Flame volume

Another important concept is that of the critical ignition volume. During the propagation of the combustion wave, the flame volume cannot continually grow beyond a critical value without an additional supply of energy. The condition that controls the critical volume for ignition is reached when the rate of increase of flame volume is less than the rate of increase of volume of the combustion products. In this condition a positive exchange of heat between the flame and the fresh mixture is achieved. 

For a point spark source, the flame volume is initially spherical and the critical ignition volume is determined by calculating the rate of change of flame volume with respect to radius compared to the rate of change of volume of the combustion products (eq. 

For a line spark source, the flame volume is initially cylindrical with the cylinder length equal to the separation distance between the electrodes. Thus, for a cylindrical flame, = e, and the critical ignition volumes are equation 7 for a spherical flame and equation 8 for a cylindrical flame where = critical ignition volume, m /kg e = thickness of flame front, m and d = flame height, m. 

Useful formulas for BLEVE fireballs (CeSP, 1989) are given by equations 9.1-27 thru 9.1-30, where M = initial mass of flammable liquid (kg). The initial diameter describes the short duration initial ground level hemispherical flaming-volume before buoyancy lifts it to an equilibrium height. 

An interesting correlation of the rate of fire growth measured by flame volume was given by Labes [24] and Waterman [25]. They show that after room flashover in a room of volume Vo, the Are volume (Vf) grows as... 

Confined fires will spread the flames across the ceiling and, in general, this will be the hottest part of the fire. If the flame volume is more than 20% of the structure volume, then all of the ceiling beams and high level piping will be engulfed. It is possible that this could lead to simultaneous failure of all of the ceiling beams and upper module structure. This could lead to the release of any inventories supported on the level above or of total structure collapse. 

Its formation can be kept to a minimum by keeping the excess air supplied to combustion units to a minimum value for safe complete combustion [56]. Burner designs that produce a more diffuse flame front (large flame volume) achieve lower peak combustion temperatures, which helps to decrease the formation of nitric oxide. Injection of ammonia into the flue gas while it is still hot can decrease NOx concentrations down to 80-120 ppm, one-third to one-half that of uncontrolled discharges [64]. Measures for NO reduction during operation of fluid catalytic crackers have been evaluated in pilot scale reactors [65]. 

In this paper we present a new technique for the synthesis of carbon film with carbynoid structures. The basis of the method described here consists of a combustion reaction between oxygen and acetylene and particular parameters for flame conditions. The flame volume can be considered as the reaction chamber as in conventional chemical vapor deposition (CvD) or physical vapor deposition (PVD) methods. This technique provides a method of synthesizing carbyne at high growth rates and of obtaining better crystals. 

In fuel-fired furnaces, heat release rate is usually expressed in heat units liberated per unit of furnace volume in unit time, commonly in Btu/ft hr or MJ/m hr. Closely related to rate of furnace heat release is the combustion volume or flame volume. Generally, the furnace volume should be at least equal to the sum of the maximum flame volume and the maximum load volume. The volume of the flame is a function of the combustion intensity condition discussed with table 3.1 subsequently, and where Fc is a configuration factor to assure that all of any one flame s volume is contiguous. 

If air and fuel are premixed upstream of a burner nozzle, mixing (and therefore combustion) may occur more rapidly than with nozzle mixing, and surely more thoroughly than with delayed mixing (perhaps with a detached flame) out in the furnace. Presumably, faster mixing and combustion will require less furnace volume, but the aerodynamics and the directions of the velocity vectors can influence flame shape to the point where flame volume may be less dependent on air or fuel momentum. 

Powders are especially powerful against flaming when the powder jet is directed to the flame zone instead of the seat of the fire. The flame volume to be controlled should not exceed the area that can be covered by a single shot of powder. If the seat of the fire comprises glowing particles, it should be sprinkled with light water until flaming has been suppressed, otherwise the flammable material may re-ignite. 

Flame Volume ratio Temperature (K) Maximum burning velocity (cms J... 

The flame volumes produced by the ignition of the hydrogen-air mixtures formed above pools of liquid hydrogen when ignited at various times from zero to 15.8 sec after spillage of the liquid on various surfaces were found to vary from essentially zero to a maximum volume equal to the lower limit mixture volume. That is,... 

The short exposures of Magnesium/Teflon/Viton (MTV) combustion show distinct areas with green and blue luminescence (Figure 9.6). The bluish green luminescence is seen aU over the flame volume. This emission can be attributed to the Mg triplet centred at 518 nm. The hght blue luminescence in contrast is... 

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