WO2014198846A1 - Heat exchanger - Google Patents

Abstract

The invention relates to a heat exchanger (1) with a first collector box (8), a second collector box (9), and a plurality of pipes (15, 16). An end face of each of the pipes (15, 16) is received in one of the collector boxes (8, 9), and the pipes produce a fluid connection between the first collector box (8) and the second collector box (9). A first number of first pipes (15) is provided, each of which has a first flow cross-sectional area, and at least one second pipe (16) is provided which has a second flow cross-sectional area, the first flow cross-sectional area being substantially smaller than the second flow cross-sectional area.

Description

 Heat exchanger

description

Technical area

The invention relates to a heat exchanger with a first header, with a second header and with a plurality of tubes, wherein the tubes are respectively received end in one of the collection box and produce a fluid connection between the first header and the second header, wherein a first Number of first tubes is provided, each having a first flow cross-sectional area, and at least a second tube is provided, which has a second flow cross-sectional area.

State of the art

Heat exchangers are used in a variety of ways to transfer wires between two fluids. In this case, a first fluid is brought into a heat exchange with a second fluid, whereby the temperature of the one fluid is relatively increased and the temperature of the other fluid is relatively lowered. Regularly, the fluids used are, for example, air, coolant or a refrigerant. There are different types of heat exchanger known. Among other things, heat exchangers are used in a tube-fin construction. Here a plurality of tubes are spaced from each other between two headers. A medium to be cooled can flow through the pipes, for example, while a medium to be heated flows around the pipes. In order to improve the heat transfer, additional heat transfer elements, such as corrugated fins, can be provided between the pipes.

A known design provides for a heat exchanger, which is flowed through in a so-called I-flow principle. The fluid flows from a collection box into the pipes and from there into the second collection box. The fluid is introduced from a fluid circuit in the first collection box and discharged from the second collection box.

Alternatively, a heat exchanger can be flowed through according to the so-called U-flow principle. Here, a fluid is introduced from a fluid circuit in the first collection box. From there, it flows through a first number of tubes into the second collection box and from there over a second number of tubes back into the first collection box. From there, the fluid is discharged from the first collection box. The first collection box is divided, for example by a partition in two independent areas. The tubes which form the fluid connection from the first collection box into the second collection box usually correspond in size, shape and number to the tubes which form the fluid connection from the second collection box into the first collection box. The U-flowed heat exchanger regularly offers twice the cooling distance compared to a L-flowed heat exchanger, but at the same time it offers only half the flow cross-sectional area. Although this is generally positive for the cooling ^¬ performance of the heat exchanger, but mostly negative for the pressure loss occurring. A disadvantage of the solutions in the prior art is in particular that by using the same pipe dimensions both for the fluid connection from the first to the second collection box and for the fluid connection from the second to the first collection box tubes of the same dimensions and often in the same number are used, which has a negative effect on the resulting pressure loss in the U-flow heat exchanger.

DESCRIPTION OF THE INVENTION, OBJECT, SOLUTION, ADVANTAGES It is the object of the present invention to provide a heat exchanger which is optimized over the solutions in the prior art. For this purpose, in particular the resulting pressure loss should be reduced within the heat exchanger. The object of the heat exchanger is achieved by a heat exchanger with the features of claim 1.

An embodiment of the invention relates to a heat exchanger with a first header, with a second header and with a plurality of tubes, wherein the tubes are each end in one of the header boxes and create a fluid connection between the first header and the second header, wherein a first Number of first tubes is provided, each having a first flow cross-sectional area, and at least a second tube is provided, which has a second flow cross-sectional area, wherein the first flow cross-sectional area is substantially smaller than the second flow cross-sectional area.

Because the first tubes in each case have a smaller cross section than the cross section of the individual second tube, a plurality of first tubes can be used with the same installation space, in particular in a tube bundle, whereby the resulting Heat exchanger surface increases, which means that a larger cooling line can be generated.

The heat exchanger is flowed through by a U-flow principle. The

Fluid is passed from a collection box over a portion of the pipes in the second collection box before it is returned via the remaining pipes back into the first collection box. This is particularly advantageous if the space specifications allow only such a heat exchanger. In this case, in particular, the position of the fluid connections to only one collecting box is advantageous. The flow cross-sectional area of the second flow channel is substantially larger than the flow cross-sectional area of the individual first flow channels. As a result, a return flow can be generated with the lowest possible pressure loss. The second flow channel essentially serves to return the fluid to the first collection box. The heat transfer is realized mainly by the first flow channels.

Furthermore, it is preferable if the total flow cross-sectional area of the first tubes occupies a proportion of the total cross-sectional area of the heat exchanger which is greater than half, wherein the total cross-sectional area of the heat exchanger is formed by the sum of the flow cross-sectional areas of the first tube and the second tube.

By a larger overall flow cross-sectional area of the first flow channels in comparison to the flow cross-sectional area of the second flow channel, it can be achieved, in particular, that the largest possible flow cross-sectional area is available for cooling the fluid flowing in the flow channels. Thus, the highest possible heat transfer can be realized and still the tree specific advantages of a U-flow heat exchanger can be used. It is also advantageous if the total flow cross-sectional area of the first tubes compared to the total flow cross-sectional area of the heat exchanger is between 50% and 90%, preferably between 60% and 80%, preferably between 70% and 80%. The highest possible proportion of the total flow cross-sectional area of the first flow channels is advantageous in order to be able to realize the largest possible heat transfer. At the same time, the flow cross-sectional area of the second flow channel must be large enough not to generate too great a pressure loss for the fluid flowing back.

It is also advantageous if the heat exchanger can be flowed through by a first fluid from the first collecting tank through the first pipes to the second collecting tank and from the second collecting tank through the second pipe to the first collecting tank. This has the advantage that initially a greater cooling takes place due to the larger heat transfer surface of the many individual first tubes, and thereafter a further cooling takes place with less pressure loss in the second tube.

Alternatively, it is expedient if the heat exchanger can be flowed through by a first fluid from the first collecting tank through the second pipe to the second collecting tank and from the second collecting tank through the first pipes to the first collecting tank. This has the advantage that initially takes place less cooling with a small pressure drop in the second tube and then there is a greater cooling due to the larger heat transfer surface of the many individual first tubes.

Furthermore, it may be particularly advantageous if the heat exchanger can be flowed through by a first fluid, wherein the flow takes place from the first header through the first tubes to the second header and from the second header through the second tube to the first header. The U-flow principle is particularly advantageous when space restrictions provide for the use of a U-flowed Wirmeübertragers.

A preferred embodiment is characterized in that the first header has a fluid inlet and a fluid outlet, wherein the first header is divided into a first chamber and a second chamber and the first chamber is in fluid communication with the first tubes and the second chamber is in fluid communication Tube is in fluid communication.

A division of the first collecting tank into two chambers is particularly advantageous in order to allow a flow according to the U-flow principle.

A fluid-tight separation of the two chambers from each other is particularly advantageous to prevent unwanted leakage currents between the two chambers.

It is also preferable if the first tubes are arranged in a juxtaposition of two mutually adjacent tube rows and the second tube is arranged below or above or laterally of the two tube rows.

By juxtaposing several rows of tubes to each other, a total of a larger heat transfer surface can be generated than with a smaller number of larger pipes. Therefore, the greatest possible heat transfer can be realized by such an arrangement, in particular on a defined maximum space.

It is also advantageous if a housing is provided, which receives the first tubes and the second tube, and which is bounded laterally by the two header boxes, wherein the first tubes and the second tube of second fluid within the housing are flowed around while they can be traversed by a first fluid. By providing a housing, which can be flowed through with a fluid, such as a coolant, an advantageous heat transfer be achieved between a fluid within the tubes and a liquid coolant. In this way, regularly larger amounts of heat can be dissipated than in a heat transfer between a first fluid and air in the event that the air serves as a coolant. This can be further increased, in particular, when the liquid coolant outside the heat exchanger is actively cooled.

Furthermore, it is preferable if the first fluid can be supplied and discharged via a collecting box, wherein a second fluid can be fed into the housing in the region of the first collecting box and can be removed from the housing in the region of the second collecting box.

In this way, a fluid which flows through the tubes, suitable to the U-flow principle of the heat exchanger flowed into this and be discharged therefrom. At the same time, the coolant can be optimally fluidically introduced into the heat exchanger, whereby the greatest possible cooling effect can be achieved.

In an alternative embodiment of the invention, provision may be made for heat transfer elements, such as corrugated ribs, to be provided between the first tubes and the second tube, and / or for heat transfer elements, such as winglets, to be provided in the first tubes.

By the heat transfer elements, the heat transfer between the fluid inside the tubes and the fluid flowing around the tubes can be increased. As a result, the cooling capacity of the heat exchanger can be improved overall.

It may also be expedient if, in addition to the plurality of first tubes, a plurality of second tubes is provided, wherein the number of second tubes is substantially smaller than the number of first tubes. The heat exchanger according to the invention is advantageously an exhaust gas cooler in one embodiment.

Advantageous developments of the present invention are described in the subclaims and the following description of the figures.

Brief description of the drawings

In the following the invention will be explained in detail by means of exemplary embodiments with reference to the drawings. In the drawings show:

1 shows a perspective view of a heat exchanger according to the invention,

Fig. 2 is a perspective view of a heat exchanger according to the invention, wherein the viewer facing the collection box is not shown, whereby an insight into the flow channels is achieved, and

Fig. 3 is a further perspective view of a heat exchanger according to Figure 2 wherein in addition, the housing is not shown, whereby an insight into the heat exchanger is achieved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a perspective view of a heat exchanger 1. The heat exchanger 1 is essentially formed from a housing 2 to which a first collecting box 8 and a second collecting box 9 are connected at the end. The collection box 9 facing away from the viewer has a fluid connection 3 at its upper area. About this fluid port 3, a fluid in the Wirmeübertrager 1 fed or discharged from this. At the end portion of the heat exchanger 1, which faces the viewer, the first collection box 8 is arranged. This collecting box 8 has a fluid connection 4, which is in fluid communication with the fluid connection 3 via the housing 2,

Via the fluid connections 3, 4, a fluid can be introduced into the heat exchanger 1 or be discharged from the heat exchanger 1.

The collecting box 8 also has a fluid connection 5 and a fluid connection 6 arranged underneath. The fluid connections 5 and 6 are for the Einbzw. Discharging a second fluid into the heat exchanger usable. The first fluid is preferably a coolant, and the second fluid, which can be introduced or removed through the fluid ports 5 and 6, is preferably an exhaust gas from an internal combustion engine.

Within the heat exchanger 1, a heat transfer between the coolant and the exhaust gas takes place.

The fluid connection 6 has a flange 7, which makes it possible to connect a pipeline, not shown in the figure, to the fluid connection 6. The fluid connection 5 has holding means to which a pipeline can be connected.

The fluid, which flows into the collecting box 8 via the fluid connection 5 or 6, is distributed within the collecting box to tubes which run inside the housing 2. The exact structure and arrangement of the tubes are shown in the following figures.

The housing 2 of the heat exchanger 1 has a total of a rectangular or qua derförmige basic shape. FIG. 2 shows a perspective view of the heat exchanger 1 according to FIG. 1. In the view of FIG. 2, the collection box 8 facing the viewer is not shown. This allows a view of the flow channels 11, 12 allows.

Inside the housing 2, a plurality of first flow channels 11 are arranged. In the embodiment of FIG. 2, the first flow channels 11 are arranged in two rows next to each other.

Below the two rows of tubes of the first flow channels 11, a second flow channel 12 is arranged. The second flow channel 12 in this case has a substantially larger flow cross-sectional area than the individual first flow channels 11. Alternatively, the arrangement can also be above or to the side thereof.

Overall, the sum of the flow cross-sectional areas of the individual first flow channels 11 is greater than the flow cross-sectional area of the second flow channel 12. Advantageously, the sum of the flow cross-sectional areas of the first flow channels 11 has a proportion of more than 50% in the total flow cross-sectional area of the first flow channels 11 and the second flow channel 12 ,

The heat exchanger 1, as shown in FIGS. 1 to 3, flows through a so-called U-flow principle. This means that the fluid flowing through the flow channels 11 and 12, respectively, flows via a collecting box 8 into the heat exchanger 1. From there it flows via the first flow channels 11 into the second collection box 9. The second collection box 9 establishes fluid communication between the uppermost first flow channels 11 and the lower second flow channel 12. Through the second flow channel 12, the fluid finally flows back into the first collection box 8. The first collection box 8 is separated in the interior via a partition in two independent areas. The first upper area stands with the first stream mungskanälen 11 in fluid communication, the lower second area is in fluid communication with the lower second flow channel 12.

The flow direction through the heat exchanger 1 can also be reversed, so that the second flow channel 12 forms the Hinströmstrecke between the collecting box 8 and the collecting box 9 and the first flow channels 11, the return flow from the collecting box 9 to the collection box. 8

Between the individual tubes 15, which form the first flow channels 11, advantageously heat transfer elements 13, such as corrugated fins are arranged. These are not visible in FIGS. 1 and 2 due to the housing 2. Also, between the tubes 15, which form the first flow channels 11 and the tube 16, which forms the second flow channel 12, heat transfer elements 13, such as corrugated fins arranged. The tubes 15 and 16 in the interior of the housing 2 are in this case of a fluid, in particular a coolant, flows around. In this case, the coolant is flowed into the housing 2 via the fluid connection 3 or via the fluid connection 4, so that it can flow around the tubes 15 or 16 within the housing 2. In this way, an advantageous heat transfer between the exhaust gas, which flows within the first flow channels 11 and the flow channel 12, to the coolant, which flows around the tubes 15 and 16, ensured.

By means of the return flow path, which is formed by the individual flow channel 12, it is possible to realize the return flow in such a way that only a small pressure loss results. The flow channel 12 has a much lower pressure loss compared to the flow channels 11. This is due to the overall large flow cross-sectional area of the second flow channel 12. The largest part of the cooling of the exhaust gas, which flows through the flow channels 11 and 12, is achieved within the flow channels 11. This is especially re due to the larger wall surface and thus the higher heat transfer area between the exhaust gas and the coolant.

Advantageously, the heat exchanger 1 can be influenced by an adaptation of the number of the first flow channels 11 or the size of the second flow channel 12 with regard to the resulting pressure loss and the maximum achievable cooling capacity.

FIG. 3 shows a further perspective view of the heat exchanger 1 according to the representation of FIG. 2. In addition, the housing 2 is not shown in FIG. It can be seen that the first flow channels 11 are formed by tubes 15 which are arranged in two rows next to one another in a stack arrangement, and the second flow channel 12 is formed by a tube 16.

Between the tubes 15 and 16 intermediate regions 14 are formed, which are filled with heat transfer elements 13. The arrangement of the heat transfer elements is optional. The coolant, which can flow into and out of the housing 2 via the fluid connection 3 or 4, can flow around the tubes 15 and 16, respectively. In this way, a maximum possible heat transfer between the exhaust gas in the first and second flow channels 11 and 12 and the cooling medium within the housing 2 is ensured.

In alternative embodiments, in particular, the number of channels shown and the geometric design of the individual flow channels may differ from the embodiments shown in FIGS. 1 to 3. The embodiment of the heat exchanger shown in FIGS. 1 to 3 is by way of example and should in particular clarify the concept of the invention. Particularly advantageous in the embodiment of the heat exchanger 1 is the recirculation of the exhaust gas through the second flow channel 12, which has a relatively large flow cross-sectional area. In particular, the occurring pressure loss for the return flow path can be kept small above this. The heat exchanger 1 shown thus combines the installation space technical advantages of a U-flow heat exchanger 1, which is characterized in particular in that the fluid connections are arranged on only one of the collecting tanks, with the high efficiency of a I -durchströmten heat exchanger. By the second flow ungskanai 12 arises for the return flow only a very small pressure loss. At the same time, the heat exchanger 1 can be built very compact.

Figures 1 to 3 are exemplary and are not limiting in nature.

Claims

claims 1. Heat exchanger (1) with a first collecting box (8), with a second collecting box (9) and with a plurality of tubes (15, 16), wherein the tubes (15, 16) each end in one of the collecting boxes (8, 9) and provide fluid communication between the first header box (8) and the second header box (9), wherein a first plurality of first tubes (15) are provided, each having a first flow cross-sectional area, and at least one second tube (16 ), which has a second flow cross-sectional area, characterized in that the first flow cross-sectional area is substantially smaller than the second flow cross-sectional area, 2. Heat exchanger (1) according to claim 1, characterized in that the total flow cross-sectional area of the first tubes (15) occupies a proportion of the total flow cross-sectional area of the heat exchanger (1), which is greater than half, wherein the total flow cross-sectional area of the Wirmeübertragers (1) by the sum of the flow cross-sectional areas of the first tube (15) and the second tube (16) is formed. 3. Heat exchanger (1) according to any one of the preceding claims, characterized in that the total flow cross-sectional area of the first tubes (15) compared to the total flow cross-sectional area of the heat exchanger (1) is between 50% and 90%, preferably between 60% and 80% , preferably between 70% and 80%. 4. Heat exchanger (1) according to any one of the preceding claims, characterized in that the heat exchanger (1) with a first fluid from the first collection box (8) through the first tubes (15) to the second collection box (9) and the second collection box ( 9) through the second tube (16) can be flowed through to the first collection box. 5. Heat exchanger (1) according to any one of the preceding claims, characterized in that the heat exchanger (1) with a first fluid from the first collection box (8) through the second tube (16) to the second collection box (9) and the second collection box ( 9) through the first tubes (15) to the first collection box (8) can be flowed through, 6. Heat exchanger (1) according to any one of the preceding claims, characterized in that the first collecting box (8) has a fluid inlet (5, 6) and a fluid outlet (5, 6), wherein the first collecting box (8) in a first chamber and a second chamber is subdivided and the first chamber in fluid communication with the first tubes (15) and the second chamber in fluid communication with the second tube (16). 7. Heat exchanger (1) according to one of the preceding claims, characterized in that the first tubes (15) are arranged in a juxtaposition of two mutually adjacent rows of tubes and the second tube (16) is arranged below or above or laterally of the two rows of tubes. 8. Heat exchanger (1) according to one of the preceding claims, characterized in that a housing (2) is provided, which receives the first tubes (15) and the second tube (16), and the side of the two header boxes (8, 9) is limited, wherein the first tube (15) and the second tube (16) of second fluid within the housing (2) are flowed around, while they are traversed by a first fluid. 9. heat exchanger (1) according to claim 8, characterized in that the first fluid via a collecting box (8) can be fed and discharged, wherein a second fluid in the region of the first header tank (8) in the housing (2) can be fed and in Area of the second header tank (9) from the housing (2) can be discharged. 10. Heat exchanger (1) according to any one of the preceding claims, characterized in that between the first tubes (15) and the second tube (16) heat transfer elements (13), such as corrugated fins, are provided and / or that in the first tubes ( 15) heat transfer elements, such as winglets, are provided. 11. Heat exchanger (1) according to any one of the preceding claims, characterized in that in addition to the plurality of first tubes (15) a plurality of second tubes (16) is provided, wherein the number of second tubes (16) is substantially smaller than that Number of first pipes (15).