Information
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Patent Grant
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6564794
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Patent Number
6,564,794
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Date Filed
Monday, January 7, 200222 years ago
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Date Issued
Tuesday, May 20, 200321 years ago
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Inventors
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Original Assignees
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Examiners
- Bennett; Henry
- Basichas; Alfred
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CPC
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US Classifications
Field of Search
US
- 126 110 R
- 126 99 D
- 165 170
- 165 159
- 165 401
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International Classifications
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Abstract
In a furnace having a plurality of parallel heat exchanger panels over which circulation air is caused to flow, and which has a tendency for hot spots to occur at particular locations on its outboard heat exchanger panels, a diverter vane is placed on the outer side of each of the outboard heat exchanger panels to divert a portion of the circulation air to the hotspot locations for cooling them to acceptable temperatures. In one form, the diverter vane is integrally formed with, and extends normally inwardly from a side baffle that extends upwardly alongside the outboard heat exchanger panel. The diverter vane is obliquely disposed with respect to the side baffle, with its lower end located near a midpoint of the heat exchanger panel and its upper end located near the hotspot location. When used with a multipass heat exchanger panel, the hotspot location is between the end of the first return bend and the commencement of the second pass, and the diverter vane is thus positioned with its top end near that location. Where a blower shelf baffle is employed, the diverter vane lower end is positioned near that location.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to furnaces and, more particularly, to an air baffle diverter vane for diverting air over a particular portion of a furnace heat exchanger for preventing hot spots.
Residential furnaces typically include a plurality of heat exchanger panels or cells arranged in parallel relationship, with the air to be heated being circulated by a blower so as to pass between the panels and over the surfaces of the panels, to be heated. The panels have associated burners for heating the air within the panels, and an inducer may be employed to draw the heated air through the panels and discharge them to a flu.
One form of heat exchanger that is commonly used in such furnaces is a so-called clamshell heat exchanger, wherein two stamped metal shells are fastened together to form a single panel having a plurality of serpentine passages, or passes, through which the hot gases can be caused to flow. Thus, a burner heats the air at an inlet end thereof, and the hot gases pass through successive passes and finally come out of the exit end of the panel to eventually be discharged to the flu. As the gases pass from the inlet to the exit end of the panel, they are cooled by the air being circulated over the surface of the panel. Thus, the gases in the first pass are at substantially higher temperatures than those downstream thereof, and care must be taken to prevent the occurrence of excessive temperatures. In particular, hot spots are most likely to occur in the vicinity of the first return bend between the first and second passes. These hot spots cause exposure to high temperatures that can cause excessive strain levels in the material of the heat exchanger structure and may eventually lead to failure.
Typically, the peak temperatures on the outside of the outboard heat exchanger panels are higher than the temperature on the inboard heat exchanger panels. In an effort to obtain greater circulation airflow over the outer sides of these outboard heat exchanger panels, so-called sidewall baffles have been applied to better channel the circulation airflow along the outer surfaces of the outdoor panels. Such sidewall baffles are generally fastened to the furnace casing or to the blower shelf and extend substantially vertically upwardly in parallel relationship with its associated outboard heat exchanger panel. While these sidewall baffles are useful in improving the air circulation over the outboard panels and thereby preventing excessive temperatures in this area, they may not be sufficient to prevent hot spots, especially in the sensitive area of the first return bend.
It is therefore an object of the present invention to provide an improved furnace heat exchanger apparatus.
Another object of the present invention is to provide a heat exchanger apparatus with reduced thermal stress.
Yet another object of the present invention is the provision for maintaining the temperatures on the surface of an outboard heat exchanger panel within acceptable limits.
Still another object of the present invention is the provision in heat exchanger apparatus for lowering both the peak temperatures on the surface of an outboard heat exchanger.
Another object of the present invention is the provision in a heat exchanger apparatus for reducing the occurrence of hot spots in the first return bend of an outboard heat exchanger panel.
These objects and other features and advantages become more readily apparent on reference to the following descriptions when taken in conjunction with the appended drawings.
SUMMARY OF THE INVENTION
Briefly, in accordance with one aspect of the invention, a diverter vane is added to the inboard side of a sidewall baffle and extends inwardly toward an outboard heat exchanger panel so as to divert a portion of the circulation airflow to particular areas on the heat exchanger panel surface which might otherwise experience hot spots.
In accordance with another aspect of the invention, the diverter vane is permanently affixed to and extends substantially normally from said sidewall baffle.
In accordance with yet another aspect of the invention, the diverter vane is disposed at an oblique angle with respect to the heat exchanger passes, with its lower end being located near a central point of said first pass and its upper end being located near the end of said first return bend.
In the drawings as hereinafter described, a preferred embodiment is depicted; however, various other modifications and alternate constructions can be made thereto without departing from the true spirit and scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a top view of a heat exchanger assembly and diverter vanes as installed in a furnace in accordance with the present invention.
FIG. 2
is a perspective view of a heat exchanger panel and a diverter vane as installed in a furnace in accordance with the present invention.
FIG. 3
is a side view of the heat exchanger panel and a diverter vane as installed in a furnace in accordance with the present invention.
FIG. 4
is a perspective view of a blower shelf, sidewall baffles and diverter vanes as installed in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to
FIGS. 1 and 2
, the invention is shown generally at
10
as applied to a furnace having a blower shelf
11
which defines the boundary between a blower compartment therebelow and a heat exchanger compartment
12
thereabove.
Attached to the blower shelf
11
is a cell panel
13
which extends upwardly and forwardly as shown and includes the integrally connected upper panel
14
, middle panel
16
, and front panel
17
. The front panel
17
defines the boundary between the circulating air below and the combustion air above. The middle panel
16
has a plurality of burner openings
18
formed therein for receiving individual burners (not shown) that extend therethrough in a conventional manner. A gas manifold (not shown) provides gas to the individual burners, and combustion air is provided to those burners, with the gas/air mixture then being ignited to provide hot gases for producing heat.
The upper panel
14
includes a plurality of spaced outlet openings
19
from which the hot gases are discharged after passing through the heat exchanger compartment
12
. A collector box (not shown) provides a common cover over the outlet openings
19
and is attached to an inducer (not shown) which acts in a conventional manner to draw the combustion gases from the burner openings
18
, through the heat exchanger compartment
12
and through the outlet openings
19
for eventual discharge to a flu.
Behind the cell panel
13
, and within the heat exchanger compartment
12
, there are provided a plurality of heat exchanger panels
21
that are arranged in a side-by-side, parallel relationship and extending upwardly as shown. Each of the heat exchanger panels
21
has an inlet opening
22
and an outlet opening
23
, with the inlet opening
22
being in registration with a corresponding burner opening
18
and with the outlet opening
23
being in registration with a corresponding outlet opening
19
of the upper panel
14
. Each of the heat exchanger panels
21
is fastened near its outlet opening
23
to the upper panel
14
and near its inlet opening
22
to the middle panel
16
. Thus each of the heat exchanger panels
21
is completely supported by the cell panel
13
, which in turn is supported by the blower shelf
11
and the furnace casing.
As will be seen in
FIGS. 2 and 3
, the heat exchanger panels
21
are of the clamshell type and include multiple serpentine passes that provide a fluidic flow of the hot gases flowing internally therein from its inlet opening
22
to its outlet opening
23
. The first pass
24
is fluidly connected to the second pass
26
by a first return bend
27
, the second pass
26
is fluidly connected to the third pass
28
by a second return bend
29
, and the third pass
28
is fluidly interconnected to the fourth pass
31
by a third return bend
32
.
In operation, the hot gases pass from the burners to the inlet openings
22
of the respective heat exchanger panels and progressively pass through the four passes to the outlet openings
23
. At the same time, the air to be heated is caused to circulate upwardly by the circulating fan located in the blower compartment. The air passes over the outer surfaces of the heat exchanger panels
21
to be heated, with the hot air then being further circulated by a duct to a space to be heated. This is a conventional operation in the industry, and though the apparatus has been described with some specificity, it may take other forms while remaining within the applicability of the present invention. For example, while the heat exchanger panel has been described as a multipass, clamshell heat exchanger, other types, such as a pipe heat exchanger, may be used. Further, the system has been described in terms of use with an inducer, but it should be understood that the present invention would also be applicable to a furnace without an inducer.
In order to obtain a relatively uniform flow of circulating air over the heat exchanger panels, it has become common practice to include a so-called blower shelf baffle
33
near the leading edge or bottom surface of the heat exchanger panels
21
. Such a baffle is generally placed just to one side of the midpoint of the heat exchanger panels
21
and extends laterally across each of the heat exchanger panels and is attached to the blower shelf
11
on either side thereof. The purpose of this baffle is to somewhat straighten (i.e. divert it to a vertical direction) the flow of air coming from the fan with a horizontal component.
Other baffles that are conventionally used include sidewall baffles and rear wall baffles. In the present apparatus, it will be seen in
FIGS. 1-4
that the sidewall baffles are shown at
34
and
36
, and the rear wall baffle is shown at
37
. The sidewall baffles
34
and
36
are mounted on the blower shelf
11
and extend vertically upward in the parallel relationship with, and spaced from, the respective outboard heat exchanger panels. Their purpose is to assist in directing the airflow along the outer surfaces of the outboard heat exchanger panels so as to enhance the heat transfer characteristics thereof. This is desirable because of the tendency of the outboard heat exchanger panels to have a less uniform distribution of airflow over their surfaces as compared with the inboard heat exchanger panels which are centrally located with respect to the airflow stream.
The rear wall baffle
37
has a similar purpose in that it again is positioned on the periphery of the airflow stream in order to provide a more uniform airflow distribution and enhanced heat transfer characteristics in that area. In particular, this baffle
37
is generally placed near the first return bend
27
, where hot spots are most likely to a occur. That is, because the hot gases are cooled as the flow proceeds along the various passes, the temperatures are the highest in the first pass. Further, because of the change of direction that occurs at the return bend
27
, the point at which hot spots are most likely to occur are at the end of the return bend
27
or the beginning of the second pass
26
. Accordingly, the rear wall baffle
37
is placed near this location and includes a plurality of generally horizontally extending baffle plates
38
that are disposed between the respective heat exchanger panels
21
and which tend to direct some of the upflowing circulating air over that area in which the hot spots are most likely to occur. The baffle plates
38
are preferably sized so as to engage the heat exchanger panels
21
on either side thereof so as to serve a second purpose of maintaining proper spacing between adjacent heat exchanger panels
21
.
The applicants have found that even with the use of the sidewall baffles
34
and
36
, and the rear wall baffle
37
, hot spots may still occur. In particular, at the critical location between the first return bend
37
and the second pass
26
of the outboard heat exchanger panels
21
, it was found that the existing baffles did not prevent hot spots. Accordingly, a diverter vane was installed near each of the outboard heat exchanger panels
21
to farther enhance the airflow distribution in this area.
The diverter vanes are shown at
39
and
41
in
FIGS. 1-4
. As will most clearly be seen in
FIG. 4
, the diverter vanes
39
and
41
are formed by simply making three sided cuts through each of the sidewall baffles
34
and
36
and bending the rectangular shaped diverter vane members
39
and
41
downwardly so that they extend substantially normally from their respective sidewall baffles
34
and
36
and leave the rectangular shaped openings
42
and
43
in the respective sidewall baffles
36
and
37
. They extend at an oblique angle to the plane of the heat exchanger passes, with one end
44
being located downwardly near the center of the first pass and the other end
46
being located upwardly near the area where the hot spots are most likely to occur as discussed hereinabove. Preferably, the lower end
44
is located near the blower shelf baffle
33
as shown in
FIGS. 1-3
such that the circulation air coming off of the blower shelf baffle
33
will be diverted by the diverter vanes
39
and
41
to channel a substantial portion of the circulatior air to the outer surface of the outboard heat exchanger panels in the critical area between the first return bend
27
and the second pass
26
thereof.
While the irvention has been described with reference to a preferred embodiment, it should be recognized that the invention is not limited to that particular embodiment. Rather, many modifications and variations will present themselves to persons skilled in the art without departing from the true scope and spirit of this invention. For example, although the diverter vanes are shown as being formed from, and integral with, the sidewall baffles, they may be separate pieces which are attached to the sidewall baffles.
Claims
- 1. An air baffle diverter vane for a furnace of the type having a plurality of heat exchanger panels aligned in parallel relationship for the transfer of heat from hot gases flowing internally therein to air being circulated over their outer surfaces, at least one of an outboard heat exchanger panel being susceptible to hot spots at a particular location on its surface, comprising:at least one side baffle mounted within the furnace, in substantial parallel relationship with, and spaced from, said outboard heat exchanger panel for directing the flow of circulated air over a side surface of said panel; and a diverter vane attached to and extending from said side baffle in the direction of said outboard heat exchanger panel for directing a portion of said circulating air over said hotspot location.
- 2. An air baffle diverter vane as set forth in claim 1 wherein said diverter vane extends substantially normally from said side baffle.
- 3. An air baffle diverter vane as set forth in claim 1 wherein said diverter vane extends at an oblique angle with respect to said side baffle, with its lower end being located near a midpoint said outboard heat exchanger panel and its upper end being located near said hotspot location.
- 4. An air baffle diverter vane as set forth in claim 1 wherein said heat exchanger panel is comprised of multiple passes with return bends therebetween.
- 5. An air baffle diverter vane as set forth in claim 4 wherein said hotspot location is between a first return bend and a second pass.
- 6. An air baffle diverter vane as set forth in claim 3 and including a blower shelf and a blower shelf baffle disposed below said heat exchanger panel and further wherein said diverter vane lower end is located near said blower shelf baffle.
- 7. An air baffle diverter vane as set forth in claim 1 wherein said diverter vane forms an integral part of said side baffle.
- 8. An air baffle diverter vane as set forth in claim 7 wherein said diverter vane comprises a portion of said side baffle which is cut out and bent over at one side thereof.
- 9. An air diverter vane arrangement for a furnace of the type having a plurality of side-by-side heat exchanger panels over which air is caused to circulate, including at least one outboard panel that is susceptible to hot spots at a particular location thereon, comprising:a side baffle mounted in the furnace near an outboard side of said at least one outboard heat exchanger panel and extending upwardly in substantially parallel relationship with said heat exchanger panei; and an air diverter vane extending from air inboard surface of said side baffle for diverting a portion of circulation air to cool the hotspot location.
- 10. An air diverter vane arrangement as set forth in claim 9 wherein said diverter vane extends substantially normally from said side baffle.
- 11. An air diverter vane arrangement as set forth in claim 9 wherein said diverter vane extends at an oblique angle with respect to said side baffle, with its lower end being located near a midpoint of said outboard heat exchanger panel and its upper end being located near said hotspot location.
- 12. An air diverter vane arrangement as set forth in claim 9 wherein said heat exchanger panel is comprised of multiple passes with return bends therebetween.
- 13. An air diverter vane arrangement as set forth in claim 12 wherein said hotspot location is between a first return bend and a second pass.
- 14. An air diverter vane arrangement as set forth in claim 11 and including a blower shelf and a blower shelf baffle disposed below said heat exchanger panel and further wherein said diverter vane lower end is located near said blower shelf baffle.
- 15. An air diverter vane arrangement as set forth in claim 9 wherein said diverter vane forms an integral part of said side baffle.
- 16. An air diverter vane arrangement as set forth in claim 15 wherein said diverter vane comprises a portion of said side baffle which is cut out and bent over at one side thereof.
US Referenced Citations (6)