Heat Exchanger
A heat exchanger for an automotive vehicle includes two headers, first tubes for carrying fluid between the headers, and second tubes for carrying engine coolant between the headers, staggered with respect to the first tubes, each tube inclined relative to an air stream entering the heat exchanger.
1. Field of the Invention
This invention relates generally to a heat exchanger for transferring heat from a heat source contained in tubes to an air stream, and, in particular, to a heater core in the passenger compartment of an automotive vehicle.
2. Description of the Prior Art
Conventionally, the tubes, which carry engine coolant through the heater core of an automotive vehicle, are arranged parallel to the stream of air that passes through the heater core. The heater core usually includes one or two rows of tubes, the second row being in-line and parallel to the first row.
Generally, fins located between the tubes and secured to the outer surface of the tubes enhance heat transfer from the coolant to the air stream.
It has long been understood that the heat transfer rate is much larger for turbulent flow than for laminar flow. Increasing turbulence of the air stream through the heater core is beneficial to the convection heat transfer rate and improves the overall performance of the heat exchanger. It is also more effective to increase the heat transfer on the air-side to improve the heat exchanger, as this is the more restrictive side compared to the rate of heat transferred from the fluid flowing inside the tube.
In order to induce turbulence in the air stream, fins on the outer surface of the tubes are usually mutually staggered and offset, but the tubes are aligned parallel to the air stream.
A need exists in the industry for techniques that further improve heat transfer in a heater core without increasing its package size.
SUMMARY OF THE INVENTIONA heat exchanger for an automotive vehicle includes two headers, first tubes for carrying fluid between the headers, and second tubes for carrying engine coolant between the headers and staggered with respect to the first tubes. Each tube is inclined relative to an air stream entering the heat exchanger.
The heater core provides improved performance over a current production heater core by up to five percent without increasing fin density or changing tube geometry. The heater core realizes an increase of about five percent in heat transfer surface area without increasing the size of the heater core.
An increase in turbulence of the air stream flowing through the heater core improves heat transfer performance of the heater core.
Design enhancements include offsetting the second row of tubes to increase impingement effect on tube surface and redirection of the air through the core face. Additionally, both the first and second tube rows may be inclined or angled relative to the air stream to increase the heat transfer surface area of the tube and to enhance impingement of the air on the tubes and fins. Both the first and second rows of tubes are angled in relation to the incoming flow of air up to 20 degrees. The optimal angle modeled in the simulations is about 15 degrees to maximize both the surface area for heat transfer and turbulence to the air flow through the core.
The scope of applicability of the preferred embodiment will become apparent from the following detailed description, claims and drawings. It should be understood, that the description and specific examples, although indicating preferred embodiments of the invention, are given by way of illustration only. Various changes and modifications to the described embodiments and examples will become apparent to those skilled in the art.
The invention will be more readily understood by reference to the following description, taken with the accompanying drawings, in which:
Referring now to the drawings, there is illustrated in
The heater core 26 illustrated in
Alternatively the tubes 30, 33 may be organized in a first bank comprising the tubes of the first row 22 and a second bank comprising the tubes of the second row 24.
In another embodiment, the tubes may be arranged in the heater core 26 as shown in
The tubes may be welded along a longitudinal seam or brazed along the seam. Alternatively, as shown in
Inclining the tubes with respect to the air stream 14 and staggering the tubes enhances turbulence of the air flow through the heater core 26 and increase the impingement effect on the surfaces of the tubes by redirecting the air at the face of the heater core. Inclining the tubes with respect to the air stream 13 and staggering the tubes improves the rate of heat transfer in the heater core.
In accordance with the provisions of the patent statutes, the preferred embodiment has been described. However, it should be noted that the alternate embodiments can be practiced otherwise than as specifically illustrated and described.
Claims
1. A heat exchanger for an automotive vehicle comprising:
- two headers;
- first tubes for carrying fluid between the headers;
- second tubes for carrying fluid between the headers, staggered with respect to the first tubes, each tube including a depth dimension that is inclined at an angle relative to an air stream entering the heat exchanger.
2. The heat exchanger of claim 1 wherein each of the first and second tubes includes a length extending mutually parallel between the headers, and substantial parallel lateral surfaces that are inclined relative to the air stream entering the heat exchanger.
3. The heat exchanger of claim 1 wherein:
- the first tubes are arranged in a first row and the second tubes are arranged in a second row;
- each of the first and second tubes has a length extending between the headers, and substantial parallel lateral surfaces, the lateral surfaces of the first and second tubes being inclined in a first direction relative to the air stream entering the heat exchanger.
4. The heat exchanger of claim 1 wherein:
- the first tubes are arranged in a first row and the second tubes are arranged in a second row;
- each of the first and second tubes has a length extending between the headers, and substantial parallel lateral surfaces, the lateral surfaces of the first tubes inclined in a first direction relative to the air stream entering the heat exchanger, the lateral surfaces of the second tubes inclined in a second direction relative to the air stream entering the heat exchanger.
5. The heat exchanger of claim 1 wherein the angle may vary in a range up to about 20 degrees.
6. The heat exchanger of claim 1 wherein the tubes folded tubes that are welded or brazed along at least one longitudinal seam.
7. A heat exchanger for an automotive vehicle comprising:
- two headers;
- first tubes for carrying fluid between the headers, each first tube inclined at an angle relative to an air stream entering the heat exchanger; and
- second tubes for carrying fluid between the headers, each second tube inclined at an angle relative to the air stream entering the heat exchanger and aligned with one of the first tubes.
8. The heat exchanger of claim 7 wherein each of the first and second tubes includes a length extending mutually parallel between the headers, and substantial parallel lateral surfaces that are inclined relative to the air stream entering the heat exchanger.
9. The heat exchanger of claim 7 wherein:
- the first tubes are arranged in a first row and the second tubes are arranged in a second row;
- each of the first and second tubes has a length extending between the headers, and substantial parallel lateral surfaces inclined in a first direction relative to the air stream entering the heat exchanger.
10. The heat exchanger of claim 7 wherein:
- the first tubes are arranged in a first row and the second tubes are arranged in a second row;
- each of the first and second tubes has a length extending between the headers, and substantial parallel lateral surfaces, the lateral surfaces of the first tubes inclined in a first direction relative to the air stream entering the heat exchanger, the lateral surfaces of the second tubes inclined in a second direction relative to the air stream entering the heat exchanger.
11. The heat exchanger of claim 7 wherein the angle may vary in a range up to about 20 degrees.
12. The heat exchanger of claim 7 wherein the tubes folded tubes that are welded or brazed along at least one longitudinal seam.
13. A heat exchanger for an automotive vehicle comprising:
- two headers;
- first tubes for carrying fluid between the headers;
- second tubes for carrying fluid between the headers, staggered with respect to the first tubes, the first ands second tubes being substantially aligned with an air stream entering the heat exchanger.
14. The heat exchanger of claim 13 wherein:
- the first tubes are arranged in a first row and the second tubes are arranged in a second row;
- each of the first and second tubes has a length extending between the headers, and substantial parallel lateral surfaces aligned with the air stream entering the heat exchanger.
15. The heat exchanger of claim 13 wherein the angle may vary in a range up to about 20 degrees.
16. A heat exchanger for an automotive vehicle comprising:
- two headers;
- first tubes for carrying fluid between the headers, each first tube inclined in a first direction at an angle relative to an air stream entering the heat exchanger; and
- second tubes for carrying engine coolant between the headers, each second tube staggered with respect to the first tubes, and inclined in a second direction at an angle relative to the air stream entering the heat exchanger.
17. The heat exchanger of claim 16 wherein:
- the first tubes are arranged in a first row and the second tubes are arranged in a second row;
- each of the first and second tubes includes a length extending between the headers, each of the first tubes includes substantial parallel lateral surfaces inclined in a first direction relative to said air stream, and each of the second tubes includes substantial parallel lateral surfaces inclined in a second direction relative to said air stream.
18. A heat exchanger for an automotive vehicle comprising:
- two headers; and
- tubes having a length extending between the headers for carrying engine coolant between the headers, and substantial parallel lateral surfaces that are inclined at an angle relative to an air stream entering the heat exchanger.
19. The heat exchanger of claim 18 wherein the angle may vary in a range up to about 20 degrees.
20. The heat exchanger of claim 18 wherein the tubes are folded tubes that are welded or brazed along at least one longitudinal seam.
Type: Application
Filed: Nov 12, 2008
Publication Date: May 13, 2010
Inventors: Timothy V. Evans (Ypsilanti, MI), Kishan Padakannaya (Canton, MI)
Application Number: 12/269,148
International Classification: F28F 9/02 (20060101);