Claims:1. A heat exchanger comprising a plurality of tubes for conveying a heat exchange fluid, said plurality of tubes passing through a plurality of apertures configured on each of a plurality of fin plates, each of said plurality of fin plates having at least one edge that is corrugated, said plurality of fin plates arranged such that their corrugations are disposed opposite in a mirror-like arrangement, wherein a trough of one of said plurality of fin plates abuts a crest of another adjacent fin plate of said plurality of fin plates.
2. The heat exchanger as claimed in claim 1, wherein a plurality of collars extends from the edges of said plurality of apertures such that each collar of said plurality of collars circumscribes each aperture of said plurality of apertures.
3. The heat exchanger as claimed in claim 1, wherein an operative top edge and an operative bottom edge of each of said plurality of fin plates are corrugated.
4. The heat exchanger as claimed in claim 1, wherein said at least one corrugated edge of each of said plurality of fin plates has a profile selected from a group consisting of a sinusoidal wave, a triangular wave, a truncated triangular wave, and a square wave.
5. The heat exchanger as claimed in claim 4, wherein said at least one corrugated edge of each of said plurality of fin plates has a sinusoidal wave shape.
6. The heat exchanger as claimed in claim 1, wherein each of said plurality of apertures and each of said plurality of tubes have a shape selected from the group consisting of a rectangle, a square, a circle, a polygon, geometrical shape, non-geometrical shape, and any combinations thereof.
7. The heat exchanger as claimed in claim 6, wherein each of said plurality of apertures and each of said plurality of tubes have a circular shape complementary to each other.
8. The heat exchanger as claimed in claim 1, wherein a material of each of said plurality of fin plates is selected from a group consisting of aluminium, copper, carbon steel, and stainless steel. , Description:FIELD
The present disclosure relates to the field of mechanical engineering. In particular, the present disclosure relates to the field of heat exchangers.
BACKGROUND
Conventional plate-fin type heat exchangers include a plurality of fin plates, which allow a passage of a plurality of tubes therethrough, to facilitate the transfer of heat. A plurality of collars is formed on the fin plate surface to increase the surface contact area between the tube and the fin plate. Each collar of the plurality of collars is a small hollow cylindrical extension that circumscribes each hole of a plurality of holes through which a plurality of tubes is passed. Spacing between the fin plates is dependent on the depth of the collar, as the spacing between the fin plates is facilitated only by the plurality of collars such that the depth of the collar is equal to the spacing between the adjacent fin plates. Conventionally, the collar is formed by performing a pressing operation on the fin plate. Hence, the depth of the collar is directly linked with the thickness of the fin plate. Reduced thickness of the fin plate puts restriction on the length of the collar to be manufactured. Also, the reduced thickness of the fin plate may produce cracks on the collar, thereby reducing the surface contact area between the collar and the tube. On the other hand, higher thickness of the fin plate reduces the performance of the heat exchanger which is not desirable.
Therefore, there is felt a need for a heat exchanger that can alleviate the abovementioned drawbacks.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to provide a heat exchanger that does not use the depth of a collar, configured on a fin plate, as the criteria for providing spacing between adjacent fin plates.
Another object of the present disclosure is to provide a heat exchanger that has a crack-free collar, configured on a fin plate, to facilitate optimal surface contact area between the collar and a tube of the heat exchanger.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
A heat exchanger comprises a plurality of tubes for conveying a heat exchange fluid. The plurality of tubes passes through a plurality of apertures configured on each of a plurality of fin plates. Each of the plurality of fin plates has at least one edge that is corrugated. The plurality of fin plates are arranged, such that their corrugations are disposed opposite in a mirror-like arrangement, wherein a trough of one of the plurality of fin plates abuts a crest of another adjacent fin plate of the plurality of fin plates.
A plurality of collars extends from the edges of the plurality of apertures which are configured on the plurality of fin plates. Preferably, the at least one corrugated edge of each of the plurality of fin plates has a sinusoidal wave profile. However, it may also have a triangular wave profile, a truncated triangular wave profile or a square wave profile. The plurality of apertures and the plurality tubes have a circular shape complementary to each other.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The heat exchanger, in accordance with an embodiment of the present disclosure, will now be described with the help of the accompanying drawing, in which:
Figure 1a illustrates an isometric view of a fin plate of a conventional heat exchanger;
Figure 1b illustrates a front view of the fin plate of the figure 1a;
Figure 1c illustrates a top view of the fin plate of the figure 1a;
Figure 2 illustrates a graphical representation of an experimental data of fin collar height achieved as a function of initial aperture diameter, for various fin plate thicknesses;
Figure 3a illustrates a desired arrangement of a fin plate and tube assembly in a conventional heat exchanger;
Figure 3b illustrates a schematic view of an arrangement of a conventional fin plate and tube assembly having a crack on a collar;
Figure 4a illustrates an isometric view of a fin plate of a heat exchanger, in accordance with an embodiment of the present disclosure;
Figure 4b illustrates a front view of the fin plate of the figure 4a;
Figure 4c illustrates a top view of the fin plate of the figure 4a; and
Figure 5 illustrates a top view of an arrangement of a plurality of fin plates and the tube in the heat exchanger of the present disclosure.
DETAILED DESCRIPTION
Figure 1a to Figure 3b show a fin plate used in a conventional heat exchanger. Figure 1a illustrates an isometric view of a fin plate of a conventional heat exchanger. Figure 1b illustrates a front view of the fin plate of the figure 1a. Figure 1c illustrates a top view of the fin plate of the figure 1a.
The conventional heat exchangers (not shown in figures) comprise a plurality of fin plates 100. The fin plate 100 has a plurality of apertures 104 configured thereon. A plurality of collars 106 is formed on the first operative surface 102 of the fin plate 100 such that each collar of the plurality of collars 106 circumscribes each aperture of the plurality of apertures 104. The plurality of apertures 104 are configured such that they register with a plurality of apertures configured on an adjacent fin plate, thereby facilitating an aligned access to a plurality of tubes 108 which allows a passage of a heat exchange fluid. Each of the plurality of collars 106 and each of the plurality of apertures 104 serve the purpose of firmly holding and supporting each of the plurality of tubes 108 passing therethrough. Further each of the plurality of collars 106 increase the surface contact area between each of the plurality of tubes 108 and each of the plurality of fin plates 100 to increase the heat transfer therebetween. The plurality of collars 106 is used to maintain the spacing between adjacent fin plates. Therefore, the spacing between the adjacent fin plates equals to the depth of the plurality of collars 106.
The collar, configured on the fin plate 100, is conventionally manufactured by pressing a die inside a hole from a single piece fin plate to create a protrusion of the collar. The dimension of the collar is associated with the thickness of the fin plate and the diameter of the tube carrying the heat exchange fluid. A thinner fin plate puts a restriction on the depth of the collar due to manufacturing limitations. On the other hand, a thicker fin plate increases the depth of the collar, but lowers the conductivity, thereby reducing the heat transfer performance of the heat exchanger.
Figure 2 illustrates a graphical representation of an experimental data of the collar height achieved as function of initial aperture diameter, for various fin plate thicknesses. A line a, line b, and line c show behavior of the fin plates having thicknesses as 0.18 mm, 0.15 mm, 0.12 mm respectively, for various values of a collar depth and an aperture required to be punched. Cracks in the collar are observed for a collar height more than 1.4 mm shown by a line d. For example, the data shows that, to achieve the depth of 1.4 mm of the collar, which corresponds to a fin frequency of 18 fins per inch, the thickness of the fin must be 0.18 mm. The fin frequency is the actual number of fins per inch length of the heat exchanger. The fin plates having thicknesses as 0.15 mm and 0.12 mm will develop the cracks in the collar. Thus, the larger depth of collar puts a limitation on the usage of the thinner fin plates. In another instance, for a tube, carrying the heat exchange fluid, having a tube diameter of 6 mm, if required fin frequency is 20 fins per inch or lower, the minimum required fin plate thickness for an aluminium fin plate is 0.2 mm or higher. An attempt to have a lower range of fin frequency with lower thickness of the fin plate results in cracks formed on the collar, thereby affecting the surface contact area between each of the plurality of tubes and the fin plate, thereby reducing heat transfer properties of the plate-fin type heat exchanger. Further, the cracks on the collar also result in overlapping of one fin over the other resulting in higher fin frequency than desired as shown in figure 3a and figure 3b.
Figure 3a illustrates a desired arrangement of the plurality of fin plates 100 and the tube 108 in the heat exchanger. The depth of collar 106 is used to maintain the spacing between adjacent fin plates of the plurality of fin plates 100. As the collar formed is crackfree, there is maximum surface contact area between the collar 106 and the tube 108, thereby facilitating maximum heat transfer therebetween. Figure 3b illustrates a schematic view of the conventional arrangement of the fin plate 100 and the tube 108 having a crack on the collar 106. The crack is developed either due to the use of a lower thickness of the fin plate 100 than the minimum required thickness, or because of having a smaller diameter of the tube 108 than the required minimum diameter for the given fin frequency. Figure 3b shows an adjacent fin plate 100 having the plurality of collars 106, stacked on the tube 108. The collar 106 is having longitudinal cracks developed due to smaller diameter of the collar 106 than the minimum required diameter and/or lower thickness of the fin plate 100 (less than the minimum required thickness).This results in overlapping of adjacent fin plates resulting in reduction in surface contact area between the collar 106 and the tube 108 by creation of non-contact surface as shown in figure 3b.
The overlapping of the adjacent fin plates results in increased fin plate frequency than desired, thereby increasing the overall weight and thermal inertia of the heat exchanger. The reduction in surface contact area between the collar 106 and the tube 108, due to development of cracks, reduces the heat transfer performance of the heat exchanger.
The conventional heat exchangers described thus far, are used in solid sorption heat pumps as adsorber and desorber, in which a heat exchanger is subjected to a temperature cycling. Higher weight and thermal inertia is undesirable for the performance of the solid sorption heat pump as it goes through the temperature cycling. This results in reduced performance in terms of reduced cooling capacity and lower coefficient of performance.
A heat exchanger, of the present disclosure, overcomes the abovementioned drawbacks by providing a fin plate that eliminates the depth of a collar as a fin plate spacing criteria.
The heat exchanger, of the present disclosure, will now be described with reference to figure 4a through figure 5.
Figure 4a illustrates an isometric view of a fin plate of a heat exchanger, in accordance with an embodiment of the present disclosure. Figure 4b illustrates a front view of the fin plate 200 of the figure 4a. Figure 4c illustrates a top view of the fin plate 200 of the figure 4a. Figure 5 illustrates a top view of arrangement of fin plates 200 and a tube 210 in the heat exchanger of the present disclosure.
The heat exchanger (not shown in figures), of the present disclosure, comprises a plurality tubes 210 for conveying a heat exchange fluid. Each of the plurality of tubes 210 pass through each of a plurality of apertures 204 configured on each of a plurality of fin plates 200. At least one edge of each of the plurality of fin plates 200 is corrugated. In a preferred embodiment, an operative top edge and bottom edge of each of the plurality of fin plates 200 are corrugated. The corrugated top and bottom edges of each of the plurality of fin plates 200 are corrugated in a way such that corrugations 208 are disposed opposite in a mirror-like arrangement, wherein a trough of one of the plurality of fin plates 200 abuts a crest of another adjacent fin plate of the plurality of fin plates 200.
The operative top and bottom edges of each of the plurality of fin plates 200 have a corrugated profile 208 whose shape is selected from a group consisting of a sinusoidal wave, a triangular wave, a truncated triangular wave, and a square wave. In a preferred embodiment, the corrugated profile 208 has a sinusoidal wave shape. The material of each of the plurality of fin plates 200 is selected from a group consisting of aluminium, copper, carbon steel, and stainless steel.
A plurality of collars 206 are formed on a first operative surface 202 of the fin plate 200, such that each collar of the plurality of collars 206 circumscribes each aperture of the plurality of apertures 204. The plurality of apertures 204 are configured such that they register with a plurality of apertures configured on an adjacent fin plate thereby facilitating an aligned access to each of the plurality of tubes 210 which allows a passage of the heat exchange fluid. Each of the plurality of collars 206 and each of the plurality of apertures 204 serve the purpose of firmly holding and supporting each of the plurality of tubes 210 passing therethrough. Further each of the plurality of collars 206 increase the surface contact area between each of the plurality of tubes 210 and each of the plurality of fin plates 200 to increase the heat transfer therebetween.
Each of the plurality of apertures 204 and each of the plurality of tubes 210 have a shape selected from the group consisting of a rectangle, a square, a circle, a polygon, geometrical shape, non-geometrical shape, and any combinations thereof. In a preferred embodiment, each of the plurality of apertures 204 and each of the plurality of tubes 210 have a circular shape complementary to each other.
The fin plate 200 eliminates the depth of a collar as a fin plate spacing criteria. Instead, corrugations 208 are formed on the operative top and bottom edges of each of the plurality of fin plates 200 to maintain the spacing between two adjacent fin plates. The adjacent plates are arranged in a way such that a trough on one fin plate touches a crest on adjacent fin plate of the plurality of fin plates 200, thereby facilitating the surface contact therebetween. Thus, the depth of the collar 206 is not used to maintain the spacing between the adjacent fin plates of the plurality of fin plates 200. The collar 206 is used only to increase the surface contact area between the fin plate 200 and the tube 210 carrying the heat exchange fluid.
Figure 5 illustrates a top view of an arrangement of the plurality of fin plates 200 and the tube 210 in the heat exchanger, in accordance with an embodiment of the present disclosure. The arrangement includes the plurality of fin plates 200 and the tube 210 passing through the plurality of collars 206. The corrugations 208 are formed on the operative top edge and operative bottom edge of each of the plurality of fin plates 200. The plurality of collars 206 has a depth lesser than the spacing between adjacent fin plates of plurality of plates 200. Therefore, the depth of the collar 206 does not serve as a fin plate spacing criteria, thereby eliminating the limitation of usage of the collar 206 for facilitating desired spacing between the fin plates 200. As the collar 206 is not functioning as the fin plate spacing criteria, the fin frequency of the fin plates in the heat exchanger becomes independent of fin plate thickness and the tube diameter. This allows a use of low thickness fins and smaller diameter tubes over a wide range of the fin frequencies. Use of the low thickness fin plates and small diameter tubes result in reduced size and weight of the heat exchanger.
The corrugations 208 provided on each of the plurality of fin plates 200 create turbulence which results in an improved heat transfer rate. The predefined phase difference between the corrugations formed on the adjacent fin plates can be upto 180 degrees so as to get different fin frequencies from the same corrugated profile. The amplitude and the pitch of the corrugated profile are decided based on the fin plate thickness and required fin frequency. For lower thickness of the fin plate, pitch of the corrugations 208 is higher and amplitude of the corrugations 208 is lower. To achieve lower fin frequency, amplitude of the corrugations 208 is kept higher.
The manufacturing of the plurality of fin plate 200 does not require any special manufacturing techniques. The plurality of fin plates 200 can be manufactured using conventional shearing, cutting, and forming process.
In an embodiment, the heat exchanger arrangement, in accordance with an embodiment of the present disclosure, is used for sorption heap pumps in mobile applications, such as automobiles, wherein an engine exhaust gas is tapped for regeneration of a working gas. The deposition of impurities, contained in exhaust gas such as dust and soot, are reduced by use of the corrugations 208. Some conventional heat exchangers use fin plates having corrugations throughout the surface of the fin plates. Such arrangement causes pressure drop in the flow of the fluid passing through the fin plate side of the heat exchanger. The fin plates, in accordance with an embodiment of the present disclosure, have corrugations only at the operative top and bottom edges and do not cause pressure drop of the fluid flowing between the fin plates. Also, the arrangement of the fin plates 200 has a negligible effect on the flow properties of a fluid passing through fin plates.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a heat exchanger that:
• does not use the depth of a collar, configured on a fin plate, as criteria for providing spacing between adjacent fin plates; and
• has a crack-free collar, configured on a fin plate, to facilitate optimal surface contact area between the collar and a tube of the heat exchanger.
The disclosure has been described with reference to the accompanying embodiments which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments so fully revealed the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.