US20100294474A1

US20100294474A1 - Heat exchanger tube

Info

Publication number: US20100294474A1
Application number: US12/470,612
Authority: US
Inventors: Sumito Furuya Hirota
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-05-22
Filing date: 2009-05-22
Publication date: 2010-11-25

Abstract

A multi-portion heat exchanger tube that increases the efficiency of heat transfer is disclosed. More specifically, a multi-portion heat exchanger tube wherein a second portion contains a significantly greater surface area than a first portion is disclosed. Even more specifically, a multi-portion heat exchanger tube wherein the first portion is significantly tubular in shape and the second portion is significantly shell shaped is disclosed.

Description

FIELD OF THE INVENTION

The current invention relates an improved heat exchanger, and more particularly, to an improved head exchanger tube that maximizes heat dispersion by increasing contact surface, reduces friction within the head exchanger tube, and create turbulent fluid flow within the heat exchanger tube.

BACKGROUND OF THE INVENTION

Heat exchangers have commonly been used to build a device that transfers heat from one medium to another. Heat exchangers are commonly used in a wide range of applications such as heating and refrigeration, air conditioning, power plants, chemical plants, petrochemical plants, petroleum refineries, natural gas refineries, and automotive industries.
Because of the various different applications for heat exchangers, various different types of heat exchangers are required to meet the specific needs of each application. Heat exchanger configurations can range from the plain and simple tube type heat exchanger, to complicated plate type heat exchangers, even to fin type heat exchangers. These various types of heat exchanger configurations all aim to maximize the exchange of heat through various ways that maximizes the contact areas of heat exchangers.
Within the tube type heat exchangers, the common practice is to carry a first fluid within the internal walls of the tube while allowing the heat exchanger tube to pass through a medium containing a second fluid. The surface area of the heat exchanger tube, which also serves as the contact area between the first fluid and the second fluid, allows the fluid to transfer heat with each other.
Newton's law of cooling sets up the basis of thermal heat energy transfer Q as a function of the heat transfer coefficient h, surface area for heat transfer A, and the temperature difference between the two surface (T_first−T_second). The formula below sets up the relationship of the above mentioned variable.
$\begin{matrix} \frac{\partial Q}{\partial t} = h * A (T_{first} - T_{second}) & (1) \end{matrix}$
Based on the above equation (1), it can be seen that one of the ways to increase the thermal heat energy transfer Q is to increase the heat transfer coefficient h. In order to increase the transfer coefficient h, materials having high conductivity such as silicon and copper can be used to make the fins of the heat exchanger which results in an increased thermal heat transfer rate Q. However, increase in conductivity of a heat exchanger tube material can only be limited to the conductivity of the materials themselves, thus limiting the development in this respect.
Alternatively, another way to increase heat transfer Q is to increase the contact surface area A. By increasing the contact surface area A between a first fluid and a second fluid. However, increasing the over contact surface area A of a heat exchanger tube also tends to increase the overall size of the heat exchanger tube itself, which can often be undesirable in applications where size reduction is a premium.
Various attempts have been made to address the issue of increasing heat transfer rate of heat exchanger tube through adjustments of the contact surface area A. For example, U.S. Pat. No. 6,739,387 to Ren for a Heat Exchanger Tubing and Heat Exchanger Assembly Using Said Tubing. In that example, a heat exchanger tubing has one or more channels formed therein for fluid flow, with channel walls between the channels having openings extending between two opposing surface of tubing. The channel walls are angled with respect to the opposing surfaces to increase the surface area of the openings. The tubing is tilted with respect to the headers in a heat exchanger assembly so that the openings in the tubing align with the direction of airflow passing over the heat exchanger.
Another example is described in U.S. Pat. No. 6,688,382 to Hargreaves for a Heat Exchanger Tube. In that example, a flat, heat exchanger tube is formed by rolling metal strip to fold inwardly the lateral edge regions of the strip to provide a tube having parallel, spaced, generally planer upper and lower walls, one of said lateral edge regions being bent to define a longitudinally extending partition wall extending within the tube towards said lower wall, and said partition wall including first and second longitudinally extending regions disposed at an angle to one another so as to provide in one face of the partition wall a longitudinally extending recess receiving the free edge portion of the other of said lateral edge regions of the strip.
A further example is described in U.S. Pat. No. 7,293,602 to Nadig et al for a Fin Tube Assembly for Heat Exchanger and Method. In that example a fin and tube assembly for use in a heat exchanger comprising a carbon steel tube, a carbon steel fin, and an external brazing compound comprising a material selected from the group consisting of nickel, chrome, copper, aluminum, zinc, and graphite brazed to the tube and fin is disclosed.
Finally, a further example is described in U.S. Pat. No. 6,343,645 to Baumann et al for a Multi-Chamber Tube and Heat Exchanger Arrangement for a Motor Vehicle. In that example a multi-chamber tube for heat exchanger arrangement of a motor vehicle has at least two chamber sections which extend parallel to each other and side-by-side. Different liquid or gaseous heat transfer media are used in the chamber sections which have widths significantly greater than their heights. At least one chamber section has a greater height than at least one other chamber section. The multi-chamber tube is used in a coolant radiator and charge air cooler combination.
It can be seen from above that despite numerous attempts to increase heat transfer Q by adjusting the contact surface area A, none of the current approaches utilizes a tubular geometry that truly optimizes the heat transfer Q without departing from the general scope and shape of the heat exchanger tube. Moreover, the prior art approaches fail to use general laws of physics and heat transfer to optimize the flow characteristics within a tube to further increase heat transfer Q.
Hence, it can be seen that there is a need in the field for a heat exchanger tube that truly optimizes the heat transfer Q between a first fluid and a second fluid while maintaining a tubular shaped that can be shaped to conform to various heat exchanging needs. Additionally, there is a need for a heat exchanger tube that further increase the heat transfer Q by adjusting the flow of a fluid within the heat exchanger tube while minimizing friction within the heat exchanger tube.

BRIEF SUMMARY OF THE INVENTION

In one aspect of the present invention is a heat exchanger tube comprising of, a first portion of a tubular shape connected to an inlet of the heat exchanger tube, a second portion of a shell shape connected to an outlet of the first portion, and a third portion identical in shape to the first portion connected to an outlet of the second portion; wherein the second portion has an increased surface area compared to said first portion to increase heat transfer.
In another aspect of the present invention is a heat exchanger tube comprising of a first portion of a tubular shape connected to an inlet of the heat exchanger tube, and a second portion of a shell shape connected to an outlet of the first portion; wherein a ratio of the surface area of the second area to the surface area of the first area is greater than 2.
These and other features, aspects and advantages of the present invention will become better understood with references to the following drawings, description and claims.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing and other features and advantages of the invention will be apparent from the following description of the invention as illustrated in the accompanying drawings. The accompanying drawings, which are incorporated herein and form a part of the specification, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention.

FIG. 1 shows a perspective view of an exemplary embodiment of the present invention;

FIG. 2 shows a top view of an exemplary embodiment of the present invention;

FIG. 3 shows a cross sectional view of an exemplary embodiment of the present invention;

FIG. 4 shows a further cross sectional view of an alternative embodiment of the present invention;

FIG. 5 shows a front view of an alternative embodiment of the present invention;

FIG. 6 shows a cross sectional view of a further alternative embodiment of the present invention;

FIG. 7 shows a perspective view of a further alternative embodiment of the present invention;

FIG. 8 shows a perspective view of a further alternative embodiment of the present invention; and

FIG. 9 shows a perspective view of an even further alternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims.
Various inventive features are described below and can each be used independently of one another or in combination with other features. However, any single inventive feature may not address any or all of the problems discussed above or may only address one of the problems discussed above. Further, one or more of the problems discussed above may not be fully addressed by any of the features described below.
The present invention generally provides a heat exchanger tube comprising of a first portion and a second portion wherein the second portion has an increased surface area when compared to the first portion; thus increasing the heat transfer rate. More specifically, the present invention provides a clamshell shaped second portion that has a lower total height and an increase diameter to achieve the increased surface area that also increases heat transfer rate of the heat exchanger tube. Even more specifically, the present invention creates a turbulent fluid flow within the heat exchanger tube due to the change in tube shape and diameter, further increasing heat transfer rate of the heat exchanger tube. The current invention is unlike the prior art where a consistent shaped heat exchanger tube is used to dissipate heat in a method that lacks efficiency and effectiveness.
FIG. 1 shows a perspective view of an exemplary embodiment of the present invention. Heat exchanger tube 100, shown here in the present exemplary embodiment may contain a first portion 102, a second portion 104, and a third portion 106 connected in series with one another. FIG. 1 shows first portion 102 connected to an inlet portion of the fluid for heat exchanger tube 100, and second portion 104 is connected down stream within the flow of the fluid at the exit end of the first portion 102 while the third portion 106 is connected at the exit end of second portion 104 further down the stream of fluid flow. Finally, inlet 101 may generally be the inlet to the first portion 102 having an outlet 103. Outlet 103 may also serves as an inlet to second portion 104, which has its own outlet 105. Finally, outlet 105 may also server as an inlet to the third portion 106, which has its own outlet 107.
First portion 102 in this current exemplary embodiment may be in the shape of a circular tube as shown in FIG. 1, however, first portion 102 may also be in an oval shaped tube, a rectangular shaped tube, a triangular shaped tube, a trapezoidal shaped tube, or any other tubular shape capable of enclosing a fluid within the first portion 102 all without departing from the scope and content of the present invention. Second portion 104 in this current exemplary embodiment may generally be in the shape of a flat shell as shown in FIG. 1; however, second portion 104 may also be in the shape of a flat pancake, a flat circle, a flat oval, a flat triangular shape, or any other flat shape capable of increasing the external surface area of second portion 104 without departing from the scope and content of the present invention. Finally, FIG. 1 also shows a third portion 106 connected to an opposite end of the second portion 104 as the first portion 102. It should be noted that the third portion 106 in this current exemplary embodiment generally mirrors the shape of the first portion 102 in size and shape, however third portion 106 may be different from first portion 102 in size, shape, dimension, length, or any other various visual characteristics to achieve the same goal of creating an outlet for the fluid without departing from the scope and content of the present invention.
In accordance with an exemplary embodiment of the present invention, the ratio of the surface area of the second portion 104 when compared to the surface area of the first portion 102 may generally be greater than approximately from 1.5, more preferably greater than approximately 2.0, and most preferably greater than approximately 3.0 to increase the surface area for heat exchange at the second portion all without departing from the scope and content of the present invention.
Additionally, also in accordance with an exemplary embodiment of the present invention, the ratio of the total length of the second portion 104 when compared to the length of the first portion 102 may generally be approximately 0.2 to approximately 1.0, more preferably the ratio may be approximately 0.4 to approximately 0.8, and most preferably the ratio may be approximately 0.5 to approximately 0.7 all without departing from the scope and content of the present invention. It should also be noted that the first portion 102, the second portion 104, and third portion 106 may also be equal length, with a longer first portion 102, or even longer second portion 104 as described above all without departing from the scope and content of the present invention. Length, as defined in this current invention may generally be along the direction of follow of the fluid, and parallel to a direction where the first portion 102, second portion 104, and third portion 106 are connected in series.
Finally, central point 108 of the second portion 104, as shown in the current exemplary embodiment may generally have an even lower height than the remainder of the second portion 104. More specifically, central point 108 may generally be the lowest point within heat exchanger tube 100 with the total height gradually ascending towards the outer perimeter area of the second portion 104 also without departing from the scope and content of the present invention.
It is worth noting that although the current exemplary embodiment depicted in FIG. 1 shows a limited number of first portion 102, second portion 104, and third portion 106, the present invention is not limited to one iteration of the above mentioned portions. The present invention may include two iterations, three iterations, or any number of iterations of the above mentioned portions all without departing from the scope and content of the present invention.
FIG. 2 shows a top view of an exemplary embodiment in accordance with the present invention. FIG. 2 shows a line A-A′ from which a cross sectional view may be created to allow an enhanced profile to be shown of the central point 208.
FIG. 3 shows a cross sectional view of the heat exchanger tube 300 as depicted in FIG. 2, taken along the line A-A′ to allow a better viewing of the central point 308 in accordance with an exemplary embodiment of the present invention. In the side profile cross sectional view depicted in FIG. 3, heat exchanger tube 300 may have a sinusoidal shape side profile 305 across second portion 304, however various other profiles such as a triangular side profile, a rectangular side profile, a jagged edged side profile, or any other side profile that allows the total height of second portion 304 to be lower than the height of the first portion 302 all without departing from the scope and content of the present invention. FIG. 3 also shows the gradually decreasing height profile from the first portion 302 towards the central point 308, and then increases back again towards third portion 306 in line with an exemplary embodiment of the present invention.
Heat Exchanger tube 300, also contains a diffuser 311 located at the fore section of the second portion 304, to help create a turbulence within the fluid. Diffuser 311, as shown in the current exemplary embodiment may generally be triangular shaped; however, diffuser 311 may be circular in shape, rectangular in shape, or any other shape capable of creating a turbulence within the fluid all without departing from the scope and content of the present invention. It should be noted that diffuser 311, used to create a turbulence in the fluid flow, may help increase heat transfer through the heat exchanger tube 300, as the fluid moves around more to allow for greater exposure; however, the current invention may also function without diffuser 311 without departing from the scope and content of the present invention.
FIG. 4 shows a cross sectional view of heat exchanger tube 400 as depicted in FIG. 2, taken along the line A-A′ in accordance with an alternative embodiment of the present invention. Heat exchanger tube 400 has a first portion 402, a second portion 404, and a third portion 406; however the second portion 404 does not have a sinusoidal side profile, but rather has a height decreasing section 410, a lower height section 412, and a height increasing section 414 to create the second portion 404 in accordance with an alternative embodiment of the present invention. In this alternative embodiment, the heat exchanger tube 400 may be used to increase the volume of fluid within second portion 402 to help with heat exchange rate. It should be noted that the alternative embodiment shown in FIG. 4 may also contain a diffuser 411 to further create turbulence; however, the diffuser 411 may be eliminated and the current invention will function without departing from the scope and content of the present invention.
FIG. 5 shows a cross-sectional view of a further alternative embodiment of the present invention taken along cross-sectional line B-B′ as shown in FIG. 4. This cross-sectional view of a further alternative embodiment of the present invention shows the internal profile of heat exchanger tube 500 allowing the arrangement of diffusers 511 in within the second portion 504. The cross-sectional view of head exchanger tube 500 shown in FIG. 5 also allows a more detailed showing of static mixers 512 that could be used to increase turbulence within the heat exchanger tube 500 in accordance with the further alternative embodiment of the present invention. Diffusers 511, as shown in the current further alternative embodiment may generally be used to create turbulence within the second portion 504 of the heat exchanger tube 500. Turbulence within a heat exchanger tube 500 may generally help increase the heat transfer of the heat exchanger tube 500 as described above. The addition of multiple diffusers 511 as shown in FIG. 5 may help further increase the heat transfer without departing from the scope and content of the present invention.
FIG. 5 also shows multiple static mixers 512 located within the first portion 502 and the third portion 506 of the heat exchanger tube 500. The tubular first portion 502 and tubular third portion 506 may contain static mixers 512 that may help further create turbulence within the tubular portions to further enhance the heat transfer of the heat exchanger tube 500. However, it should be noted that the current invention may function without the need of static mixers 512 within the heat exchanger tube 500 without departing from the scope and content of the present invention.
Turning now to FIG. 6, which shows a frontal profile of heat exchanger tube 600 in accordance with an exemplary embodiment of the present invention. FIG. 6 shows the first portion 602 in a circular shaped tube; however, as indicated above, first portion 602 may also be a oval shaped tube, rectangular shaped tube, triangular shaped tube, trapezoidal shaped tube, or any other tubular shape capable of enclosing a fluid within the first portion 602 all without departing from the scope and content of the present invention. Additionally, second portion 604 as shown in the current exemplary embodiment is in a shape of a flat shell as shown in FIG. 6; however, second portion 604 may also be in the shape of a flat pancake, a flat circle, a flat oval, a flat triangular shape, or any other flat shape capable of increasing the external surface area of second portion 604 without departing from the scope and content of the present invention
FIG. 7 shows a cross sectional view of heat exchanger tube 700 as depicted in FIG. 2, taken along the line A-A′ in accordance with a further alternative embodiment of the present invention. Heat exchanger tube 700, as shown in FIG. 7 may have an additional vertical support rod 710 located at the central point 708 of the second portion 704; however support rod 710 need not be placed at the central point 708, but may also be placed at an fore section of second portion 704, an aft section of second portion 704, or any other location within the second portion 704 all without departing from the scope and content of the present invention. Support rod 710, as shown in the current further alternative embodiment may be used to provide additional support for second portion 704 from compression and expansion of due to the fluid flow within heat exchanger tube 700. Moreover, support rod 710 may also serve the purpose of further creating turbulence within the fluid flow within heat exchanger tube 700 to further enhance heat exchange without departing from the scope and content of the present invention. Although FIG. 7 may show one support rod 710 located at the central point 708 of the second portion 704, numerous additional support rods may be used to increase turbulence and increase structural rigidity all without departing from the scope and content of the present invention. Heat exchanger tube 700, similar to all the other embodiments, may also contain a diffuser 711 to further create a turbulent flow within the heat exchanger tube 700; however, diffuser 711 is not necessary, and heat exchanger tube 700 may function without diffuser 711 without departing from the scope and content of the present invention.
FIG. 8 shows a perspective view of a further alternative embodiment of the present invention wherein the second portion 804 of heat exchanger tube 800 may contain a plurality of heat exchanger fins 820 at an external surface of the heat exchanger tube 800. Heat exchanger fins 820, as shown in the current exemplary embodiment, may generally be placed perpendicular to the direction of flow of the fluid within heat exchanger tube 800 to help increase the surface area of the second portion 804 that is available for heat transfer without departing from the scope of the present invention. Plurality of heat exchanger fins 820 may generally be long rectangular shaped, but may also be a pyramid shaped, a round shape, or any other shape that increases the surface area of second portion 804 all without departing from the scope of the present invention. Moreover, although the current exemplary embodiment may show a plurality of nine heat exchanger fins 820 in FIG. 8, the current invention could contain two heat exchanger fins, three heat exchanger fins, four heat exchanger fins, or any number of heat exchanger fins that increases the overall surface area of second portion all without departing from the scope and content of the present invention. Finally, heat exchanger fins 820 may generally be aligned in a direction the is parallel to a direction of flow of an external fluid to maximize heat transfer; however heat exchanger fins 820 may be perpendicular to the direction of flow of the external fluid, or even angled to the flow of the external fluid all without departing from the scope and content of the present invention.
FIG. 9 shows a further alternative embodiment of the present invention wherein the heat exchanger fins 920 are placed in parallel to the direction of flow of the fluid within the heat exchanger tube 900 to help increase the surface area of the second portion 904 that is available for heat transfer without departing from the scope of the present invention. Similar to the heat exchanger fins 820 shown in FIG. 8, the heat exchanger fins 920 may take on different shapes or different iterations all without departing from the scope of the content of the present invention. Finally, heat exchanger fins 920 may generally be aligned in a direction the is parallel to a direction of flow of an external fluid to maximize heat transfer; however heat exchanger fins 920 may be perpendicular to the direction of flow of the external fluid, or even angled to the flow of the external fluid all without departing from the scope and content of the present invention.
FIG. 10 shows a further alternative embodiment of the present invention wherein the heat exchanger tube 1000 is capable of taking on a curved shape instead of a straight shape as shown in the previous embodiments. Heat exchanger tube 1000, as shown in the current exemplary embodiment in FIG. 10, may bend at the first portion 1002, and the third portion 1006 due to the ease of bending of a circular shaped tube, especially when compared to a shell shaped second portion 1004. However, the current invention may contain bends at the first portion 1002, the second portion 1004, the third portion 1006, or any other portion along the heat exchanger tube to conform to the needs and orientations of the application all without departing from the scope and content of the present invention
In order to create the shell shaped second portion 1002 in accordance with an exemplary embodiment of the present invention, two shell plates may generally be matched with each other forming a top portion of the shell shaped second portion 1002 and the bottom portion of the shell shaped second portion 1002 of the present invention. Once the top and bottom portions of the shell shaped second portion 1002 are prepared, a connector may be used around the perimeter edges to create a connection between the top and bottom portions of the shell shaped second portion 1002 to join the two portions. Once the portions are joined, the connections may be heated and rapidly cooled to create a shrink the fitting. The shrinkage of the fitting may generally create a tight seal that allows the shell shaped second portion 1002 to maintain the physical shape while increasing heat transfer characteristics. Although the above described methodology used by the present exemplary embodiment is currently shown, shell shaped second portion may also be formed using a pressed methodology or a die casting methodology all without departing from the scope and content of the present invention.
It should be understood, of course, that the foregoing relates to exemplary embodiments of the present invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims. More specifically, it should be understood that although various modifications of the heat exchanger tube are shown here to accommodate various needs and requirements of a heat exchanger. Various other combinations of circular tube portions and flat shell shaped portions may be used to increase heat transfer of the heat exchanger tube without departing from the scope and content of the present invention.

Claims

1. A heat exchanger tube comprising:

a first portion of a tubular shape connected to an inlet of said heat exchanger tube;

a second portion of a shell shape connected to an outlet said first portion; and

a third portion identical in shape to said first portion connected to an outlet of said second portion;

wherein the second portion has an increased surface area compared to said first portion to increase heat transfer.

2. The heat exchanger tube of claim 1, wherein the height of the second portion is equal to or lower than the height of the first portion.

3. The heat exchanger tube of claim 1, wherein the height of the second portion is equal to or lower than half of the height of the first portion.

4. The heat exchanger tube of claim 1, wherein the height of the second portion is equal to or lower than one third of the height of the first portion.

5. The heat exchanger tube of claim 3, wherein a ratio of a surface area of said second portion to a surface area of said first portion is greater than 2.

6. The heat exchanger tube of claim 3, wherein a ratio of a surface area of said second portion to a surface area of said first portion is greater than 3.

7. The heat exchanger tube of claim 3, wherein a ratio of a surface area of said second portion to a surface area of said first portion is greater than 4.

8. The heat exchanger tube of claim 5, wherein said second portion is further comprised of a diffuser located at an entry point of said second portion to create a turbulent fluid flow within said heat exchanger tube.

9. The heat exchanger tube of claim 8, wherein said shell shaped second portion further comprises of a central point, wherein said central point is the lowest point of said heat exchanger tube.

10. The heat exchanger tube of claim 5, wherein the ratio of the length of the second portion to the length of the first portion is 0.2 to 1.0.

11. The heat exchanger tube of claim 5, wherein the ratio of the length of the second portion to the length of the first portion is 0.5 to 0.8.

12. The heat exchanger of claim 10, wherein said second portion is further comprising of a plurality of heat exchanger fins perpendicularly placed around an external surface area of said second portion.

13. A heat exchanger tube comprising:

a second portion of a shell shape connected to an outlet of said first portion;

wherein a ratio of the surface area of said second portion to the surface area of said first portion is greater than 2.

14. The heat exchanger tube of claim 13, further comprising of a diffuser located at an entry point of said second portion to create a turbulent flow within said heat exchanger tube.

15. The heat exchanger tube of claim 14, wherein said shell shaped second portion further comprises of a central point, wherein said central point is the lowest point of said heat exchanger tube.

16. The heat exchanger tube of claim 14, wherein said second portion is further comprising of a plurality of heat exchanger fins perpendicularly placed around an external surface area of said second portion.