This application is directed, in general, to a heating furnace unit, and more specifically, to a heating furnace unit that employs a heat exchanger unit having a converging-diverging combustion zone.
Current furnace heat exchanger flames are long. For example the flame's length that can extend substantially through one or more passes of a heat conduction tube of the heat exchanger. As a result, the flame can distribute heat over a substantial length of the heat exchanger's heat conduction tube. In the presence of such a long flame, however, it is often not desirable to have intrusive heat transfer enhancements (e.g., dimples) because there is a significant danger of overheating the heat exchanger, or, of quenching the flame and producing carbon monoxide (CO). Consequently, the first pass of a furnace heat exchanger often runs cooler than desired, and thus represents inefficiently used surface area for heat exchange. Another consequence of using a long flame can be poor mixing between the fuel (e.g., natural gas or propane) and air. This, in turn, can result in CO or soot production under certain operating conditions.
One embodiment of the present disclosure is a heating furnace unit. The unit comprises a mounting panel, a burner assembly and a heat exchanger. The burner assembly is mounted to one side of said mounting panel, the burner assembly having at least one burner located therein. The heat exchanger is mounted to an opposite side of said mounting panel. The heat exchanger has at least one continuous combustion tube, wherein said combustion tube includes at least a first pass and a second pass. The first and second passes are interconnected by a curved pass of the combustion tube. One end of the combustion tube has a first opening that is coupled to the burner assembly. The combustion tube has at least three zones. A converging first surface of the first zone extends an entire length of the first zone and converges towards a direction of a flame emitted by the one burner during an operation of the heating furnace and forms a first non-straight angle with a diverging second surface of the second zone. The second surface extends an entire length of the second zone and diverges away from the direction of the flame. The second surface has a second non-straight angle with a third surface of the third zone. The first zone is nearest of the three zones to the burner assembly and extends to the first opening and the second zone is in-between the first zone and the third zone. The first, second and third zones are within a flame length configured to be emitted from said burner. The first non-straight angle is located on the opposite side of the mounting panel. The first non-straight angle and the second non-straight angle are within the first pass and are nearer to the first opening upstream end than the curved pass.
Another embodiment of the present disclosure is a method of manufacturing a heating furnace unit. The method comprises providing a mounting panel, providing a burner assembly having at least one burner located therein and providing a combustion tube of a heat exchanger. The combustion tube includes at least a first pass and a second pass, the first and second passes interconnected by a curved pass of the combustion tube. The method comprises mounting the burner assemble to one side of the mounting panel and mounting the heat exchanger to an opposite side of the mounting panel. The method comprises coupling one end of the combustion tube to the burner assembly such that the at least one burner can emit a flame into an opening in the one end. The combustion tube has at least three zones. A converging first surface of the first zone extends an entire length of the first zone, converges towards a direction of the flame emitted by the one burner during an operation of the heating furnace and forms a first non-straight angle with a diverging second surface of said second zone. The second surface extends an entire length of the second zone and diverges away from the direction of the flame. The second surface has a second non-straight angle with a third surface of the third zone. The first zone is nearest of the three zones to the burner assembly and extends to the first opening and the second zone is in-between the first zone and the third zone. The first, second and third zones are within a flame length configured to be emitted from said burner. The first non-straight angle is located on the opposite side of the mounting panel. The first non-straight angle and the second non-straight angle are within the first pass and are nearer to the first opening upstream end than the curved pass.
Reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
Embodiments of the present disclosure enhance fuel air mixing, and hence promote heat release, early in the length of the flame, and, thereby use the heat exchanger's surface area more efficiently, and, allows for cleaner burning of the fuel. In particular, as further disclosed herein, it was discovered that such efficiencies are facilitated by the presence of one or more diverging or converging zones in a combustion tube.
One embodiment of the present disclosure is a heating furnace unit.
The heating furnace unit 100 comprises a burner assembly 105 having at least one burner 110 located therein. The unit 100 also comprises a heat exchanger 120 having at least one continuous combustion tube 125. One end 130 of the combustion tube 125 has an opening 135 that is coupled to the burner assembly 105. For example, in some embodiments, the coupling can include direct mechanical coupling while in other case the coupling can include fluid coupling with no direct mechanical contact. The combustion tube 125 has at least three zones 205, 207, 209. The first zone 205 of the combustion tube 125 is nearest of the three zones 205, 207, 209 to the burner assembly 105 (
The term zone, as used herein, refers to a section of the combustion tube whose surface (e.g., outer and inner surface, or in some cases only the inner surface) forms a non-straight angle or angles (e.g., acute, right, obtuse or reflex angles) with respect to the surface or surfaces of the adjacent zone or zones. When the surface refers to an inner surface of the tube 125, the non-straight angle or angles refer to interior angles of the surface. When the surface refers to an inner surface and an outer surface of the tube 125, the non-straight angle or angles refer to both interior angles of the inner surface and the corresponding exterior angle of the outer surface. In some embodiments, the interior angle and corresponding exterior angle are related by the relationship that the sum of the two angles equals 360 degrees.
For instance, as illustrated for the example embodiment shown in
In still other embodiments, the outer surfaces 310, 315, 320 may not have non-straight exterior angles. For instance, as depicted in
In some embodiments of the unit 100, such as depicted in
There are numerous other configurations that the zones 205, 207, 209 of the combustion tube 125 can have to enhance fuel air mixing. This is further illustrated in
In some embodiments, the second outer surface of the second zone curvilinearly diverges from the first zone to the third zone. For instance, as shown in
In some embodiments of the unit 100, such as depicted in
In some embodiments, more than one of the zones 205, 207, 209 can be converging or diverging zones. For instance, as illustrated in
For instance, as shown
For instance, as shown
As shown in
In some embodiments, a portion of one or more of the outer surfaces 310, 315, 320 (and/or inner surfaces 310′, 315′, 320′) of the three zones 205, 207, 209 does not have non-straight angles 312, 318 (and/or angles 322. 328). That is, portions 450, 452, 454 of one or more of the outer surfaces 310, 315, 320 (and/or inner surfaces 310′, 315′, 320′) of one or more of the three zones 205, 207, 209 can form a straight exterior angle 460, 465 with another one of the outer surfaces 310, 315, 320 of the three zones 205, 207, 209. For instance, as shown in
In some embodiments of the heat exchanger 120, such as shown in
As further illustrated in
One of ordinary skill in the art, based upon the present disclosure, would appreciate the scope of other configurations that zones of the combustion tube 125 could have. One skilled in the art would also appreciate that the particular dimensions and structural configuration of the combustion tube 125 could be adjusted based on other factors to achieve an optimal balance between efficiency, heat exchanger temperature, combustion performance and sound levels.
One of ordinary skill would appreciate that the heating furnace unit 100 would include additional components. As non-limiting examples, the unit 100 can further include a mounting panel 150 configured couple the burner assembly 105 and heat exchanger 120 together. One skilled in the art would understand that the unit could also include other components such as an air circulating means (e.g., an air blower; not shown). The unit 100 can further include a collection assembly 155 that is coupled to an opposite end 160 of the combustion tube 125 which is configured to route exhaust gases to other components of the unit 100 (e.g., secondary heat exchanges, discharge flues, etc. . . . ; not shown). The burner assembly 105 can further include a burner enclosure 165 configured to hold the one or more burners 110 therein and facilitate coupling of the burner assembly 105 to the heat exchanger 120. The heat exchanger 120 can further include one or more frames 170 adapted to hold at least one of the combustion tubes 125 and configured couple the combustion tube 125 openings 135, 160 to the burner assembly 105 and collection assembly 155.
Another embodiment of the present disclosure is a method of manufacturing a heating furnace unit.
The method 500 comprises a step 510 of providing a burner assembly having at least one burner located therein. The method 500 also comprises a step 520 of providing a combustion tube 125 of a heat exchanger 120. The method further comprises a step 530 of coupling one end 130 of the combustion tube 125 to the burner assembly 105 such that the at least one burner 110 can emit a flame 210 into an opening 135 of the one end 130 of the combustion tube 125.
As discussed in the context of
In some embodiments, the step 520 of providing the combustion tube 125 includes a step 540 of forming the three zones 205, 207, 209 which includes bending a portion of one or more metal sheets (e.g., aluminum sheets) to form the non-straight first angle and the non-straight second angle. In some cases, for instance, one or more of the first, second or third surfaces of a single metal sheet can be bent, as part of step 540, to form the first and second angles to thereby fashion each of the zones 205, 207, 209 into one of converging, diverging or straight zones. In other cases, separate sheets of metal can be bent, as part of step 540, to form separate pieces that correspond to the three zones 205, 207, 209.
In some embodiments, the step 520 of providing the combustion tube 125 includes a step 550 of forming the three zones 205, 207, 209 which includes coupling separate first, second and third metal sheets together to form the first and second angles.
For instance, in some cases coupling the separate first, second and third metal sheets together in step 550 can include a step 560 of bonding the first and the second metal sheets together and a step 565 of bonding the second and the third metal sheets together. Examples of suitable bonding processes include riveting, welding, or bolting the pieces together.
Another embodiment of the present disclosure is a method of using a heating furnace unit.
The method 600 comprises a step 610 of emitting a flame 210 from a burner 110 located in a burner assembly 105. One of ordinary skill in the art would be familiar with appropriate gases (e.g., natural gas), gas flows and ignition processes to achieve step 610.
The method also comprises a step 620 of directing the flame 210 into a combustion tube 125 of a heat exchanger 120, the burner 110 coupled to an opening 135 in one end 130 of the combustion tube 125. The combustion tube 125 has three zones 205, 207, 209 configured as previously described in the context of
Forced mixing of the gases by passing the gases and flame through the three zones 205, 207, 209 facilitates the early release of heat in the combustion tube 125 resulting in a uniform temperature in the combustion tube 125. One ordinary skill in the art would be familiar with procedures to measure the temperature in combustion tube 125, e.g., using commercially available thermal imaging equipment.
In some embodiments, under a steady-state output of the flame 210 (e.g., from a constant flow of gases into the burner 110), at least a first passage 230 and a second passage 235 of the combustion tube 125 have a substantially same average temperature (e.g., within about ±10 percent). In some embodiments of the combustion tube 125, having more than two passes, the average temperature in any one pass is substantially the same (e.g., within about ±10 percent) as the average temperature in any other pass. Additionally, the resulting uniform temperature throughout the combustion tube 125 with the three zones 205, 207, 209 facilitates having a low average temperature throughout the entire tube 125. For instance, in some cases, with a steady-state output of the flame 210, the average temperature in the first passage 230 and the second passage 235 of the combustion tube 125 equals about 650° F. or less.
One skilled in the art would appreciate that the method 600 could include additional steps to using a heating furnace unit 100, e.g., to heat a building or other enclosed structure. Non-limiting examples of such steps could include transferring air over the heat exchanger 120 and into a room (step 630) and re-circulating the air from the room back to the heat exchanger 120 (step 640).
Those skilled in the art to which this application relates will appreciate that other and further additions, deletions, substitutions and modifications may be made to the described embodiments.
This application claims the benefit of U.S. Provisional Application Ser. No. 61/295,501, filed by Shailesh S. Manohar, et al., on Jan. 15, 2010, entitled “An Improved Heating Furnace for a HVAC System,” and U.S. Non-Provisional application Ser. No. 12/834,123, filed by Floyd E. Cherington, et al., on Jul. 12, 2010, entitled “Converging-Diverging Combustion Zones For Furnace Heat Exchanges,” incorporated herein by reference in its entirety.
Number | Date | Country | |
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61295501 | Jan 2010 | US |
Number | Date | Country | |
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Parent | 12834123 | Jul 2010 | US |
Child | 14507148 | US |