César Treviño

Bio: César Treviño is an academic researcher from National Autonomous University of Mexico. The author has contributed to research in topics: Heat transfer & Ignition system. The author has an hindex of 18, co-authored 125 publications receiving 1266 citations. Previous affiliations of César Treviño include University of California, San Diego & ETSI.

Velocity field measurements in granular gravity flow in a near 2D silo

Abstract: Using particle image velocimetry (PIV) we studied experimentally the whole velocity field during the discharge of monodisperse granular material from a flat-bottomed 2D silo. We have characterized important quantities of this flow such as the transversal flow oscillations, the mean velocity field and the velocity fluctuations.

The Influence of the Lewis Numbers of the Reactants on the Asymptotic Structure of Counterflow and Stagnant Diffusion Flames

Abstract: The asymptotic structure of counterflow and stagnant diffusion flames are analyzed in the limit for large values of the overall, nondimensional activation energy, Ta , characterizing the rate of the reaction and results are given for small values of the stoichiometric fuel to oxygen mass ratio. The chemical reaction between the fuel and the oxidizer is represented by a one-step, irreversible process. A new approach is developed to characterize the influence of the Lewis number of the fuel, LF and the Lewis number of the oxidizer, L0 , on the outer and inner structure of near equilibrium diffusion flames. Explicit algebraic formulas to predict the critical conditions of flame extinction are also given. For counterflow diffusion flames at fixed values of L0 , the flame moves significantly toward the oxidizer stream and the heat losses toward the oxidizer region of the flame increase significantly with decreasing values of LF . The value of the maximum flame temperature is relatively insensitive to ...

The conjugate conduction–natural convection heat transfer along a thin vertical plate with non-uniform internal heat generation

Abstract: The steady state heat transfer characteristics of a thin vertical strip with internal heat generation is studied in this work. The nondimensional temperature distribution in the strip is obtained as a function of the following parameters: (a) the intensity and distribution of the internal heat sources, (b) the aspect ratio of the strip, (c) the longitudinal heat conductance of the strip and (d) the Prandtl number of the fluid. Both the thermally thin and the thick wall approximations are considered in this paper. The total thermal energy or averaged temperature of the strip is found to decrease as the influence of the longitudinal heat conduction effects in the strip decreases in the thermally thin wall regime. After reaching a minimum, it increases again in the thermally thick wall regime.

The toroidal thermosyphon with known heat flux

Abstract: This paper discusses the behavior of a toroidal thermosyphon with known heat flux around the loop. Criteria are first established for steady state solutions. The transient governing equations are then transformed to an infinite set of ordinary differential equations. The flow velocity, however, can be determined from a set of three equations which decouple from the rest. The existence and stability of the critical points of these equations are examined, and typical numerical solutions for different values of the governing parameters are presented. Chaotic solutions are shown to be possible.

A reduced reaction mechanism for the combustion of n-butane

Abstract: A C1–C3 short chemical-kinetic mechanism (the San Diego mechanism), which involves 235 elementary reactions among 40 such species, is extended to C4 by adding 22 chemical-kinetic steps, among 7 additional species, with their associated reaction-rate parameters, to include the ignition and combustion of n-butane over a range of conditions that encompasses both low-temperature and high-temperature chemistry, as well as both high and low pressures. Tests of predictions against measured ignition delays and laminar burning velocities are reported, as are comparisons with recent measurements in jet-stirred reactors, supporting the predictions of the mechanism, which may be useful in combustion computations, especially when larger mechanisms would be too time-consuming to be accommodated.

Numerical Heat Transfer And Fluid Flow

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The CSP method for simplifying kinetics

Abstract: The Computational Singular Perturbation (CSP) method of simplified kinetics modeling is presented with emphasis on its comparative merits versus conventional methodologies. A new “refinement” procedure for the basis vectors spanning the fast reaction subspace is presented. A simple example is first worked through using the conventional partial-equilibrium and quasi-steady approximations, and is then treated in some detail using CSP.

On-off intermittency and intermingledlike basins in a granular medium

Abstract: Molecular dynamic simulations of a medium consisting of disks in a periodically tilted box yield two dynamic modes differing considerably in the total potential and kinetic energies of the disks. Depending on parameters, these modes display the following features: (i) hysteresis (coexistence of the two modes in phase space); (ii) intermingledlike basins of attraction (uncertainty exponent indistinguishable from zero); (iii) two-state on-off intermittency; and (iv) bimodal velocity distributions. Bifurcations are defined by a cross-shaped phase diagram.

Monoliths in Heterogeneous Catalysis

Abstract: The use of structured catalysts in the chemical industry has been considered for years. Conventional fixed-bed reactors have some obvious disadvantages such as maldistributions of various kinds (including a nonuniform access of reactants to the catalytic surface), high pressure drop in the bed, etc. Structured catalysts are promising as far as elimination of these setbacks is concerned. Two basic kinds of structured catalysts can be distinguished: Structural packings covered with catalytically active material, similar in design to those used in distillation and absorption columns and/or static mixers. Good examples of catalysts of this kind are those offered by Sulzer, clearly developed by Sulzer column packings and static mixers. As in packed beds, there is an intensive radial convective mass transport over the entire cross-section of these packings. Structural packing catalysts and the reactors containing them are, however, not within the scope of this review. Monolithic catalysts are continuou...