Patent Application
20160313074
The present invention relates to heat exchangers and, more particularly, to concentric tubular heat exchangers enclosing an ascending central heat source with a radially arranged downdraft tube configuration around the central tube periphery.
This invention relates generally to heat exchangers, more particularly to tubular heat exchangers, and specifically to cylindrical tubular heat exchangers enclosing a central heat source.
In the field of heat exchangers, a need has arisen for a heat exchanger that is easily serviceable to maintain high efficiency throughout the life of the unit. A major drawback of conventional heat exchangers is a lack of internal accessibility due to their rigid welded construction, preventing easy routine maintenance necessary to clean residual combustion byproducts from the internal surfaces of such heat exchangers. Additionally, conventional heat exchangers are generally located remotely from the heat source due to their enclosed configurations, which can cause a loss of heat. Additionally, conventional heat exchangers do not employ well thought out compact designs needed to optimize overall system integrity.
Only in large commercial and industrial heat exchangers and boilers are the internal surfaces somewhat more accessible, primarily due to the physical size of the components, allowing more room to get in and clean.
Most heat exchangers are mechanically formed and welded and are not conducive to internal cleaning of residual combustion byproducts, gradually reducing overall efficiency throughout the life of the unit, which is particularly disadvantageous when used in conjunction with solid and biomass type fuels which generally produce more combustion byproducts than liquid and gaseous fuels.
Conventional heat exchangers generally don't enclose the entire heat source, resulting in greater heat loss.
Conventional heat exchangers generally require more space than the present invention for an equivalent amount of heat exchange.
It is thus a primary object of the present invention to provide a novel tubular heat exchanger.
It is further an object of the present invention to provide such a novel tubular heat exchanger which is of simple construction.
It is further an object of the present invention to provide such a novel tubular heat exchanger which can be quickly and easily internally accessed to facilitate convenient cleaning of the internal surfaces of the heat exchanger.
It is further an object of the present invention to provide such a novel tubular heat exchanger which is small in size, relatively inexpensive, and extremely efficient in its operation.
It is further an object of the present invention to provide such a novel tubular heat exchanger to provide an optimum design which surrounds and can enclose a centrally located heat source.
It is further an object of the present invention to provide such a novel tubular heat exchanger which is easily expanded by the lengthening of it's tubular components to increase the available heat transfer area.
In accordance with the present invention, there is provided a tubular heat exchanger wherein a center tube is employed to enclose an initially ascending internal heated fluid. This ascending internal heated fluid, typically produced by a combustion heat source, is then radially disbursed as it converges toward the internal surface of the top cover of the heat exchanger assembly. The internal heated fluid is drawn or forced outwardly to the internal extremities of the top cover by the updraft flow of the ascending heated fluid, which forces or draws the internal heated fluid downwardly, apportioning the now descending internal heated fluid into a series of equally spaced radially arranged heat exchange tubes attached by an annular flange to the center tube and the top cover. The heat exchange tubes concentrically surround the center tube and are uniformly spaced outwardly from and parallel to the center tube of the heat exchanger assembly. The heat exchange tubes are attached at the bottom to an exhaust collection manifold to which is attached the exhaust outlet pipe or pipes. The internal heated fluid descends axially inside the heat exchange tubes, gradually disbursing heat outwardly through the walls of the heat exchange tubes. The mostly cooled heated fluid is then collected and recombined below in the exhaust collection manifold which is attached to the exhaust outlet pipe or pipes which are in turn vented into the outside atmosphere.
The heat transfer fluid, most often external air, is forced or drawn into the space surrounding the bottom of the exhaust collection manifold. A certain portion of the heat exchange fluid is forced or drawn into the bottom of the inlet tube which extends through the exhaust manifold assembly surrounding the center tube. This inner portion of the heat exchange fluid and is then forced or drawn through the inlet tube, ascending into the inner space between the center tube and the heat exchange tubes which surround the center tube. As the heat transfer fluid ascends axially in the inner space surrounding the heat exchange tubes, it is gradually heated by the heat transferred from the internal heated fluid inside the heat exchange tubes which is conducted outwardly through the walls of the heat exchange tubes. The heat transfer fluid continues to ascend toward the top flange of the center tube as the heat exchange process continues, being forced or drawn outwardly through the axial gaps between the radially arranged heat exchange tubes.
Additionally, the outer portion of the heat transfer fluid below the exhaust collection manifold is forced or drawn into the area around the outside of the exhaust collection manifold and then into the space above the top of the exhaust collection manifold below the bottom flange portion of the outer heat shield assembly which is connected via spacer lugs to the top of the exhaust collection manifold. This outer portion of the heat exchange fluid then enters into the space around the outsides of the heat exchange tubes between the heat exchange tubes and the cylindrical midsection portion of the outer heat shield. The outer portion of the heat transfer fluid then ascends axially in the space between the heat exchange tubes and the outer heat shield, also being gradually heated by the heat transferred from the heated fluid which is inside the heat exchange tubes being conducted outwardly through the walls of the heat exchange tubes. The heated outer portion of the heat transfer fluid continues ascending inside the outer heat shield assembly towards the top flange of the center tube, recombining with the inner portion of the heat transfer fluid which is being forced outwardly through the axial gaps between the radially arranged heat exchanger tubes. As the recombined heated heat transfer fluid ascends above the top cover of the center tube, it draws additional heat from the top cover transferred from the internal heated fluid inside the center tube below the top cover, through the top of the cover, which heat radiates upwardly and outwardly from the top and sides of the top cover, additionally heating the already heated heat transfer fluid, completing the final heat exchange stage from the internal heated fluid to the external heat exchange fluid. The fully heated heat exchange fluid finally exits from the upper plenum of the heat shield assembly to be utilized in a heating system.
A complete understanding of the present invention may be obtained by reference to the accompanying drawings, when considered in conjunction with the subsequent, detailed description, in which:
For purposes of clarity and brevity, like elements and components will bear the same designations and numbering throughout the FIGURES.
In accordance with the teachings of the present invention, there is shown in the drawings a heat exchanger assembly, generally designated 10. Therein is provided a tubular heat exchanger assembly 10 wherein a cylindrical center tube is attached securely in rigid sealing engagement with the top flange 13 of the of the center tube assembly 11. Radially arranged in equally spaced configuration and in press fit side sealing engagement with the top flange 13 of the center tube assembly 11 and the top portion of the exhaust collection manifold assembly 16 are twenty-four heat exchange tubes 12. The exhaust collection manifold assembly 16 is also sealed at both ends by removable end plates 26 bolted securely in sealing engagement to the end flanges 19 of the exhaust collection manifold assembly 16 by a series of spaced screws 20. Also attached in face sealing relation to the top flange 13 of the center tube assembly 11 by a series of radially spaced screws 21 is the removable top cover 14 of the center tube assembly 11. In the preferred form, the tubular heat exchanger assembly 10 employs twenty-four heat exchange tubes 12. The previously mentioned components basically comprise what shall hereinafter be referred to as the heat exchanger core elements. These heat exchanger core elements are surrounded by the outer heat shield assembly 34 consisting of the lower flange region 35, cylindrical midsection 36, and the upper plenum region 37. This outer heat shield assembly 34 attaches by the lower flange region 35 thereof to the top of the exhaust collection manifold assembly 16 via four spacer lugs 33, fastened by a group of four screws.
The basic embodiment of the heat exchanger core assembly provides for a continuous internal flow passage for an internal heated fluid from originating from a heat source either within or entering into the bottom of the center tube assembly 11 via the inlet pipe portion thereof, ascending axially inside the center tube assembly 11 towards and into the internal space within the removable top cover 14, therein apportioned into the radially arranged heat exchange tubes 12. The internal heated fluid then descends axially inside of the heat exchange tubes 12 which flow into the exhaust collection manifold assembly 16 and from there into the exhaust outlet pipe 17 or pipes and finally venting into the atmosphere. This internal fluid flow path is sealed from the external areas around these core elements allowing only the heat to be transferred by conduction through the walls of the components, particularly the heat exchange tubes 12, into the externally flowing heat transfer fluid, which basically flows around the outsides of the heat exchanger core components in a flow direction opposite of the internal flow of the internal heated fluid. This heat transfer fluid is generally external air forced or drawn by mechanical means such as a fan or by convection draft. As previously stated, the external heat transfer fluid basically flows in a direction opposite from the flow direction of the internal heated fluid, which is considered the preferred flow relationship for optimum heat transfer.
Thus the invention disclosed herein may be embodied in other specific forms without departing from the spirit or general characteristics thereof, some of which forms have been indicated, the embodiments described herein are to be considered in all respects illustrative and not restrictive. The scope of the invention is to be indicated by the present description as well as by the appended claims, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.
The center tube assembly 11 is employed to enclose an ascending internal heated fluid from either an internal or external heat source. The heated fluid ascends inside the aforementioned center tube assembly 11, being forced or drawn upwardly by either mechanical means, such as fan, or by convection draft. The ascending internal heated fluid is then radially disbursed as it converges towards the space inside the internal surfaces of the removable top cover 14 of the tubular heat exchanger assembly 10 above the top flange 13 of the center tube assembly 11. The heated fluid is then forced or drawn outwardly into the internal extremities of the removable top cover 14 by the updraft flow of the internal heated fluid, which thereby forces or draws the heated fluid downwardly, apportioning the heated fluid into equally spaced radially arranged heat exchange tubes 12 which are in side-sealed engagement with the center tube assembly 11 and the removable top cover 14 by means of the annular top flange 13. The aforementioned heat exchange tubes 12 concentrically axially surround and are radially spaced outwardly from the center tube of the center tube assembly 11 of the heat exchanger assembly and attach at the bottom in side-sealing engagement with the top wall of the exhaust collection manifold assembly 16 adjacent to the inlet tube portion 18 thereof. The internal heated fluid continues to descend inside the heat exchange tubes 12, gradually disbursing heat outwardly through the walls of the heat exchange tubes 12 until the internal heated fluid exits the bottom of the heat exchange tubes 12. The mostly cooled internal heated fluid is then collected and recombined in the exhaust collection manifold assembly 16 which is attached in sealing relation with the exhaust outlet pipe 17 or pipes. The mostly spent heated fluid is finally vented from the exhaust collection manifold assembly 16 into the outer atmosphere via the attached exhaust outlet pipe 17 or pipes.
The heat transfer fluid, most often external air, is forced or drawn either by convection or mechanical means such as fan or other methods of forcing or inducing a draft into the space below and around the exhaust collection manifold assembly 16 and is therein apportioned into the inner and outer portions of the heat transfer fluid. The inner portion of the heat transfer fluid is forced or drawn into the bottom of the inlet tube portion 18 of the exhaust collection manifold assembly 16 and is then forced or drawn upwardly into the space outside of the center tube of the center tube assembly 11 and into the space around the inner outsides of the heat exchange tubes 12, which surround the center tube of the center tube assembly 11, all of which are surrounded by the cylindrical midsection 36 of the outer heat shield assembly 34 which is concentrically radially spaced around the outer outsides of the heat exchange tubes 12. As the inner portion of the heat transfer fluid ascends in the space surrounding the heat exchange tubes 12 between the center tube and the heat exchange tubes 12, it is gradually heated by the heat transferred from the heated fluid inside the heat exchange tubes 12 which is conducted through the walls of the heat exchange tubes 12, as well as by heat that may be conducted through the outer wall of the center tube. As the heat transfer fluid ascends towards the top flange 13 of the center tube assembly 11, it is forced or drawn outwardly from the space between and surrounding the heat exchange tubes 12 through the radially spaced axial gaps between the heat exchange tubes 12. The mostly heated inner portion of the heat exchange fluid is then recollected into the upper plenum region 37 of the outer heat shield assembly 34 which encompasses the top of the heat exchanger adjacent to the removable top cover 14.
Additionally, the outer portion of the heat transfer fluid in the space around and below the exhaust collection manifold assembly 16 is simultaneously forced or drawn around the outside of the exhaust collection manifold assembly 16 above the top of the exhaust collection manifold assembly 16 below the lower flange region 35 of the outer heat shield assembly 34, drawing some of the residual heat from the mostly spent internal heated fluid inside the exhaust collection manifold conducted through the walls of the exhaust collection manifold. This outer portion of the heat transfer fluid is then forced or drawn into the space around the outer outsides of the heat exchanger tubes within the cylindrical midsection 36 of the outer heat shield assembly 34. This outer portion of the heat exchange fluid is also simultaneously gradually heated as it ascends in the space surrounding the heat exchange tubes 12 inside the cylindrical midsection 36 portion of the outer heat shield assembly 34, therein recombining with the heated inner portion of the heat transfer fluid. As the recombined heated heat transfer fluid ascends above the top cover of the center tube assembly 11, it draws additional heat from the top cover transferred from the internal heated fluid inside the center tube assembly 11 below the top cover, conducted through the top wall of the cover, which heat radiates upwardly and outwardly from the top and sides of the top cover adding even more heat to the heated heat transfer fluid, completing the final heat exchange stage from the heated fluid to the heat exchange fluid via the tubular heat exchanger assembly 10. The fully heat diluted heat exchange fluid continues ascending out of the upper plenum region 37 of the outer heat shield assembly 34 above the top cover exiting the top plenum ready to be utilized in a heating system.
It should be appreciated that while the preferred embodiment of the present invention utilizes both an inner portion and an outer portion of the heat exchange fluid to optimize efficiency, that either the inner potion or the outer portion of the heat exchange fluid can facilitate a complete heat exchange system by themselves.
The heat exchanger assembly can utilize either an internal or external heat source for the heated fluid, as explained below.
Shown in
Also shown in
The unique design of the present invention provides convenient access to the internal surface areas of the heat exchanger via the removable top cover 14 of the center tube assembly 11 assembly as well as by the removable end plates 26 of the exhaust outlet manifold assembly. This convenient internal accessibility allows for simple cleaning of the internal surfaces of the heat exchanger using brushes and various other types of common utensils to remove built up residual combustion byproducts from the internal surfaces of the tubes and other components of the heat exchanger to maintain maximum heat transfer efficiency throughout the life of the unit.
Another important feature of this cylindrical tubular heat exchanger is the ease of expansion of the heat exchange surface areas by merely increasing the length of the center tube and heat exchange tubes 12.
Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the example chosen for purposes of disclosure, and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention.
Having thus described the invention, what is desired to be protected by Letters Patent is presented in the subsequently appended claims.
