Patent Application
20140131022
1. Field of the Invention
The present invention relates generally to heat exchanger tubes and heat exchangers and, more specifically, to heat exchanger tubes and heat exchangers with a cylindrical tubular member having plurality of flow altering members within each tubular member. The flow altering members are each paired with a chamber assembly attached to the external surface of the cylindrical tubular member.
2. Discussion of the Related Art
Heat exchangers are commonly utilized in systems where it is desired for heat to be removed. Typical basic heat exchangers are made of generally straight pipes, which channel heat exchanging medium within. Headers or manifolds are typically attached to each end of the pipes. These headers and manifolds act as receptacles for the heat exchanging medium. The efficiency of pipe heat exchangers is limited by the amount of surface area available for the transfer of heat. In a tube and chamber heat exchanger, a plurality of tube and chamber assemblies extend in spaced relation between a pair of headers or manifolds, forming the core of a heat exchanger. Heat exchanging performance of the heat exchanger is dictated by the overall surface area provided by the plurality of tube and chamber assemblies.
To increase surface area to enhance heat exchange performance, typical heat exchangers such as condensers, incorporate a flat-tube design, usually of extruded tubular material with extended surfaces provided by corrugated fin material, the corrugated fin material being generally interposed between a pair of extruded tubular materials. This type of heat exchanger typically includes flattened tubes having a fluid passing therethrough and a plurality of corrugated fins extending between the tubes. The fins are attached to the tubes to effectively increase the surface area of the tubes, thereby enhancing the heat transfer capability of the tubes. A number of tubes and fins may be stacked on top of each other, with a small opening to allow passage of air therethrough. To further improve heat transfer efficiency, the tube's wall thickness may be made thinner. As a result, the parts are lighter in weight, which in turn makes the overall heat exchanger lighter in weight. However, the pressure resistance is reduced, and the thinner tubes are more prone to damage. Also, the assembly process is complicated due to the fragile nature of the parts. In addition, extruded tubes are prone to plugging during the manufacturing process, particularly if a brazing process is utilized. The complexity of the extruding process results in higher costs and higher defect rates. Furthermore, as flat tubes are generally extruded into shape utilizing metal extrusion processes, only material that can be easily extruded into shape is typically made into flat tubes, restricting the available materials for flat tubes generally to aluminum and various aluminum alloys known in the art.
The overall cost for the flat tube heat exchanging system is higher because a powerful compressor is necessary to move the heat exchanging medium through the smaller openings of the tubes. Conversely, if a higher powered compressor is not utilized, then additional tubes are necessary to obtain the desired heat exchanging performance because the smaller tubes reduce the flow of the heat exchange medium significantly. The addition of tubes increase the overall cost for the heat exchanging system. Currently, this type of heat exchanger is used in applications requiring high heat exchanging capabilities, such as automotive air conditioner condensers.
In another tube-and-fin design, the tube can be of a serpentine design, therefore eliminating the need for headers or manifolds, as the tube is bent back and forth in an “S” shape to create a similar effect. Typical applications of this type of heat exchanger, besides condensers, are evaporators, oil coolers, and heater cores. This tube-and-fin design is also utilized in radiators for automobiles. Outside of the automotive field, the tube and fin design is implemented by industrial oil coolers, compressor oil coolers, and in other similar applications requiring a higher efficiency heat exchanger. The serpentine design is essentially a single, long tube material with a single chamber to transfer a heat exchange medium from the inlet of the serpentine design heat exchanger to the outlet, thereby increasing the pressure resistance of heat exchange medium travelling through the heat exchanger. This is detrimental to the performance of a heat exchanger, especially in an application such as an evaporator, wherein pressure drop significantly diminishes the performance of the compressor, for example.
A variation on the tube-based heat exchanger involves stacking flat ribbed plates. When stacked upon each other, these ribbed plates create chambers for transferring heat exchanging medium. In essence, this type of heat exchanger performs substantially the same as tube-and-fin type heat exchangers, but is fabricated differently. This type of heat exchanger is commonly implemented by contemporary evaporators.
In another variation of a tube heat exchanger, a bundle of tubes are arranged to form a heat exchanger generally known in the art as shell-and-tube heat exchanger. In a shell-and-tube heat exchanger, a plurality of generally straight tubes are bundled together, leaving sufficient space between the tubes to allow a first heat exchanging medium to flow around the exterior of the individual tubes, and a second heat exchanging medium to flow within the individual tubes. The heat exchanging medium that flows on the exterior of the individual tubes and the heat exchanging medium that flows within the individual tubes may be of the same type of heat exchanging medium, or may be of different types. This type of a heat exchanger typically involves having a first end of bundled tubes to be coupled to a first manifold, and a second end of the bundled tubes to be coupled to a second manifold. The entire tube bundle is typically enclosed in a water-tight vessel. Shell-and-tube heat exchangers are generally used in application requiring extremely high pressure, and typically employ two heat exchange mediums, with one heat exchange medium flowing inside the tube bundle, and a second heat exchange medium flowing around the tube bundle within the water-tight vessel. Shell-and-tube heat exchangers are also commonly utilized in large scale heat exchanging devices for commercial and industrial applications requiring large heat exchanging capacity. Shell-and-tube heat exchangers typically bundle together generally straight tubes with no surface enhancements either to the inside or the outside of the tubes, resulting in limited heat exchanging performance characteristics. This causes shell-and-tube heat exchanger to be larger in size to meet a desired heat exchanging performance, thus requiring a large footprint for installation purposes.
Another variation of a heat exchanger is a chamber and tube design with a medium directing member inserted within the chamber assembly. The chamber and tube design heat exchanger functions by preventing the heat exchange medium from flowing in a straight line, and causing turbulent flow within the heat exchanger by forcing the heat exchange medium to constantly change directions within the heat exchanger, first by a medium directing member and then by a chamber assembly. As a heat exchange medium enters the chamber and tube design heat exchanger, the heat exchange medium flows in a straight line through a straight tube section. At the end of the straight tube section is the medium directing member. The function of the medium directing member is to alter the direction of the heat exchange medium flow from the generally straight line flow to almost a perpendicular flow, while leading the heat exchange medium into the chamber section of the heat exchanger. The chamber section is connected to the tube section, and is generally of a larger diameter than the tube section. As the heat exchange medium is introduced into the chamber assembly, the flow of heat exchange medium follows in two semi-circular paths. At the end of the semi-circular paths, the heat exchange medium again encounters the medium directing member. As the heat exchange medium again encounters the medium directing member, the flow is restored into a generally straight flow, as the heat exchange medium is led to yet another tube section of the heat exchanger. This process repeats itself within the length of a chamber and tube design heat exchanger.
The present invention is an enhanced tubular heat exchanger comprising a cylindrical tubular member with a plurality of chamber assemblies coupled to the external surface of the cylindrical tubular member. The cylindrical tubular member is hollow, allowing fluid flow within, with plurality of flow altering members coupled at predetermined intervals within the fluid flow path of the cylindrical tubular member along the longitudinal length of the cylindrical tubular member. The flow altering members positioned inside the cylindrical tubular member substantially alter the flow path of the heat exchange medium flowing inside the cylindrical tubular member, preventing the heat exchange medium from continually flowing in a generally straight line from the inlet of the cylindrical tubular member to the outlet of the cylindrical tubular member.
The flow altering members placed inside the cylindrical tubular member may be each paired with an inlet orifice and an outlet orifice formed on the wall of the cylindrical tubular member. The flow altering member has an angled plane on the side facing the flow of heat exchange medium within the cylindrical tubular member. The inlet orifice and the outlet orifice are formed on the wall of the cylindrical tubular member, each inlet orifice and outlet orifice going through the entire thickness of the material forming the cylindrical tubular member, creating a flow path for heat exchange medium from the interior of the cylindrical tubular member to the exterior of the cylindrical tubular member. A plurality of chamber assemblies are coupled on the exterior of the cylindrical tubular member. The chamber assemblies are generally of larger diameter than the diameter of the cylindrical tubular member, and have an axial span generally drastically shorter than the axial span of the cylindrical tubular member. The chamber assemblies are hollow, allowing for fluid flow within. Chamber assemblies may be circular, but can be a cylinder, rectangular, or of other geometric shapes. Chamber assemblies are positioned along the length of the cylindrical tubular member, each chamber assembly overlapping a pairing of an inlet orifice and an outlet orifice formed in the wall of the cylindrical tubular member. One end of the cylindrical tubular member may connect to a header or a manifold. A second end of the cylindrical tubular manifold may connect to another header or a manifold.
Heat exchange medium flows from the header or the manifold into the cylindrical tubular member. The heat exchange medium within the cylindrical tubular member flows in a first line of flow generally parallel to the cylindrical tubular member. The heat exchange medium, flowing in the first line of flow inside the cylindrical tubular member, travels towards a flow altering member. The flow altering member has an angled surface facing the flow of heat exchange medium and directs the flow of heat exchange medium towards the first inlet orifice formed in the wall of the cylindrical tubular member, said inlet orifice going through the entire thickness of the wall forming the cylindrical tubular member. Flow altering members generally feature an angled surface on the side facing the flow of the heat exchange medium, allowing a smooth, yet substantial change in directional flow of the heat exchange medium.
The heat exchange medium flowing in the cylindrical tubular member initially flows in a first line of flow. A plurality of flow altering members are coupled within the inner surface of the cylindrical tubular member. The heat exchange medium, as it encounters the flow altering member, is directed to flow in a second line of flow. The second line of flow is generally at an acute angle, approaching an angle, in some embodiment of the present invention, that is generally perpendicular to the first line of flow, guiding the flow of heat exchange medium towards the inlet orifice. A chamber assembly, being hollow, is coupled to the external surface of the cylindrical tubular member. The chamber assembly generally is of larger diameter than the cylindrical tubular member, with an axial length generally substantially shorter than that of the cylindrical tubular member. The chamber assembly is in fluid communication with the inlet orifice of the cylindrical tubular member. The heat exchange medium exits the cylindrical tubular member through the inlet orifice and enters the chamber assembly. Once inside the chamber assembly, the heat exchange medium is dispersed within the chamber assembly, led towards the outlet orifice formed in the wall of the cylindrical tubular member.
Although not to be limiting, the outlet orifice is positioned on a side of the wall of the cylindrical tubular member that is generally opposite the side on which the inlet orifice is positioned. In other embodiments, the position of the inlet orifice and the outlet orifice may be offset. The chamber assembly is in fluid communication with both the inlet orifice and the outlet orifice formed on the wall of the cylindrical tubular member. This arrangement allows the heat exchange medium that exits the cylindrical tubular member through the inlet orifice to enter the chamber assembly and to re-enter the cylindrical tubular member through the outlet orifice. The heat exchange medium flowing back into the cylindrical tubular member through the outlet orifice encounters a flow altering member. The flow altering member has an angled surface on a side facing the outlet of the cylindrical tubular member and generally restores the heat exchange medium's directional flow to that of the first line of flow. This process is repeated throughout the length of the cylindrical tubular member. At the end of the tubular member, heat exchange medium may exit to a second header or a manifold.
As the heat exchange medium flows through the cylindrical tubular member and a plurality of chamber assemblies, heat contained within the heat exchange medium is absorbed by the material comprising the cylindrical tubular member and the chamber assemblies. Heat absorbed by the tubular member and the chamber assemblies is then released to the environment external to the assemblies.
In an embodiment of the present invention, the heat exchange medium flows into the cylindrical tubular member from the first manifold, attached on a first end of the cylindrical tubular member. The heat exchange medium flows in a first line of flow in the cylindrical tubular member, generally along the long axis of the cylindrical tubular member. As the heat exchange medium approaches a first flow altering member, the heat exchange medium is directed to flow in a second line of flow, generally perpendicular to the first line of flow. The flow altering members are generally coupled to the inner surface of the cylindrical tubular member. As the heat exchange medium is directed in the second line of flow by the flow altering member, the heat exchange medium exits the cylindrical tubular member through the inlet orifice formed on the wall of the cylindrical tubular member and enters the chamber assembly. Once inside the chamber assembly, the heat exchange medium is directed to flow in a third line of flow, the flow dictated by the inner contour of the chamber assembly. Although not meant to be limiting, the third line of flow of heat exchange medium may be at least one semi-circular flow pattern. The heat exchange medium then exits the chamber assembly and re-enters the cylindrical tubular member through the outlet orifice, the outlet orifice being formed on the wall of the cylindrical tubular member. Once the heat exchange medium re-enters the cylindrical tubular member, the heat exchange medium is directed to flow generally in the first line of flow by the flow altering member, the flow altering member featuring an angled surface on the side facing the heat exchange medium flow. The process repeats itself within the cylindrical tubular member, until the heat exchange medium reaches the end of the cylindrical tubular member, which medium then exits the cylindrical tubular member and enters the second header or a manifold.
In embodiments of the present invention, the cylindrical tubular member may comprise a seamless tubular structure, or a seamed tubular structure. Seamless tubular structures may be formed by extrusion, by casting, or by other forming methods. Seamed tubular structures may be formed by high frequency welding, other welding methods, or mechanical means.
In an embodiment of the present invention, heat exchanging characteristics may be enhanced by adding additional plate materials on the surface of the cylindrical tubular member or on one or more surfaces of the chamber assemblies. Adding additional plate materials on the surface, increases the overall surface area of the heat exchanger, and the performance of the heat exchanger is enhanced by having more surface area to dissipate heat away from the heat exchanger. The additional plate material may comprise a substantially thinner material in comparison to the material comprising the cylindrical tubular member, thereby further enhancing the heat transfer performance of a heat exchanger for particular applications.
In an embodiment of the present invention, the cylindrical tubular member and the chamber assemblies for a heat exchanger are provided, for example, for a condenser, evaporator, radiator, etc. The heat exchanger may also be a heater core, intercooler, or an oil cooler for an automotive application (e.g., steering, transmission, engine, etc.) as well as for non-automotive applications. An advantage of the present invention is that the heat exchanger has a larger surface area for radiating heat over a shorter distance than that of a conventional heat exchanger, with the surface area provided by both the cylindrical tubular member and the chamber assemblies. With the provision of a large surface area for exchanging heat, the efficiency of the heat exchanger is greatly increased. Additionally, the structural rigidity provided by having the cylindrical tubular member comprised of a single seamless or seamed tube lends itself for use in high internal or external pressure applications.
Another advantage of the present invention is that the overall length of the enhanced tube for heat exchanging applications may be shortened compared to a conventional heat exchanger, which in turn provides for a lower overall cost, as less raw material and less packaging are necessary. Additionally, the cylindrical tubular member may be made from a thicker gage material, allowing the heat exchanger to be used for high pressure applications. Furthermore, the smaller footprint of the present invention lends itself to be used in applications where space is limited. Yet another advantage of the present invention over a conventional heat exchanger is that the manufacturing process may be simpler because the present invention requires less fragile components and less manufacturing steps. The present invention provides an easy to assemble heat exchanger, providing enhanced heat exchanging performance while being cost effective. The present invention also excels in high pressure applications typical of commercial and industrial applications, by providing a rigid cylindrical tubular member, which can be manufactured of thick gage tubular material. The entire unit may be brazed together, or any portion of the unit can be brazed first, and then additional components may be brazed, soldered together, or attached by mechanical means, with or without utilization of gaskets.
The present invention also lends itself for ease of assembly by having a single piece cylindrical tubular member. The cylindrical tubular member may be a single piece tubular structure with plurality of an inlet orifices and outlet orifices formed at predetermined intervals in the wall of the cylindrical tubular member. The orifices can be machine drilled, punched out by pressing, or formed by other mechanical means, as long as the method used creates orifices that go through the entire thickness of the wall of the cylindrical tubular member. A plurality of flow altering members may be inserted inside the cylindrical tubular member to align with an inlet orifice and an outlet orifice pairing. In an embodiment of the present invention, a plurality of flow altering members may be formed from a single piece of material, or a plurality of flow altering members may be coupled together to form a single piece of material with a plurality of flow altering features. In another embodiment of the present invention, a plurality of flow altering members may be inserted inside the cylindrical tubular member, with the length of each flow altering members predetermined, so that once the individual flow altering members are inserted into the cylindrical tubular member end-to-end, each flow altering member aligns to a pairing of an inlet orifice and an outlet orifice. On the outer surface of the cylindrical tubular member, a plurality of chamber assemblies are coupled, each chamber assembly being positioned over a pair comprising of an inlet orifice and an outlet orifice.
Chamber assemblies may be mechanically coupled to the outer surface of the cylindrical tubular member, or may be attached by other means, such as brazing, soldering, or welding, for example. A plurality of chamber assemblies may be first combined together to form a unitary unit of a plurality of chamber assemblies, prior to coupling the chamber assemblies to the cylindrical tubular members. By combining a plurality of chamber assemblies prior to coupling to the cylindrical tubular members, the assembly process is simplified. Additionally, a plurality of chamber assemblies may be formed from a single piece of material, by stamping, casting, hydroforming, or other machining processes.
In another embodiment of the present invention, fins or plate members may be attached to the outside surface of the cylindrical tubular member, to the outer surface of chamber assemblies or to surfaces of both the cylindrical tubular member and the chamber assemblies. Fins or plate members attached to the outer surface further increase the surface area of a heat exchanger, thereby enhancing the performance characteristics of the heat exchanger. Fins and plate members provide an economical means to increase the heat exchanging capability of a heat exchanger by enhancing the surface area available for heat transfer, without greatly increasing the size of a heat exchanger or costing more to produce a heat exchanger.
In yet another embodiment of the present invention, the chamber assembly size may vary from one chamber assembly to the next.
In another embodiment of the present invention, a plurality of cylindrical tubular member may be bundled together to form a heat exchanger with a plurality of cylindrical tubular members. One end of the bundled cylindrical tubular member may connect to a first manifold or a header, and a second end of the bundled cylindrical tubular member may connect to a second manifold or a header. In an embodiment of the present invention, the size of the cylindrical tubular member may vary from one cylindrical tubular member to the next.
In yet another embodiment of the present invention, a plurality of cylindrical tubular member may be bundled together, leaving enough space between each of the bundled tubes to allow flow of heat exchange medium around the exterior of the individual cylindrical tubular member. The first end of the bundled cylindrical tubular member may connect to a first manifold or a header. The second end of the bundled cylindrical tubular member may connect to a second manifold or a header. The entire area comprising the bundled cylindrical tubular member may be sealed in a water tight vessel, allowing a heat exchange medium to flow on the outer surface of the bundled cylindrical tubular member. The vessel may have an inlet to allow a first heat exchange medium to flow inside the vessel. The vessel may also have an outlet to allow the first heat exchange medium to exit the vessel. Furthermore, the vessel may feature baffles to direct flow of heat exchange medium within the vessel. In an embodiment of the present invention, a second heat exchange medium may flow within the bundled cylindrical tubular member. The first heat exchange medium flowing outside the bundled cylindrical tubular member and the second heat exchange medium flowing inside the bundled cylindrical tubular member may be a gas, a liquid, or a combination of both.
In a further embodiment of the present invention, each chamber assembly may disperse heat exchanging medium throughout the chamber, which further enhances the heat exchanging capabilities of the present invention. Also, the cylindrical tubular manifold may also mix heat exchanging medium.
In another embodiment of the present invention, the inner surface of the cylindrical tubular manifold may feature indentations to increase the surface area. Also, in yet another embodiment of the present invention, the inner surface of the chamber assembly may also feature indentations to increase the surface area. In a further embodiment of the present invention, the flow altering member may also feature indentations. In an embodiment of the present invention, the chamber assembly may have other surface features such as, but not limited to, indentations, louvers, dimples, as well as other extended surface features to alter the fluid flow characteristics within the chamber assembly.
The cylindrical tubular member and the chamber assemblies may be made of aluminum, either with cladding or without cladding. The flow altering member may be made of aluminum, either with cladding or without cladding. The cylindrical tubular member, the chamber assemblies, and the flow altering members may also be made of stainless steel, copper or other ferrous or non-ferrous materials. The cylindrical tubular member, the chamber assemblies, and the flow altering members may also be a plastic material or other composite materials.
The cylindrical tubular member, the chamber assemblies, and the flow altering members may be manufactured by stamping, cold forging, casting, hydroforming, or machining.
Other features and advantages of the present invention will be readily appreciated, as the same becomes better understood after reading the subsequent description taken in conjunction with the accompanying drawings.
Referring to the drawings and in particular
Referring to
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Referring now to
Referring to
In another embodiment of the present invention, referring to
Thus, in embodiments of the present invention, the heat exchanger (e.g. 300), features two heat exchange mediums, one heat exchange medium flowing inside the plurality of cylindrical tubular members 100, and second heat exchange medium flowing outside the plurality of cylindrical tubular members 100. The first heat exchange medium flowing inside the plurality of cylindrical tubular members 100 may contain heat, transferring heat to the second heat exchange medium flowing outside of the plurality of cylindrical tubular members 100. In another embodiment of the present invention, the heat exchange medium flowing inside the plurality of cylindrical tubular members 100 may absorb heat from the second heat exchange medium flowing outside the plurality of cylindrical tubular members 100.
In another embodiment of the present invention, both an inlet and an outlet can be positioned on a first manifold, with a second manifold facilitating the return of heat exchange medium towards the first manifold. Referring to
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Now referring to
Now referring to
The heat exchange medium flowing in the tubular structure 110 initially flows in a first line of flow. As the heat exchange medium travels within the tubular structure 110, the heat exchange medium comes into contact with a flow altering member 150. As the heat exchange medium contacts the flow altering member 150, the flow of the heat exchange medium is directed towards a second line of flow, the directional change being dictated by the angled planar surface 170 of the flow altering member 150, and by the channel formed by the first lateral wall 155, the second lateral wall 160, and the base wall 165 of the flow altering member 150. The heat exchange medium directed in the second line of flow is then led out of the tubular structure 110 into a chamber assembly 125. Referring to
Referring to
Throughout the transport of the heat exchange medium through the cylindrical tubular member 100, the heat contained within the heat exchange medium is transferred to the material comprising the cylindrical tubular member 100. The heat absorbed by the cylindrical tubular member 100 is then transferred to the environment outside of the cylindrical tubular member 100. Although not meant to be limiting, common heat exchange medium known in the art includes various refrigerants (i.e.; R-134A, R-410A), ammonium, gases, water, oils, and various mixtures of chemicals.
As previously explained, a first heat exchange medium may flow within the cylindrical tubular member 100 and a second heat exchange medium may flow on the outside of the cylindrical tubular member 100. The first heat exchange medium may be a heat exchange medium known in the art, such as various refrigerants (i.e.; R-134A, R-410A), ammonium, gases, water, oils, and various mixtures of chemicals. The second heat exchange medium may also be various refrigerants (i.e.; R-134A, R-410A), ammonium, gases, water, oils, and various mixtures of chemicals. When more than one heat exchange medium is utilized, heat from the first heat exchange medium may be absorbed by the second heat exchange medium, or vice versa.
Referring to
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The tubular structure 15 and chamber assembly 20 may be made of aluminum, either with cladding or without cladding. The tubular structure 15 and chamber assembly 20 may also be made of stainless steel, copper, or other ferrous or non-ferrous material. The tubular structure 15 and chamber assembly 20 may also be a plastic material or other composite materials. Likewise, the flow altering member may also be made of aluminum, either with cladding or without cladding. The flow altering member may also be made of stainless steel, copper or other ferrous or non-ferrous materials. The flow altering member may also be a plastic material or other composite materials. Also, an embodiment of the present invention allows for the tubular structure 15 and chamber assembly 20 to be made of different material from each other. Additionally, a gasket material may be used to seal between the tubular structure 15 and the chamber assembly 20.
The tubular structure 15 may be made of seamless tube, utilizing an extrusion process. The tubular structure may also be made of a seamed tube, utilizing ultrasonic welding, roll-forming process, or other mechanical means or casting methods.
Many modifications and variations of the present invention are possible in light of the above teachings. For example, the various embodiments of the flow altering members may be used in conjunction with tubular structures other than in the combinations described above and illustrated in the drawings Therefore, within the scope of the appended claims, the present invention may be practiced other than as specifically described.
