FR2998954A1 - Heat exchanger i.e. thermoelectric generator for car, has outlet collecting box to allow circulation of exhaust fumes through beam, where exhaust fumes create depression in outlet collecting box with respect to beam - Google Patents

Abstract

The exchanger (10) has a beam (11) for permitting a flow of exhaust fumes of an engine and a coolant. An inlet collecting box (30) is provided for inlet of the exhaust fumes in the beam, and an outlet collecting box (31) is provided for outlet of the exhaust fumes from the beam. The outlet collecting box is intended to allow the circulation of the exhaust fumes through the beam from the inlet collecting box to the outlet collecting box, where the exhaust fumes create a depression in the outlet collecting box with respect to the beam.

Description

Heat exchanger, in particular thermoelectric generator. The present invention relates to a heat exchanger.

The invention applies to any type of heat exchanger, especially for a motor vehicle, such as exchangers for exchanging heat between two fluids or electric thermo generators in which the heat exchanger serves to create a temperature gradient between the opposite faces of electric thermo elements. In this field, it is known heat exchangers comprising a beam formed of a plurality of stacked tubes for the flow of a first fluid and a second fluid. Such heat exchangers comprise a manifold for entering the first fluid into the bundle and a manifold for first fluid outlet of the bundle. An inlet manifold guides the first fluid to the inlet manifold.

The inlet manifold has a passage section of the first fluid much lower than an inlet face of the first fluid in the beam and thus guides the first fluid mainly to a zone of the input face of the beam which does not represent the all of this face. The distribution of the first fluid in the different tubes of the beam therefore depends mainly on the configuration of the input box, which limits the room for maneuver. The invention aims at improving the situation and thus concerns a heat exchanger comprising a beam intended to allow a flow of a first fluid and a second fluid flowing in contact with the beam, said exchanger comprising an inlet manifold first fluid in the beam and an outlet manifold of the first beam fluid. According to the invention, the outlet manifold is configured to allow the circulation of a fluid drawing said first fluid through the beam from the inlet manifold to the outlet manifold. The configuration of the outlet manifold can thus improve the distribution of the first fluid in the beam. An irregular distribution of the first fluid in the beam generated, for example, by the input manifold can thus be restored by the configuration of the outlet manifold. According to one aspect of the invention, said fluid sucking the first fluid through the beam creates a vacuum in the outlet manifold box vis-à-vis the beam. The depression thus created makes it possible to obtain the desired suction effect. The depression is at the output of the beam, for example at a selected portion of the beam output.

According to an exemplary embodiment of the invention, the configuration of the inlet manifold causes a guiding of the first fluid towards the beam by creating one or more areas of the bundle firstly fed with fluid and one or more zones of the bundle. firstly fed fluid disadvantageously and the outlet manifold is configured to circulate said fluid drawing the first fluid through the beam at the at least one disadvantaged area. Thus, the outlet collector box makes it possible to homogenize the distribution of the first fluid between the zones fed with the first fluid in a less favored manner, called less-favored zones, and the zones that are fed with the first fluid preferentially, called preferential zones, thus improving the performances. of the exchanger. According to a first aspect of the invention, said outlet collecting box comprises a circuit connecting it to a part of the exchanger located upstream of the beam, said circuit being arranged to deflect a fraction of the first fluid so that it enters the outlet collecting box without passing through the beam, said fraction of the first fluid being said fluid drawing said first fluid through the beam.

According to a second aspect of the invention, the exchanger comprises an inlet pipe of the first fluid in the inlet manifold box, said inlet pipe being inclined with respect to a direction perpendicular to a direction in which the first fluid crosses the beam. The inclination of the inlet manifold also improves the distribution of the first fluid in the bundle.

According to an exemplary embodiment of the invention, the first fluid is intended to enter the inlet manifold box by a first side of the inlet manifold box. Although this inclination favors the distribution of the fluid over the entire beam, it nevertheless remains a disadvantaged area located at said first side. However, the LFA represents less than 50% of a surface through which the first fluid enters the beam.

Furthermore, according to the first aspect of the invention, said deflection circuit of a fraction of the first fluid may connect, for example, the exchanger at the first side of the header and in particular the inlet manifold at the outlet manifold box. Said fraction of the first fluid diverted between, for example, in the outlet manifold at a zone of the outlet manifold located opposite the first side of the inlet manifold with respect to the bundle so that the fraction of the first deflected fluid sucks the first fluid flowing in the inlet manifold box in particular at the first side of the inlet manifold box, that is to say in particular at the level of the zone disadvantaged. According to an exemplary embodiment of the invention, said circuit is configured to bring said fraction of first fluid substantially tangential to an output face of said beam.

Advantageously, said fraction of the first fluid represents at most 10% of the total flow of the first fluid in the exchanger. Advantageously, the circuit comprises a valve for adjusting the flow rate of said fraction of the first fluid. According to one aspect of the invention, the input manifold comprises a volume greater than the outlet manifold. The upper volume of the inlet manifold allows the exchanger to further homogenize the distribution of the fluid in the beam and to minimize the pressure drop. According to an exemplary embodiment, said exchanger is a thermoelectric generator. Advantageously, the heat exchanger comprises electric thermo elements for creating an electric current from a temperature gradient applied between two of their faces and wherein said beam is configured to create the temperature gradient between said faces of said elements. electric thermo. The homogeneity of the distribution of the fluid in the beam is then particularly advantageous. Indeed, it causes a homogeneity of the temperature gradient between the input and the output of the beam to have thermo elements made of identical materials and / or to arrange them in the same distribution over the entire beam.

The invention will be better understood in the light of the following description which is given for information only and which is not intended to limit it, accompanied by the attached drawings, in which: FIG. embodiment of the exchanger according to the invention, - Figure 2 illustrates in perspective and partially the exchanger of Figure 1. As shown in Figures 1 and 2, the invention relates to a heat exchanger, including a electric heat exchanger. Such an exchanger 10 comprises a beam 11 defining a first circuit 1, able to allow the circulation of a first fluid, in particular the exhaust gas of an engine, and a second circuit 2, able to allow the circulation of a second fluid, especially a heat transfer fluid of a cooling circuit, for example lower temperature than the first fluid. The first circuit 1 here comprises tubes, called first tubes 8, for the circulation of the first fluid. The beam 11 is, for example, in a substantially parallelepiped shape so that it comprises six faces. It thus comprises an inlet face 21 located on the side of an inlet of the first fluid in the exchanger 10, an outlet face 22 situated on the side of an outlet of the first fluid of the exchanger 10 and opposite to the inlet face 21. It also comprises a first lateral face 23, situated on the side of an inlet of the second fluid in the bundle 11, and a second lateral face 24 opposite to said first lateral face 23 with respect to the bundle 11, said first and second lateral faces connecting the inlet face 21 to the exit face 22. Said beam 11 also comprises a first longitudinal face 25 and a second longitudinal face (not visible), opposed to each other and connecting the inlet face 21 to the exit face 22 and the first side face 23 to the second side face 24. The six faces 21, 22, 23, 24, 25 of the beam 11 define between them an internal volume inside which is the first and the second circui ts 1, 2. We define a first direction L in the direction of a length of the exchanger 10, that is to say a direction perpendicular to the first and second lateral faces 23, 24, a second direction I in the direction of the width of the exchanger 10, that is to say perpendicular to the first and second longitudinal faces, and a third direction H in the direction of the height of the exchanger 10, that is to say say perpendicular to the input face 21 and the output face 22. The first, second and third directions L, I, H are here perpendicular to each other.

The exchanger 10 also comprises an inlet manifold 30 of the first fluid located at the inlet face 21 of the bundle 11 and an outlet manifold 31 of the first fluid located at the outlet face 22 of the first fluid. fluid. The inlet and outlet manifolds 30, 31 each comprise a manifold (not visible) and a respective inlet and outlet cover 36. The manifolds are here plates, arranged on the inlet and outlet faces. output 21, 22 of the beam and of substantially identical dimensions to the latter. The inlet cover 35 forms with the inlet manifold an internal volume within which the first fluid flows. A first end of the first tubes 8 enters the inlet manifold 30, at the inlet manifold, in order to open into the latter and allow the first fluid to enter the first tubes 8.

The exchanger 10 comprises an inlet pipe 33 defining the inlet of the first fluid in the inlet manifold 30. The configuration of the inlet manifold 30 and in particular of the inlet pipe 33 causes a guide of the first fluid to the beam 11, that is to say towards the input face 21 of the beam 11 by creating one or more areas of the beam 11 fed preferentially with a first fluid and one or more zones of the beam 11 fed with first fluid in a disadvantaged way. In the illustrated example, the first fluid enters the inlet manifold box at a first side of the inlet manifold box 30 located on the side of the first side face 23. Due to the configuration of the box inlet manifold 30 and / or inlet manifold 33 the first fluid is here guided preferentially to a zone of the input face 21 of the beam located on the side of a second side of the collector box of input 30 located on the side of the second side face 24 of the beam 11. On the other hand, the disadvantaged area (s) is located here at a zone of the input face (21) of the beam located on the first side of the collector box. input 30, that is to say on the side by which the first fluid enters the inlet manifold. The less-favored area here represents less than 50% of a surface through which the first fluid enters the beam 11, that is to say less than 50% of the input face 21 of the beam 11. The exit cover 36 forms with the outlet manifold an internal volume within which the first fluid flows. The output manifold 31 is located at the outlet face 22 of the bundle 11.

The exchanger 10 comprises an outlet pipe 34 defining the outlet of the first fluid of the outlet manifold 31. A second end of the first tubes 8 enters the outlet manifold to open into the outlet manifold box 31 and to allow the first fluid to exit the first tubes 8 and to enter the outlet manifold 31. The outlet manifold 31 then guides the first fluid to the outlet manifold 34 so that it exits the outlet. exchanger 10.

According to the invention, the outlet manifold box 31 is configured to allow the circulation of a fluid drawing the first fluid through the bundle 11 from the inlet manifold 30 to the outlet manifold 31. Improved in this way the homogeneity of the distribution of the first fluid in the beam.

The outlet collection box 31 may include a circuit 41 connecting it to a part of the exchanger 10 located upstream of the beam 11. The circuit 41 is arranged to deflect a fraction of the first fluid so that it enters the box outlet manifold 31 without passing through the beam 11. The fraction of the first deflected fluid is the fluid drawing the first fluid through the beam 11 according to the invention. In the example illustrated, the fraction of the first fluid is diverted from the inlet pipe 33 and goes towards the outlet manifold 31. It is deflected at the first side of the inlet manifold box 30 and enters into the outlet manifold 31 at a first side of the outlet manifold 31 located on the side of the first side face 23 of the beam 11, that is to say vis-à-vis the first side of the input manifold with respect to the beam 11.

The circuit 41 deflecting said fraction of the first fluid upstream of the bundle 11 comprises a deflection tubing 42, connected to the inlet pipe 33 and the outlet manifold 31. This circuit 41 here comprises a valve 43 for regulating the flow rate of the fraction of first fluid diverted into the circuit 41 and the flow rate of the one which continues its normal path, that is to say passing through the manifold inlet 30 before passing through the beam 11. The valve 43 is, for example, located in the deflection tubing 42. The fraction of first fluid diverted by this circuit 41 represents less than 10% and in particular 5% of the total flow of the first fluid flowing in the exchanger 10.

Said circuit 41 comprises, for example, a rectilinear portion, issuing from said inlet manifold and comprising said valve, extended by a curved portion to the outlet manifold, said curved portion being configured to fit said first fluid of said substantially tangentially in said outlet manifold.

The fluid sucking the first fluid through the beam 11, that is to say here the fraction of first fluid deviated, creates a depression in the outlet manifold 31 opposite the beam 11. This depression goes cause the suction of the first fluid flowing in the inlet manifold 30 through the beam 11. This vacuum is located in particular in a zone near the beam 11, that is to say at its exit face 22. It is mainly located near the deflection tubing 42, that is to say on the first side of the outlet manifold 31. Thus the fraction of the first fluid diverted mainly attracts the first fluid circulating in the collector box of entry 30 at an area corresponding to the less-favored areas. The inlet pipe 33 protrudes with respect to the first lateral face 23 of the bundle 11. It extends in a plane defined by the first and third directions L and H and is inclined relative to the first direction L. The tubing The inlet is here inclined also with respect to the third direction H. Thus the first fluid flows in the inlet manifold 30 in an inlet direction inclined with respect to the first direction L, that is to say inclined relative to a direction perpendicular to the direction of flow of the first fluid in the beam 11, and / or relative to the third direction H. The inclination of the inlet pipe 33 relative to the first direction L allows the inlet tubing 33 to minimize the size of the disadvantaged area or zones, that is to say here the area of the inlet face 21 located on the first side of the inlet manifold 30. The inclination of the inlet tubing 33 by This helps to improve the distribution of the first fluid in the beam. By way of example, the inclination of the tubing is approximately 15 ° to 45 ° and in particular 30 ° with respect to said first direction L. The outlet tubing 34 protrudes with respect to the second lateral face 24 of the exchanger 10 and extends in a plane defined by the first and third directions L and H in an inclined manner with respect to the first direction L. The outlet pipe 34 is here inclined also with respect to the third direction H. Thus the first fluid flows in the outlet manifold 31 in an outlet direction inclined relative to the first direction L. The respective inclination of the inlet and outlet pipes gives the first fluid a substantially S-shaped flow flattened. The input manifold 30 here comprises a convergent shape, that is to say a decreasing volume, from its first side to its second side, that is to say from the first side face 23 up to At the second side face 24. On its side, the outlet manifold box 31 here comprises a divergent shape, that is to say an increasing volume, from its first side to its second side. The input manifold 30 comprises a volume greater than the outlet manifold 31. In the case where the exchanger 10 is a thermoelectric generator, it also comprises elements 3, called electrical thermo, for generating an electric current in the presence of a temperature gradient generated by the first and second circuits. These are, for example, substantially parallelepiped shaped elements generating an electric current, according to the Seebeck effect, when they are subjected to said gradient between two of their opposite faces 4a, 4b, said active faces. Such elements allow the creation of an electric current in a load connected between said active faces 4a, 4b. In a manner known to those skilled in the art, such elements are constituted, for example, of Bismuth and Tellurium (Bi2Te3) or of Cerium, Cobalt, Iron and Antimony (CeyCoxFe4xSbi2) or Lead and Tellurium ( PbTe) or Silicon and Germanium (SiGe).

The exchanger 10 comprises, for example, fins 5, here in heat exchange relation with the second circuit 2, that is to say here the cold circuit. A temperature gradient is thus ensured between said fins 5 and the first circuit 1, here the hot circuit 1. Said thermo elements 3 are here in contact with the fins 5 and the first tubes 8 at the level, in particular, of their active faces 4a , 4b. In other words the electric thermo elements are arranged between the fins 5 and the first circuit 1 so as to be in contact with the fins 5 and the first tubes 8. This ensures a current generation by the electric thermo elements 3.

The fins 5 have two large surfaces 7a, 7b opposite planes and making it possible to establish a surface contact between one of said large surfaces 7a, 7b and the thermoelectric elements 3 at the or their active faces located vis-à-vis -vis 4a. Moreover, said fins 5 may have tracks (not shown) for conduction of the current generated by said electric thermo elements 3. It will thus be possible to conduct the current, according to any desired circuit topology, to the surface of the fins 5 by grouping the tracks. in series and / or in parallel. Such tracks may also be provided on the first tubes 8 in order to fulfill the same function.

Said first tubes 8 are, for example, substantially rectangular section tubes comprising two large opposite parallel faces on which are disposed the electric thermo elements 3 by one of their active face 4b. They are configured to allow the circulation of exhaust gas and are, in particular, stainless steel. They are formed, for example, by profiling, welding and / or brazing. They may have a plurality of passage channels of the first fluid, separated by partitions connecting the opposite planar faces of the tubes. The second circuit 2 comprises, for example, second tubes 9, for the circulation of the second fluid, in particular a liquid. The fins 5 are provided in heat exchange relation with the second tubes 9. The fins 5 are crossed by the second tubes 9. The fins 5 have, for example, orifices for the passage of the second tubes 9. Said second tubes 9 are, for example, aluminum or copper and have a round, oval and / or flat section. The second tubes 9 extend, for example, in the first direction L, that is to say that they extend from the inlet face 21 to the outlet face 22. The first tubes 8 's thus extend substantially perpendicular to the second tubes 9 and substantially parallel to the fins 5. The second fluid enters here in the exchanger 10 through an inlet port 37 located on the first side face 23 through the exchanger 10 in the direction of the first direction L to the second side face 24, is turned around by means of a collector and leaves the exchanger 10 at an inlet orifice 38.

The contact between the first tubes 9 and the cold fins 5 is achieved, for example, by an expansion of the material of the first tubes 9 as in the heat exchangers known under the name of mechanical exchangers in the field of heat exchangers for motor vehicles.

The exchanger 10 here comprises several rows of first tubes 8 superimposed in parallel in the first direction L. The rows of first tubes 8 are thus superimposed from the first side face 23 to the second side face 24. The first tubes 8 of the same row are here arranged parallel to each other and extend in the third direction H. The fins 5 are arranged between each row of first tubes, parallel thereto, that is to say that the fins 5 are superimposed alternating with the rows of first tubes 8 in the first direction L, with rows of electric thermo elements 3 arranged between a fin 5 and a row of first tubes 8 neighbors.

The exchanger 10 also comprises several rows of second tubes 9 superimposed parallel to each other along the second direction I. The rows of second tubes 9 are thus superimposed from the first longitudinal face to the second longitudinal face of the beam 11. The second tubes 9 of the same rank are here arranged parallel to each other in the third direction H. The first row of tubes 8 is called the first tubes 8 situated at the same level in the second direction I and belonging to rows of first different tubes 8. Thus, the rows of first tubes 8 are superposed parallel to each other in the second direction I, that is to say between the first longitudinal face 25 and the second longitudinal face. The rows of first tubes 8 are here superposed alternately with the rows of second tubes 9 in the second direction I.

The second tubes 9 may also be positioned in rows lying in planes parallel to the first and second directions L and I. The rows of second tubes 9 are therefore orthogonal to the rows of first tubes 8.

The first tubes 8 extending along the third direction H of the exchanger are shorter than the second tubes 9 extending in the first direction L of the exchanger. There is thus an elongated form of exchanger in said first direction L, and its configuration remains favorable to integration into a vehicle.

Claims (12)

REVENDICATIONS1. a heat exchanger (10) comprising a beam (11) for allowing a flow of a first fluid and a second fluid, said exchanger (10) comprising an inlet manifold (30) of the first fluid in the beam (11) and an outlet manifold (31) of the first fluid of the beam (11), characterized in that the outlet manifold (31) is configured to allow the circulation of a fluid sucking said first fluid to through the beam (11) from the inlet manifold (30) to the outlet manifold (31), said fluid sucking the first fluid through the beam (11) creating a vacuum in the outlet manifold (31) vis-à-vis the beam (11). The heat exchanger (10) according to claim 1, wherein the configuration of the inlet header (30) causes a guiding of the first fluid to the beam (11) creating one or more zones of the beam (11). firstly fed preferentially with fluid and one or more areas of the beam (11) fed in a least favored fluid first and the outlet manifold (31) is configured to circulate said fluid sucking the first fluid through the beam (11); ) at the level of the disadvantaged area or zones. 3. [heat exchanger (10) according to any one of claims 1 or 2, wherein the first fluid is intended to enter the inlet manifold (30) by a first side of the inlet manifold box (30). 4. heat exchanger (10) according to any one of claims 2 or 3, wherein the disadvantaged area is less than 50% of a surface by which the first fluid enters the beam (11). A heat exchanger (10) according to any one of the preceding claims, wherein the exchanger (10) comprises an inlet manifold (33) of the first fluid in the inlet manifold (30), said manifold inlet (33) being inclined with respect to a direction perpendicular to a direction in which the first fluid passes through the beam (11). 6. heat exchanger (10) according to one of the preceding claims, wherein said outlet manifold (31) comprises a circuit (41) connecting it to a portion of the exchanger (10) located upstream of the beam ( 11), said circuit (41) being arranged to deflect a fraction of the first fluid so that it enters the outlet manifold (31) without passing through the beam (11), said fraction of the first fluid being said fluid sucking said first fluid through the beam (11). The heat exchanger (10) of claim 6, wherein said circuit (41) is configured to input said first fluid fraction substantially tangentially to an exit face (22) of said beam (11). 8. Heat exchanger (10) according to any one of claims 8 or 7, wherein the circuit (41) comprises a valve (43) for adjusting the flow rate of said fraction of the first fluid. 9. Heat exchanger (10) according to any one of the preceding claims, wherein the inlet manifold (30) comprises a volume greater than the outlet manifold (31). 10. Heat exchanger (10) according to any one of the preceding claims, wherein said exchanger (10) is a thermoelectric generator_ 11. heat exchanger (10) according to claim 10, wherein said heat exchanger (10) comprises electric thermo elements (3) for creating an electric current from a temperature gradient applied between two of their faces. (4a, 4b) and wherein said beam is configured to create the temperature gradient between said faces of said electric therrno elements. 12. Use of the heat exchanger (10) according to any one of claims 6 to 8, wherein said fraction of the first fluid is at most 10% of the total flow of the first fluid in the exchanger (10).