Hydrogen oxygen mixtures

Figure 7-42A. Detonation velocities for hydrogen/oxygen mixtures. Note detonation range compared to flammability range of 4% to 95%. By permission. Ref. [41]., Stuii, The Dow Chemical Co. and The American Institute of Chemical Engineers Monograph No. 10, Vol. 73 (1977).

Figure 7-53. Detonation velocity, V, static pressure, Pg, and reflected pressure, Pp developed by detonation wave propagating through hydrogen-oxygen mixtures in a cylindrical tube at atmospheric pressure at 18°C. By permission, U.S. Bureau of Mines, Bulletin 627 [43].

Kuznetsov, M., Alekseev, V., Matsukov, L, and Dorofeev, S., DDT in a smooth tube filled with a hydrogen-oxygen mixture. Shock Waves, 14, 205-215, 2005. 

Gardner, W.E. and Pugh, A., The propagation of flame in hydrogen-oxygen mixtures, Trans. Faraday Soc., 35 283, 1939. 

GP 11] [R 19] Based on an analysis of the thermal and kinetic explosion limits, inherent safety is ascribed to hydrogen/oxygen mixtures in the explosive regime when guided through channels of sub-millimeter dimensions under ambient-pressure conditions [9], This was confirmed by experiments in a quartz micro reactor [9],... 

Figure 3.51 Schematic flow scheme of a micro-reactor system used for burning hydrogen and oxygen at large throuputs. A mixer is applied for reducing the volume of the explosive hydrogen/ oxygen mixture in advance to the reaction [115],...

Remember the explosive mixture limits are wide and different from other fuels even very rich hydrogen-air or hydrogen-oxygen mixtures can burn violently. 

Pre-addition of nitrogen oxide (or nitrosyl chloride as its precursor) to stoicheio-metric hydrogen-oxygen mixtures at 240 mbar/360°C will cause immediate ignition under a variety of circumstances. 

Detonation pressure and temperature of hydrogen-oxygen mixtures starting from 101.3 kPa (1 atm) and 298 K (25°C). Chapman-Jouguet calculations using the Gordon-McBride code. (After Gordon, S. and McBride, B.J.,... 

This equation suggests that if a given hydrogen-oxygen mixture, which could have a characteristic value of/dependent on the mixture composition, is raised to a temperature and pressure that satisfy the equation, then the mixture will be explosive. 

The checkers found that the reduction requires 4-5 days, whereas the submitter reported the reaction requires 24 hours. Fresh catalyst is added whenever the rate of hydrogen uptake significantly decreases. When fresh catalyst is added to the reaction vessel, it is important that it first be wet with solvent and that the hydrogen be well evacuated. Opening the mixture to the atmosphere without careful evacuation will produce a hydrogen-oxygen mixture which may explode on contact with fresh catalyst. 

The ensuing flame then ignites the Hydrogen/Oxygen mixture thus providing pressure source two. 

Also, if the Hydrogen/Oxygen mixture ignites, the total pressure will not be higher than it was before, it could only be lower due to unavoidable losses. So we should think further. 

SocJapan 36(10), 1233-36 (1963) CA 59, 15113 (1963) (Ignition delay of hydrogen-oxygen mixtures in a shock tube) 24) B. Lemcke, "Double Shock Tube for Simulating Blast Loading in Supersonic Flow , AIAA-J 1, 1417-18 (June 1963) 25) R.A. Strehlow,... 

Zel dovich Kompaneets (i960), 170-85 (Spin and spinning detonation) 21) D.H. Edwards Sc T.G. Jones, BritJApplPhys 11, 190-94 (May I960) (Vibration phenomena in detonation waves in hydrogen-oxygen mixtures). 22) Dunkle s Syllabus (1960-1961) p lid (Discussion on work of Fay Opel listed here as Ref 17) 23) B. Lewis ... 

Exptl results indicated a reaction zone thickness varying inversely with initial pressure for hydrogen-oxygen mixtures. This was in agreement with the data for U versus d if Fay s theory is accepted as correct... 

Reactions of Hydrocarbons in Slowly Reacting Hydrogen—Oxygen Mixtures... 

Fig. 13.4 Explosion limits for a stoichiometric hydrogen-oxygen mixture in a spherical vessel [241]. The temperatures and pressures correspond to the initial reaction conditions in the spherical vessel containing the reactants.

Use the reaction mechanism for the I2-O2-H2 system developed in the previous problem. Evaluate whether addition of I2 to a stoichiometric hydrogen-oxygen mixture at atmospheric pressure can shift the explosion limit to temperatures above 900 K. 

The H + O2 competition is responsible for several important aspects of combustion phenomena. For example, the second explosion limit for hydrogen-oxygen mixtures is explained by the competition between H + O2 branching and termination (Section 13.2.6). The observed reduction in hydrocarbon-air flame speeds with increased pressure between 1 and 10 atm is caused by the branching-termination competition. For a given temperature, as the pressure increases, the concentration of [M] increases, which favors the termination reaction. Thus the chain branching competes less favorably for a greater portion of the flame, which diminishes the flame speed [427]. 

M. Murayama and K. Uchida. Synthesis of Uniform Diamond Films by Flat Flame Combustion of Acetylene/Hydrogen/Oxygen Mixtures. Combust. Flame, 91 239-245,1992. 

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