Liquid heaters and vaporizers – Stand boiler – Fluid fuel burner
Reexamination Certificate
1999-07-12
2002-03-12
Lu, Jiping (Department: 3749)
Liquid heaters and vaporizers
Stand boiler
Fluid fuel burner
C122S044200, C122S155200, C138S038000, C029S890046
Reexamination Certificate
active
06354248
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to water heaters, water heater flues and heat exchange elements which are or can be installed in flues of water heater systems.
BACKGROUND OF THE INVENTION
Prior art heat exchangers for hot water heaters generally comprise individual fins or vanes welded in predetermined patterns on the flue, so that air passing through the flue will be caused to flow in a spiral fashion. The fins or vanes also act as heat exchange elements which help to conduct heat to the flue wall and thus to the water contained in the vessel through which the flue passes.
In Australian patent application 18306/76 published on Apr. 13, 1978 there was described a series of individual vanes placed in helical fashion around the circumference of a flue and angled to the longitudinal direction of the flue so as to produce a swirling effect. Each vane was individually welded to the flue.
U.S. Pat. No. 2,950,740 which issued on Aug. 30, 1960, describes a similar arrangement to that described in the Australian patent application 18306/76. Whereas U.S. Pat. No. 3,349,754 which issued on Oct. 31, 1967 discloses a modified construction to that of U.S. Pat. No. 2,950,740, but modified by the individual vanes terminating at a central core region of the flue. Each of the above US patents, like the Australian reference, discloses individually located and welded vanes or fins. These vanes or fins arm relatively time-consuming to install if welded to the flue manually. Otherwise, to weld by machine requires complicated and expensive machinery.
Another difficulty with prior art constructions is that those fins closest to the combustion chamber tend to oxidise and progressively disintegrate. This can occur because of the damage caused by the absorption of excessive heat.
Corrosion can also occur in the fins elsewhere along the flue, if the flue is relatively efficient in extracting heat form the exhaust gases. This is particularly the case at the downstreams portions of the flue, because by the time the gases reach these portions, the temperature of the exhaust gases can drop below the dew point of the moisture contained in the gases. This will result in deposition of moisture on the downstream portions of the flue. If moisture builds up sufficiently and if combustion in the combustion chamber is switched off (such as when the water reaches the desired temperature), then the moisture can spread or drip to other portions of the flue causing erosion and creating a relatively hostile environment for the flue and fins.
One common solution to this moisture, corrosion and hostile environment is to enamel the interior of the flue. However, with individual fins being welded to flues, this is generally not done, because of difficulties in attempting to enamel fins having sharp edges and the like. In such situations it has been found that enamel does not stick the fins. If they are enamelled, because the enamel may only temporarily stick to the metal, and because of the hostile environment at the upstream end of the flue, the excessive heat will cause the enamel linings to disintegrate. Once this disintegration of the enamel occurs, corrosion or oxidation starts in the fins or vanes, which can then continue into other areas, accelerating the deterioration of the flue system, and thus the water heater.
SUMMARY OF THE INVENTION
The present invention provides a heat exchange element adapted to be attached to a surface of a flue of a water heater, and having an imaginary X axis along its length and an imaginary Y axis across its width being orthogonal to said X axis, and an imaginary Z axis orthogonal to the X and Y axes; said Z axis having a positive and negative direction, said negative direction beginning at, and extending away from a rear surface and said positive direction beginning at, and extending away from a front surface; a support member extending in the X axis direction having at least one vane on each of two opposing sides of said support member, said vanes being spaced apart in the Y direction on the supporting member; said vanes extending generally away from said front surface in a direction having a positive Z direction component.
The present invention also provides a heat exchange element adapted to be attached to an inside surface of a flue of a water heater, and having an imaginary X axis along its length and an imaginary Y axis across its width orthogonal to said X axis and an Z axis orthogonal to the X and Y axes; said Z axis having a positive and negative direction, said negative direction beginning at, and extending away from a rear surface and, said positive direction beginning at, and extending away from a front surface; a support member extending in the X axis direction having at least one vane extending in a direction having a positive Z direction component away from said front surface and on at least one side of said support member, wherein said support member is of a length greater than the extent of said at least one vane from said support
The present invention provides a heat exchange element including:
an elongate base portion, having front and rear longitudinally extending surfaces, the rear surface being of a profile to substantially match a surface of flue to which said element is to be attached;
a plurality of vanes arranged along the base portion and projecting forwardly relatively to said front surface, said element having an imaginary X axis along its length and an imaginary Y axis across its width, said Y axis being orthogonal to said X axis, and an imaginary Z axis orthogonal to the X and Y axes; said Z axis having a positive and negative direction, said negative direction beginning at, and extending away from the rear surface and said positive direction beginning at, and extending away from the front surface.
Preferably said element is formed from a sheet material and is folded into a desired shape.
Preferably said element is formed from a channel member.
Preferably said element is formed from a substantially L-shaped member.
Preferably said element is constructed so that the X axis is positionable substantially parallel to a longitudinal axis of a flue.
Preferably each vane is an elongated tab or finger like projection.
Preferably at least one vane is oriented at an angle in the range of 0° to 35° to said X axis.
Preferably there is located one vane only on each of two opposing sides of said element parallel to said X axis, each vane extending parallel to said X-axis and being of substantially the same length as said support member.
Preferably said element is constructed so that when said X axis is positioned substantially parallel to said longitudinal axis of said flue, said vane means is at substantially the same angle to said longitudinal axis of said flue as it is to said X axis.
Preferably said rear surface includes a contour which substantially matches the contour of a surface of a flue to which it is to be attached.
Preferably said contour renders said element positionable relative to said flue, so that said X axis is only positionable substantially parallel to said longitudinal axis of said flue.
Preferably said rear surface includes a shape which provides at least one band, extending parallel to said X axis, by means of which said element can contact and be attached to said inside surface of said flue.
Preferably said rear surface includes, about said X axis, an external radius, not larger than an inside radius of said flue, said external radius being adapted to be connected to said inside surface of said flue.
Preferably said rear surface of said support member has a contour, shape or radius which provides said rear surface with a concave or convex shape relative to said negative direction of said Z axis.
Preferably at one end of said element said vane or vanes terminate at a lesser distance from said support member than the vanes or a portion of the vane, at the second end of said element.
Preferably at one end of said element said vanes have the same length for a predetermined length of said element, whereupon the length of said van
Lu Jiping
Schnader Harrison Segal & Lewis LLP
Southcorp Australia Pty. Ltd.
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