EP4775911A1

EP4775911A1 - Heat exchanger

Info

Publication number: EP4775911A1
Application number: EP25151006.1A
Authority: EP
Inventors: Tomas KOLEK; Martin MYSLIKOVJAN; Tomas VEVERKA; Ladislav HANEL; Lukas BERANEK; Jan Forst
Original assignee: Valeo Electrification SAS
Current assignee: Valeo Electrification SAS
Priority date: 2025-01-09
Filing date: 2025-01-09
Publication date: 2026-07-15
Also published as: WO2026149791A1

Abstract

A heat exchanger (100) comprising a first manifold (10), a second manifold (20), and a plurality of flat tubes (200) connecting the first manifold with the second manifold; the plurality of flat tubes (200) being arranged alternatingly with a plurality of heat dissipation elements (50), wherein each flat tube (200) is arranged to meander between respective heat dissipation elements (50) with its co-planar sections (211, 212, 213, 214), with the co-planar sections (211, 212, 213, 214) being connected to each other with integral reversal elements (215) arranged beyond the heat dissipation elements (50), wherein the first and second manifolds (10, 20) have a circular cross-section.

Description

TECHNICAL FIELD

The invention relates to a heat exchanger. In particular, the invention relates to the heat exchanger for a motor vehicle.

BACKGROUND OF THE INVENTION

The present invention relates to the field of heat exchanger and in particular to heat exchangers intended to be traversed by a fluid under high pressure. In this respect, the invention relates more particularly to air conditioning gas coolers, inner gas coolers or evaporators capable of being traversed by a refrigerant fluid in the supercritical state, as is the case for natural gases such as carbon dioxide, also known as CO2 or R744. Such heat exchangers find particular application in motor vehicles.
A known fluid refrigerant circuit forms a closed loop in which the refrigerant fluid flows in order to dissipate or collect calories through heat exchangers. The heat exchanger comprises the manifold to connect said heat exchanger to the fluid refrigerant circuit, said manifold linking pipes from the fluid refrigerant circuit to the heat exchanger core, in order for the refrigerant fluid to flow through heat exchanger tubes.
In a fluid refrigerant circuit traversed by a refrigerant fluid in the supercritical state, this refrigerant fluid remains essentially in the gaseous state and under a very high pressure, which is usually around 100 bars. As a result, heat exchangers must be able to withstand such high pressure, the recommended burst pressure being generally three times the value of the nominal operating pressure, burst pressure thus reaching around 300 bars.

SUMMARY OF THE INVENTION

An object of the invention is a heat exchanger comprising a first manifold, a second manifold, and a plurality of flat tubes connecting the first manifold with the second manifold; the plurality of flat tubes being arranged alternatingly with a plurality of heat dissipation elements, wherein each flat tube is arranged to meander between respective heat dissipation elements with its co-planar sections, with the co-planar sections being connected to each other with integral reversal elements arranged beyond the heat dissipation elements, wherein the first and second manifolds have a circular cross-section.
In one option, the first and second manifolds are formed of a continuous side wall and terminate on one end with an end baffle.
In one option, the first and second manifolds include positioning cutouts in the vicinity of the end baffle.
In one option, the first and second manifolds include intermediate openings in which ends of the flat tubes are arranged, the intermediate openings being crescent shaped.
In one option, the flat tubes penetrate only a portion of depth of each intermediate opening.
In one option, the flat tubes extend to 30% - 65%, in particular 37,5% - 50%, of respective diameters of the first and second manifolds.
In one option, wall thickness of the first and second manifolds is 14% to 20% of their diameters.
In one option, the heat exchanger further comprise connection sleeves into which the first and second manifolds are respectively inserted.
In one option, the first and second manifolds each have at least one straight section to which the flat tubes are connected and a bent section which terminates with a connection sleeve.
In one option, the bent sections are arranged so that the connection sleeves open in a direction perpendicular to the direction of extension of the straight sections.
In one option, the connection sleeves open in a direction parallel to the general axis of extension of the flat tubes.
In one option, the connection sleeves open in a direction perpendicular to the general axis of extension of the flat tubes.

BRIEF DESCRIPTION OF DRAWINGS

The present invention will be described in greater detail below with reference to the drawings. In the drawings:

Fig. 1 shows a heat exchanger in a perspective view;
Fig. 2 shows a partial view of the heat exchanger from below;
Fig. 3 shows a cross-section of a manifold;
Fig. 4 shows a partial view of the heat exchanger from the back;
Fig. 5 shows a view on the manifolds from the front;
Fig. 6 shows a flat tube;
Fig. 7 shows a second example of the manifolds;
Fig. 8 shows a third example of the manifolds; and
Fig. 9 shows a fourth example of the manifolds.

DETAILED DESCRIPTION OF THE INVENTION

Fig. 1 shows a heat exchanger 100 in a perspective view. The heat exchanger 100 is intended to be used in a fluid refrigerant circuit. The heat exchanger 100 comprises a header box 1 and heat exchange tubes 200. The heat exchanger 100 can be used as an evaporator or as a condenser.
The header box 1 extends along a first axis X and a second axis Y perpendicular to the first axis X, the first axis X and the second axis Y defining a plane XY.
The heat exchanger tubes 200 extend away from and towards the header box 1 along a third axis Z, said third axis Z being perpendicular to the plane XY.
The header box 1 comprises a first manifold 10 and a second manifold 20, connected fluidically by the flat tubes 200.
The first manifold 10 and the second manifold 20 include connection sleeves 53 into which the first and second manifolds 10, 20 are respectively inserted.
In general, the connection sleeves 53 are intended to fluidically connect the header box 1 to the fluid refrigerant circuit.
The heat exchanger 100 comprises a gap 50 between the first manifold 10 and the second manifold 20, said gap 50 extends all along the header box 1 along the first axis X. This configuration allows the header box 1 to limit the heat exchange between the first manifold 10 and the second manifold 20. In other words, the gap 50 reduces the thermal coupling of the first manifold 10 and the second manifold 20. Thus, this configuration allows an improved efficiency of the heat exchanger 100.
Fig. 2 shows a partial view of the heat exchanger 100 from below, with Fig. 3 showing a cross-section of a manifold, in particular the first manifold 10, with the second manifold 20 having analogous structure.
In one example, the heat exchanger 100 comprises a first manifold 10, a second manifold 20, and a plurality of flat tubes 200 connecting the first manifold with the second manifold. The plurality of flat tubes 200 being arranged alternatingly with a plurality of heat dissipation elements 50. Each flat tube 200 is arranged to meander between respective heat dissipation elements 50 with its co-planar sections 211, 212, 213, 214, with the co-planar sections 211, 212, 213, 214 being connected to each other with integral reversal elements 215 arranged beyond the heat dissipation elements 50. The first and second manifolds 10, 20 have a circular cross-section.
The first and second manifolds 10, 20 can include intermediate openings 31 in which ends of the flat tubes 200 are arranged, the intermediate openings 31 being crescent shaped.
The flat tubes 200 can penetrate only a portion of depth of each intermediate opening 31. In other words, there are still section of material of the manifolds 10, 20 not reached by the tubes, i.e. the tube does not cross the whole crescent shape of the openings.
The flat tubes 200 extend to 30% - 65%, in particular 37,5% - 50%, of respective diameters of the first and second manifolds 10, 20.
Fig. 4 shows a partial view of the heat exchanger 100 from the back, while Fig. 5 shows a view on the manifolds 10, 20 from the front.
The first and second manifolds 10, 20 can be formed of a continuous side wall and terminate on one end with an end baffle 51. In other words, the manifolds 10, 20 can be made of a single sheet of material which is shaped into a cylinder.
Wall thickness of the first and second manifolds 10, 20 can be 14% to 20% of their diameters.
The first and second manifolds 10, 20 can include positioning cutouts 52 in the vicinity of the end baffle 51. They can serve as a way to fix and control the rotation and position of the tube during the production.
Fig. 6 shows a flat tube 200 for the heat exchanger 100. The flat tube 200 may comprise first tubular element 211, a second tubular element 212, a third tubular element 230 and a fourth tubular element 240. The third tubular element 230 and a fourth tubular element 240 are essentially the same as the first tubular element 211 and the second tubular element 212. Each tubular element 211, 212, 230, 240 may comprise two juxtaposed longer walls 213 having essentially flat surface. In other words, the longer walls 213 are substantially identical wall portions arranged in parallel and facing each other with their respective flat surfaces. The tubular elements 211, 212, 230, 240 may also comprise two shorter walls 214 connecting the longer walls 213 to form a closed profile, and an axis of elongation. The flat tube 200 may further comprise two open ends 219. The term open end refers to a terminal ends of the tubular element 211, 212, 230, 240 which allows the fluid to enter or exit the entire flat tube 200.
The open ends 219 of the flat tube 200 are arranged on the same side and at the same level, whereas the longer walls 213 of the adjacent tubular elements 211, 212 are arranged so that their flat surfaces are coplanar with respect to each other. In order to achieve such configuration, the flat tube 200 may further comprise at least one reversal element 215 configured to fluidly connect the first tubular element 211 and the second tubular element 212, with similar reversal element connecting the third tubular element 230 and the fourth tubular element 240. The reversal elements 215 may be made integral with the rest of the flat tube 200.
The reversal elements 215 may thus be interpreted as any integral section of the flat tube 200 which is configured to change the intended flow of the fluid within the flat tube 200. In particular, the reversal elements 215 may be configured to provide the counter flow of the fluid within two neighboring straight sections of the flat tube 200, i.e. the first tubular element 211 and the second tubular element 212, et cetera.
The reversal element 215, may comprise, inter alia, a first twisted section 215A and at least one second twisted section 215B. A term "twisted" refers to essentially helical or semi-helical shape of the section. The twisted section 215A, 215B allow smoother transition of the channel of the fluid, without drastic change of the hydraulic diameter within the reversal element 215. Moreover, if the flat tube 200 is an extruded flat tube comprising micro channels, said channels remain their desired shape.
The integrity between the tubular elements 211, 212, 230, 240 and the reversal element 215 may be described, so that the first twisted section 215A may protrude directly from first tubular element 211, and the second twisted section 215B may protrude directly from the second tubular element 212. The twisted sections 215A, 215B may be then joined together to form a fluidal communication between the neighboring tubular elements 211, 212, 230, 240. Naturally, it is also true that the second twisted section 215B may protrude directly from the first twisted section 215A, so other ways of describing the twisted sections 215A 215B are also possible. For example, the first twisted section 215A may protrude in helical manner in the counterclockwise direction with respect to the first tubular element 211, yet with respect to the second twisted section 215B it may protrude in a clockwise direction. Similarly, the second twisted section 215B may protrude in helical manner in the counterclockwise direction with respect to the second tubular element 212, yet with respect to the first twisted section 215B it may protrude in a clockwise direction.
The reversal element may comprise an essentially U-shaped section 216 that connects the first twisted section 215A and the second twisted section 215B. The U-shaped section 216A may be of relatively small curvature, or of bigger curvature. The smaller curvature of the U-shaped section is formed to the extent that is allowed by mechanical properties of the material from which the flat tube 200 is made of. Small curvature allows packing the consecutive tubular elements 211, 212, 230, 240 closer to each other, which improves packaging. The bigger curvature on the other hand facilitates thermal decoupling of the consecutive tubular elements 211, 212, 230, 240 and allows relatively smoother transfer of the fluid therein.
As mentioned in previous paragraphs, the second twisted section 215B protrudes helically in one direction, wherein the first twisted section 215A protrudes helically in the same direction as the second twisted section 215B. Alternatively, the second twisted section 215B protrudes helically in one direction, wherein the first twisted section 215A protrudes helically in different direction than the second twisted section 215B. The helical direction of protrusion means that the sidewalls 214 remain substantially equidistant with respect to each other, but the axis of elongation of the tubular element 211, 212, 230, 240 is disordered.
The reversal elements 215 allow to change the intended flow direction of the fluid, without the necessity to provide additional manifolds. It may significantly reduce the overall cost and weight of the heat exchanger 100 while keeping the desired packaging. The reversal elements 215 having the twisted sections 215A, 215B further allow to form the substantially equidistant path for the fluid throughout the flat tube 200, unlike in the flat tube comprising direct U-turn, wherein the sidewalls 214 are at some point of different length.
Each flat tube 200, including both the tubular element 211, 212, 230, 240 and the reversal elements 215 may comprise a set of micro channels 217 extending between the open ends of the flat tube 200. Naturally, the micro channels are continuous throughout the reversal elements 215, i.e. the micro channels in the reversal elements are configured to link fluidly the corresponding micro channels in respective tubular elements 211, 212, 230, 240. The tubular elements 211, 212, 230, 240 may be of the same size, i.e. their external dimensions such as: width, measured as the distance between the outer faces of the shorter walls 214; the length- measured along the longer walls 213, as the distance between the open ends of the flat tube; or as the height, measured as the distance between the outer faces of the longer walls of the same tubular element 211, 212, 230, 240.
The flat tube 200 may be implemented in a heat exchanger 100. The exchanger 100 may comprise, inter alia: the plurality of flat tubes 200 which arranged in a stacking direction, wherein the stacking direction is perpendicular to the flat surfaces of the flat tubes 211, 212, 230, 240.
Fig. 7 shows a second example of the manifolds, with Fig. 8 showing a third example of the manifolds and Fig. 9 showing a fourth example of the manifolds.
The first and second manifolds 10, 20 each can have at least one straight section S to which the flat tubes 200 are connected and a bent section B which terminates with a connection sleeve 53.
The bent sections B can be arranged so that the connection sleeves 53 open in a direction perpendicular to the direction of extension of the straight sections S.
The connection sleeves 53 can open in a direction parallel to the general axis of extension of the flat tubes 200. For example, the connection sleeves 53 can open upwards or downwards relative to the heat exchanger, for example along the Z axis.
The connection sleeves X can open in a direction perpendicular to the general axis of extension of the flat tubes 200. For example, the connection sleeves 53 can open to the sides relative to the heat exchanger, for example along the Y axis.
Such an arrangement allows assembly flexibility in view of different possible piping configurations of the heat exchange system.

Claims

A heat exchanger (100) comprising
a first manifold (10),

a second manifold (20), and

a plurality of flat tubes (200) connecting the first manifold with the second manifold;

the plurality of flat tubes (200) being arranged alternatingly with a plurality of heat dissipation elements (50),
wherein each flat tube (200) is arranged to meander between respective heat dissipation elements (50) with its co-planar sections (211, 212, 213, 214), with the co-planar sections (211, 212, 213, 214) being connected to each other with integral reversal elements (215) arranged beyond the heat dissipation elements (50),

wherein the first and second manifolds (10, 20) have a circular cross-section.
A heat exchanger (100) according to claim 1, wherein the first and second manifolds (10, 20) are formed of a continuous side wall and terminate on one end with an end baffle (51).
A heat exchanger (100) according to claim 2, wherein the first and second manifolds (10, 20) include positioning cutouts (52) in the vicinity of the end baffle (51).
A heat exchanger (100) according to any preceding claim, wherein the first and second manifolds (10, 20) include intermediate openings (31) in which ends of the flat tubes (200) are arranged, the intermediate openings (31) being crescent shaped.
A heat exchanger (100) according to claim 4, wherein the flat tubes (200) penetrate only a portion of depth of each intermediate opening (31).
A heat exchanger (100) according to claim 4, wherein the flat tubes (200) extend to 30% - 65%, in particular 37,5% - 50%, of respective diameters of the first and second manifolds (10, 20).
A heat exchanger (100) according to any preceding claim, wherein wall thickness of the first and second manifolds (10, 20) is 14% to 20% of their diameters.
A heat exchanger (100) according to any preceding claim, further comprising connection sleeves (53) into which the first and second manifolds (10, 20) are respectively inserted.
A heat exchanger (100) according to claim 1, wherein the first and second manifolds (10, 20) each have at least one straight section (S) to which the flat tubes (200) are connected and a bent section (B) which terminates with a connection sleeve (53).
A heat exchanger (100) according to claim 1, wherein the bent sections (B) are arranged so that the connection sleeves (53) open in a direction perpendicular to the direction of extension of the straight sections (S).
A heat exchanger (100) according to claim 10, wherein the connection sleeves (53) open in a direction parallel to the general axis of extension of the flat tubes (200).
A heat exchanger (100) according to claim 10, wherein the connection sleeves (53) open in a direction perpendicular to the general axis of extension of the flat tubes (200).