HEAT EXCHANGER

A high pressure heat exchanger having a first manifold and a second manifold connected fluidly by a plurality of tube sets arranged in a spaced manner along the manifolds. At least one of the manifold includes a rear cover, a header with slots receiving tube end sections of the tube sets and several internal plates interposed between the header and the rear cover and configured to create a flow path within the manifold, this flow path being in fluid connection with the tubes to allow a circulation of a refrigerant in the tubes and the manifold. The header has preferably at least a first area adjacent to at least one of the slots and having a first thickness and at least a second area surrounding at least partially the first area and having a second thickness, the first thickness being smaller than the second thickness.

TECHNICAL FIELD

The invention relates to a heat exchanger, especially to a high pressure heat exchanger for automotive industry.

BACKGROUND OF THE INVENTION

In known heat exchangers, configured to exchange heat between two fluids, it is common to provide two manifolds connected fluidly by plurality of tubes. One of the fluids is guided between said manifolds via these tubes, while the second fluid is guided around and in a space between the tubes to enable heat exchange. The tubes can be for example flat tubes. The tubes are secured in the manifolds in a fluid-tight manner.

When the fluid traveling between the manifolds and in the tubes is a high pressure fluid, like R744 (CO2), the heat exchanger has to be adapted accordingly. In particular, high pressure fluid imposes additional design constrains on the heat exchanger, as the pressure of the fluid necessitates higher mechanical resistance of its components. This pressure can exceed 120 bars.

In case of heat exchangers comprising flat tubes, the manifolds have slots with shape corresponding to the cross-section of the tubes. The flat tubes are mounted in these slots. As the number of tubes is linked to the efficiency of the heat exchange, it is generally preferable to increase the number of tubes to improve the heat exchange between fluids. However, as the number of tubes grows, the distance between the consecutive slots in the manifold decreases. At some point, the distance becomes too small to ensure a proper mechanical resistance of the manifold, given that the fluid which travels through the tubes and which enters said manifold operates at high pressure.

It is therefore an object of the invention to provide an improved high-pressure heat with satisfying mechanical resistance.

BRIEF SUMMARY OF THE INVENTION

The object of the invention is a high pressure heat exchanger comprising a first manifold and a second manifold connected fluidly by a plurality of tube sets arranged in a spaced manner along the manifolds, wherein at least one of the manifold comprises a rear cover, a header with slots receiving tube end sections of the tube sets and at least one internal plate interposed between the header and the rear cover and configured to create a flow path within the manifold, this flow path being in fluid connection with the tubes to allow a circulation of a refrigerant in the tubes and the manifold, and wherein the header has preferably at least a first area adjacent to at least one of the slots and having a first thickness w1and at least a second area surrounding at least partially the first area and having a second thickness w2, first thickness w1being smaller than second thickness w2.

According to one aspect of the invention, each slot of the header is adjacent to first areas with first thickness so that that the thickness of the header is locally smaller, around the slots, than in the rest of the header.

According to one aspect of the invention, in the first area, the thickness has a minimum value w1min on the side adjacent with the slot.

According to one aspect of the invention, first thickness w1may be variable from a minimum value w1min at the contact with the tube in the slot up to the second thickness w2. This may be advantageous to form the tapered guiding shape.

According to one aspect of the invention, the heat exchanger has the following ratios:

3<h/w1<h/(c*60%), in particular 3<h/w1<h/c where h is the height of the distribution channel of the manifold and w1is the wall thickness of the header in the first zone, where thickness w1is minimum in the first area, and c is smallest wall thickness in tubes.

Dimensions h and w1and w2are measured relatively to the same axis.

According to one aspect of the invention, the manifold comprises a plurality of internal pates stacked together, which may be in number of 2, 3, 4 or 5 or even more plates.

According to one aspect of the invention, at least some of the internal plates have slots extending in different directions, in particular perpendicular directions so as to create U form flow paths.

According to one aspect of the invention, at least one plate has parallel longitudinal slots in particular forming group of two slots, these two slots being aligned.

According to one aspect of the invention, two of the internal plates have parallel slots and one of the internal plate has slots perpendicular to slots of the two other plates.

According to one aspect of the invention, internal plates are flat stamped plates.

According to one aspect of the invention, internal pates create internal channels for distribution of refrigerant.

According to one aspect of the invention, the plates may have different shapes in order to create manifolds with more sophisticated flow paths for instance for more than two passes.

According to one aspect of the invention, each rear plate is working like a closing plate, preventing from leak of refrigerant outside manifold region.

According to one aspect of the invention, the rear plate is configured to close the slots of the adjacent internal plate.

According to one aspect of the invention, the header is configured to stick together all internal plates in position before and during brazing process.

According to one aspect of the invention, the header comprises two lateral walls, in particular two lateral folded walls, to stack the internal plates and the rear cover all together. The slots are formed on a main wall of the header, said main wall being flat. The lateral walls are connected to this main wall.

According to one aspect of the invention, each header forms a part with an accurate shape wit slots in order to create a brazing connection with the tubes.

According to one aspect of the invention, the header is configured with a shape ensuring proper guiding of tubes into the slots during assembly of core.

According to one aspect of the invention, each slot having a tapered shape to guide the tubes during their insertion.

The guiding shape may rectilinear or rounded.

An advantage of the invention is to use a header with globally small thickness in order to easier bend it around other plates and to have as small radiuses in the corners as possible.

In parallel the invention makes it possible not to increase the thickness of the manifold too much in order to cut the slots precisely without creating major deformations.

According to one aspect of the invention, the headers are made in stamping process.

According to one aspect of the invention, the distance between slots on the header is sufficient, for instance above 7 mm, and the size of the slots is relatively small, so that it is possible to punch slots in a way to create drafted angles whose are guiding tubes during assembly of the tubes.

According to one aspect of the invention, the internal plates which are added are configured to support the structure between the slots.

According to one aspect of the invention, an internal plate is brazed with the header.

According to one aspect of the invention, the internal plates enable to withstand high pressure despite limited thickness of header in order to create the guiding surfaces in the first area of small thickness.

According to one aspect of the invention, the internal plates have slots to form flow paths within the manifold, these slots communicating each with another in a certain manner to form the flow paths.

The invention, in particular thanks to internal plates, enables to create a robust structure of manifold, for instance which is able to withstand pressure up to 26 MPa or even bigger for other applications. The invention also enables to use an assembly of parts made in reasonably cheap for serial processes such as stamped components instead of machining components. Each manifold is assembled for instance from few internal plates together with a header.

According to one aspect of the invention, the heat exchanger comprises rows of tubes connecting the manifolds forming an inlet row and an outlet row for refrigerant.

According to one aspect of the invention, the refrigerant is flowing from an inlet through the manifold to first row of the tubes. Then the refrigerant is flowing through the tubes to opposite manifold where the refrigerant is transferred from first row of the tubes to the second row of the tubes. Then the refrigerant is flowing through the second row to the manifold forming IN/OUT and to the connecting block ensuring tight hydraulic connection with the rest of the system.

According to one aspect of the invention, the heat exchanger for cooling a heat source of a motor vehicle has coolant channels forming a coolant flow path and refrigerant channels forming a refrigerant flow path.

According to one aspect of the invention, the refrigerant flow path is deviated at least once in the shape of a U.

According to one aspect of the invention, the refrigerant channels in the tubes have a ratio of at least 0.3 between their wall thickness and the diameter.

According to one aspect of the invention, a web is placed between two refrigerant channels in the tubes and has a width b equal to at least 40% of the diameter of the refrigerant channel.

According to one aspect of the invention, the heat exchanger is a chiller.

According to one aspect of the invention, the refrigerant is CO2, also called R744. However, the invention is not limited to such a refrigerant.

According to one aspect of the invention, the connecting block is attached to one the manifolds.

According to one aspect of the invention, each tube set comprises a first tube and a second tube, wherein each of the first and the second tubes comprises an intermediate tube section between two opposing tube end sections, and the manifolds comprise slots receiving the tube end sections in a fluid-tight manner.

According to one aspect of the invention, in the tube set, at least the first tube comprises a bent tube section between the tube end section and the intermediate tube section, so that the intermediate tube sections of the first and second tubes run substantially in a parallel and spaced manner to each other, while the tube end tube sections are stacked on each other within a single slot.

According to one aspect of the invention, the bent tube section comprises two opposing turns.

According to one aspect of the invention, both the first tube and the second tube comprise bent tube sections.

According to one aspect of the invention, the spaces between the tubes in a tube set have equal height to the spaces between the tube sets.

According to one aspect of the invention, a flow disruptor is arranged in a space between the first tube and the second tube in the tube set.

According to one aspect of the invention, a flow disruptor is arranged in a space between the tube sets.

According to one aspect of the invention, a tube height h1of flat tubes is between 2 mm and 3 mm, a flow disruptor height h2is between 1.7 mm and 2.5 mm, and a material height h3between consecutive slots is (2*h2)−a, a being between 0.4 and 0.8 mm.

According to one aspect of the invention, a third tube is located between the first tube and the second tube, so that the end sections of the tubes are stacked on each other within a single slot.

According to one aspect of the invention, a tube height h1of flat tubes is between 2 mm and 3 mm, a flow disruptor height h2is between 1.7 mm and 2.5 mm, and a material height h3between consecutive slots is (3*h2)−a, a being between 0.4 and 0.8 mm.

DETAILED DESCRIPTION OF THE INVENTION

FIG.1shows a known heat exchanger1with flat tubes11in partial cross-section. The heat exchanger1comprises a plurality of flat tubes11for guiding the first fluid, in particular a fluid operating at high pressure, for example R744. These tubes11are connected at their end portions with manifolds10a,10b.The flat tubes11are arranged in horizontally parallel rows so that the first fluid can enter through the block30into the first manifold10a,travel through the first column of tubes11, reach the second manifold10band make a U-turn, returning to the first manifold10avia second column of tubes11, and then exit through outlet channel in the manifold10aand the connecting block30.

FIG.2shows the heat exchanger ofFIG.1in greater detail. The flat tubes11are placed in slots13of the manifold10b(in a consecutive manner along the vertical direction). The other ends of the tubes11are situated in manifold10ain an analogous manner. The heat exchanger1further comprises flow disruptors15, which disrupt the flow of the second fluid, in order to improve the heat exchange with the first fluid. The tube height h1is slightly smaller than manifold material height h3between consecutive slots13. The flow disruptor15has a height h2. As the height of the disruptor15approaches the h1value, h3also decreases, which is detrimental to the manifolds strength. The following embodiments propose avoiding this negative dependency.

FIG.3shows a heat exchanger according to the invention in a first embodiment. The example is explained relative to manifold10b,but this description applies to manifold10ain an analogous manner. A plurality of tube sets20, each comprising a first tube11and a second tube12, is arranged along the manifold10bin a spaced manner. Each of the first and the second tubes11,12comprises an intermediate tube section11abetween two opposing tube end sections11b.The manifolds10a,10bcomprise slots13, in which the tube end sections11bof tubes11,12are mounted in a fluid-tight manner. Within the tube set20, at least the first tube11comprises a bent tube section11cbetween the tube end section11band the intermediate tube section11a. The intermediate tube sections11aof the first and second tubes11,12then run substantially in a parallel and spaced manner to each other, while the tube end sections11bare stacked on each other within a single slot13. Because at least one of the tubes11,12is bent in this manner, the distance between the consecutive slots13is enlarged. It is therefore clear that by the term ‘bent’ it is understood any shape which allows providing two sections of the tube11, preceding the bend and following the bend, which would run in parallel but in shifted relation, as shown in the drawings. For example, the first tube11is bent so that it has two opposing bends (i.e. forms a chicane). Preferably, the tube bent section11cis located close to the tube end section11b.Consequently, the disruptors15can occupy most of the space between the tubes11,12and prevent excessive by-passing of the second fluid. In the example ofFIG.3, the second tube12is a straight (i.e. non bent) flat tube, which nevertheless comprises an intermediate portion11aand a tube end section11b,the tube end section10bbeing placed in the slot13.

The arrangement according to the invention improves mechanical resistance of the header103, and at the same time allows application of known, standard flow disrupters15. The number of tubes11,12applied along the manifold consequently can also be greater.

FIG.4shows a heat exchanger according to the invention in a second embodiment. This embodiment differs from the first embodiment in that a third tube16is present in the tube set20. It has the same shape as the first tube11, but is arranged inversely and stacked below the second tube12.

For embodiment with three tubes11,12,13in one header slot13, the overall tube height h1is preferably between 3 mm and 4.5 mm, the flow disruptor height h2is between 1.7 mm and 2.5 mm, and the material height h3between the consecutive tube slots13is (3*h2)−a, a being between 0.4 and 0.8 mm.

For the above examples, the boundary values of the ranges are understood to be not

FIG.5shows a heat exchanger according to the invention in a third embodiment. It differs from the previous embodiments in that both the first tube11and the second tube12comprise tube bent sections11c,and there is no flat tube between them. The disruptors15can be located between the tubes11,12and/or between the consecutive tube sets20.

For embodiments with two tubes11,12in one header slot13, the overall tube height h1is preferably between 2 mm and 3 mm, the flow disruptor height h2is between 1.7 mm and 2.5 mm, and the material height h3between the consecutive tube slots13is (2*h2)−a, a being between 0.4 and 0.8 mm.

For the above examples, the boundary values of the ranges are understood to be not excluded.

The spaces between the tubes11,12,13in a tube set20can have equal height to the spaces between the tube sets20. This can enable applying identical flow distributors15.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of drawings, the disclosure, and the appended claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to the advantage.

FIGS.6to8discloses another embodiment of the invention.

A high pressure heat exchanger100is shown onFIGS.6to8. The high pressure heat exchanger100comprises a first manifold101and a second manifold (not shown) connected fluidly by a plurality of tube sets20arranged in a spaced manner along the the first manifold101and the second manifold, wherein the first manifold101comprises a rear cover102, a header103with slots104receiving tube end sections11bof the tube sets20and internal plates105interposed between the header103and the rear cover102and configured to create a flow path106within the first manifold101, this flow path being in fluid connection with the tubes11to allow a circulation of a refrigerant in the tubes and the manifold101.

The header103has preferably a first area110adjacent to each slot104and having a first thickness w1and a second area111surrounding the first area110and having a second thickness w2, the first thickness w1being smaller than the second thickness w2.

Each slot104of the header103is adjacent to the first areas110with the first thickness so that that the thickness of the header103is locally smaller, around the slots104, than in the rest of the header103.

In the first area110, the thickness has a minimum value w1min on the side adjacent with the slot104.

First thickness w1may be variable from a minimum value w1min at the contact with the tube11in the slot104up to the second thickness w2. This may be advantageous to form a tapered guiding shape125.

The heat exchanger has the following ratios: 3<h/w1<h/(c*60%), in particular 3<h/w1<h/c where h is the height of the distribution channel of the manifold and w1is the wall thickness of the header103in the first zone, where thickness w1is minimum in the first area, and c is smallest wall thickness in tubes11.

When w1is variable in the first area110, w1is taken as its smallest value w1min in the first area110.

Dimensions h, w1and w2are measured relatively to the same axis perpendicular to the plane of the internal plates105.

The first manifold101comprises a plurality of internal pates105stacked together, which may be in number of 3.

The internal plates105have internal slots115extending in different directions, in particular perpendicular directions so as to create U form flow paths.

Some internal plates105can have parallel longitudinal internal slots115, in particular forming group of two slots, these two slots115being aligned.

Two of the internal plates105have parallel internal slots115and one of the internal plate105has internal slots115perpendicular to the internal slots115of the two other internal plates105.

The internal plates105are flat stamped plates.

The internal pates105create internal channels for distribution of refrigerant.

The rear cover102works as a closing plate, preventing from leak of refrigerant outside the first manifold101region.

The rear cover102is configured to close the internal slots115of the adjacent internal

The header103is configured to stick together all internal plates105in position before and during brazing process.

The header103comprises two folded lateral walls117, to encompass and stack the internal plates105and the rear cover102all together. The slots104are formed on a flat main wall118of the header103. The lateral walls117are connected to this main wall118.

The header103forms a part with an accurate shape of slots104in order to create a brazing connection with the tubes11.

The header103is configured with a shape ensuring proper guiding of tubes11into the slots104during assembly of heat exchanger core.

Each slot104has a tapered shape125to guide the tubes11during their insertion.

The guiding shape may be of a rectilinear shape126on the bottom ofFIG.9, or of a rounded shape125on the top ofFIG.9.

The header103can have globally small thickness in order to easier bend it around other plates and have as small radiuses in the corners as possible.

In parallel the invention makes it possible not to increase the thickness of the first manifold101too much in order to cut the slots104precisely without creating major deformations.

The header103can be made in stamping process.

The distance between slots104on the header103is sufficient, for instance above 7 mm, and the size of the slots104is relatively small, so that it is possible to punch the slots104in a way to create drafted angles for guiding the tubes11during assembly.

The internal plates105are configured to support the structure between the slots104.

The internal plate105is brazed with the header103.

The internal plates105enable to withstand high pressure despite limited thickness of header103in order to create the guiding surfaces in the first area110of small thickness.

The internal plates105have internal slots115to form flow paths within the first manifold101, these internal slots115communicating each with another in a certain manner to form the flow paths.

The invention, in particular thanks to internal plates105, enables to create a robust structure of the first manifold101, for instance which is able to withstand pressure up to 26 MPa or even bigger for other applications. The invention also enables to use an assembly of parts made using reasonably cheap serial processes such as stamped components instead of machining components.

The heat exchanger100comprises rows of tubes11connecting the first manifold101and the second manifold and forming an inlet row and an outlet row for refrigerant.

The refrigerant is flowing from an inlet through the second manifold to first row of the tubes11. Then the refrigerant is flowing through the tubes11to opposite first manifold101where the refrigerant is transferred from first row of the tubes11to the second row of the tubes11. Then the refrigerant is flowing through the second row to the second manifold having IN/OUT connections and to the connecting block ensuring tight hydraulic connection with the rest of the system.

The heat exchanger100for cooling a heat source of a motor vehicle has coolant channels forming a coolant flow path and refrigerant channels120forming a refrigerant flow path.

The refrigerant flow path is deviated at least once in the shape of a U.

The refrigerant channels120in the tubes11have a ratio of at least 0.3 between their wall thickness and their diameter.

A web121is placed between two refrigerant channels120in the tubes11and has a width b equal to at least 40% of the diameter of the refrigerant channel120.

Internal plates105, header103and rear cover102can be made of metal.

The heat exchanger100is a chiller.

According to one aspect of the invention, the refrigerant is CO2. However, the invention is not limited to such a refrigerant.

According to one aspect of the invention, the connecting block is attached to the first manifold101or the second manifold.