HEAT EXCHANGER COMPRISING A CORE OF TUBES
The invention concerns a heat exchanger (1) comprising an inlet tank (2), having a fluid inlet (4),and an outlet tank (3), having a fluid outlet (5),and a core (6) of tubes (7, 8) joining said inlet tank (2) and said outlet tank (3) together and creating a plurality of fluid flow paths (P1) from said inlet tank (2) to said outlet tank (3), wherein said tubes (7, 8) belong to a primary and a secondary group of tubes(7, 8). According to the invention said inlet tank (2) and said outlet tank (3) have header plates(9, 10), which form core interfaces and comprise throughout identical tube insertion orifices for both the primary group of tubes (7) and the secondary group of tubes (8).Further, the tubes being a member of the primary group are base tubes (7)and the tubes being a member of the secondary group are adaptation tubes (8), which differ from the base tubes (7) and a reused to locally change properties of the heat exchanger (1) in critical areas of the heat exchanger (1).
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The present invention concerns a heat exchanger comprising an inlet tank, having a fluid inlet for a fluid, and an outlet tank, having a fluid outlet for said fluid, and a core of tubes joining said inlet tank and said outlet tank together and creating a plurality of fluid flow paths for said fluid from said inlet tank to said outlet tank, wherein said tubes belong to a primary and a secondary group of tubes.
PRIOR ARTA heat exchanger according to the preamble is known from the patent U.S. Pat. No. 4,791,982. The heat exchanger revealed in that patent is a coolant radiator which has a core comprising tubes belonging to a primary and a secondary group of tubes. There is a difference in tube size between the two groups, which is used mainly to improve flow distribution and hence efficiency especially at low flow rates.
OBJECT OF THE INVENTIONA drawback of the prior art heat exchanger is that its technical concept is rather limited when it comes to versatility. Since it comprises use of differently sized tubes, it necessitates use of header plates having tube insertion orifices, which are sized and placed according to a unique pattern for each series of heat exchangers. This makes production of small series of heat exchangers inefficient and hampers production versatility. Against that background an object of the present invention is to improve the known heat exchanger, such that production thereof is simplified and in particular rendered more efficient and versatile.
SUMMARY OF THE INVENTIONAccording to the invention this is achieved by means of a heat exchanger according to the preamble, said heat exchanger being characterized in that said inlet tank and said outlet tank have header plates, which form core interfaces and comprise throughout identical tube insertion orifices for both the primary group of tubes and the secondary group of tubes, in that the tubes being a member of the primary group are base tubes, and in that the tubes being a member of the secondary group are adaptation tubes, which differ from the base tubes and are used to locally change properties of the heat exchanger in critical areas of the heat exchanger, and.
Use of header plates with throughout identical tube insertion orifices, does of course necessitate use of tubes having a throughout identical outer shape, as they otherwise would not fit the header plates. This is however no problem, as tube characteristics can be varied internally in different ways, e.g. by choosing an appropriate tube wall thickness, by providing dimples or turbulators or by using different tube inserts. Hence, the invention renders it possible for instance to efficiently produce small series of adapted heat exchangers by means of identical header plates but different tubes at chosen positions.
According to one embodiment said secondary group of tubes in order to prolong life of the heat exchanger comprises adaptation tubes each providing an enhanced strength compared to a basic strength provided by each one of said base tubes, wherein said adaptation tubes are used in areas of the heat exchanger where stress levels tend to be higher than a medium stress level of the entire heat exchanger. Areas of a heat exchanger where such strengthening tubes are useful are e.g. corner areas of a substantially parellelepipedic heat exchanger core.
According to a further embodiment said adaptation tubes can provide an enhanced strength by having a wall thickness exceeding a wall thickness of the base tubes. Increasing tube wall thickness is an easy way to enhance strength, but if the tubes are sheet metal pipes, which is normal procedure in the art, it requires use of differently gauged sheet metal for the tubes pertaining to the first and the second group, respectively.
According to a further embodiment said adaptation tubes provide an enhanced strength by comprising stiffening inserts arranged in tube openings. Providing stiffening inserts is also an easy way to enhance strength and makes use of tubes having an identical wall thickness possible. However, production, insertion and fastening of such stiffening inserts are aspects to be considered.
According to a further embodiment said adaptation tubes provide an enhanced strength by comprising stiffer turbulators than turbulators arranged in said base tubes. In the art use of so-called turbulators inside of heat exchanger tubes is quite common. In the light of this, use of differently designed turbulators to achieve a heat exchanger according to the invention is an attractive solution.
According to a further embodiment said adaptation tubes provide an enhanced strength by comprising internal stiffening ribs. Internal stiffening ribs can be provided e.g. by embossing sheet metal, of which tubes are produced, accordingly.
According to a further embodiment said adaptation tubes provide an enhanced strength by comprising extra durable tube seams created by means of all smooth tube walls. When producing tubes of sheet metal, a brazing seam running along the tube is created. This seam is rendered more durable if the original sheet is all smooth and void of for instance embossed dimples.
According to a further embodiment said heat exchanger comprises a first row of tubes and a second row of tubes, wherein at least a plurality of the tubes of the first row belong to the primary group of tubes and all tubes of the second row belong to the secondary group of tubes. A solution like this can be advantageous for instance if the heat exchanger is a coolant radiator which is bolted to another unit, such as a charged air cooler, which helps stabilizing the coolant radiator tube row next to it.
According to a further embodiment said secondary group of tubes in order to improve efficiency of the heat exchanger comprises adaptation tubes, each providing a lower flow resistance than a flow resistance provided by each one of said base tubes, wherein said adaptation tubes are arranged in areas of the heat exchanger where fluid flow levels tend to be lower than a medium fluid flow level of the entire heat exchanger. Areas of a heat exchanger where low flow tends to be a problem are mainly areas remote of a fluid in or outlet, areas in the shadow of brackets or the like, and areas immediately beneath a fluid inlet.
According to a further embodiment said adaptation tubes provide a lower flow resistance by comprising turbulators causing a lower flow resistance than turbulators being arranged in said base tubes. As indicated before, turbulators inside of heat exchanger tubes are quite common, and, thus, use of differently designed turbulators to achieve a heat exchanger according to the invention is an attractive solution.
According to a further embodiment said adaptation tubes provide a lower flow resistance by having all smooth walls, while said base tubes have dimpled walls. In the art dimples are used to promote heat exchange. However, dimples do also cause some extra flow resistance, which can effectively be avoided by all smooth tube walls.
According to a further embodiment said heat exchanger comprises a first row of tubes and a second row of tubes, wherein all tubes of the first row belong to the secondary group of tubes and all tubes of the second row belong to the primary group of tubes. A solution like this can be advantageous for instance if the fluid inlet and outlet of the heat exchanger tend to promote flow through the second row.
According to a further embodiment said secondary group comprises adaptation tubes, each providing a lower flow resistance than a flow resistance provided by each one of said base tubes, wherein said adaptation tubes are arranged in the heat exchanger in an alternating pattern mixed with base tubes. A solution like this is advantageous for instance if fluid flow through the heat exchanger is highly dependent on rpm of an engine cooled by means of the heat exchanger. In such a case alternate tubes in a certain pattern help promoting an even flow of fluid through the entire heat exchanger.
According to a further embodiment said adaptation tubes provide a lower flow resistance by comprising turbulators causing a lower flow resistance than turbulators being arranged in said base tubes. The advantage of different turbulators has already been discussed in the above.
According to a further embodiment said adaptation tubes provide a lower flow resistance by having all smooth walls, while said base tubes have dimpled walls. As indicated before, dimples cause some extra flow resistance, which can effectively be avoided by all smooth tube walls.
According to a further embodiment said alternating pattern comprises a row of alternatingly a base tube and an adaptation tube. In some instances it shows to be advantageous to mix tubes in the indicated way to arrive at an optimum fluid flow distribution at all fluid flow rates.
According to a further embodiment said alternating pattern comprises a row of alternatingly two base tubes and an adaptation tube. Again, the purpose of such a solution is to optimize performance of a heat exchanger, especially at low to high fluid flow rates.
According to a further embodiment said secondary group of tubes is subdivided into at least two kinds of differently designed tubes. Use of differently designed tubes for the second group of tubes further enhances versatility of the heat exchanger according to the invention.
In the drawings embodiments of heat exchangers according to the invention are shown schematically. In the drawings:
In the following preferred embodiments of the invention are described with reference being had to the drawings. In the drawings like reference signs indicate similar elements.
In
Portions of the top plate 9 of the heat exchanger 1 are illustrated in greater detail in
In order to enhance cooling, tubes 7, 8 of the coolant radiator can comprise dimples, which are shown in
To render that possible in an effective way the header plates 9, 10 of the heat exchanger 1 according to the invention comprise throughout identical tube insertion orifices 11. In these tubes 7, 8 belonging to a primary and a secondary group of differently designed tubes are inserted in a tightly fitting way and fastened, e. g. by brazing.
The tubes 7 belonging to said primary group are in this context called base tubes 7, as they so to say fulfill basic heat exchange demands of a heat exchanger 1. The tubes 8 belonging to said secondary group are in this context instead called adaptation tubes 8, as they are used to locally change properties of the heat exchanger 1 in critical areas. Where these critical areas are to be found and how they are dealt with according to the invention is explained below by means of examples relating only to the top header plate 9.
The header plates 9 of
In the embodiment of
In
An adaptation tube 8 of this kind renders it possible to strengthen the structure without a pressure drop increase or a thicker tube wall thickness, but lessens heat rejection to some extent.
In the embodiment shown in
In
In
I
In order to enhance cooling, the tubes 27, 28 of a CAC 21 are usually provided with turbulators, by which are meant formed metal sheet inserts brazed to the inside of said tubes. In the drawings in
Depending on temperatures, pressures and geometry, in a CAC 21 fluid flow through different tubes 27, 28 of the CAC core 26 is difficult to distribute evenly. Due to rather high temperatures in a CAC 21, this can easily lead to structural failure. Further, inefficiently used tubes 27, 28 do lower overall efficiency.
To mitigate these problems tanks 22, 23 of a CAC 21 usually are formed such that they taper from a fluid inlet 24 or fluid outlet 25, but that measure alone does not really suffice. Hence, according to the principle of the present invention even for the CAC heat exchanger 21 tubes 27, 28 belonging to two different groups of tubes are used for flow and temperature tuning and structural integrity. How this is done is illustrated by means of the embodiments shown in
In
The header plate 29 comprises a number of identical tube insertion orifices 31, in which tubes 27, 28 fit tightly by being brazed or welded. The insertion orifices 31 are in this case arranged horizontally and in a single row, one above the other. However, they could also be arranged vertically and/or in two or more rows.
In
The embodiment of
In
In
In the final drawing figure,
A person skilled in the art is aware that alterations of the embodiments described are possible within the scope of the appended claims.
Claims
1. A heat exchanger comprising one inlet tank, having a fluid inlet for a fluid, and one outlet tank, having a fluid outlet for said fluid, and a core of tubes joining said one inlet tank and said one outlet tank together and creating a plurality of fluid flow paths for said fluid from said one inlet tank to said one outlet tank, wherein said tubes belong to a primary and a secondary group of tubes,
- wherein said one inlet tank comprises a first header plate, which forms a core interface of said one inlet tank,
- wherein said one outlet tank comprises a second header plate, which forms a core interface of said one outlet tank,
- wherein said first and second header plates comprise throughout identical tube insertion orifices for both the primary group of tubes and the secondary group of tubes, and
- wherein the tubes being a member of the primary group are base tubes, and the tubes being a member of the secondary group are adaptation tubes, which are designed differently than the base tubes of the primary group and are used to locally change properties of the heat exchanger in critical areas of the heat exchanger.
2. The heat exchanger according to claim 1, wherein said secondary group in order to prolong life of the heat exchanger comprises adaptation tubes each providing an enhanced strength compared to a basic strength provided by each one of said base tubes, wherein said adaptation tubes are used in areas of the heat exchanger where stress levels tend to be higher than a medium stress level of the entire heat exchanger.
3. The heat exchanger according to claim 2, wherein said adaptation tubes provide an enhanced strength by having a wall thickness exceeding a wall thickness of the base tubes.
4. The heat exchanger according to claim 2, wherein said adaptation tubes provide an enhanced strength by comprising stiffening inserts arranged in tube openings.
5. The heat exchanger according to claim 2, wherein said adaptation tubes provide an enhanced strength by comprising first turbulators that are stiffer than second turbulators arranged in said base tubes.
6. The heat exchanger according to claim 2, wherein said adaptation tubes provide an enhanced strength by comprising internal stiffening ribs.
7. The heat exchanger according to claim 2, wherein said adaptation tubes provide an enhanced strength by comprising extra durable tube seams created by all smooth tube walls.
8. The heat exchanger according to claim 2, wherein said heat exchanger comprises a first row of tubes and a second row of tubes, and wherein at least a plurality of the tubes of the first row belong to the primary group of tubes and all tubes of the second row belong to the secondary group of tubes.
9. The heat exchanger according to claim 1, wherein said secondary group in order to improve efficiency of the heat exchanger comprises adaptation tubes, each providing a first flow resistance that is lower than a second flow resistance provided by each one of said base tubes, wherein said adaptation tubes are arranged in areas of the heat exchanger where fluid flow levels tend to be lower than a medium fluid flow level of the entire heat exchanger.
10. The heat exchanger according to claim 9, wherein said adaptation tubes provide a lower flow resistance by comprising first turbulators that cause a lower flow resistance than second turbulators being arranged in said base tubes.
11. The heat exchanger according to claim 9, wherein said adaptation tubes provide a lower flow resistance by having all smooth walls, while said base tubes have dimpled walls.
12. The heat exchanger according to claim 9, wherein said heat exchanger comprises a first row of tubes and a second row of tubes, and wherein all tubes of the first row belong to the secondary group of tubes and all tubes of the second row belong to the primary group of tubes.
13. The heat exchanger according to claim 1, wherein said secondary group comprises adaptation tubes, each providing a lower flow resistance than a flow resistance provided by each one of said base tubes, wherein said adaptation tubes are arranged in the heat exchanger in an alternating pattern mixed with base tubes.
14. The heat exchanger according to claim 13, wherein said adaptation tubes provide a lower flow resistance by comprising first turbulators that cause a lower flow resistance than second turbulators being arranged in said base tubes.
15. The heat exchanger according to claim 13, wherein said adaptation tubes provide a lower flow resistance by having all smooth walls, while said base tubes have dimpled walls.
16. The heat exchanger according to claim 13, wherein said alternating pattern comprises a row of alternatingly a base tube and an adaptation tube.
17. The heat exchanger according to claim 13, wherein said alternating pattern comprises a row of alternatingly two base tubes and an adaptation tube.
18. The heat exchanger according to claim 1, wherein said secondary group of tubes is subdivided into at least two kinds of differently designed tubes.
Type: Application
Filed: Apr 20, 2015
Publication Date: Feb 16, 2017
Applicant: TITANX ENGINE COOLING HOLDING AB (Sölvesborg)
Inventors: Arnaud Contet (Sölvesborg), Anders Brorsson (Sölvesborg), Fredrik Lomnitz (Karlshamn)
Application Number: 15/306,062