Fuels luminosity

The luminometer index (ASTM D 1740) is a characteristic that is becoming less frequently used. It is determined using the standard lamp mentioned above, except that the lamp is equipped with thermocouples allowing measurement of temperatures corresponding to different flame heights, and a photo-electric cell to evaluate the luminosity. The jet fuel under test is compared to two pure hydrocarbons tetraline and iso-octane to which are attributed the indices 0 and 100, respectively. The values often observed in commercial products usually vary between 40 and 70 the official specification is around 45 for TRO. 

Some potential problems of alcohol fuels have been addressed by a dding small amounts of gasoline or specific hydrocarbons to the fuel, reducing the flammabihty envelope and providing luminosity in case of fine. 

The fire ha2ard of methanol appears to be substantially smaller than the fire ha2ard of gasoline, although considerably greater than the fire ha2ard of diesel fuel. The lack of luminosity of a methanol flame is stiH a concern to some, and M85 (or some other methanol fuel with an additive for flame luminosity) may become the standard fuel for this reason. 

Methanol, a clean burning fuel relative to conventional industrial fuels other than natural gas, can be used advantageously in stationary turbines and boilers because of its low flame luminosity and combustion temperature. Low NO emissions and virtually no sulfur or particulate emissions have been observed (83). Methanol is also considered for dual fuel (methanol plus oil or natural gas) combustion power boilers (84) as well as to fuel gas turbines in combined methanol / electric power production plants using coal gasification (85) (see Power generation). 

Luminosity is the amount of chemical energy in the fuel that is released as thermal radiation. 

No attempt will be made here to enter into a more detailed discussion of the physics of the SFR, but a few comments will be made on the basis of some very simple parameterizations. Considering for example the exponential time-dependence of Eq. (7.12), the restriction on b(T) in Eq. (7.5) implies that v-1 > 0.9 T 10 Gyr. A related argument can be made about the past evolution of the luminosity of the disk - closely related to both the SFR and the IMF - from considerations of nuclear fuel consumption. All energy radiated corresponds to the synthesis of helium and/or heavy elements from hydrogen at a rate... 

For premixed fuel-air systems, results are reported in various terms that can be related to a critical equivalence ratio at which the onset of some yellow flame luminosity is observed. Premixed combustion studies have been performed primarily with Bunsen-type flames [52, 53], flat flames [54], and stirred reactors [55, 56], The earliest work [57, 58] on diffusion flames dealt mainly with axisymmetric coflow (coannular) systems in which the smoke height or the volumetric or mass flow rate of the fuel at this height was used as the correlating parameter. The smoke height is considered to be a measure of the fuel s particulate formation and growth rates but is controlled by the soot particle bumup. The specific references to this early work and that mentioned in subsequent paragraphs can be found in Ref. [50],... 

A. Dilution of fuel jet until no luminosity [Smith, C. A., M.S.E. Thesis, Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, Nar Jersey (1990)]. 

FIGURE 8.15 Typical temperature profiles along the centerline of laminar hydrocarbon fuel jets diluted with N2 to the point of no luminosity when burning in overventilated air streams. H is the height of the flame Zis the distance from jet exit along the centerline. 

Due to methanol s corrosivity and its affinity for water, it cannot be readily distributed in today s fuel infrastructure. Methanol burns with a nearly invisible flame. Available luminosity additives won t reform in the low-temperature methanol steam reformers. Methanol is more acutely toxic than gasoline. Additives that are likely to be needed for safety and health reasons will impact the fuel processor s performance and cost. 

Figure 24.5 Variation in mean temperature Tmean (1), mean mole fraction X112O (2), RMS temperature at the driving frequency fo Trms (3), and luminosity L (4), with relative phase of fuel and air, 6 tuei in the forced 5-kilowatt combustor. Normalization values Tmean = 1740, AH2O = 0.105, and Trms = 60 K. Steady parameters = 0.75, fo = 100 Hz, Aair = 25 W, and Atuei = 1.1 W. Vertical dotted lines correspond to relative phase values which yield Trms values greater than...

When large spherical AP particles dg = 3 mm) are added, large flamelets are formed in the dark zone.Pl Close inspection of the AP particles at the burning surface reveals that a transparent bluish flame of low luminosity is formed above each AP particle. These are ammonia/perchloric acid flames, the products of which are oxidizer-rich, as are also observed for AP composite propellants at low pressures, as shown in Fig. 7.5. The bluish flame is generated a short distance from the AP particle and has a temperature of up to 1300 K. Surrounding the bluish flame, a yellowish luminous flame stream is formed. This yellowish flame is produced by in-terdiffusion of the gaseous decomposition products of the AP and the double-base matrix. Since the decomposition gas of the base matrix is fuel-rich and the temperature in the dark zone is about 1500 K, the interdiffusion of the products of the AP and the matrix shifts the relative amounts towards the stoichiometric ratio, resulting in increased reaction rate and flame temperature. The flame structure of an AP-CMDB propellant is illustrated in Fig. 8.1. 

Diffusion Flame. When a slow stream of fuel g s flows from a tube into the atmosphere, air diffuses across the boundary of the stream and Brms an envelope of expl mixture around a core of gas. The core decreases in height until it disappears at some distance above the tube. It thus assumes the shape of a cone. On ignition, a flame front spreads thru the mixture and stabilizes itself around the cooe of fuel gas. The hydrocarbons in common fuel gases crack to form free C H. The shell of carbon-bearing gas so formed gives such flames their luminosity Turbulent Jet Flame. When a gas stream issues from an orifice above a certain critical velocity, it breaks up into a turbulent jet that entrains the surrounding air. The flame of such a jet consists of random patches of combustion and no cohesive combustion surface exists... 

M85 is used to represent a fuel blend of 85% methanol and 15% gasoline. The gasoline portion is added for cold-start and flame luminosity reasons. 

One FBC currently operating in Japan uses a revolving-type fluidized bed that allows relatively large tire chunks (up to 10 inches) to be fed to the chamber.4 The central portion of this bed is more fluidized than the outer portions, so solids flow to the center, where fuel is injected.4 Deflectors above the outer bed area "lap" waves of material back to the center.4 An air distributor directs non-combustibles to drain chutes on each side of the bed.4 The amount of fluidizing air and overfire air is automatically proportioned by optical devices that measure furnace luminosity.4... 

Yes, but as a result of the contraction, the temperature of the core increases, so the fusion rate and luminosity continue even though the fuel supply decreases. It is this process of contraction and temperature increase that keeps the Sun stable over billions of years. Without it, life wouldn t have had time to develop, and you, Mr. Plex, would not be here talking to me. ... 

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