element (20) by thermal spraying as a thermally sprayed layer on the outer circumferential surface (22) of the outer tube (18) is arranged.