EP2831527B1 - Heat exchanger, in particular for a vehicle - Google Patents

Description

The invention relates to a heat exchanger, according to the preamble of claim 1, in particular for vehicles, in particular electric and / or hybrid vehicles.

Such an exchanger is known, for example, from the document JP 2001 235 255 A .

In vehicles with thermal engines, it is known to use the heat generated by the engine to heat the passenger compartment of the vehicle. In electrically powered vehicles, the heat generated by the electric machine used to drive the vehicle is too weak to provide such a function. An identical problem arises, albeit to a lesser extent, in hybrid vehicles, that is to say, with both thermal and electric motorization.

To solve this problem, it has already been proposed to operate air conditioning loops in a reversible manner. They are thus configured to alternatively introduce cold air or hot air into the passenger compartment, this depending on the user's request.

They use a heat exchanger, located on the front of the vehicle, to be swept by a flow of air at room temperature passing through the calender. Said exchanger serves to condense the refrigerant circulating in the air conditioning loop when it is used to cool the passenger compartment and evaporate said fluid in the opposite case, that is to say, when the air conditioning loop operates as a pump heat to warm the cabin.

The thermal performance of such exchangers is difficult to optimize because the solutions to improve their operation as a condenser are generally opposed to those to improve their operation as an evaporator.

More specifically, in the condensers or evaporators of the type intermediate tubes, it has long been known that it is advantageous to circulate the refrigerant in series in passes grouping a given number of tubes. In condensers, it is Also known for a long time that decreasing the number of tubes from one pass to the other makes it possible to optimize the heat exchange while limiting the pressure drops. Those skilled in the art also know that such a distribution of the tubes is unfavorable to the operation of the evaporators.

A first solution to avoid this situation is to reverse the flow direction of the fluid in the exchanger but such a solution increases the complexity of the air conditioning loop.

For the heat exchangers to be used alternately condenser and evaporator, without inversion of the direction of circulation of the refrigerant in the exchanger, the skilled person is naturally led to propose exchangers with a most symmetrical configuration possible to avoid penalizing one mode of operation with respect to the other. In the case of multi-pass intercalated tube exchangers, this results in the use of two passes, having a number of tubes per pass identical or at least remaining close to one pass to another.

However, a particularly critical problem is the risk of icing of the exchanger in heat pump mode. The occurrence of such a phenomenon tends to block all or part of the heat exchange, due to the increase in the pressure drop on the air. The degradation of the heat exchange due to icing tends to lower the evaporation temperature and the pressure of the refrigerant inside the exchanger, which increases the risk of icing of the exchanger.

Another particularly critical problem relates to the internal pressure drop at the exchanger. In evaporator mode, it is known that the density of the coolant is lower than in condenser mode which has the effect of increasing the pressure drop. It thus seems essential to seek to reduce the pressure drop in evaporator operation to improve thermal performance.

To avoid such a risk it has already been imagined to use a reduced number of tubes in the first pass, while placing this first pass in the lower part of the exchanger, the exchanger being positioned in a substantially vertical plane and the tubes being oriented substantially horizontally.

However, tests carried out by the applicant have shown that some of the tubes of such an exchanger participate little or not in the exchange. These are in particular the tubes of the second pass located near the first pass. It seems moreover that this problem is more general and is also encountered in exchangers having a greater number of passes, a different distribution of tubes per pass and / or a different orientation, including vertical tubes.

The present invention aims to improve the situation and proposes for this purpose a heat exchanger according to claim 1.

According to the invention, said first collector comprises a partition configured to disrupt the flow of fluid between the first and second parts of said tubes.

The applicant has found that the use of such a partition makes it possible to improve the distribution of the refrigerant inside the tubes of the bundle, which has the effect of increasing the heat exchange while controlling the pressure losses. , especially in the evaporator operating mode. Although such a partition seems to have to accelerate the refrigerant by decreasing its passage section and thus disadvantage the supply to the tubes downstream, there is instead a favored supply of said tubes. Without pretending to be an explanation, such a phenomenon could have its origin in the two-phase state of the refrigerant during its passage from one pass to another.

• le faisceau est configuré pour que les passes soient orientées horizontalement lorsque l'échangeur est en utilisation,
• la section de passage pour le fluide frigorigène dans la première passe représente 40 à 70%, notamment 50 à 70%, de la section de passage pour le fluide frigorigène du faisceau,
• la section de passage pour le fluide frigorigène dans la première passe est strictement supérieure à 40%, notamment 50%,
• la cloison se trouve à une distance d d'une zone de passage entre la première partie et la seconde partie dudit premier collecteur, et la cloison est positionnée au choix:
  • dans ladite première partie, la distance d étant inférieure à la moitié d'une longueur axiale de ladite première partie dudit premier collecteur,
  • dans ladite seconde partie, la distance d étant inférieure à la moitié de la longueur axiale de ladite seconde partie dudit premier collecteur,
• la cloison se trouve au niveau de ladite zone de passage,
• la cloison de perturbation de la circulation du fluide frigorigène est un déflecteur orienté de façon à diriger le fluide frigorigène vers le faisceau,
• la cloison de perturbation de la circulation du fluide frigorigène est disposée transversalement à un axe longitudinal du premier collecteur,
• la cloison de perturbation de la circulation du fluide réfrigérant présente un ou plusieurs orifices de passage dudit fluide
• les orifices de passage sont régulièrement répartis à la surface de la cloison de perturbation de la circulation du fluide frigorigène,
• les orifices de passage sont répartis de façon à canaliser le fluide en direction des tubes de la seconde partie de tubes se trouvant à proximité de la cloison de séparation,
• les orifices de passage sont plus nombreux et/ou de surface plus importante dans une moitié de la cloison de perturbation de la circulation du fluide frigorigène, se trouvant à proximité des tubes,
• ledit échangeur est configuré pour être positionné en face avant de véhicule automobile, ledit véhicule étant, notamment, un véhicule électrique et/ou hybride.

According to different embodiments, which may be used separately or in combination:

• the beam is configured so that the passes are oriented horizontally when the exchanger is in use,
• the passage section for the refrigerant in the first pass represents 40 to 70%, especially 50 to 70%, of the passage section for the refrigerant of the beam,
• the passage section for the refrigerant in the first pass is strictly greater than 40%, especially 50%,
• the partition is at a distance d from a passage zone between the first part and the second part of said first manifold, and the partition is positioned at the choice:
  • in said first portion, the distance d being less than half an axial length of said first portion of said first manifold,
  • in said second portion, the distance d being less than half the axial length of said second portion of said first collector,
• the partition is at the level of said passage zone,
• the refrigerant circulation disturbance partition is a deflector oriented so as to direct the refrigerant towards the bundle,
• the perturbation partition of the refrigerant circulation is arranged transversely to a longitudinal axis of the first collector,
• the partition for disturbing the circulation of the refrigerant fluid has one or more orifices for the passage of said fluid
• the passage orifices are regularly distributed on the surface of the refrigerant circulation disturbance partition,
• the passage orifices are distributed so as to channel the fluid towards the tubes of the second part of tubes located near the partition,
• the passage orifices are more numerous and / or of greater surface area in one half of the refrigerant circulation perturbation partition, close to the tubes,
• said exchanger is configured to be positioned on the front face of a motor vehicle, said vehicle being, in particular, an electric and / or hybrid vehicle.

• la figure 1 illustre en vue de face, de façon schématique, un exemple d'échangeur thermique conforme à l'invention,
• la figure 2 illustre en perspective un premier exemple de réalisation d'une cloison de perturbation de la circulation du fluide frigorigène d'un échangeur conforme à l'invention,
• les figures 3 à 9 illustrent en vue de face d'autres exemples de réalisation de ladite cloison,
• la figure 10 illustre de façon schématique selon un plan de coupe axial, un exemple supplémentaire de réalisation de ladite cloison.

The invention will be better understood, and other objects, details, features and advantages thereof will become more clearly apparent in the following detailed explanatory description of several embodiments of the invention given as examples. purely illustrative and non-limiting examples, with reference to the attached schematic drawings.
On these drawings:

• the figure 1 illustrates in front view, schematically, an example of a heat exchanger according to the invention,
• the figure 2 illustrates in perspective a first embodiment of a partition for disturbing the circulation of the refrigerant of an exchanger according to the invention,
• the Figures 3 to 9 illustrate in front view of other embodiments of said partition,
• the figure 10 schematically illustrates in an axial sectional plane, a further embodiment of said partition.

As illustrated in figure 1 the invention relates to a heat exchanger 1 configured to operate alternately in evaporator and condenser mode. It is in particular a heat exchanger intended to be used in an air conditioning loop of the passenger compartment of a vehicle, in particular a motor vehicle, which can alternatively be used to heat the passenger compartment and to air-condition it. Thus, when a request from the user corresponds to a heating demand, the loop will operate as a heat pump and the exchanger will serve as an evaporator. When the demand of the user corresponds to an air conditioning demand, the loop will operate in a cooling loop and the exchanger will serve as a condenser. The invention will particularly find its applications in vehicles with electric drive and / or hybrid, for the reasons already developed above.

Said exchanger comprises a bundle of tubes 2, allowing a heat exchange between a refrigerant flowing in said tubes and an outside air flow. It may for this purpose be provided with spacers 3, including corrugated inserts, located between the tubes 2 to increase the exchange surface between the tubes and the outside air flow. Said exchanger here comprises a first and second manifolds 4, 5 in which the tubes open through the opposite ends 2A of said tubes 2. Said tubes 2 are, for example, parallel to each other. They can be of substantially the same length. Said collectors 4, 5 are here parallel and oriented substantially perpendicularly to the tubes 2.

Preferably, the tubes extend substantially parallel to the transverse axis of the vehicle, the collectors then extending to the right of the tubes.

The circulation of the refrigerant in the exchanger takes place in at least two passes. The exchanger is thus configured to establish a series flow for the refrigerant by first passing, according to an arrow marked 6, in a first portion 4 of said tubes 2, opening into a first portion 4a of the first collector 4, then passing, according to an arrow marked 7, in said first collector 4 and finally passing, according to an arrow marked 8, in a second portion of said tubes 2, opening into a second portion 4b of said first collector 4. The refrigerant circulates in the exchanger from bottom to top, that is to say the first pass disposed below the second pass along a vertical axis of the reference associated with the vehicle.

To ensure circulation in different passes, the first collector 4 and / or the second collector 5 are provided with separating partitions 9, dividing said collectors into different chambers 5a, 5b and forcing the refrigerant to pass through the connected tubes 2 to the so-called upstream chamber, located on one side of one of said partition walls, then by the opposite manifold and by the tubes connected to the so-called downstream chamber, located on the other side of said partition wall . Said partition walls are preferably sealed.

The tubes 2 of the bundle are here distributed in a first pass and a second pass, respectively corresponding to the first part and to the second part of said tubes 2. figure 1 said passes are separated by a dashed line. In such a case, a single partition 9, located in the second collector 5, at the separation between the passes, is used. It is here represented in dashed lines because it is inside said second collector 5.

Said exchanger may further comprise, for example, an inlet 10 and / or an outlet 11 for the refrigerant, here located on the same collector, in this case the second collector 5.

According to the invention, said first collector 4 comprises a partition 12 configured to disrupt the flow of fluid between the first part and the second part of said tubes 2, namely, here, the first pass and the second pass.

It has been found that said partition 12 for disrupting the circulation of the fluid between the two passes makes it possible to promote a better distribution of the refrigerant flow in all the tubes of the bundle, more specifically when this flow takes place from the bottom up. The heat exchange is thus improved while controlling the pressure drops.

It should be noted that the partition or walls of disturbance of the circulation of the refrigerant are of different functions from those of the partition walls. The partition walls serve to define a flow in several passes in the beam while the walls of disruption of the circulation of the refrigerant serve, said flow in passing being established, to make turbulent the flow of the fluid during its passage from one pass to another. The partition or walls of disturbance of the circulation of the refrigerant also being inside the collector or collectors, that illustrated in FIG. figure 1 is represented in dotted lines.

The refrigerant in the first pass represents, for example, 50 to 70% of the passage section for the refrigerant of the beam. According to a first variant, the passage section for the refrigerant is identical in each pass. In other words, if the tubes 2 of the bundle are all identical, each pass has the same number of tubes 2.

However, according to another variant, it was found that one obtained superior results by using a passage section for the refrigerant in the first pass strictly greater than 50%, in particular of the order of 60%. Thanks to said fluid flow disruption partition, although the operation in the form of a condenser is then favored, the operation in the form of an evaporator remains satisfactory. In other words, according to this other variant, if the tubes 2 of the beam are identical, the first pass comprises 50 to 70% of the tubes, in particular 60% of the tubes 2.

Said disturbance partition 12 is here at a passage zone 13 between the first 4a and the second portion 4b of the first collector 4. This being, alternatively, it may be slightly remote. More specifically, it may be at a distance d from said passage zone 13 being positioned either in said first portion 4a, the distance d being then less than half an axial length of said first portion 4a of the first collector 4 or in said second part 4b, the distance d being then less than half the axial length of said second part 4b of the first collector 4.

The partition 12 disturbance of the circulation of the refrigerant may be configured to preferentially orient the refrigerant to the tubes 2 of the second part of tubes located near the partition 9 separation in the second collector 5. It will be possible note that said tubes 2 in question are here opposite the outlet 11 for the refrigerant, and arranged above the partition 12 disturbance.

According to a first exemplary embodiment, the partition 12 for disturbing the circulation of the refrigerant fluid is arranged, for example, transversely, in particular perpendicularly, to a longitudinal axis of the first collector and has one or more orifices for the passage of the refrigerant. By this is meant that said partition 12 disturbance of the circulation of the refrigerant has a periphery coming into contact with the first collector 4 by marrying the inner contour of the latter. Said passage orifices are, in particular, of round or rectangular section. They are opening and pass said refrigerant from said first 4a to said second portion 4b of the first collector 4. The partitions illustrated in FIGS. Figures 2 to 9 correspond to this exemplary embodiment.

According to the variants of Figures 2, 4 and 5 , the passage openings 14 are regularly distributed on the surface of the partition.

According to the variant of the figure 3 , there is provided a single passage opening 14, in particular in the center of the partition.

According to the variants of Figures 6 to 9 , the passage orifices 14 are distributed so as to channel the refrigerant towards the tubes of the second part of tubes 2 in the vicinity of the partition 9 of the second collector 5. Said passage orifices 14 are thus more numerous and / or of greater surface in one half of the partition being close to the tubes 2.

According to the variant of the figure 6 the passage orifices 14 are distributed in parallel rows, each having the same number of orifices, the section of the passage orifices being increasing from one row to the other.

According to the variant of the figure 7 , the passage orifices 14 are of the same section and distributed in parallel rows having an increasing number of orifices.

According to the variant of the figure 8 , the passage orifices 14 extend along the same transverse direction and have the same dimension in said transverse direction while their dimension in the direction perpendicular to said transverse direction increases from a through hole 14 to the other.

According to the variant of the figure 9 , the passage orifices 14 extend along the same transverse direction and have an increasing dimension in this direction from a through hole 14 to the other, their dimension in the direction perpendicular to said transverse direction remaining constant.

As a further variant, not illustrated, the partition 12 for disrupting the circulation of the refrigerant may consist of a filter-type element arranged transversely in the first collector 4.

According to the embodiment of the figure 10 the refrigerant circulation disturbance partition 12 is a deflector 15 oriented to direct the refrigerant towards the bundle. Said deflector 15 extends over only a portion of the first manifold 4 and has a free edge 16 facing the second portion 4b of said manifold 4.

Said exchanger is, for example, aluminum or aluminum alloy. It is made, for example, by brazing. The tubes 2 may be of the flat type and / or present several circulation channels for the refrigerant. This is, for example, extruded tubes or tubes with an internal disruptor defining said channels. The collectors 4, 5 are, in particular, substantially rectangular section. They may be formed of a collector plate, wherein said tubes 2 are introduced by corresponding orifices, and a closing lid, in combination with two end walls, said collectors.

Said exchanger is in particular configured to be positioned on the front face of a motor vehicle, in a substantially vertical orientation, the circulation of the refrigerant taking place from bottom to top. In other words, the first pass is, for example, the lower pass.

Claims (12)

1. Heat exchanger, said heat exchanger comprising a bundle of tubes (2), allowing heat exchange between a refrigerant fluid flowing in said tubes (2) and an external air flow, and a first collector (4), said heat exchanger being configured to establish a series flow for the refrigerant fluid between a first part of said tubes (2), leading into a first part (4a) of said first collector, said first collector (4) and a second part of said tubes (2), leading into a second part (4b) of said first collector (4), said first collector (4) comprising a baffle (12) configured to disrupt the flow of the fluid between the first and the second part of said tubes (2), the tubes (2) of the bundle being distributed in a first pass and a second pass, corresponding to the first part and the second part, respectively, of said tubes (2), the heat exchanger being characterized in that said baffle (12) is configured to preferentially orient the refrigerant fluid towards tubes of the second part of tubes (2) located close to a baffle (9), referred to as a separating baffle, of a second collector (5) of the heat exchanger into which the tubes (2) of said bundle lead, said separating baffle (9) defining said series flow, said tubes of the second part of tubes (2) located close to said separating baffle (9) being located opposite an outlet orifice (11) for the refrigerant fluid out of the heat exchanger.
2. Heat exchanger according to Claim 1, wherein the flow cross section for the refrigerant fluid in the first pass represents 40 to 70% of the flow cross section for the refrigerant fluid of the bundle.
3. Heat exchanger according to Claim 1, wherein the flow cross section for the refrigerant fluid in the first pass is strictly greater than 40%.
4. Heat exchanger according to any one of Claims 1 to 3, wherein the baffle (12) is located at a distance d from a passage zone between the first part and the second part of said first collector (4), and the baffle (12) is positioned either:

   - in said first part (4a), the distance d being less than half an axial length of said first part (4a) of said first collector (4), or

   - in said second part (4b), the distance d being less than half the axial length of said second part (4b) of said first collector (4).
5. Heat exchanger according to Claim 5, wherein the baffle (12) is located at said passage zone.
6. Heat exchanger according to any one of the preceding claims, wherein the baffle (12) for disrupting the flow of the refrigerant fluid has one or more through-orifices (14) for said fluid.
7. Heat exchanger according to Claim 6, wherein the through-orifices (14) for refrigerant fluid are distributed regularly over the surface of the baffle (12) for disrupting the flow of the refrigerant fluid.
8. Heat exchanger according to Claim 6, wherein the through-orifices (14) are distributed so as to channel the fluid in the direction of the tubes of the second part of tubes (2) located in the vicinity of the separating baffle (9).
9. Heat exchanger according to Claim 6 or 8, wherein the through-orifices (14) are more numerous and/or have a larger area than half the baffle (12) for disturbing the flow of the refrigerant fluid, located in the vicinity of the tubes (2).
10. Heat exchanger according to any one of Claims 1 to 9, wherein the baffle (12) for disturbing the flow of the refrigerant fluid is disposed transversely with respect to a longitudinal axis of the first collector.
11. Heat exchanger according to any one of Claims 1 to 9, wherein the baffle (12) for disturbing the flow of the refrigerant fluid is a deflector (15) oriented so as to direct the refrigerant fluid towards the bundle.
12. Heat exchanger according to any one of the preceding claims, wherein said heat exchanger is configured to be positioned in the front end of a motor vehicle.

Images