Flat-plate combustion

Another apparently undesirable aspect is the general layout of the reactor systems used in combination with the analysis technique [3-5]. The arrangement of samples on flat plates can be an acceptable compromise when it comes to simple reactions with essentially one reaction product, as with CO oxidation to C02 or the combustion of H2 and 02 to water. In the latter case, diffusion limitations... 

Robben, F., Schefer, R., Agrawal, V., and Namer, I., "Catalyzed Combustion in a Flat Plate Boundary Layer I. Experimental Measurements and Comparison with Numerical Calculations," Presented at Fall Meeting, Western States Section, The Combustion Institute, Stanford, CA, October 1977. 

The heat recovery heat exchanger is of flat-plate type Fig. 9). This construction was selected because of the low investment costs. Primary flow is moist, nearly saturated exhaust air from the drying silo, The secondary flow is outdoor air, which is used as combustion air and drying air. 

Several flame impingement studies ([21,25,34]) measured total radiant emission with hollow, gold-plated, ellipsoidal radiometers. These were developed by the International Flame Research Foundation (IFRF) in IJmuiden, the Netherlands [89]. Measurements at the IFRF indicated that radiation may account for as much as half of the total heat flux to a target located in a hot furnace. The radiation was primarily from fhe hof refractory walls. Vizioz attempted to isolate this radiation from the hot combustion gases. The radiation reflected and emitted from a flat plate target was measured with a narrow angle radiometer. 

In catalytic channels, the flat plate surface temperature in Eq. (3.32) is attained at the channel entry (x O). As the catalytic channel is not amenable to analytical solutions, simulations are provided next for the channel geometry shown in Fig. 3.3. A planar channel is considered in Fig. 3.3, with a length L = 75 mm, height 21) = 1.2 mm, and a wall thickness 5s = 50 pm. A 2D steady model for the gas and solid (described in Section 3.3) is used. The sohd thermal conductivity is k = 6W/m/K referring to FeCr alloy, a common material for catalytic honeycomb reactors in power generation (Carroni et al., 2003). Surface radiation heat transfer was accounted for, with an emissivity = 0.6 for each discretized catalytic surface element, while the inlet and outlet sections were treated as black bodies ( = 1.0). To illustrate differences between the surface temperatures of fuel-lean and fuel-rich hydrogen/air catalytic combustion, computed axial temperature profiles at the gas—wall interface y=h in Fig. 3.3) are shown in Fig. 3.4 for a lean (cp = 0.3) and a rich cp = 6.9) equivalence ratio, p = 1 bar, inlet temperature, and velocity Tj = 300 K and Uin = 10 m/s, respectively. The two selected equivalence ratios have the same adiabatic equilibrium temperature, T d=1189 K. 

Garcia-Ybarra, P.L., Trevino, C. Asymptotic analysis of the boundary layer H2 ignition by a hot flat plate with thermal diffusion. Combust. Flame 96, 293-303 (1994)... 

Schefer RW Catalyzed combustion of H2/air mixtures in a flat plate boundary layen II. Numerical model. Combust Flame 45 171—190, 1982. 

A flat material of thickness is placed on a hot plate of controlled temperature Tb. The material is energetic and exothermic with a heat of combustion of Ahc and its reaction is governed by zeroth-order kinetics, Ae E RT the mass loss rate per unit volume. Notation is as used in the text. The differential equation governing the process to ignition is given as... 

The pintle injector is unique among the various injector options which have been successfully used in hquid rocket engines. Many early liquid engine injectors utilized impinging jets that create a spray due to the impact of the two streams, or coaxial injectors that mix propellants from shear or swirl induced in the inner fluid. These injector types are implemented in a flat face injector plate at the head-end of the combustion chamber. This resultant flowfield shown in Fig. 28.1c yields a curved spray/combustion zone which is substantially different than those formed by flat face-type injectors. 

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