Hydrogen-air flames

Flame Photometric Detector3 With the flame photometric detector (FPD), as with the FID, the sample effluent is burned in a hydrogen/air flame. By using optical filters to select wavelengths specific to sulfur and phosphorus and a photomultiplier tube, sulfur or phosphorus compounds can be selectively detected. 

Dependence of Flame Species Concentrations upon Additive Concentrations. A method of determining the dependence of various ionic, neutral molecule, and excited species concentrations on the concentration of hydrocarbon added to a hydrogen/oxygen or hydrogen/air flame (based on a principle similar to that of flame ionization detectors... 

Comparison of static- and dynamic-extinction stretch rates for various hydrogen/air flames. When the equivalence ratio is sufficiently rich, the dynamic-extinction strain rate can be substantially lower than the corresponding static extinction limit. 

Sung, C.J., Makino, A., and Law, C.K., On stretch-affected pulsating instability in rich hydrogen/air flames Asymptotic analysis and computation. Combust. Flame, 128, 422, 2002. 

D. Escudi4 P- Paranthoen, and M. Trinite 1983, Modification of turbulent tiow-field by an oblique premixed hydrogen-air flame, in Flames, Laser and Reactive Systems (selected papers from the Eighth International Colloquium on Gasdynamics of Explosions and Reactive Systems), Progress in Astronautics and Aeronautics Series, AIAA Inc. publishers, pp. 147-163. 

M.S. Wu, S. Kwon,J. Driscoll, andG.M. Faeth 1990, Turbulent premixed hydrogen-air flames at high Reynolds numbers. Combust. Set. Technol. 73(l-3) 327-350. 

In this section we apply the adaptive boundary value solution procedure and the pseudo-arclength continuation method to a set of strained premixed hydrogen-air flames. Our goal is to predict accurately and efficiently the extinction behavior of these flames as a function of the strain rate and the equivalence ratio. Detailed transport and complex chemical kinetics are included in all of the calculations. The reaction mechanism for the hydrogen-air system is listed in Table... 

Strain Rate Extinction. We performed a sequence of strain rate calculations for an 8.4% and a 9.3% (mole fraction) hydrogen-air flame. The equivalence ratios of these flames are = 0.219 and = 0.245, respectively. In both cases the Lewis number of the deficient reactant (hydrogen) was significantly less than one. In particular, at the input jet, the Lewis numbers were equal to 0.29 for both the 8.4% flame and the 9.3% flame. We also found that these values did not change by more than 15% through the flame. 

Figure 2. Temperature profile in K for the 9.3% (mole fraction) hydrogen-air flame with a strain rate of a = 200 sec ...

Figure 7. Extinction curve illustrating the maximum temperature versus the equivalence ratio for hydrogen-air flames with a strain rate of a = 1000...

Ab initio calculations addition of hydroxide ion to formaldehyde, 212 energy surfaces, 201-211 Adaptive continuation method, hydrogen-air flame, 417 Adaptive mesh... 

Flame temperature. The hydrogen-air flame is hotter than methane-air flame and cooler than gasoline at stoichiometric conditions (2207°C compared to 1917°C for methane and 2307°C for gasoline). 

Tin compounds are converted to the corresponding volatile hydride (SnH4, CH3 SnH3, (CH3 )2 SnH2, and (CH3 >3 SnH) by reaction with sodium borohydride at pH 6.5 followed by separation of the hydrides and then atomic absorption spectroscopy using a hydrogen-rich hydrogen-air flame emission type detector (Sn-H band). 

For metals and crystals, cleavage can attempt similar feats, but the results are not as good. Metal surfaces formed by cleavage are usually not atomically flat. When an Au wire is flame-annealed in a hydrogen-air flame, the Au(lll) face is formed preferentially, since it has a lower surface energy than the Au(100) or Au(110) faces, but these Au(lll) faces resemble New Mexico mesas the atomically flat region may be only 50 x 50 nm, and is surrounded by one- or two-atom steps leading down to the plain, and then on to the next mesa. 

Polycrystalline platinum was cleaned by heating in hydrogen-air flame and then dipped in to the electrolyte. The potential was scanned in the electrolyte from 50 mV to 1600 mV for I min, at a scan rate of 10 V/s. For infrared spectroscopy, the electrode was cleaned with filming sulfuric acid followed by the potential cycles described above until the voltammogram became that of clean platinum. 

Figure 5.4 Schematic of the geometrical configuration for hydrogen-air flame and sofid fuel. The geometry corresponds to the experimental setup. The initial shape of the HED fuel was a circular arc segment as shown above. The relevant material properties air density = 1.91 kg/m , hydrogen density = 0.0898 kg/m . For the turbulent quantities at the inlet k = (O.OSf/miet) = 9.59 (m/s), = C fc / /(0.03Liniet) = 6360 m /s , jjkt = Cfe = 0.00248 kg/ms. For the fuel sample, m.p. is 450 K, latent heat of fusion is 72.7 J/g. Dimensions in mm. Air inlet velocity 103.3 m/s, hydrogen injection velocity 800 m/s...

Seshadri, K., N. Peters, and F. A. Williams. 1994. Asymptotic analyses of stoichiometric and lean hydrogen-air flames. Combustion Flame 96 407-27. 

Vlachos, D. G. 1995. The interplay of transport, kinetics, and thermal interactions in the stability of premixed hydrogen/air flames near surfaces. Combustion Flame 103(l-2) 59-75. 

Driscoll et al. [5] studied NO emission properties of turbulent partially pre-mrxed hydrogen-air and methane-air flames. The emission results for hydrogen-air flames showed that the emission index decreased monotonically with increasing levels of partial premixing because of the reduction in residence time caused by increasing jet velocity. The results for the methane-air flames were more complicated. 

Electrolytic conductivity detector (i) Pure hydrogen/Air flame... 

---