CA1119497A - Method and apparatus for fuel economy - Google Patents

Abstract

METHOD AND APPARATUS FOR FUEL ECONOMY

Abstract of the Disclosure There are disclosed means and method for improving the efficiency of combustion in an automatic gas-fired furnace through retardation, without restriction, of the exhaust emission of the products of combustion, which are caused to dwell longer in the combustion chamber to elevate the temperature, not only through the impound-ment of what would otherwise be waste heat, but by the conversion of CO gas and excess air to CO2 gas, thus, reducing the two former, increasing the latter, along with temperature. This reduces the condensate in the exhaust chimney. An enlarged chamber in the exhaust gas conduit is incorporated within and beneath the line of exhaust flow from furnace to chimney. A baffle plate, approxi-mately equal in area to the cross-sectional area of the conduit, is immovably secured in the top of the chamber normal to the line of exhaust flow. The chamber is completely closed except for the exhaust flow entry and exit ports. The chamber affords clearance beneath or around the baffle for the unimpeded passage of the exhaust gases equal in area, or greater than, that of the exhaust gas conduit.

Description

l~L~ 7 METHOD AND APPA~TUS FOR FUEL ECONOMY
Background and Summary of the Invention This inv~ntion rela~es to improving ~ c~ustion efficiRncy of autcmatic ~urnac2s ~nd hot wa~r heaters~ More particularly, this invention relates to an improved method and apparatus for exhausting waste combustion products from an automatic, gas-fired furnace system, to reduce the amount of valuable heat and fuel escaping with the combusted gases.
: Furnace systems, ~uch as those used in residential 1.0 houses, small and large buildings, industry and the like, are often fueled with fuel~, such as ~il, coal, natural gas and the li~e. Such furnace systems produce combustion s products or flue gase~ which munt be dispo~ed of in the atmosphere through flue gas ductwork.
One disadvantage of such Eurnace systems i5 that such flue or combustion gases retain or otherwise have a signifi-cant amount of valuable heat, and heat-producing components, derived from fuel combustion. Unless such heat, actual and potential, is recovered, it escapes to the atmosphere ~0 and reduces the overal.l fuel efficiency of the furnace system.

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3'7 j~ Many devices have been suggested by the prior art Il to recover some of this energy from furnace system ¦ combuqtion gases. Often, these systems are mere auxiliary heat exchangers, which while being complex, expensive, requiring substantial maintenance, and frequently being too bulky to be compati~le with the space requirements, do no more than recover a part of the sensible heat without recovering the latent heat (unspent fuel potential in the exhaust gases) Thus, the average building owner, or resident, who has a furnace system for heating purposes, loses a significant amount of available energy when the combustion gases are exhausted to the atmosphere. Such losses result in reduced furnace efficiency and increased fuel consumption, ~ox a given level of useful heating produced.
This is generally true, regardless of whether the furnace is manually or automatically controlled, and regardless of the type of fuel employed. Modern heating systems are, however, preponderantly automaticaliy contxo~led and operated, and it is toward such systems that the present invention is aimed, especiallyl automatic, gas-fired systems.
Therefore, one object of the present invention is to provide an improved method and apparatu~ for e~hausting combustion gases from a furnace.
Another object of the present invention is to provide an apparatus and method useful for improving the operating eficiency of a furnace.
A still further object of the present invention is to provide an apparatus to reduce the amount of energy exhausted with the combustion gases from a furnace by impounding waste heat, incraasing the CO2 content, lowering the CO and excess air to raise the temperature and lower the condensa~e in the exhaust chi~ney.

¦ Other objects and advantages of the present inven-tion will become apparent hereinafter.
An improvement in exhaustin~ combustion gases from a furnace -to achieve the~e objec~s has now been discovered~
One embodiment of the present invention comprises a conduit means in f]uid communication with the furnace for conducting combustion gases from the furnace to a chimney, the conduit means being appropriate in size and style to that for which the furnace was designed for voiding combu~tion gases. Also included i~ a flow redirection means located within the conduit means in the pa~h of ~low o~ combustion gases withln the conduit means. This flow redirection means acts to change the direction of flow of at least a portion o the combus~ion gases flowing through the conduit means. The flow redirection means acts to change the direction of f 1GW of at least a portion of the combustion gases flowing through the conduit means. The flow redirec~ion means is designed so tha-t the cross-sectional area available or gas flow at the location of the flow redirection means is at least as great as the cross-sectional area of the conduit means directly upstream ordownstream of the flow redirection means.
The use of the present invention provides surprising benefits. The quantity of heat and uncombusted gases leaving the furnace with the combusted gases is reduced. At least a portion of the heat potential which is not lost in the comhustion gases i5 available for effectively heating a heat-exchanger. In short, improved furnace effi~iency, e.g., heating effectiveness, fuel economy~ and the like, can be obtained by using the present invention.

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The flow redirection means of the present invention may change the direction of only a portion o f the combus-tiOII gases flowing -through the conduit. Preferably, such flow redirection means changes the direction of flow of a major portion, if not all, of such combustion gasP~.
In a preferred embodiment, the flow redirection means comprises a flow baffle loca~ed substantially across the flow of combustion ~ases in the conduit, so that a~
least a portion of the gases are caused to flow around the flow baffle; and an added area located in assoc:iation with the 10w baffle prov~fdes cross-sectional area available for flow of combustion gasPs at the location of the flow baffle. In normal use, the flow baffle means is stationary.
However, the flow baffle means is removable and replaceable by one of another size so that the amount or fraction of combustion gasfes redirected by the flow redirection means can be varied dependin~ on the combustion requirements of the individual atmospheric burner.
As noted previously, the cross-sectional area available

2~ for the flow of combustion gas at the location of the flow redirection means is at least equal to, or preferably greater than, the cross-sectional area for combustion gas flow in the conduit directly upstream of the flow redirection meanR .
The cross-s2ctional area of the conduit for combustion gas flow is preferably substantiall~ constant upstream of the flow redirection means. Preferably, the portion of the conduit down~stream from the flow redirection means also has a substantially constant gas flow cross sectional area.

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jlUsually~ the conduit has a substant.ially circulat cross-~section normal to the general direction of flow of ¦combus~ion gases. Additionally, the general direction ¦and volume of combustion gas flow, e.g., i~ the conduit, i9 substantially the same both upstream and down~ream of the flow redirection me~ns. In other words, the flow redirection mean~ does not need to permanently chanye the flow direction or volume of combustion gases in order to perorm its function in the present invention.
~.. Under existing public utili~y and utility associations' standards for automatic gas-fired furnaces, no structure in the exhaust gas conduit, that reduces the efective area of the latter to a lesser area than that for which a furnace or combustion chamber is designed, is permissible during the operational period of the furnace. The present invention meets this requirement by interposing a baffle across the main body of exhaust flow in the effluent conduit irom a combustion chamber in said conduit, which, while . ~eing hermetically closed to the ambient atmosphere, is capable of receiving and forwarding ~he full volume of exhaust flow diverted into the chamber by the baf~le without restric-tion or substantiaI pressure difference. The baffle, in diverting the flow, sets up eddy currents that incr~ease the frictional resistance to the flow of the exhaust gases, causing an acceptable degree of retardation thereof, to effect a dwell in the products of combustion, and a rnomen-tary detainment of otherwise waste heat and fuel, in the combustion chamber. The au~mented combustion cycle, with enhanced temperature and time parameters thus afforded, 9'~

causes carbon monoxide (CO) and excess air still resident in the combustion chamber as the result of said baffle, to be converted to carbon dioxide (CO2), an exothermic reaction that further elevates the heat in the system, without regard to new fuel input from the supply source.
This reduces excess air in the system, and also reduces condensation in the exhaust effluent.
The invention, in its broadest aspect, contemplates the method of improving the efficiency of combustion of hydrocarbon fuel in a heat-exchanger automatic furnace system, having an exhaust conduit for the venting oE the products of combustion that includes retarding the Elow of the products of combustion by interposing a fixed baffle in the exhaust conduit, providing an unrestric-ted area of flow around the baffle substantially equal to or greater than that of the exhaust conduit, and in stream with the lat-ter, while excluding ambient and o-ther extraneous gases therefrom. The retardation of flow effects a dwell in the exhaust of waste heat and products of combustion from the system, thereby augmenting the combustion cycle by enhancing its temperature and time parameters, thus con-verting an essential part of the residual CO to CO2, so as further to augment the heat in the heat exchanyer system, while reducing condensate in the products oE combustion ultimately vented through the exhaust conduit.
The invention also encompasses apparatus for improving the efficiency of combustion of hydrocarbon fuel in a hea-t-exchanger automatic furnace system which comprises an exhaust conduit for venting the effluent products of combustion gases from the system. A means for imposing a dwell in the flow of the effluen~ gases, without obstruc~i-6.

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the latter, incl~ldes a fixed baEfle in the exhaust concluit, and an enlarged chamber in stream with ~he exhaust conduit, hermetic~lly closed to the ambient atmosphere, enclosing the baffle. The chamber and baffle are construc-ted and arranged to provide an un-restricted area of flow around the baffle subst~ntially equal to or greater than that of the exhaust conduit, so as to retard, without restricting, the flow of the products of combustion therethrough. The dwell augments the combustion cycle by anhancing the tempera-ture and time parameters oE the la-tter -to decrease the CO, the excess air, and -the H2O condensate and -to increase the ~2~ in the products of combustion ultimately discharged through the exhaust conduit, thus, further to augment the heat in the furnace system without input of additional fuel.
In a further embodiment, the invention contemplates apparatus for improving the efficiency of combustlon in a heat-exchanger automatic gas-fired furnace system, which comprises an exhaust conduit for venting the effluen-t products of combustion gases from the sys-tem.
A means for imposing a dwell in the flow of the ef~luent gases, without restricting the latter, includes a ixed baffle in the condui~ to deflect the flow of some ox all of the gases, which includes a means Eor reducing its effective area so as to deflect less of the exhaust gases passing thereby. An enlarged chamber in stream with the exhaust conduit, hermetically closed to the ambient atmosphere, encloses the baffle into which effluent gases are deflected. The enlarged chamber comprises a Tee union in the exhaust conduit having a through-flow for effluent gases between inlet and outlet ports at opposite , 7.

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ends o~ the Tee; the depending leg of the Tee being hermeticall~ sealed against the ingress and egress of gases, with the baffle being fixedly mounted normal to the through-fl.ow of effluent gases to deflect the gases into the leg of the Tee in their passage to the outlet port.
The baffle is centered with respect to the central ax.is of the depending leg of the Tee. The chamber and baffle are constructed ancl arranged to provide an unrestricted area of flow around the baffle substantially equal to or greater than the exhaust conduit, so as to re~ard, without restric-t-ing, the flow of the products of combustion thereth:rough.
The dwell augments the combustion cycle by enhancing the temperature and time parameters of the latter to decrease the CO, the excess air, and the H2O condensate, and to increase the CO2, in the products of combustion ultimately discharged through the exhaust conduit, thus, further to auqmen-t the heat in the furnace system without the input of additional fuel.
These and other aspects and advantages of the present invention are set for~ll in the following detailed descrip-tion and claims, particularly when considered in conjunc-tion with the accompanying drawings in which like parts bear like reference numerals.
Brief Description of the Drawings Figure 1 is a schematic illustration of a system including an embodiment of the present invention.
Figure 2 is a cross-sectional elevational view, taken along line 2-2 of Figure 1.
Figure 3 is a longitudinal sectional elevational view, taken along line 3-3 of Figure 2.
Description of the Preferred Embodiment Referring now to the drawings, home heating system 10 is shown and includes furnace 12, chimney 14 and ductwork subsystem shown ~enerally at 16 which provides fluid communi-cation between Eurnace 12 and chimney 14.
Furnace 12 functions as follows: Return cool air, e.g., from the rooms of a house, is drawn into the intake of blower 18 which forces this air -through furnace 12 and plenum chamber 20 into the individual rooms of the house to provide warmth. Af-ter cooling, the room air is re-turned to the furnace 12 by the blower 18 and the cycle is repeated. While wi-thin the furnace, the cool air from blower 18 is heated by heat exchange with gases produced by the combustion of fuel, e~g., natural gas and air.
The products of combustion or combustion gases, after being subjected to hea-t exchange with ~he air which passes into plenum chamber 20, are disposed of, e.g., to the atmosphere, through ductwork subsystem 16 and chimney 14. Thus, the combustion gases exit from furnace 12 through outlet 22, elbow 24, first conduit section 26, tee 28, second conduit section 30 and chimney 14, which exhausts to the outer atmosphere. Outlet 22, elbow 24, first conduit section 26 and second conduit section 30 each has su~stantially constant and equal cross-sectional areas normal to the general direction of flow of the combustion gases.
Tee 28 is crimp-fitted between first conduit section 26 and second conduit section 30. Baffle 32 is removably secured to the top wall of tee 2~ by means of a threaded extension 34 of baffle 32 and wing nut 36. Baffle 32 is placed normal to the general direction of gas flow directly in the center of the path of the combustion gases as these gases flow through first conduit section 26. If desired, the position of baffle 32 can be adjusted by turning threaded extension 34. Baffle 32 may be proportioned so that a minor portion of the combustion gases from first conduit section 26 can pass between the top insides of tee 28 and upper edges of baffle 32, or these parts may be conformed for a seal fit. However, the lower sides and 9~

closed bottom of tee 28 are constructed so that the total ¦ cross-sectional area normal to the general direction of combustion gas flow (as shown in Fiyure 3) and available for gas flowl is at least as large or larger in the plane defined by baffle 32 than the area in either the first conduit section 26, or the second conduit section 30.
The bo-ttom of tee 28 is closed hy cap 38. Thus, no extraneous gases, e.g., ambient air, flow into tee 28.
l Home heating system 10 and ductwork subsystem 16 ~ function as follows: After room air-combustion gas heat exchange in furnace 12, the room air enters plenum chamber 20 as noted above. The combustion gases flow through outlet 22 into first conduit section 26. As the combustion gases pass through first conduit section 26 and enter tee 28, the flow path of the yases is disturbed by the presence of baf~le 32 SQ that a substantial portion of such gases is forced to flow around baffle 32 before entering second conduit section 30. From second conduit section 30, the combustion gases enter chimney 14 and are exhausted to the outer atmosphere.
The present apparatus and its mode o~ operation,..as described, unexpectedly materially reduced ~aluable energy loss in the combustion gases exhausted to the atmosphere, and increased combustion efficiency.

Examples I and II
The following examples illustrate, without limitation, the present invention:

Two identical automatic, gas-fired furnaces, Westinghouse Electric Model No. 110 P A, each with a rated heat output .~
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of 100,000 BTU hr~, were selected for testin~.
Furnace No. 1 had a combustion gas exhaust system, as illustrated in the drawings. First and second conduit sections had a diameter of five inches. Baffle 32 was l¦approximately two feet from the outlet 22 and had a substan-l~tially circular configuration with a diameter of about five inches. The length of tee 28, from the top wall to the closed bottom was about nine inches.
l Furnace No. 2 had a combustion gas exhaust system ¦ which did not include a tee 28. A single sec-tion oE conduit, ~ having a diameter similar to that of the firs~ and second ¦Iconduit sections, above, was used between furnace outlet 22 and chimney 14.
Each furnace was automatically run in a similar manner, e.g., at the same fuel and combustion air flow r~te and house room air flow rate, over the same period of time.
Temperature readings were taken at similar locations for ~each furnace respectively. Results of these tests are summarized as follows:

Furnace No. 1Furnace No. 2 (present invention) Temperature i~
the chimney, F. 140 188 Temperature in breeching loOation in furnace, F. 460 330 Temperature of air in plgnum chamber, F. 133 110 30A comparison of the temperature obtained with furnaces 1 and 2 indicate~ quite clearly that Furnace 1, equipped with the present apparatus, provides more heat per period 11.

of fuel ~o the house. Thus, Furnace No. 1 can be used ~o heat a house warmer than Fu:rnace No. 2 with a given amount ~of fuel, or ~o reduce the amoun-t oE fuel required for a given level of heating. In any event, Furnace No. 1 with the present .innovative exhaust systern provides improved fuel efficiency than does Furnace No. 2 with conventional combustion gas exhaust ductwork.
The invention herein shown and described may be analogized with a dam in a watercourse, where the water is caused to dwell by impoundment behind the dam, from whence it ultimately flows unrestrictedly downstream in -the same vol~ne of effluent as its influent upstream of the dam.
Such an impoundment can provide for a more efficient use of the water through hydraul.ic mechanics than could the dynamics of the uninhibited flow of the original stream. In the instant case, the dwell in outflow of otherwise waste gases, decreases carbon monoxide and excess air, increases carbon dioxide, elevates the heat exchanger temperature, without a corresponding fuel input, reduces condensation in the exhaus-t effluent, and, so, materially increases the combustion efficiency of the system within the proscriptive industry standards of unrestricted exhaust flow.
While this invention has been described with respect to various specific em~bodiment~ and examples, it is to be understood that the invent.ion is not limited thereto, and that it can be variously practiced within the scope of the following claims:

Claims (11)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. The method of improving the efficiency of combustion of hydrocarbon fuel in a heat-exchanger auto-matic furnace system, having an exhaust conduit for the venting of the products of combustion that includes:
(1) retarding the flow of said products of combustion by interposing a fixed baffle in said exhaust conduit, (2) providing an unrestricted area of flow around said baffle substantially equal to or greater than that of said exhaust conduit, and in stream with the latter, while (3) excluding ambient and other extraneous gases therefrom, (4) said retardation of flow effecting a dwell in the exhaust of waste heat and products of combustion from said system, thereby (5) augmenting the combustion cycle by enhancing its temperature and time parameters, thus (6) converting an essential part of the residual CO to CO2, so as further to augment the heat in the heat exchanger system, while (7) reducing condensate in the products of combustion ultimately vented through the exhaust conduit.

2. The invention of claim 1, in which the furnace system is an automatic, gas-fired system.

3. The invention of Claim 2, including (1a) Regulating the retardation of flow by adjusting the effective area of said fixed baffle in said exhaust conduit so as to accord with different draft conditions and combustion requirements among different furnace instal-lations.

4. Apparatus for improving the efficiency of combustion of hydrocarbon fuel in a heat-exchanger auto-matic furnace system comprising:
(1) an exhaust conduit for venting the effluent products of combustion gases from said system, (2) means for imposing a dwell in the flow of said effluent gases, without obstructing the latter, including:
(3) a fixed baffle in said exhaust conduit, (4) an enlarged chamber in stream with said exhaust conduit, hermetically closed to the ambient atmosphere, enclosing said baffle, (S) said chamber and baffle being constructed and arranged to provide an unrestricted area of flow around said baffle substantially equal to or greater than that of said exhaust conduit, so as to retard, without restricting, the flow of the products of combustion therethrough, (6) whereby said dwell augments the combustion cycle by enhancing the temperature and time parameters of the latter to decrease the CO, the excess air, and the H2O condensate and to increase the CO2, in the products of combustion ultimately discharged through the exhaust conduit, thus, further to augment the heat in said furnace system without input of additional fuel.

5. The invention of Claim 4, in which said fixed baffle has a maximum effective area that is approximately equal to the cross-sectional area of said exhaust conduit disposed normal to the flow of exhaust gases therethrough, and a lesser effective area capability to accord with reduced draft and the combustion requirements of given furnace installations.

6. The invention of Claim 4, in which said enlarged chamber comprises a Tee union in said exhaust conduit having a through-flow for exhaust gases between inlet and outlet ports at opposite ends of the head of the Tee, the depending leg of the Tee being hermeti-cally sealed against the ingress and egress of gases, said baffle being fixedly mounted normal to said through-flow of exhaust gases to deflect the gases into the leg of the Tee in its passage to the outlet port, said baffle aligning with the central axis of the depending leg of the Tee, and being capable of adjustment to a lesser effective area so as to deflect less of the exhaust gases passing thereby.

7. The invention of Claim 4, in which said enlarged chamber comprises a Tee union with two ports for admitting and exhausting flue gases, respectively, the third port being hermetically sealed, said baffle being centrally mounted in said chamber normal to the flow of flue gases therethrough to deflect a portion of the flow through the enlarged chamber without restricting said flow.

8. The invention of Claim 4, in which the effective area of the baffle ranges from unity relative to the cross-sectional area of the exhaust conduit to a lesser value so as to effect less deflection of the exhaust gases.

9. The invention of Claim 4, Claim 5 or Claim 6, in which the furnace system is an automatic, gas-fired system.

10. The invention of Claim 7 or Claim 8, in which the furnace system is an automatic, gas-fired system.

11. Apparatus for improving the efficiency of combustion in a heat-exchanger automatic gas-fired furnace system, comprising:
(1) an exhaust conduit for venting the effluent products of combustion gases from said system, (2) means for imposing a dwell in the flow of said effluent gases, without restricting the latter, including:
(3) a fixed baffle in said conduit to deflect the flow of some or all of said gases, (a) said baffle including means for reducing its effective area so as to deflect less of the exhaust gases passing thereby (4) an enlarged chamber in stream with said exhaust conduit, hermetically closed to the ambient atmosphere, enclosing said baffle into which effluent gases are deflected, (a) said enlarged chamber comprising a Tee union in said exhaust conduit having a through-flow for effluent gases between inlet and outlet ports at opposite ends of said Tee, the depending leg of the Tee being hermetically sealed against the ingress and egress of gases, said baffle being fixedly mounted normal to said through-flow of effluent gases to deflect the gases into the leg of the Tee in their passage to the outlet port, said baffle being centered with respect to the central axis of the depending leg of the Tee,

Claim 11, (cont'd.) (5) said chamber and baffle being constructed and arranged to provide an unrestricted area of flow around said baffle substantially equal to or greater than said exhaust conduit, so as to retard, without restricting, the flow of the products of combustion therethrough, (6) whereby said dwell augments the combustion cycle by enhancing the temperature and time parameters of the latter to decrease the CO, the excess air, and the H2O condensate, and to increase the CO2, in the products of combustion ultimately discharged through the exhaust conduit, thus, further to augment the heat in said furnace system without the input of additional fuel.