US3667451A

US3667451A - Gas-fired heater means

Info

Publication number: US3667451A
Application number: US66800A
Authority: US
Inventors: James D Boucher
Original assignee: General Electric Co
Current assignee: Trane US Inc
Priority date: 1970-08-25
Filing date: 1970-08-25
Publication date: 1972-06-06
Anticipated expiration: 1989-06-06
Also published as: AU456348B2; AU3271971A; GB1347509A; DE2140810A1; FR2106010A5

Abstract

The present invention provides improved gas-fired heater means for supplying heat to a space, such as a room, house, building or the like. The improved heater means includes heat exchanger means for transferring heat generated by the combustion of a fuel gasair mixture to an air stream circulated between the heat exchanger means and the space, and pressurized combustor means for mixing fuel gas with pressurized air and burning that mixture to provide a source of heat to the heat exchanger means. In accordance with the present invention, the pressurized combustor means has its discharge fluid-connected to the upper portion of the heat exchanger means, and its vent for exhausting the waste products of combustion to the atmosphere is fluid-connected to the heat exchanger means lower portion. With this arrangement, the combustion products will be forced downward through the heat exchanger means and out through the vent by the pressurized air during operation of the combustor means, but condensate which may deposit within the heat exchanger means during dormancy of the combustor means will be directed away from the combustor means by gravity.

Description

States Patent [54] GAS-FIRED HEATER MEANS [72] Inventor: James D. Boucher, Tyler, Tex.

[73] Assignee: General Electric Company [22] Filed: Aug. 25, 1970 [21] Appl.No.: 66,800

[52] US. Cl. ..l26/1l0 R, 126/91 A, 126/1 16R,

[51] lnt.C1. .....F24h 3/06 [58] Field ofSearch ..126/90,9l,91 A, 110, 110 B, 126/116, 116 B, 431/181,182,190, 350, 351, 352,

[ June 6, 1972 Primary ExaminerCharles J. Myhre Attorney-Francis H. Boos, Jr., Walter E. Rule and Frank L. Neuhauser [57] ABSTRACT The present invention provides improved gas-fired heater means for supplying heat to a space, such as a room, house, building or the like. The improved heater means includes heat exchanger means for transferring heat generated by the combustion of a fuel gas-air mixture to an air stream circulated between the heat exchanger means and the space, and pressurized combustor means for mixing fuel gas with pressurized air and burning that mixture to provide a source of heat to the heat exchanger means. In accordance with the present invention, the pressurized combustor means has its discharge fluidconnected to the upper portion of the heat exchanger means, and its vent for exhausting the waste products of combustion to the atmosphere is fluid-connected to the heat exchanger means lower portion. With this arrangement, the combustion products will be forced downward through the heat exchanger means and out through the vent by the pressurized air during operation of the combustor means, but condensate which may deposit within the heat exchanger means during dormancy of the combustor means will be directed away from the combustor means by gravity.

2 C aims, 3 Drawing Figures GAS-FIRED HEATER MEANS CROSS-REFERENCE TO RELATED APPLICATION The present invention is directed to further improvement of that described in detail in co-pending, commonly assigned US. Pat. application Ser. No. 47,433 filed June 18, 1970, by Roy W. Abbott.

BACKGROUND OF THE INVENTION This invention relates to means for supplying heat to a space, such as a room, house, building or the like and, more particularly, to improved gas-fired heater means for supplying such heat.

Heretofore, conventional gas-fired space heater or furnace means have most frequently employed rather crude cast iron or steel heat exchangers having thegeneral shape of a hollow box or clam shell to transfer heat generated by the combustion of a combustible gas-air mixture to an air stream circulated between the heatexchanger and the space to be heated. And, these conventional heat exchangers have usually been combined with similarly unsophisticated combustor or burner means which have been very much like those used in gas cooking ranges and wherein the combustion air that is mixed with the fuel gas is supplied to the burner or combustor at atmospheric conditions. In these conventional heater means, the atmospheric combustor is located beneath the heat exchanger and the combustion products rise upwardly by natural convection through the heat exchanger and are discharged to the atmosphere via a vent or flue that is connected to the top of the heat exchanger. Frequently, such conventional heatexchangers are utilized in combination with a cooling unit which provides means for removing heat from the same space air stream. Of course, the heater means will bedormant during periods of operation of such cooling means, and, when the exterior of the heat exchanger of such conventional heater means is subjected to the chilled space air stream during operation of. the cooling means, this chilling often causes moisture to condense within the warmer interior of the heat exchanger of the dormant heater means. And, since the conventional atmospheric burner means are located beneath the heater means heat exchanger, this condensate will be directed by gravity toward the burner and deposited upon it. Collection of such condensate causes deterioration of the burner and will be detrimental to its subsequent operation.

The aforenoted Abbott patent application describes gasfired heater means which are superior to the aforedescribed conventional means in that they permit considerable weight and volume reduction-in heat exchanger means material by employing a combination of highly efficient heat exchanger means for transferring heat generated by the combustion of a combustible gas-air mixture to an air stream circulated between the heat exchanger means and the space to be heated, and high intensity combustor means for mixing fuel gas with pressurized air to produce and burn the combustible gas-air mixture. However, even its pressurized combustor means are located beneath. its heat exchanger means and, thus, are also subject to similar problems from condensate deposition to those previously noted with respect to conventional gas-fired heater means.

SUMMARY OF THE INVENTION In accordance with present invention, it has been found that the aforenoted problems of condensate collection upon the combustor or burner means of gas-fired space heater means can be eliminated. The improved gas-fired space heater means of the present invention is generally similar to that described in the aforenoted Abbott patent application in that it employs a combination of highly efficient heat exchanger means for transferring heat generated by the combustion of a fuel gas air mixture to an air stream circulated between the heat exchanger means and the space to be heated, and high intensity combustor means for mixing fuel gas with pressurized air and burning that mixture to provide a source of heat for the heat exchanger means. However, in accordance with the present invention, the discharge outlet from the pressurized combustor means is fluid-connected to the upper portion of the heat exchanger means and the vent for exhausting the waste products of combustion to the atmosphere is fluid-connected to the heat exchanger means lower portion. Hence, with this improved inverted" arrangement that is provided by the present invention, the combustion products will be forced downward through the heat exchanger means and out through the vent by the pressurized air during operation of the combustor means, but condensate which may deposit within the heat exchanger means during dormancy of .the combustor means will be directed away from the combustor means by gravity.

BRIEF DESCRIPTION OF THE DRAWING The present invention is illustrated in the accompanying drawing,- wherein:

FIG. 1 is a somewhat schematic, partly sectioned, front elevational view of a space air-conditioning unit incorporating a presently preferred form of the improved gas-fired space heater means of the present invention;

FIG. 2 is a greatly enlarged fragmentary sectional view taken along lines 2--2 of FIG. 1; and

FIG. 3 is a fragmentary sectional view taken along lines 3- 30f FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing and, more particularly to FIG. 1 thereof, there is illustrated somewhat schematically, an airconditioning unit, generally designated 10. The air-conditioning unit 10 is fluid-connected by right and left hollow conduit means 11 and 12 to a space 13 (shown in block), such as a room, house, building or the like, so as to condition the air contained within the space 13, as by supplying heat to or removing heat from an air stream, indicated by arrows 14, that is circulated between the space 13 and air-conditioning unit 10 through the conduit means 11 and 12 by space air blower means 15. As shown, the airconditioning unit 10 employs a presently preferred form of the improved gas-fired heater means, generally designated 16, that are provided in accordance with the present invention, to supply heat to the air stream 14, in combination with cooling means, including an evaporator section 17, to remove heat from the air stream 14.

As illustrated in FIG. 1, the air-conditioning unit 10 includes a generally rectangular hollow box-like cabinet 18 that is subdivided by vertically arranged partition 19 into a left compartment 20 and a right compartment 21. The cabinet left compartment 20 has an air inlet opening 22 in its upper wall that is fluid-connected to the space 13 by the left conduit means 12, while the upper wall of the cabinet right compartment 21 has an air outlet opening 23 that is fluid-connected to the space 13 by the right conduit means 11. The cabinet left compartment 20 houses the cooling means evaporator section 17 and the space air blower means 15, while the cabinet right compartment 21 houses presently preferred forms of heat exchanger means 24 and pressurized combustor means 25 that are combined in accordance with the present invention to produce the improved gas-fired heater means 16.

'As shown in FIGS. 1-3, the improved heater means 16 of the present invention is generally similar to a form of those described in the aforenoted Abbott patent application except that, in particular accordance with the present invention, the positions of the highly efficient heat exchanger 24 and the high intensity pressurized combustor means 25 are inverted as compared with those described by Abbott and, thus, provide advantages which will be described in detail hereinafter.

As further illustrated in FIGS. 1-3 the presently preferred form of the pressurized combustor means 25 includes an inverted, generally horizontally arranged, elongate trough 26 of inverted U-shape having generally vertically arranged, downwardly extending

side walls

27 and 28 that are provided with a plurality of apertures along their upper and lower edges to respectively define primary combustion air inlet apertures 29 and secondary combustion air inlet apertures 30. Combustion air is introduced into the inverted trough 26 through the primary and secondary combustion

air inlet apertures

29 and 30 under pressure that is provided by combustion air blower means 31. The combustion air blower 31 is housed in the upper right hand comer of the cabinet right compartment 21 and has its inlet connected to a combustion air intake conduit 32 which extends outwardly from the cabinet 18 through an opening 33 provided in the right side wall thereof. The combustion air blower 31 has its outlet connected via a combustion air blower discharge conduit 34 to a box-like combustion air supply plenum 35 that is located around the inverted trough 26. A generally horizontally disposed gas supply conduit 36 extends longitudinally through the inverted trough 26' and is provided with plural gas inlet apertures 37 located above the primary combustion-air inlet apertures 29. The inlet of the gas supply conduit 36 is connected via an electric control valve 38 of a well-known type to a source (not shown) of pressurized fuel gas, such as natural gas, propane, or the like. The fuel gas inlet apertures 37 are arranged such that the gas enters the inverted trough 26 generally parallel to the generally vertically arranged, downwardly extending

trough side walls

27 and 28 and is turbulently mixed as indicated by the arrows 39 with the pressurized combustion air that is admitted via the generally horizontally disposed primary combustion air inlet apertures 29.

The rich combustible fuel gas-air mixture, which results i from the turbulent mixing of the pressurized fuel gas that is discharged from the gas inlet apertures 37 with the pressurized air that enters the inverted trough 26 through the primary combustion air inlet apertures 29, moves downwardly through the inverted trough 26 and is ignited by means of a high voltage spark produced in a well-known manner by an electric spark plug 40 or similar igniter device that is generally horizontally arranged at the left end of the inverted trough 26 at a point vertically spaced between the primary combustion air inlet apertures 29 and the secondary combustion air inlet apertures 30. This ignited mixture of fuel gas and primary combustion air is then further turbulently mixed as indicated by the arrows 41 with the pressurized air, which enters the inverted trough 26 through the generally horizontal secondary combustion air inlet apertures 30 along the lower edges of the downwardly extending

side walls

27 and 28 of the inverted trough 26, and produces a generally downwardly extending, extremely high intensity heat source or flame 42.

In accordance with the present invention, the highly intense heat from this generally downwardly extending flame 42 is now discharged to an inlet at the upper end of the presently preferred form of the high intensity heat exchanger means 24 via hollow box-like interconnecting conduit means 43. The intensity of the heat source or flame 42 that is produced by the high intensity combustor means 25 is generally similar to that produced by the combustor means described in the aforenoted Abbott patent application, and typically is at least 300,000 BTU per hour per cubic foot of the interconnecting conduit means 43, an intensity level far exceeding any previously achieved with the prior atmospheric combustion air burners which have heretofore been commonly employed in gasfired space heaters.

As further shown in FIGS. 1-3, the presently preferred form of the highly efficient heat exchanger means 24 that are provided in accordance with the present invention comprises a plurality generally vertically arranged hollow tubes 44. In accordance with a particular aspect of the present invention, the tubes 44 have their upper ends fluid-connected in parallel to the lower end of the interconnecting conduit means 43 provided between the bottom of the inverted trough 26 and the top of the heat exchanger means 24, while their lower ends are fluid-connected in parallel to an exhaust plenum 45, which directs the waste products of combustion to atmospheric exhaust vent means, including a generally elbow-shaped vent pipe 47 having an inlet leg 47a and outlet leg 47b. The vent pipe inlet leg 47a is connected to the exhaust plenum 45 at the bottom of the heat exchanger 24 and extends outwardly from the air-conditioning unit cabinet 18 through an opening 48 provided in the lower end of the cabinet right side wall, while the vent pipe outlet leg 47!) extends upwardly outside the cabinet 18. In particular accordance with the present invention, the outwardly extending vent pipe inlet leg 47a is sloped downwardly toward its intersection or elbow 47c with its upwardly extending outlet leg 47b and liquid drain means 47d is provided at its lowest point, as at the bottom of the vent pipe elbow 470.

Also, as in the case of the upright heat exchanger means described in the aforenoted Abbott patent application, the outer surfaces of the hollow tubes of the improved inverted heat exchanger means 25 of the present invention are provided with fin means 49 of the so-called spine-fin type" that are generally similar to those described in detail in commonly assigned prior art U.S. Pat. No. 2,983,300, except that the tubes 44 and the fins 49 for the heat exchanger 25 are preferrably formed of a ferrous metal, such as steel, rather of nonferrous aluminum or copper as in the air-cooling exchanger described in U.S. Pat. No. 2,983,300. As further shown in FIGS. 2 and 3, twisted ribbon-like turbulence promoters 50 are provided in the lower or exit ends of each of the heat exchanger tubes 44 in order to provide a balance of heat transfer between the finned outer surfaces and bare inner surfaces of the tubes 44.

As shown in FIG. 1, the space air blower 15 has its inlet 51 aligned with the air-inlet opening 22 for the cabinet left compartment 20 and has its discharge 52 fluid-connected to the cabinet right compartment 21 via an opening 53 that is provided in the partition 19 and is arranged such that rotation of its impeller 54 by its electric motor 55 will cause the air stream 14 to be circulated between the space 13 and the finned exteriors of the heat exchanger tubes 44. Hence, during operation of the combustor means 25 of the gas-fired space heater means 16, the right space air conduit means 1 I serve as means for directing heated air from the air-conditioning unit cabinet 18 to the space 13 or as the so-called warm air conduit means, the left conduit means 12 serve as means for returning air from the space 13 to the air-conditioning unit cabinet 18 for the reception of heat or as the so-called return air conduit means, and the space air blower 15 serves as a means for circulating air between the space 13 and the improved gas-fired heater means 16 which are provided in accordance with the present invention. Thus, during operation of the combustor means 25 of the improved heater means 16, the products resulting from the combustion of the pressurized fuel gas and combustion air mixture produce the highly intense heat source 42 and they and the heat generated thereby are forced downwardly under the pressure provided by the combustion air blower means 31 through the interconnecting conduit means 43 and the tubes 44 of the inverted heat exchanger 24, with the heat therefrom being transferred by conduction, convection, and radiation, first to the interiors of the tubes 44, then to the finned exteriors of the tubes 44 and finally to the space air stream 14 that is circulated across the finned exterior of the tubes 44 by the space air blower 15. And, the waste products of combustion are forced from the lower ends of the tubes 44 into the exhaust plenum 45 at the bottom of the heat exchanger 24, then outwardly and downwardly through the vent pipe inlet leg 47a and finally upwardly to the atmosphere through the vent pipe outlet leg 47b by the pressurized air supplied by the combustion air blower 31. The rate of transfer of heat to the air stream 14 that can be accomplished with the presently preferred form of the inverted heat exchanger means 24 is similar to that of the upright means described in the aforenoted Abbott patent application, and typically is at least 3,500 BTU of heat per hour per pound of material that is used in the tubes 44 and the fins 49, a rate far exceeding any previously achieved with the rather crude prior art boxlike or clam shell shaped heat exchangers which have heretofore been commonly employed in gas-fired space heaters.

Of course, there will often be times, as during periods of hot outdoor air temperatures, when the combustor means 25 of the inverted gas-fired heater means 16 will be turned OR or dormant, and the cooling means 17 that are combined with it in the air conditioner unit will then be started up and operated to remove heat from the air stream 14. It is during these dormant periods of its combustor means 25 that the improved inverted gas-fired heater means 16 of the present invention provides particular advantage over both the conventional heater means and those described in the aforenoted Abbott patent application. Turning now especially to FIG. 1, it will be observed that the cooling means evaporator section 17, which is housed within the left cabinet portion 20 of the airconditioning unit 10, is interposed between the cabinet air inlet 22 and the inlet 51 for the space air blower 15, whereby, during periods of operation of the, cooling means 16 and dormancy of combustor means of the gas-fired heater means 16, the space air stream 14 will be chilled by passage through the cooling means evaporator section 17 prior to its passage across the heat exchanger tubes 44 of the dormant heater means 16 enroute to the space 13 via the right conduit means 1 1. And, this passage of chilled air across the exteriors of the heat exchanger tubes 44 of the dormant heater means 16 often causes moisture to condense within the warmer int'eriors of the heat exchanger tubes 44 of the dormant heater means 16, which may be warmed by various ambient heat sources, e.g. back flow of outside air through the vent pipe 47. However, with the improved inverted gas-fired space heater means 16 that are provided in accordance with the present invention, condensate, which may deposit within the heat exchanger means 24 during dormancy of the combustor means 25, will be directed downwardly away from the combustor means 25 by gravity and out to the atmosphere via the drain means 47d which is provided in the lowest point of the vent pipe 47 that is connected to the exhaust plenum 45 that is located at the lower portion of the improved inverted heat exchanger means 24. Hence, no condensate will collect upon the combustor means 25 and the problems formerly presented by this in conventional gas-fired heater means are eliminated.

It should be apparent to those skilled in the art that while there have been described what, at present, is considered to be a presently preferred embodiment of this invention in accordance with the Patent Statutes, changes may be made to the disclosed apparatus without actually departing from the true spirit and scope of this invention. It is therefore, intended that the appended claims shall cover such modifications and applications that may not depart from the true spirit and scope of the present invention.

What is claimed is:

1. improved gas-fired space heater means, comprising:

heat exchanger means for transferring heat generated by the combustion of a combustible gas-air mixture to an air stream circulated between said heat exchanger means and the space to be heated;

said heat exchanger means comprising a plurality of vertically extending finned tubes connected in parallel to a fluid inlet adjacent the upper portion of said heat exchanger and a fluid outlet adjacent the lower portion of said heat exchanger;

pressurized combustor means positioned above said heat exchanger for mixing fuel gas with pressurized air to produce and burn said gas-air mixture;

said combustor means comprising a horizontally extending, elongate member of inverted U-shape cross section and including opposed vertical side walls, the open bottom of said member being in communication with said heat exchanger inlet;

a gas supply means in the upper portion of said elongate member, said supply means extending longitudinally of said member and having gas apertures therein for the flow of gas into said member substantially parallel to the side walls thereof;

means for introducing pressurized air into said member comprising at least one row of Iprimary combustion air apertures in each of said side wal s ad acent said gas apertures and at least one row of secondary combustion air apertures in the lower portion of each of said side walls;

said heat exchanger means outlet being fluid-connected to vent means for exhausting said pressurized gas-air mixture to the atmosphere such that products of combustion of said gas-air mixture will be forced downward through said heat exchanger means and out through said vent means by said pressurized air during operation of said combustor means, and condensate which may form within said heat exchanger means during dormancy of said combustor means will be directed away from said combustor means by gravity.

2. A space heater according to claim 1 in which said vent means includes a downwardly slanting inlet portion and a condensate drain means connected to the lower end of said slanting inlet portion

Claims

1. Improved gas-fired space heater means, comprising: heat exchanger means for transferring heat generated by the combustion of a combustible gas-air mixture to an air stream circulated between said heat exchanger means and the space to be heated; said heat exchanger means comprising a plurality of vertically extending finned tubes connected in parallel to a fluid inlet adjacent the upper portion of said heat exchanger and a fluid outlet adjacent the lower portion of said heat exchanger; pressurized combustor means positioned above said heat exchanger for mixing fuel gas with pressurized air to produce and burn said gas-air mixture; said combustor means comprising a horizontally extending, elongate member of inverted U-shape cross section and including opposed vertical side walls, the open bottom of said member being in communication with said heat exchanger inlet; a gas supply means in the upper portion of said elongate member, said supply means extending longitudinally of said member and having gas apertures therein for the flow of gas into said member substantially parallel to the side walls thereof; means for introducing pressurized air into said member comprising at least one row of primary combustion air apertures in each of said side walls adjacent said gas apertures and at least one row of secondary combustion air apertures in the lower portion of each of said side walls; said heat exchanger means outlet being fluid-connected to vent means for exhausting said pressurized gas-air mixture to the atmosphere such that products of combustion of said gas-air mixture will be forced downward through said heat exchanger means and out through said vent means by said pressurized air during operation of said combustor means, and condensate which may form within said heat exchanger means during dormancy of said combustor means will be directed away from said combustor means by gravity.

2. A space heater according to claim 1 in which said vent means includes a downwardly slanting inlet portion and a condensate drain means connected to the lower end of said slanting inlet portion.