US1994968A - Heat generator - Google Patents

Description

March 19, 1935. J. J. sLoYAN HEAT GENERATOR Filed 00'@ 29, 1930 4 Sheets-Sheet 2 IN NTR ATTORNEY March 19, 1935.

J. J. sLoYAN 1,994,968

HEAT GENERATOR Filed Oct. 29, 1930 4 Sheets-Sheet 3 ATTORNEY March 19, 1935. J. J. sLoYAN HEAT GENERATOR Filed OC. 29, 1930 4 Sheets-Sheet 4 INVENTOR ATTORNEY CII Patented Mar. 19, '1935 UNi'rED arras .triislifr":oF-ricajff 1.394.958 l HEAT GENERATORA Y Jerome J. Slo-yan, Red Bank',4 J. Appunti@ october 2.9, 1930, seriaiNo. 492,132 2 Claims.. (C1.` 15s-#28j This invention relates to improvements in heat generators and methods of burning` less volatile grades of liquid fuel.

n burning the less volatile grades of liquid Y fuel the same problems of vaporiza'tion, ho'mo,

geneity of the fuel and air mixture andthernaintenance of the proper ratioof fueland air atall rates of combustion are present as in the case of the more volatile grades of oil but are more diflcult of s-olution. An accurate and sensitive control of the rate of combustion is not onlyjdesirable but for Certain'uses is essenial. ,In-,addition there are the commercial requirements of obtaining the maximum temperature fronr'the fuel and the control of the chemical structure` of the products of combustion. Y The present devices in use ior'the 'burning of the less volatile grades of liquid fuel are in 'the' main complicated, diiicult to start; of costly con# struction and are lacking in accuracy 'and' sensitiveness of control of the rate of combustion and of control of the chemical structures of the prod-i' ucts of combustion as well as lacking inl thermal efficiency, nor are Such devices generally offunit construction and yet capable of lexpansion for in' creased capacity.

The objects of this invention are: I To provide a heat generator thatffwill satisfactorily burn the less volatile grades of liquid lfuel and to make provision to burn the. less volatile grades satisfactorily in a relatively short time after the device has been initially started.

To effect a transfer of heat from the flame to air that is to be subsequently mixed with the fuel. The heat thus transferred effecting a rise inair temperature which will in turn vthoroughly va@ porize the fuel. y

To add heat to the fuel and airmixture after it has left the carburetorrin order to make up for the temperature drop which occurs due to vafpcrization of the liquid fuel.

To provide a heat generator having a relatively high overall thermal efiiciencyby using the heat that must necessarily be removed wfrom certain elements for mechanical reasons in other elements and processes wherein it is essential `and by further using the heat thus saved effectively on the material to be heated. Y

To provide a heat generator which is of simple and unit construction and wherein' the desired results are effected by the (natural) physical relation which exists between the various elements and processes, rather than by a complicity of manually or automaticallyoperated moving m'einbers.

Referring to the drawings: l j

Figure llfis a lview partly in'section andpartl'y in elevationof la ydevice,embodying the principles' of my invention.v Figure 2 is a sectionalview along the line 2, v2, of Figurel lookingin the di-v rectionof thef arrows. Figures 3 isa viewfof a modification of l,the device partly in sectionand partly'in elevation with the blower and lead removed andk a portion of the `housing broken away. Figure4 is a sectional view'of Figure S'along'the line 4, 4, looking inthe direction o f the arrows. Figure .5 is ajdetailrplan viewof Figure 3. Figure 6 is a view in side elevation, partly in sectionfof a modied form of device wherein the coolingy of the antechamber is accomplished through the passing'ofy the cooling air overjand around thermally connected v'to. the`l ante combustion chamber wall. Figure'? is a plan view, partlyin section and parts broken offof a vmodifiedv form of device wherein ya spiral n directs 'the passage of the coolingfair around the antecombustion chamber `wall. Figure 8 is a view in longitudinal section-'wherein the vaporizingand mixing means is within thehousing. Figure!) is a sectional view of Figure 8, alongthe line 9, 9, looking inthe direction ofthe arrows. n v j In carrying out my invention, Ipropose to provide a construction ofthe casing assembly which is` both uniquefA and simple. l'Ante'combustion chamber `1, has a conically shaped interi'orand exterior, its A smallest endextending into housing` 2, so that the end of larger diameter is flush with'rthe end ofthe casir'ig. The endof larger diameter is; either threaded'o'r welded to theend of housing 2v tos-insure 'an air-,tight joint. 'That endlo'f lsmaller diameter which extends into housing '2 isairtightly connected through pipes 3,4,- 5

to the carburetor dischargeSO. Pipe 5 isfwelded to housing v2; where it passes through *housing 2 to makea joint that is airy-#tight Sheath '6 of such shape anddimension and soflocated within housing" 2`4 with reference to antecombustion chamber l, as to form a circumferential air passagewaywfl, having a predetermined transverse cross sectional area `(transversevvith relation to' its circumference )v andalongitudinal airpassage-I vs /"a'yf,A having a predetermined transverse cross sectional area A(transverse with relation toi its longitudinal axis) As clearly shown in the drawings, sheath 6 is progressively spaced furthe-rl from antecoinbustion chamber l overthe'airpassageway 8 from the larger toward the smaller end of antecombustion chamber l, 4so as to make air passageway 8; approach anequal cross sectional area 'throughoui',.` Extendingfurther backward from the antecombustion chamber through housf ing 2, sheath 6 is connected with T, 9, which in turn is connected through pipes 10, 11, 12, to the carburetor inlet 13. Between antecombustion chamber 1 and T, 9, sheath 6 envelopes pipes` 3 and 4, which convey the fuel and air mixture from the carburetor to the antecombustion chamber. Pipe 10 is welded to housing 2 where it passes through the casing Vto prevent the leakage of air to or from housing 2. `The outer perimeter of the end of larger diameter of sheath 6 is a snug fit in housing 2 but does not of necessity have to be air-tight because the only exit for air that is delivered into air passageway 8 is through pipe 10 leading to the carburetor inlet, all Vother possible exits being made air-tight. Sheath 6 acts merely as a directing means `and is surrounded by immovable air (immovable because it has no exit) hence the possibility of leakage of air from within sheath 6 to the space 14 betweensheath 6 and housing2 is negligible.Y Forthe same-reason it is unnecessary that Ipipe 4 or spark plug housing 15 form "air-tight jointswith sheath 6 Where they pass through it.

Spark plug? housing 15 extends through'` the Wall of housing 2 through sheath' 6 and through the wall 16.of antecombustion chamber 1.` The joints formed by itself, and the antecombustion chamber 1, and housing 2 are made air-tight. kEnd plate 18 li'sair-tightly secured to housing 2. Pipe 19 connectingsheath `6 andrelief valve 20, passes through end plate 18. The joint formed by the vend plate 18 around pipe 19 is made airtight.l

.'Ijhermometer 21 is conveniently locatedin the pipe `line `from `sheath 6 to the carburetor inlet 13,.to register the temperature ofthe airas it enters the carburetor. l j i. The carburetor 22 used is an air sealed carburetorV as y.more fully describedin my patent application filed September 13, 1928, Serial Number 305,832. Its inlet 13 is air-tightly connected through pipe' connection 10, l1, and 12, to sheath 6, y and its discharge is air-tightly connected through pipe connections `3, .4 and 5 to the antecombustion chamber 1.

The more volatile fuel used for initial starting is conveyed from a source of supply (not shown) through pipe 24, to fuel pump 25 wherefromjt delivered through valve 26 and pipe 27to thecarburet'or. The less volatile fuel used for continuous operation is conveyed by pipe 24 from a source of supply (not shown) through valve 28 thenV either through heating coil 29 or through pipe 24 -to fuel pump 3(7),.Wherefrom it is delivered through fuel filter 31, through valve 26" and -pipc` 27, to the carburetor 22. Valve 28 is-a threeway valve.`

Fuel pumps 25 and 30 are the magnetic bellows type andautomatically cease to function when the fuel in the carburetor has reached a predetermined level.

Integral with housing 2 is flange 17 which is secured to rear wall 32 of main combustion chamber 33 by bolts or clamps so that antecombustion chamber 1 and main combustion chamber 33 are joined to form substantially a single chamber. `Housing. 2 extends a short distance through ang`e17 to protect from flame impingement the heat insulating gasket 34 which is located between yflange and main combustion chamberrear wall '1, enters the top of housing 2 adjacent to fiange 17. It is important that the air passing through pipe 36 absorb as little heat as possible prior to its coming in contact with the surface of the wall 16 of antecombustion chamber 1 otherwise it will not have the cooling effect on said Wall that. is intended. In order that pipe 36 shall absorb as little radiant heat from flange 17 or housing 2 as possible it is led in obliquely to housing 2 and ange 17 and is also disposed in a vertical plane (see Figure 5).

Blower 37 is conveniently mounted by bracket 39 on housing 2.

It should be noted that as the heated air passes from passageway 8 on its way to the carburetor, it passes over and around those pipes which' conduct the mixture of fuel vapor and air to the interior of antecombustion chamber 1. As the heated air passes through carburetor 22 it gives up some heat in order to effect vaporization of the liquidvfuel and by so doing its temperature is lowered. Itis therefore evident that the temperature of the mixture as it passes through pipes 3, 4 and 5 to the interior of the combustion chamber is much below that of the air passing around said pipes, so that the mixture will absorb some heat from the air passing around the `pipes and the heat absorbed will aid in retaining the fuel in the vapo-r state and in a homogeneous mixture with the air until the instant combustion takes place.

,By completek combustion of a hydrocarbon such as liquid fuel, we mean that all the carbon is oxidized to carbon dioxide and all of the hydrogen is oxidized to water. If the quantityof air which is known to be required chemically is' not supplied, then combustion will be incomplete and some of the carbon will be only partially oxidized to carbon monoxide. In order to approach complete combustion of the fuel in devices now used, more air than is chemically necessary must usually be supplied and even then frequently too much carbon escapes in the monoxide form.

Only that portion of the fuel which is vaporized and in contact with air will combust. When liquid fuel is atomized (broken up into small globules by some mechanical means) only the surface of each globule vaporizes and lif sufficient air is present in that vicinity at the time of combustion to mix with the vapor, complete combustion of that fuel which has vaporized from the globules will result. Tocontinue combustion of this globule, the next layer must vaporize, and if air has displaced these gases of combustion resulting from the combustion of the first layer, then combustion of the second layer will occur andfso on until the combustion of the entire globule has been completed. But if the original globule were surrounded by only the exact quantityof air chemically required, some of the unused air would be carried away by the combustion gases and the remaining part of the globule although vaporized would not have sufficient air present to combine with it, hence, it would pass away either partially burned to a monoxide or not burned at all. In order then to approach complete combustion of the globule, an excess of air must necessarily be supplied.

It is quite evident that the more minute the globules and the more evenly they are distributed throughout the air the more complete will be the combustion and the less will be the quantity of excess' air required. If vaporization of the fuel is resorted to, still better and more rapid combustion Will result because particles of fuel vapor are infinitely smaller than the smallest globule. Vaporization in reality effects a change consumed, requiring no air replenishment as in the case' of the surface-ofthe fuelglobule.

Even though the fuel is thoroughly vaporized and the required quantity of air is present, it`

need not follow that combustion will be complete. It is imperative that the two be thoroughlyfnixed, that is, each fuel particle must be surrounded by its requisite vquantity of air. This is known as a homogeneous mixture.

Thus far, I-hav'e` shown what is' necessary if complete combustion is to occur and if the -quantity of excess vair requiredis to be reduced to a minimum.

To obtainA complete combustion without hav ing to resort to excess air is ofv vital importance.

The quantity of yairwhich is in excess is inert and, being present, must be heated and consequently prevents the combustion temperature from rising to a degree to which it otherwise woul'd, were'this inert matter not present. The importance of obtaining maximum temperature from the burning of fuel, when air is used as a source ofoxygen, should require no comment.'

Excess air and lack of homogeneity both lower the rate of flame propagation i. e. the velocity at which the flame propagates itself throughout the mixture,*hence, combustion will be more rapid and the flame willbe'located within the antecombustion chamber when the-quantity of air in excess is reduced to a minimum and the mixture produced is homogeneous. Another very important reason for desiring to minimizethe quantity of excess airis because of its disastrous oxidizing effect on boiler tubes, metal furnace parts,I and metals in the process of their manufacture. A

It will be'shown inthe device Iam about-to describe thatv the fuel is first atomized, then vaporized by, and homogeneously` mixed with the air, and that the flame resulting from the combustion is so located by the Vhigh rate of flame propagation obtained, which is in excess of 16 ft. per sec., that it is made to effect a desirable transfer of heat to the -air that is subsequently to be used to support combustion of the fuel; that the device affords a wide but sensitive variation in the control of the combustion rate Without sacrificing any ofits thermal efficiency. A"The operation of my-device is as followsz' Air from-a source of supply such as blower 37 is delivered through pipe 86, thence through passageway 7., formed between antecombustion chamber wall 16 and housing 2', and passageway 8, formed between wall 16 and sheath 6. Conducted further through sheath 6, it passes around the mixing chamber `formed by pipes A3, ,4 and 5, thence through pipes 9,10, 11, l2 and 13 through a metering, mixing,v and atomizing device 22. mixing and atomizing device 22 is substantially an, air sealed, pressure equalized,v constant level, automotive carburetor wherein the liquid fuel Vis effected to be discharged into the air stream at a metered rate which depends on the velocity of the air stream (rate of air flow). When no air flows, no.. fuel is caused to flow because if no pressure difference exists in the air Metering,V

stream, no .pressure difference exists onthe fuel.

' Because of the'small vorifices .throughvwhich the fuel is 'discharged' into thezairistream' and the comparatively high velocity of the air stream, it is delivered in a' minutelyv atomized spray. On starting, a more volatile grade offueliis supplied through pipe 24 and` Valve -26 tothe constant level chamber 84 so that the normalatmospheric temperature Aof this ai'r` stream is sufficient to cause a partial vaporization ofthe globules of the spray just ment-ioned. The mixture of fuel vaport and air thus-produced `is then conducted past safety 'fire screen 40'into antecombustion chamber 1 where 'initial ignition is effected by a high y tension current supplied to spark plugll. To 'in-.- surecontinuance of flame, atvstarting when the device is'cold it isv suggested 'that the spark be left on for a short period of time. i 'f In a short time some of the heat from the ame in antecombustion chamber' 1 willbe transferred through'walll of said chamber to the air passing through passageways 7 and 8 causingA said air to rise in temperature. As this heated air, passing through the metering, mixing, and atomizing device'22, comes in Contact with the fuelspray, the globules are thoroughly vaporized and theresulting vapor is homogeneously mixed withthe air as the two pass through the mixing chambers and safety re screen 40, so that when the'mixture is now delivered into antecombustion chamber -1, it is in condition for complete combustion at a higher rate of ame propagation thany when the device was cold at the'time'of starting. As

ymixture wil-l continue to increase with an increase in the air temperature until a temperature which effects complete vaporization of the fuel spray has been attained. Thereafter, raising of the air temperature will' not increase homogeneity and will not cause an increase in the rate of flame propagation. I have found when the fuel is thor.-

oughly vaporized, that the flame propagation rate is'unchanged by a change in the combustion rate', provided the mixture ratio is maintained constant, and that an 4increase in the fuel percentage increases thez rate of flame propagation. 4It should be'noted that 'the flame was initially ignited on the antecombustion` chamber side of safety re screen 40 and that said screen prevents the pre-i'gnition'of the mixturey prior-to its passage therethrough, even though'the velocity ofthe mixture through the screenV is less than the rate offlame propagation. The reason for using the screen should be so evident that `discussion of its function should not be necessary. l 1 'Let it be supposed thatthe rate of flame propagation is 16 ft. per sec. and let it be assumedthat butterfly valve 38; is'only slightly open permitting a quantityof mixtureto bedelivered that will flow throughscreen 40 at a velocity of 8` ft. per sec; Screen and the entire flame, because 'of being small, will only contact with a part of the surface area of `wall 16. *HeatI will .be .transferred through that part ofthe surface of wall 16, .with which the flame contacts, to the smalll quantity of air passingrover the outer surface of said. wall 'as theair passes through passagewaysv'l andLS-L The. rear 'of theflame will be locatedat the I Now as valve 38 is further opened, permitting-of the mixture velocity tol increase to-16 ft. per sec.

through rezscreen 40, the rear, of the llame will still be located at the screen but the flame will be larger and will therefore contact with a greater surface area of wall 16, effecting a greater transfer of heat to the air and a corresponding increase in air temperature, even though'the quantity of air being Aheatedis greater than before. Suppose, now, valve 38 is further opened and the mixture isdelivered through screen 40 at the rate of 24 ft. per sec. the flame will thenbe removed from thescreen because the mixture velocity exceeds the rate of flame propagation by 8 ft. per sec.

. If no envelope such as wall 16, of antecombustion chamber 1, existed,fthe flame would assume a certain natural shape 'of its own, but just where it would start to form at various combustion rates would be difcult to ascertain and to cause an accurate, or rather denite rate of `transfer of heat, from it, to the air, would be Idifficult.rv If, on the other hand, walls 16 are made sufficiently closev livered into antecombustion chamber.` A cross section of antecombustion chamber in square inches at which rear of flame will occur.

Or if we refer to the last position of butterfly valve opening discussed, which permitted a mixture velocity past screen 40, of 24 ft. p er sec. then the rear of flame will occur in that cross section of antecombustion chamber 1, which is 11/2 Atimes the cross sectional area of the screen, because it is at this location that the mixture will have dropped in pressure and the correspondingly lowered velocity will equal the rate of ame propagation, i. e. 16 ft. per sec.

To go further, if the butterflyv valve is further opened, permitting the mixture to be delivered through the screen at 32 ft. per sec. the cross sectional area whereat the rear of the'flamewill occur will be twice that of the cross sectional area of the screen. And so, on furtheropening of the butteriiy and corresponding increase in the rate of combustion and increase of mixture velocity through the screen, the rear of the flame is further disposed into larger antecombustion chamber cross sections, until full opening of valve 38, might cause the llame to be entirely removed from the antecombustion chamber, provided the pressure and capacity of the blower was sufficiently great to cause such an extreme quantity ofV air and subsequent 'quantity of mixture to be delivered.

It should beevident from the foregoing, without having` to resort to mathematics, after the maximum surface area of wall 16 has been contacted by ame, that further increasing the rate `of combustion causes a decrease in the surface area With which the flame contactsfor the simple reason that the flame is being disposed out of vantecombustion chamber 1 as the combustion rate is increased.

Just what decrease in antecombustionr chamber surface area will be effected by Various increases in the combustion rate will naturally de-f pend on thecontour of the chamber wall. Inan should be borne in mind that this only holdstruel when the combustion rate which causes theflame to contact with the maximum surface area has been exceeded. If the antecombustion. chamber is -abnormally long, and the mixture is not subjected to apressure which'will deliver-a suiiicient quantity to cause a rate of combustion thatgwill in turn produce a flame large enough to contact with the availablel antecombustion chamber ,surface area, this condition would not obtain, but rather, the surface area wouldincrease with the combustion rate, which is not necessary nor desirable, r f

The conditions `which I have found to be desired are these; Y Q

l. The design of an antecombustion chamber and the use of an air pressure, which will cause a sufcient surface area to be contacted by the flame at the maximum combustion rate desired, in order to effect a suflicient transfer of heatto the air so that the air will be raised to a temperature which will produce good vaporization of the fuel and the production of a thoroughly homogeneous mixture and thereby effect complete combustion of the fuel with vthe least quantity-of air in excess. I i

2. An antecombustion chamber, the maximum surface areay of which, when contacted by flame at a certain combustion rate will not be so great as to permit of a quantity of heat to be transferred to the air that will raise the airtoa temperature thatwould prove harmful to the device, or cause pre-ignition.

3. A sufficient surface area of the antecombustion chamber to be contacted by a small flame, so that the temperature to which the air willbe heated, at the minimum combustion rate desired, will be sufcient to cause a thoroughly homogeneous'mixture to be produced.

li. That the maximum temperature towhich the air will be heated should be attained at a combustion rate about three or four times the minimum combustion rate and that further increases in the combustion rate should be accompanied by decreases in air temperature.

The conventional type of automotive carburetor (which has been air sealed and pressure equalized to function at pressures in excess of atmospheric because lthe pressure of the air supply isin excess of the atmosphere) has been used in conjunction with my device because of several Vdesirable functions which it so well performs,

3.V A butterfly valve Vis themeans employed for 6. After such settings are made as give the mixture ratio desired, no further manual adjustment is necessary. The butterfly valve maybe Yoperated by thermostat or other means to effect whatever Variation or constancy of combustion Vrate that is desired without further attention from the operator. By my having adapted such a means as conventional automotive carburetor to the device which I have described for the transfer of heat from the flame to the air, I have perfected a novel method for the combustion of liquid fuel which embodies the following salient features:

l. Rapid and complete combustion of the less volatile grades of liquid fuel.

2. Maximum temperature from the combustion of liquid fuel when air is used as a sourceof oxygen. Because of a perfectly homogeneous te a mixture being produced, the quantity of excess Aair required is reduced to a minimum.

3. The automatic heating of air, to a predetermined maximum temperature which it is dennitely known will not be exceeded in a given unit, by a natural physical means without the need of havinga resort to a complicity of mechanical devices.

4. Entire control of combustion rate `in a single and simple butterfly valve.

5. The wide variation in the rates of combustion which can be obtained in a given unit, and the sensitive control of the variation in the cornbustion rate afforded.

The unique but natural physical co-relations and their .interdependence which exist, between rate of combustion, flame location, suiface'area contacted by name, velocity of air passing over the surface area and temperature to which the air is heated, should ,be understood,because no other device yet disclosed suggests that any thought was given to their existence.

The'effect of vaporization on homogeneity and the subsequent increase in the rate of flarne propagation are discussed heretofore. It should be stated here thatafter complete vaporization of the fuel and the homogeneous mixing of the fuel Vapor and air have been attained, further increase in the air temperaturelwill not increase the rate of flame propagation. In other words, superheating the vapor will not increase the homogeneity of the mixture and having reached so called maximum homogeneity no increase in the flame propagation rate will result. it is realized that increasing the percentage of fuel in the mixture will increase vthe rate of flame propagation, but increasing the fuel percentage beyond that which theairpercentage will cornpletely consume is outside of this discussion, although use is made of it on starting, by tempor- .arily supplying a slight excess of fuel.

That flame location is the resultof the rate of "flame propagation and the velocity of the mixantecornbustion chamber.y have y been founclto have anr effectA on final air:

that surface area contacted by llame is the result ture entering the antecombustionchamber, and.

of flame locationl are discussedy 'in detail hereto- If the Ymixture ratio of ,fueland air is constant for all combustion rates then the Velocity and quantity of air flowing between the sheath and thecuter surface of the antecombustion chamber wall must vary directly as the combustion .r ate "31 have already discussedr the relative ysurface areas vof the ant'ecoinbustioh chamber which 'are contacted by llame at various combustion rates.

Starting with thelowest combustion rate prac'- ticable, we have this condition; a small flame starting at' the re' screen and spending 'itself aefcre its exit from the mouth of Vthe antecofnbustion chamber. of the chamber' wall surface is contacted ,by the flame, the forward portion' of the 'chamber Wall receiving heat only from Vthe hot gas after cornbusticn is complete. A quantityof air, proportional to the combustion rate, is flowing over the .relatively small surface with which the flame contacts, and heat is transferred to it, raising its temperature.

if now the combustion rate "is doubled, the

flame is enlarged, a 'greater surface area is conf tacted, and twicetheamount of air is flowing over the surface. f

The airis now heatedto a higher temperature tlianbefore because the surface Aarea contacted by flame has increased more'rapidly than vthe Vquantity ofthe air passingover this surface.

Whether or not thel flame has "been removed from the` screen atthis pointis of little concern, the fact is a greater surface areais contacted.

" As the combustion rateiswfurther increased; a

Consequently, only the rear y point will socnbe reached wherev the maximum surface area will be contacted by ame. At this point,4 the air will be Vheated to a maximum temperature.

' Further increasing the combustion rate is now accompanied by adecrease in the surface area contacted by flame but the quantity and velocity 'of air contacting with the other side of the wall are' ofcourse increasing in direct ratio with the combustion rate. The net resultfbeing that the "f nal air temperature now decreases as combustion rate is increased.

It is very evident', therefore, that the final temperature to* whichv the air is heated isclosely related to the surface area contacted by flame and the quantity and-Velocity, of air passing over said surface. v

Itwill vbe seen from the foregoing and from the previous ydiscussionthat ythe final temperature -to which thel air' isheated at;- various combustion rates is dependent on the size and contourof the Other factors which vSo far mention has' only :been made v'of nal" 'air temperature, for'in fact', it `is this whicleffectsl vaporization of the fuel'. However, final air temperature is only the result of the quantity of Vheat transferred andthe weight of airA lto which the heat is transferred.

Knowing the weight of vair fiewingper hour,

' the initial and nal temperatures,the heatabsorbed by or transferred to the. air may readily b eomnuted by the, formula his 1 .Where Q=B. t. u.

lWhere Q=B. t. u. absorbedor transferred per hr.

C=Specific heat of air W=Weight of air flowing per hr. rfi-:Final air temperature t=,Initia1 air temperature From the above, it is seen that if the same quantity of heat was absorbed by a lesser quantity'of air, the final air temperature would be higher and vice-versa. But the quantity of heat absorbed by the air must be equal to the quantity-of heat transferred to it from the flame through the surface of the antecombustion chamber wall. Luckes formula for heat transfer is- QA=KO A han transferred per hr. A--Area in square feet through which transfer is in process (the area contacted by flame.) lim-:Mean temperature difference for the process which in this case would be the mean temperature diierence existing between the flame and the y initial and final air temperatures. K0=Coeflicient of heat transfer, which is the conductance of the antecombustion chamber wall and iiuid lm of which the latter is of greater importance. The velocity at which Athe air passes over the wall has a marked effect on the fluid film. According to the experiments of Hinlein the value of K0 varies approximately as the square root of .the air velocity. However, tests 'which I have made'lead meto believe K0 varies almost directly as the air velocity. In fact, if Hinleins values for Ko were used it would be found that the air temperature would drop so rapidly with increase of the combustion rate that the maximum capacity of a given burner assembly *would be materially reduced by lack of sufficient air temperature to effect proper vaporization.

The size and contour of the antecombustion chamber, the annular cross Asection of the pas-V sageway between the sheath and the antecombustion chamber and the method of joining the f chambers are all factors which have a direct bearing-on the final temperature to which the air, that is subsequently to Y, be heated. Y

vaporize the fuel, will f y Although I have shown the blower as forcing the air through the device I do not desire to be limited in this respect as it can be located between the device and the intake of the carburetor or between the carburetor discharge and the device.

In Figures 3, 4, 5, amodied form of my invention is illustrated. Pipe 60, delivers air into passageway 61 tangentially and inso'doing causes the air to have; an unidirectionalcourse there- In other matters of construction and operation this modied form approximates that of the In some applications its use may be very desiris equipped with an integral spiral iin 73.y

able, vfor instance, where the heat rgenerator is to be installed in batteries of two or more, it may at times be desirable not to operate all ofthe units in the battery. Where this -is 'done it is possible that those unitsnot being operated may become overheated due to radiation from their respective main combustion chambers. i The Ause of rrelief valve 20, located as in Figure 1, permits of air being circulated as a cooling medium around the antecombustion chamber and"said air to be discharged into the atmosphere without having to passvthrough carburetor 22. lTo furnish a supply of compressed air from a single source to a batteryvof heat generators described herein is entirely feasible and nothing herein is meant to be construed otherwise.

In Figure 6 is shown another modified form of my invention wherein the outersurface of antecombustion chamber 1`V is equipped with fins 62 to expose a greater surface area to the air which is effected to pass over said surface on its way to the carburetor from a difference in pressure creating device. If desired the fins could be replaced by pegs. y'

Figure 7 shows another modified form 'of my invention,y wherein the antecombustion rchamber The air is discharged into casing 72 from a source of pressure and is effected to'traverse `aspiral path, over the total siu'face of the antechamber, on its way to the carburetor. 1'

In Figure 8 is shown another modified form of my device wherein the carburetor '75 is located within the housing 2' which surrounds that portion of the combustion chamber l'adjacent to the entrance of the fuel and airkmixture and herein referred to as the antecombustion chamber. Such vconstructionl has certain advantages since it reduces to a minimum the distance travelled by the air or the mixture to and from the vaporizing and mixing means; a further advantage is to effect a direct heating of the fuel in the carburetor bowl which is desirable when very viscous fuels are used.

' to come intointimate contact with the outer wall or surface of the antecombustion chamber,'to absorb heat from said wall and-thereby effect a cooling of the chamber-wall and av preheating of the air used in combustion.

Carburetor 75 is located'entirely within housing 2 and has its discharge 80' air-tightly connected to the small end or entrance of antecom- 465 bustion chamber 1 and has its intake *13 located on the same center line as its'discharge with the float chamber so located as to supply fuel to the jets which are in' said intake and discharge Pipe '78 conducts fuel from an' external line. source of supply to the float chamber of -carburetor`75. Pipe 78 is preferably flexibleto Still another advantage is that the housing itself functions to afford permit of ready assembly and whereit passes through housing 2', it is air-tightly secured to 'prevent leakage of air to or from the"housing.y

A removable plug 79 may be located as indicated in housing 2' under the carburetor oat chamber to permit of flexible pipe '78 being connected to the float chamber. End cap 18 is removably but tightly secured to housing 2' to permit of removal thereof in order to obtain access to carburetor 75 when necessary but must be secured to prevent leakage. Relief valve 20 in addition to its functions as heretofore set forth affords protection should excess pressures arise for any reason and is located at any convenient part of the housing or as shown in end cap 18'.

Carburetor buttery shaft 81 is flexibly butk securely connected to an extension 82 which passes through a stufling box 83 to the outside of housing 2', permitting of carburetor butterfly 38' being operatedfrom without housing 2 and yet permitting. easy removal of carburetor 22' from the housing 2.

Various changes might bev made in the location and construction of certain elements and still fall within the scope of my invention. Certain of such changes I have illustrated in the various modifications.

In conclusion, thel device which I have described provides for the metering of liquid fuel and air in constant ratio irrespective of the rate of combustion, the thorough vaporization of the less volatile grades of liquid fuel and the homogeneous mixing of the fuel vapor and air. Heating of the air to a temperature which will effect this thorough vaporization and homogeneity is accomplished by a means heretofore never employed. The method is unique in that it is thermodynamically balanced and requires no mechanical or manually operated contrivances to positively prevent overheating of the air at any combustion rate. Further, a single unit affords a wide but sensitive variation in the control of the rates of combustion without sacrificing any of the eiiiciency of combustion because the air is heated to a sufficient temperature over a range to effect good vaporization and homogeneity, and the means provided for metering and mixing. the fuel and air does effect constancy of mixture over a similar wide range. Liquid fuel is burned completely with a minimum of excess air resulting in much higher temperatures from the combustion of liquid fuel than have heretofore been obtained. And withal, it is simple and economical to construct, operate and maintain.

Although the burner has been illustrated as f operating in a horizontal position, it is to be understood that it is equally adapted to operate at any angle including the positions in which the mouth of the burner would be pointing directly upwardly or directly downwardly.

This application is a continuation of my copending application for Heat generator, Serial Number 318,900, led November 12, 1928.

Having described by invention it is obvious that many kmodifications may be made in the same within the scope of the claims without departing from the spirit thereof. v

I claim:

1. In a fuel burner of the carbureting type having a combustion chamber that diverges from adjacent the point of admission of the combustible mixture thereto and employing preheated air as the carbureting medium, means surrounding said combustion chamber and forming therewith an air preheating passage of approximately uniform cross-sectional area throughout the major portion of its length and which communicates at one end with the carbureting device, means at the other end of said passage for distributing the air entering said passage uniformly about the entrance thereto,

and means for causing air to flow through `said passage.

` 2. In a fuel burner of having a combustion chamber' that diverges from adjacent the point of admission vof the combustible mix-ture thereto and employing preheated air as the carbureting medium, means surrounding said combustion chamber and forming therewith an air.v preheating passage of approximately uniform cross-sectionalv area which communicates at one end with the carbureting device, means at'the other end of said passage for distributing the air entering said the carbureting type throughout the major portion of its length and 1' passage uniformly about the entrance thereto,

means for causing air to flow through said passage, means forming a passage for delivering a combustible mixture of fuel and air to said combustion chamber, and means forming substantially an extension of said air passageway and surrounding said mixture delivering passage for transferring thereto a part of the heat of said preheated air prior to the point of entrance of vsaid mixture into said combustion chamber.

JEROME J. SLOYAN.

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