U.S. patent application number 11/222350 was filed with the patent office on 2007-03-08 for looped system fuel-fired fluid heating/storage device.
Invention is credited to Jeffrey M. Haney, Ozzie Missoum, Phillip W. Stephens, Gregory M. Welk, Qian Zhang.
Application Number | 20070051359 11/222350 |
Document ID | / |
Family ID | 37828919 |
Filed Date | 2007-03-08 |
United States Patent
Application |
20070051359 |
Kind Code |
A1 |
Missoum; Ozzie ; et
al. |
March 8, 2007 |
Looped system fuel-fired fluid heating/storage device
Abstract
A fuel-fired commercial water heater has a three-pass condensing
type heat exchanger disposed within its tank and having a vertical
flue connected at its lower end to a central collector plenum
horizontally circumscribed by an outer plenum to which an exhaust
pipe is coupled. A series of vertical tube structures are disposed
above and intercommunicate the central and outer collector plenums.
The outlet of a fuel burner is coupled to the upper end of the flue
and is operative to sequentially flow combustion gases downwardly
through the flue into the central collector plenum, upwardly and
then downwardly through the tube structures into the outer
collector plenum and then outwardly through the exhaust pipe.
Inventors: |
Missoum; Ozzie; (Pike Road,
AL) ; Welk; Gregory M.; (Prattville, AL) ;
Zhang; Qian; (Montgomery, AL) ; Stephens; Phillip
W.; (Millbrook, AL) ; Haney; Jeffrey M.;
(Montgomery, AL) |
Correspondence
Address: |
HAYNES AND BOONE, LLP
901 MAIN STREET, SUITE 3100
DALLAS
TX
75202
US
|
Family ID: |
37828919 |
Appl. No.: |
11/222350 |
Filed: |
September 8, 2005 |
Current U.S.
Class: |
126/110R |
Current CPC
Class: |
F24H 1/285 20130101;
Y02B 30/00 20130101; Y02B 30/102 20130101; F24H 8/00 20130101 |
Class at
Publication: |
126/110.00R |
International
Class: |
F24H 3/06 20060101
F24H003/06 |
Claims
1. A fuel-fired fluid heating apparatus comprising: a tank for
holding a fluid to be heated; a heat exchanger disposed in said
tank and having an interior combustion gas flow path defined by: a
first pass section having an inlet portion and an outlet portion
spaced apart from said inlet portion of said first pass section in
a first direction, a central collector plenum coupled to said
outlet portion of said first pass section, a second pass section
having an inlet portion coupled to said central collector plenum
and an outlet portion spaced apart from said inlet portion of said
second pass section in a second direction opposite from said first
direction, a third pass section having an inlet portion coupled to
said outlet portion of said second pass section and an outlet
portion spaced apart from said inlet portion of said third pass
section in said first direction, an outer collector plenum
circumscribing said collector plenum and being coupled to said
outlet portion of said third pass section, and an exhaust section
coupled to said outer collector plenum; and a combustion system
operative to flow hot combustion gases into said inlet portion of
said first pass section and then through the balance of said flow
path.
2. The fuel-fired fluid heating apparatus of claim 1 wherein: said
fuel-fired fluid heating apparatus is a fuel-fired water
heater.
3. The fuel-fired fluid heating apparatus of claim 1 wherein: said
heat exchanger is a condensing type heat exchanger.
4. The fuel-fired fluid heating apparatus of claim 1 wherein: said
combustion system includes a fuel burner having an outlet coupled
to said inlet portion of said first pass section.
5. The fuel-fired fluid heating apparatus of claim 1 wherein: said
first direction extends generally downwardly, and said second
direction extends generally upwardly.
6. The fuel-fired fluid heating apparatus of claim 5 wherein: said
outer collector plenum has a vertically sloped bottom side with a
lowermost portion, and said exhaust section has an inlet portion
coupled to said lowermost portion.
7. The fuel-fired fluid heating apparatus of claim 6 further
comprising: a condensate drain line interconnected between a bottom
side portion of said central collector plenum and said exhaust
section.
8. The fuel-fired fluid heating apparatus of claim 5 wherein: said
central collector plenum extends downwardly beyond said outer
collector plenum.
9. The fuel-fired fluid heating apparatus of claim 8 wherein: said
central collector plenum has a domed bottom side.
10. The fuel-fired fluid heating apparatus of claim 1 wherein: said
central collector plenum extends past said outer collector plenum
in said first direction.
11. The fuel-fired fluid heating apparatus of claim 1 wherein: said
second and third pass sections are at least partially defined by a
U-tube structure extending parallel to said first pass section and
having a first open end coupled to said central collector plenum,
and a second open end coupled to said outer collector plenum.
12. The fuel-fired fluid heating apparatus of claim 1 wherein: said
second and third pass sections are defined by a plurality of U-tube
structures circumferentially spaced around and extending parallel
to said first pass section, each of said U-tube structures having a
first open end coupled to said central collector plenum, and a
second open end coupled to said outer collector plenum.
13. The fuel-fired fluid heating apparatus of claim 1 wherein: said
fuel-fired fluid heating apparatus further comprises a transfer
plenum disposed exteriorly of said tank, said second pass section
is defined by at least one straight second pass tube having an
inlet end coupled to said central collector plenum and an outlet
end coupled to said transfer plenum, and said third pass section is
defined by at least one straight third pass tube having an inlet
end coupled to said transfer plenum and an outlet end coupled to
said outer collector plenum.
14. The fuel-fired fluid heating apparatus of claim 13 wherein:
said at least one straight second pass tube is a plurality of
straight second pass tubes circumferentially spaced around said
first pass section, and said at least one straight third pass tube
is a plurality of straight third pass tubes circumferentially
spaced around said plurality of straight second pass tubes.
15. A fuel-fired water heater comprising: a tank for holding water
to be heated; a condensing type heat exchanger disposed within said
tank and having: a vertically extending flue having an upper inlet
end and a lower outlet end, a central collector plenum coupled to
said lower outlet end of said flue, an outer collector plenum
horizontally circumscribing said central collector plenum, a
plurality of vertically extending inverted U-tubes horizontally
spaced around said flue, each said inverted U-tube having a lower
inlet end coupled to said central collector plenum, and a lower
outlet end coupled to said outer collector plenum, and an exhaust
pipe having an inlet portion coupled to said outer collector
plenum; and a fuel burner having an outlet coupled to said upper
inlet end of said flue, said fuel burner being operative to flow
combustion gases through said flue and then the balance of said
condensing type heat exchanger.
16. The fuel-fired water heater of claim 15 wherein: said
fuel-fired water heater is a commercial water heater.
17. The fuel-fired water heater of claim 15 wherein: said inlet
portion of said exhaust pipe is coupled to a lower side of said
outer collector plenum, and said fuel-fired water heater further
comprises a condensate line disposed within said tank and
interconnected between said inlet portion of said exhaust pipe and
a bottom side portion of said central collector plenum.
18. The fuel-fired water heater of claim 15 wherein: said outer
collector plenum has a bottom side that slopes downwardly toward
said inlet portion of said exhaust pipe, said bottom side having a
lowermost portion to which said inlet portion of said exhaust pipe
is coupled.
19. The fuel-fired water heater of claim 15 wherein: a portion of
said central collector plenum extends downwardly beyond said outer
collector plenum.
20. The fuel-fired water heater of claim 19 wherein: said portion
of said central collector plenum has a downwardly domed
configuration.
21. A fuel-fired water heater comprising: a tank for holding water
to be heated; a transfer plenum disposed exteriorly of said tank at
an upper end portion thereof; a condensing type heat exchanger
disposed within said tank and having: a vertically extending flue
having an upper inlet end and a lower outlet end, a central
collector plenum coupled to said lower outlet end of said flue, an
outer collector plenum horizontally circumscribing said central
collector plenum, a first plurality of vertical tubes horizontally
spaced around said flue and having lower inlet ends coupled to said
central collector plenum, and upper outlet ends coupled to said
transfer plenum, a second plurality of vertical tubes disposed
horizontally outwardly of and horizontally spaced around said first
plurality of vertical tubes, said second plurality of vertical
tubes having upper inlet ends coupled to said transfer plenum, and
lower outlet ends coupled to said outer collector plenum, and an
exhaust pipe having an inlet portion coupled to said outer
collector plenum; and a fuel burner having an outlet coupled to
said upper inlet end of said flue, said fuel burner being operative
to flow combustion gases through said flue and then the balance of
said condensing type heat exchanger.
22. The fuel-fired water heater of claim 21 wherein: said
fuel-fired water heater is a commercial water heater.
23. The fuel-fired water heater of claim 21 wherein: said inlet
portion of said exhaust pipe is coupled to a lower side of said
outer collector plenum, and said fuel-fired water heater further
comprises a condensate line disposed within said tank and
interconnected between said inlet portion of said exhaust pipe and
a bottom side portion of said central collector plenum.
24. The fuel-fired water heater of claim 21 wherein: said outer
collector plenum has a bottom side that slopes downwardly toward
said inlet portion of said exhaust pipe, said bottom side having a
lowermost portion to which said inlet portion of said exhaust pipe
is coupled.
25. The fuel-fired water heater of claim 21 wherein: a portion of
said central collector plenum extends downwardly beyond said outer
collector plenum.
26. The fuel-fired water heater of claim 25 wherein: said portion
of said central collector plenum has a downwardly domed
configuration.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention generally relates to fuel-fired fluid
heating devices and, in representatively illustrated embodiments
thereof, more particularly provides a fuel-fired water heater
having a specially designed multi-pass condensing type heat
exchanger incorporated therein.
[0002] Conventional fuel-fired water heaters are typically of a
"single pass", non-condensing configuration, meaning that the hot
combustion gases used to heat the tank-stored water are subjected
to only a single pass through a heat exchanger structure (usually a
vertical flue) within the tank before being discharged from the
water heater to, for example, an external vent structure, and that
flue gas condensation does not occur to any appreciable degree in
the heat exchanger structure within the water heater tank. In this
conventional type of fuel-fired water heater, the overall thermal
efficiency is typically limited to about 80-85%. Various proposals
have been made to provide fuel-fired water heaters with condensing
type single-pass heat exchangers (i.e., in which flue gases
condense within the heat exchanger). However, previously proposed
single-pass condensing type heat exchange structures incorporated
in fuel-fired water heaters typically provide the water heaters
with thermal efficiencies limited to the 85-90% range.
[0003] In an attempt to increase this thermal efficiency to above
95%, multi-pass condensing heat exchangers of varying
configurations and types have been proposed for installation within
the tank portions of fuel-fired water heaters. While such
previously proposed multi-pass condensing type heat exchangers have
met this thermal efficiency goal, they have also undesirably
presented various problems, limitations and disadvantages. These
include increased heat exchanger complexity, higher material and
fabricational costs, condensate management problems, increased
operational noise, and reduced heat exchanger operational life.
[0004] It would thus be desirable to provide a fuel-fired water
heater, or other type of fuel-fired fluid heating device, with an
improved multi-pass condensing type heat exchanger. It is to this
goal that the present invention is primarily directed.
SUMMARY OF THE INVENTION
[0005] In carrying out principles of the present invention, in
accordance with representative embodiments thereof, a fuel-fired
fluid heating apparatus is provided that is representatively a
fuel-fired commercial water heater, but could alternatively be
another type of fuel-fired water heater or another type of
fuel-fired fluid heating apparatus such as, for example, a
boiler.
[0006] In general, the apparatus comprises a tank for holding a
fluid to be heated, and a heat exchanger disposed in the tank and
having an interior combustion gas flow path defined by (1) a first
pass section having an inlet portion and an outlet portion spaced
apart from the inlet portion of the first pass section in a first
direction, (2) a central collector plenum coupled to the outlet
portion of the first pass section, (3) a second pass section having
an inlet portion coupled to the central collector plenum and an
outlet portion spaced apart from the inlet portion of the second
pass section in a second direction opposite from the first
direction, (4) a third pass section having an inlet portion coupled
to the outlet portion of the second pass section and an outlet
portion spaced apart from the inlet portion of the third pass
section in the first direction, (5) an outer collector plenum
circumscribing the collector plenum and being coupled to the outlet
portion of the third pass section, and (6) an exhaust section
coupled to the outer collector plenum. Additionally, the apparatus
comprises a combustion system operative to flow hot combustion
gases into the inlet portion of the first pass section and then
through the balance of the heat exchanger.
[0007] In a first embodiment thereof, the apparatus is a fuel-fired
water heater comprising a tank for holding water to be heated, and
a condensing type multi-pass heat exchanger disposed within the
tank. The heat exchanger includes (1) a vertically extending flue
having an upper inlet end and a lower outlet end, (2) a central
collector plenum coupled to the lower outlet end of the flue, (3)
an outer collector plenum horizontally circumscribing the central
collector plenum, (4) a plurality of vertically extending inverted
U-tubes horizontally spaced around the flue, each inverted U-tube
having a lower inlet end coupled to the central collector plenum,
and a lower outlet end coupled to the outer collector plenum, and
(5) an exhaust pipe having an inlet portion coupled to the outer
collector plenum. The water heater also comprises a fuel burner
(which may be either a powered fuel burner or a non-powered burner)
having an outlet coupled to the upper inlet end of said flue, the
fuel burner being operative to flow combustion gases through the
flue and then the balance of the condensing type heat
exchanger.
[0008] In a second embodiment thereof, the apparatus is a
fuel-fired water heater comprising a tank for holding water to be
heated, a transfer plenum disposed exteriorly of he tank at an
upper end portion thereof, and a condensing type multi-pass heat
exchanger disposed within the tank. The heat exchanger includes (1)
a vertically extending flue having an upper inlet end and a lower
outlet end, (2) a central collector plenum coupled to said lower
outlet end of said flue, (3) an outer collector plenum horizontally
circumscribing the central collector plenum, (4) a first plurality
of vertical tubes horizontally spaced around the flue and having
lower inlet ends coupled to the central collector plenum, and upper
outlet ends coupled to the transfer plenum, (5) a second plurality
of vertical tubes disposed horizontally outwardly of and
horizontally spaced around the first plurality of vertical tubes,
the second plurality of vertical tubes having upper inlet ends
coupled to the transfer plenum, and lower outlet ends coupled to
the outer collector plenum, and (6) an exhaust pipe having an inlet
portion coupled to the outer collector plenum. The water heater
also comprises a fuel burner (which may be either a powered fuel
burner or a non-powered fuel burner) having an outlet coupled to
the upper inlet end of the flue, the fuel burner being operative to
flow combustion gases through the flue and then the balance of the
condensing type heat exchanger.
[0009] According to other aspects of the invention a portion of the
central collector plenum extends downwardly past the outer
collector plenum, the outer collector plenum has vertically sloped
lower side having a lowermost portion to which an inlet portion of
the exhaust pipe is connected, the bottom side of the central
collector plenum has a downwardly domed configuration, and a sloped
condensate drain line extends within the tank from the bottom side
of the central collector plenum to an inlet portion of the exhaust
pipe within the tank.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic cross-sectional view through a
representative fuel-fired water heater having incorporated therein
a specially designed condensing type multi-pass heat exchanger
embodying principles of the present invention; and
[0011] FIG. 2 is a schematic cross-sectional view through an
alternate embodiment of the FIG. 1 water heater.
DETAILED DESCRIPTION
[0012] Schematically illustrated in cross-section in FIG. 1 is a
looped system fuel-fired fluid heating/storage device embodying
principles of the present invention, the device representatively
being a fuel-fired commercial water heater 10 having a specially
designed condensing type multi-pass heat exchanger 12 submerged in
the pressurized stored water 14 in an externally insulated tank
portion 16. As used herein the term "commercial" water heater
means, as commonly accepted in the water heater industry, a water
heater having a firing input rate typically above about 75,000
Btu/Hr., and a heated water temperature of about 180.degree. F. or
above. While the illustrated device 10 is representatively a
commercial water heater, it could alternatively be a non-commercial
water heater, or another type of fuel-fired fluid heating device,
such as for example, a boiler, without departing from principles of
the present invention.
[0013] During firing of the water heater 10, hot flue gases 18 from
a fuel burner 20 atop the water heater are flowed through the heat
exchanger 12 to transfer combustion heat, with a thermal efficiency
of 95% or above, to the stored water 14. Burner 20 may be either a
powered fuel burner or a non-powered fuel burner. On demand,
pressurized heated water 14 stored in the tank 16 may be withdrawn
therefrom through a tank-mounted outlet fitting 21. Automatically,
the withdrawn water 14 is replaced with pressurized cold water,
from a source thereof, through a tank-mounted inlet fitting 23.
[0014] The heat exchanger 12 is of a three-pass configuration and
includes a vertical flue portion 22 connected at its upper end to
the outlet of the burner 20 and connected at its lower end to an
inverted dome-shaped central primary flue gas collector plenum 24
horizontally circumscribed by an annular secondary flue gas
collector plenum 26 that has a bottom wall which is vertically
sloped downwardly and rightwardly as indicated by the slope arrow
27 in FIG. 1. A series of vertically extending inverted U-tubes 28
(only two of which are shown in FIG. 1) are spaced around the
central flue 22. Each inverted U-tube 28 has one leg 28a connected
to and communicated with the central plenum 24 and another leg 28b
connected to the annular outer plenum 26 as shown. A combustion gas
exhaust pipe 30 is connected to the underside of the annular plenum
26 and has, external to the water heater, a condensate drain
fitting 32. A submerged condensate line 34 is interconnected
between the underside of the central plenum 24 and an inlet portion
of the exhaust pipe 30 as shown.
[0015] During firing of the water heater 10, the flue gas 18
discharged from the burner 20 sequentially makes a first pass
downwardly through the vertical central flue portion 22, a second
pass from the central plenum 24 upwardly through the U-tube legs
28a, and a third pass downwardly through the U-tube legs 28b into
the annular outer plenum 26, with condensation 35 from the flue gas
18 being formed within the U-tube legs 28b as shown. Condensate
from the annular plenum 26 flows into the exhaust pipe 30, and any
condensate which may be in the central plenum 24 also flows into
the exhaust pipe 30 via the submerged, sloped condensate line
34.
[0016] The modified water heater 10a shown in FIG. 2 is identical
to the FIG. 1 water heater 10 with the exception that in the
modified heat exchanger 12a the inverted U-tubes 28 (see FIG. 1)
are replaced with straight vertical second pass tubes 36 and
straight vertical third pass tubes 38. As illustrated in FIG. 2,
the second pass tubes 36 are interconnected between the plenum 24
and an upper transfer plenum 40 disposed in insulation 42 above the
top end 44 of the top of the tank 16, and the third pass tubes 38
are interconnected between the plenums 26 and 40.
[0017] During firing of the water heater 10a, flue gases 18 from
the burner 20 sequentially flow downwardly through the vertical
central flue portion 22 into the central plenum 24, upwardly from
the plenum 24 through the vertical tubes 36 into the top plenum 40,
and then downwardly from the top plenum 40 through the vertical
tubes 38 into the bottom annular plenum 26 from which they are
discharged via the exhaust pipe 30. Condensate 35 formed in the
third pass tubes 38 is discharged from the heat exchanger 12a in a
manner similar to that previously described in conjunction with the
FIG. 1 heat exchanger 12.
[0018] Compared to conventional multi-pass condensing type heat
exchangers utilized in fuel-fired water heaters, the heat
exchangers 12,12a representatively illustrated and described herein
provide a variety of advantages which may include, for example, the
capability of providing their associated water heaters with thermal
efficiencies well above 95%, simplified heat exchanger
configuration, reduced material and fabricational costs, quieter
operation, increased heat exchanger life, and improved condensate
management.
[0019] As will be readily appreciated by those of skill in this
particular art, the representatively illustrated heat exchangers 12
and 12a, could have other orientations within their associated
water heaters 10 and 10a without departing from principles of the
present invention. For example, the heat exchangers 12 and 12a,
with minor modifications thereto, could alternatively be
horizontally oriented within their associated water heaters 10 and
10a.
[0020] The foregoing detailed description is to be clearly
understood as being given by way of illustration and example only,
the spirit and scope of the present invention being limited solely
by the appended claims.
* * * * *