Flame comparison

Fig. 33. Recombination in lean hydrogen + nitrogen + oxygen flames. Comparison of measured points of Kaskan [179] for flame L of Table 32, re-calibrated as described in text, with computed lines. Solid line, rate coefficients as in set 2 of Table 30 broken lines, as set 2 of Table 30, but with kji = 4 x 10> (curve A) and 1.2 x 10 (curve B).

Fig. 9. Measured OH ( ), CH3 ( ), NO ( ), CH ( ) and CN (A) absolute concentrar tion profiles in the 10 Torr CH4/O2/NO flame. Comparison with results from chemical kinetics modeling using the Lindstedt reaction mechanism (—) Ref. 67, the GRI 2.11...

Fio. 26. Distribution of particle diameters in an ethylene sooting flame. Comparison between model predictions and the experimental data (Zhao et al., 2003). 

A comparison between the beam intensity before and after the flame provides a measurement of the quantity of photons absorbed and therefore the concentration of the atom being analyzed. The comparison can be made directly by a double beam analyzer. See Figure 2.7 in which the beam is divided into 2 branches one of which traverses the flame, the other serving as... 

Laboratory experiments using rodents, or the use of gas analysis, tend to be confused by the dominant variable of fuel—air ratio as well as important effects of burning configuration, heat input, equipment design, and toxicity criteria used, ie, death vs incapacitation, time to death, lethal concentration, etc (154,155). Some comparisons of polyurethane foam combustion toxicity with and without phosphoms flame retardants show no consistent positive or negative effect. Moreover, data from small-scale tests have doubtful relevance to real fine ha2ards. 

Commercial Hquid sodium alumiaates are normally analyzed for total alumiaa and for sodium oxide by titration with ethylene diaminetetraacetic acid [60-00-4] (EDTA) or hydrochloric acid. Further analysis iacludes the determiaation of soluble alumiaa, soluble siHca, total iasoluble material, sodium oxide content, and carbon dioxide. Aluminum and sodium can also be determiaed by emission spectroscopy. The total iasoluble material is determiaed by weighing the ignited residue after extraction of the soluble material with sodium hydroxide. The sodium oxide content is determiaed ia a flame photometer by comparison to proper standards. Carbon dioxide is usually determiaed by the amount evolved, as ia the Underwood method. 

Flame Retardants. The amount of research expended to develop flame-retardant (FR) finishes for cotton and other fabrics has been extremely large in comparison to the total amount of fabrics finished to be flame retardant. The extent of this work can be seen in various reviews (146—148). In the early 1960s, a substantial market for FR children s sleepwear appeared to be developing, and substantial production of fabric occurred. In the case of cotton, the finish was based on tetrakis(hydroxymethyl)phosphonium chloride (THPC) or the corresponding sulfate (THPS). This chemical was partly neutralized to THPOH, padded on fabric, dried under controlled conditions, and ammoniated. The finish was subsequently oxidized, yielding a product that passed the test for FR performance. This process is widely preferred to the THPOH—NH process. 

Comparison of Various Flame Arrester Standards and Codes... 

Table 8-1 presents a comparison of test requirements in various US and foreign standards and codes for end-of-line and in-line deflagration flame arresters. A comparison of test requirements in various US and foreign standards and codes for in-line detonation flame arresters is similarly presented in Table 8-2. The UL and EM test criteria closely follow the USCG criteria.

Comparison of Test Parameters of Various Standards for End-of-Line and In-Line Deflagration Flame Arresters (Adapted from Lapp and Werneburg 1999)... 

Experiments on a small scale with stoichiometric methane-air mixtures were carried out by Chan et al. (1980). Comparisons of results of these experiments with those performed by Moen et al. (1982) revealed that simple scaling is not possible for the results of explosions with very high flame speeds, in other words, flame speeds resulting from very intense turbulence. 

I lere, too, computer based predictions about the nature of these flames require information about the chemicals and science of diffusion flames for the predictions to be accurate. The predictions are made accurate by comparison with measured chemical species concentrations, measured temperatures, and flow characteristics. 

Adiabatic Reaction Temperature (T ). The concept of adiabatic or theoretical reaction temperature (T j) plays an important role in the design of chemical reactors, gas furnaces, and other process equipment to handle highly exothermic reactions such as combustion. T is defined as the final temperature attained by the reaction mixture at the completion of a chemical reaction carried out under adiabatic conditions in a closed system at constant pressure. Theoretically, this is the maximum temperature achieved by the products when stoichiometric quantities of reactants are completely converted into products in an adiabatic reactor. In general, T is a function of the initial temperature (T) of the reactants and their relative amounts as well as the presence of any nonreactive (inert) materials. T is also dependent on the extent of completion of the reaction. In actual experiments, it is very unlikely that the theoretical maximum values of T can be realized, but the calculated results do provide an idealized basis for comparison of the thermal effects resulting from exothermic reactions. Lower feed temperatures (T), presence of inerts and excess reactants, and incomplete conversion tend to reduce the value of T. The term theoretical or adiabatic flame temperature (T,, ) is preferred over T in dealing exclusively with the combustion of fuels. 

When a water-based fluid makes contact with a flame or a hot surface its water component evaporates and forms a steam blanket that displaces oxygen from around the hot area, and this obviates the risk of fire. Water-based products all contain at least 35% water. Because water can be lost by evaporation, they should not be subjected to operating temperatures above about 60°C (140°F). Table 52.8 shows a comparison of oil and FR fluids. 

Spraying conditions make hardness values so variable that unless they are accurately known no comparisons are possible. Brinell hardness figures for sprayed molybdenum vary from 350 when produced with a reducing flame to 725 with an oxidising flame, and while a thick sprayed deposit of 0-8% carbon steel can give a figure of 330, the hardness of a particle obtained by micro hardness methods will be about 550. 

A comparison of Horton s data for composite propellants with the theoretical results of Hart and Friedly is difficult. The theoretical studies are based on premixed flames, which are more appropriate for double-base propellants. The applicability of premixed flames to composite propellants is open to question, as indicated in Section II. Brown et al. (B13) have indicated that the data are consistent with the expected contributions of surface reactions in the transient combustion process. These comparisons are preliminary, however, and more research is required to study these observations in detail. 

The results show that at 2 torr, ku = 2.5 X 10 8 and at 760 torr ku = 1.0 X 10 8 cm.3 molecule-1 sec.-1 This is reasonably good agreement in view of the possible errors. Furthermore, the values of ku obtained are consistent with earlier estimates based on comparisons with similar reactions (10, 19). Our purpose in presenting it here is to illustrate the potential use of flames in estimating more accurate rate constants for reactions like Reaction 14. Of course, the influence of diffusion must always be accounted for in such estimations diffusion is particularly important at low pressures and for small ion concentrations. (It is often advantageous to work at low pressures because the spatial resolution is much better than at 1 atm. At low pressures most measurements are made in or close to the reaction zone itself. At high pressures, where the reaction zone is thinner, measurements are made both in the reaction zone and in the burned gases.)... 

Methyl parathion was determined in dog and human serum using a benzene extraction procedure followed by GC/FID detection (Braeckman et al. 1980, 1983 DePotter et al. 1978). An alkali flame FID (nitrogen-phosphorus) detector increased the specificity of FID for the organophosphorus pesticides. The detection limit was in the low ppb (pg/L). In a comparison of rat blood and brain tissue samples analyzed by both GC/FPD and GC/FID, Gabica et al. (1971) found that GC/FPD provided better specificity. The minimum detectable level for both techniques was 3.0 ppb, but GC/FPD was more selective. The EPA-recommended method for analysis of low levels (<0.1 ppm) of methyl parathion in tissue, blood, and urine is GC/FPD for phosphorus (EPA 1980d). Methyl parathion is not thermally stable above 120 °C (Keith and Walters 1985). 

The results obtained by Kuila et al. and Acharya et al. [63,64] from the EVA elastomer blended with lamellar-like Mg-Al layered double hydroxide (LDH) nanoparticles demonstrate that MH nanocrystals possess higher flame-retardant efficiency and mechanical reinforcing effect by comparison with common micrometer grade MH particles. Kar and Bhowmick [65] have developed MgO nanoparticles and have investigated their effect as cure activator for halogenated mbber. The results as shown in Table 4.2 are promising. 

Comparison of the C2 radical mole fraction profile measured by LIF and CRDS in a flat, premixed fuel-rich propene flame at 50mbar. 

Comparison between flame-sampled PIE curves for (a) m/z = 90 (C H ) and (b) m/z = 92 (C Hg) with the PIE spectra simulated based on a Franck-Condon factor analysis and the cold-flow PIE spectrum of toluene. Calculated ionization energies of some isomers are indicated. (From Hansen, N. et al., /. Phys. Chem. A, 2007. With permission.)... 

Lamprecht, A., Atakan, B., and Kohse-Hoinghaus, K., Fuel-rich propene and acetylene flames A comparison of their flame chemistries. Combust. Flame, 122, 483, 2000. 

At present, several theories have taken the finite flame diameter into consideration. Some of their predictions are presented in Figure 4.2.13 for comparison. 

Comparison between the measured growth rate, and the growth rate calculated from Equation 5.1.22, for propane-air flames in a Im tube according to Ref. [46]. 

G. Searby, J.M. Truffaut, and G. Joulin. Comparison of experiments and a non-linear model for spatially developing flame instability. Physics of Fluids, 13 3270-3276, 2001. 

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