PLASTIC HEAT EXCHANGER
The invention relates to a plastic heat exchanger (1), in particular for automotive applications, having an inlet tank (2) which has an inlet (5) for a first fluid and surrounds an inlet chamber (6), having an outlet tank (3) which has an outlet (7) for the first fluid and surrounds an outlet chamber (8), having multiple plastic tubes (4) which are tightly connected to the inlet tank (2) and to the outlet tank (3) and connect the inlet chamber (6) to the outlet chamber (8) so they communicate with one another and around which a second fluid flows during operation. To improve the heat transfer, at least some of the plastic tubes (4) have at least one longitudinal section (9) in which ring-shaped areas (13) having variable cross sections follow one another in the longitudinal direction of the tube.
The present invention relates to a plastic heat exchanger, in particular for automotive applications.
A heat exchanger usually has an inlet tank that has an inlet for a first fluid and surrounds an inlet chamber. Furthermore, an outlet tank is also provided that has an outlet for the first fluid and surrounds an outlet chamber. The plastic heat exchanger also has several plastic tubes which are tightly connected to the inlet tank and to the outlet tank. The plastic tubes connect the inlet chamber to the outlet chamber so they communicate, and a second fluid flows around them during operation of the plastic heat exchanger.
Plastic heat exchangers are characterized by a lightweight design and low manufacturing cost in comparison with traditional metal heat exchangers. However, the plastic tubes have a reduced coefficient of thermal conductivity in comparison with metal tubes. To be able to achieve a heat transfer comparable to that of a metal heat exchanger, a plastic heat exchanger must be designed with larger dimensions.
The present invention relates to the problem of providing an improved embodiment for a plastic heat exchanger, which is characterized in particular by the fact that it allows an improved heat exchange which can be utilized in particular to design the plastic heat exchanger to be smaller and/or more compact.
According to the invention, the solution of this problem is achieved by the subject matter of the independent claim. Advantageous embodiments are the subject matter of the dependent claims.
The invention is based on the general idea of furnishing at least some of the plastic tubes in at least one longitudinal section with ring-shaped areas having varying cross sections following one after the other in the longitudinal direction of the tube. In said longitudinal sections, the ring-shaped areas create turbulence during operation of the heat exchanger due to the varying cross sections, this turbulence leading to crosscurrents and/or to a transverse mixing of the first fluid flowing in the plastic tubes. The heat exchange between the respective plastic tube and the first fluid can be improved significantly in this way. Subsequently, the ability to transfer heat between the first fluid and the second fluid can be increased throughout the entire heat exchanger, so that the heat exchanger can be designed to be more compact, i.e., smaller on the whole, while achieving the same performance. It is noteworthy here that the plastic tubes need not be provided with varying cross sections over their entire length but instead over only longitudinal sections or partial sections of the plastic tubes, which may turn out to be comparatively short in comparison with the total length of the respective plastic tubes.
The longitudinal sections in which the ring-shaped areas with varying cross sections follow one another may be designed, for example, in the manner of bellows or in the manner of a corrugated tube. In this way, a plurality of such ring-shaped areas with a varying cross section can be implemented in a comparatively small longitudinal section to produce the desired disturbance in interfacial flow.
With the plastic tubes, the longitudinal sections having the varying ring areas can be manufactured by forming by upsetting so that this is performed during the manufacture of the plastic tubes in particular. Extrusion of plastic tubes may be extruded especially economically, for example. In a state in which they have not yet completely hardened, the plastic may then be formed by upsetting especially easily to form said longitudinal sections.
According to an especially advantageous embodiment, the plastic tubes may each have an inlet section connected to the inlet tank, an outlet section connected to the outlet tank and a central section connecting the inlet section to the outlet section. The wall thickness of the plastic tubes in the central section is smaller than that in the inlet section and/or than that in the outlet section. To be able to join the plastic tubes to the inlet tank and/or to the outlet tank, a minimum wall thickness is necessary. In this embodiment, however, the plastic tubes have this minimum wall thickness only in the inlet section and in the outlet section. In the central section in between, the wall thickness is reduced. In this way, the heat transfer through the plastic tubes and thus between the two fluids can be improved.
Additional important features and advantages of the invention are derived from the dependant claims, the drawings and the respective description of the figures on the basis of the drawings.
It is self-evident that the features mentioned above and those yet to be explained below may be used not only in the particular combination given but also in other combinations or alone without going beyond the scope of the present invention.
Preferred exemplary embodiments of the invention are depicted in the drawings and are explained in greater detail in the following description, where the same reference numerals refer to the same or similar or functionally identical components.
Schematically in the drawings:
According to
In a primary application the heat exchanger 1 may be used as a charge air cooler on a turbo charge engine application. The inlet tank 2 has an inlet 5 for a first fluid, which may be a gas or a liquid. The inlet tank 2 surrounds an inlet chamber 6. The outlet tank 3 has an outlet 7 through which the first fluid can be escape. The outlet tank 3 surrounds an outlet chamber 8. The plastic tubes 4 are tightly connected to the inlet tank 2 on the one hand and to the outlet tank 3 on the other hand. For example, the inlet tank 2 and the outlet tank 3 may also be made of plastic. Then the plastic tubes 4 are expediently tightly connected to the respective tank 2, 3 by means of welded joints. The plastic tubes 4 implement a communicating connection between the inlet chamber 6 and the outlet chamber 8. This means that the first fluid can flow out of the inlet chamber 6 through the plastic tubes 4 into the outlet chamber 8 during operation of the heat exchanger 1. The plastic tubes 4 have a second fluid flowing around them during operation of the heat exchanger 1, the second fluid optionally being a gas or a liquid.
At least some of the plastic tubes 4, preferably all the plastic tubes 4, each have at least one longitudinal section 9, which is characterized in that ring-shaped areas with a varying flow-through cross sections follow one another in the longitudinal direction of the tube. The plastic tubes 4 preferably have a circular cross section and are each designed to be straight in the example in
Accordingly, the longitudinal direction of the tube is either straight or curved. In the example shown in
In the example of
According to
The ring-shaped areas 13 having varying cross sections and/or the longitudinal sections 9 may be implemented by forming the plastic tube 4 by upsetting, for example. Such forming by upsetting may be implemented in a particularly favorable manner during the production of the plastic tubes 4, e.g., during an extrusion operation.
According to
According to
The respective longitudinal section 9 may then be arranged in the inlet section 19. Alternatively, the respective longitudinal section 9 may be arranged in the outlet section 20. It is likewise possible to arrange the respective longitudinal section 9 in the central section 21. Furthermore, the respective longitudinal section 9 may be arranged in one of the transitional areas 22, e.g., at the transition 22 between the inlet section 19 and the central section 21 or at the transition 22 between the central section 21 and the outlet section 20. In addition, essentially an embodiment in which the respective longitudinal section 9 is arranged in the central section 21 is conceivable, a greater wall thickness being implemented here in the central section 21, e.g., for simplified implementation of this longitudinal section 9. This greater wall thickness in the central section 21 is labeled as 23′ in the variant illustrated in
The inlet section 19 preferably amounts to max. 20% of the total length 12 or max. 10% of the total length 12 of the respective plastic tube 4. The outlet section 20 comprises max. 20% or max. 10% of the total length 12 of the respective plastic tube 4.
The reduced wall thickness 23 in the central section 21 improves not only the heat transfer between the two fluids but at the same time it also leads to substantial weight savings for the heat exchanger 1. In addition, manufacturing costs can be reduced because substantially less plastic material is needed.
Claims
1. A plastic heat exchanger, in particular for automotive applications,
- having an inlet tank (2) which has an inlet (5) for a first fluid and surrounds an inlet chamber (6),
- having an outlet tank (3) which has an outlet (7) for the first fluid and surrounds an outlet chamber (8),
- having multiple plastic tubes (4) which are tightly connected to the inlet tank (2) and to the outlet tank (3) and connect the inlet chamber (6) to the outlet chamber (8) so they communicate with one another and around which a second fluid flows during operation,
- wherein at least some of the plastic tubes (4) each have at least one longitudinal section (9), in which ring-areas (13) having varying cross sections follow one another in the longitudinal direction of the tube.
2. The plastic heat exchanger according to claim 1, wherein the respective longitudinal section (9) is designed in the manner of bellows or in the manner of a corrugated tube.
3. The plastic heat exchanger according to claim 1, wherein the respective longitudinal section (9) is designed by forming the plastic tube (4) by upsetting during production of the plastic tube (4) in particular.
4. The plastic heat exchanger according to claim 1, wherein the ring-shaped areas (13) have a corrugated profile or a sawtooth profile or a rectangular profile or a stepped profile or a combination thereof in the longitudinal direction of the tube.
5. The plastic heat exchanger according to claim 1, wherein
- the ring-shaped areas (13) have ring bulges (15) all of which protrude inward or all of which protrude outward or one of which protrudes inward and the others of which protrude outward,
- the ring bulges (15) connect tube areas (16) having constant or stepped cross sections to one another in the longitudinal direction of the tube.
6. The plastic heat exchanger according to claim 1, wherein the plastic tubes (4) each have an inlet section (19) connected to the inlet tank (2), an outlet section (20) connected to the outlet tank (3) and a central section (21) connecting the inlet section (19) to the outlet section (20), the wall thickness (23) thereof being smaller than the wall thicknesses (24, 25) of the inlet section (19) and of the outlet section (20).
7. The plastic heat exchanger according to claim 6, wherein the wall thickness (23) of the central section (21) is from 30% up to and including 70% of the wall thickness (24) of the inlet section (19) or the wall thickness (25) of the outlet section (20), such that the wall thickness (23) of the central section (21) amounts to in particular approx. 50% of the wall thickness (24) of the inlet section (19) or the wall thickness (25) of the outlet section (20).
8. The plastic heat exchanger according to claim 6, wherein the reduced wall thickness (23) of the central section (21) is implemented exclusively by reducing the outside cross section (26) of the plastic tube (4).
9. The plastic heat exchanger according to claim 6, wherein the reduced wall thickness (23) of the central section (21) is implemented exclusively by widening the inside cross section (27) of the outlet tube (4).
10. The plastic heat exchanger according to claim 6, wherein the reduced wall thickness (23) of the central section (21) is implemented by reducing the outside cross section (26) of the plastic tube (4) and by widening the inside cross section (27) of the plastic tube (4).
11. The plastic heat exchanger according to claim 6, wherein the respective longitudinal section (9) is situated in the inlet section (19).
12. The plastic heat exchanger according to claim 6, wherein the respective longitudinal section (9) is situated in the outlet section (20).
13. The plastic heat exchanger according to claim 6, wherein the respective longitudinal section (9) is situated in the central section (21).
14. The plastic heat exchanger according to claim 6, wherein the respective longitudinal section (9) is situated at the transition (22) between the inlet section (19) and the central section (21).
15. The plastic heat exchanger according to claim 6, wherein the respective longitudinal section (9) is situated at the transition (22) between the central section (21) and the outlet section (20).
16. The plastic heat exchanger according to claim 6, wherein the respective longitudinal section (9) is situated in the central section (21) such that the central section (21 ) has a greater wall thickness (23′) in the area of the longitudinal section (9) than upstream or downstream thereof.
17. The plastic heat exchanger according to claim 6, wherein the inlet section (19) comprises max. 20% or max. 10% of the total length (12) of the respective plastic tube (4).
18. The plastic heat exchanger according to claim 6, wherein the outlet section (20) comprises max. 20% or max. 10% of the total length (12) of the respective plastic tube (4).
19. The plastic heat exchanger according to claim 1, wherein at least two such longitudinal sections (9) are arranged in the respective plastic tube (4) with a distance between them in the longitudinal direction of the tube.
20. The plastic heat exchanger according to claim 19, wherein the longitudinal sections (9) within the respective plastic tube (4) are a distance (28) apart from one another, said distance being at least five times greater than the inside diameter (30) of the plastic tube (4).
21. The plastic heat exchanger according to claim 1, wherein the respective longitudinal section (9) extends from 5% up to and including 10% of the total length (12) of the respective plastic tube (4).
22. The plastic heat exchanger according to claim 1, wherein the longitudinal sections (9) are arranged so they are offset relative to one another in the longitudinal direction of the tube in the case of neighboring plastic tubes (4).
23. The plastic heat exchanger according to claim 1, wherein the inlet tank (2) is made of plastic and is welded to the plastic tubes (4).
24. The plastic heat exchanger according to claim 1, wherein the outlet tank (3) is made of plastic and is welded to the plastic tubes (4).
Type: Application
Filed: Dec 5, 2008
Publication Date: Jun 10, 2010
Inventors: Bobbye K. Baylis (Harrow), Paul D. Daly (Troy, MI), Ian R. McLean (Chatham)
Application Number: 12/329,225