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Preeti Aghalayam

Bio: Preeti Aghalayam is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Underground coal gasification & Catalysis. The author has an hindex of 22, co-authored 59 publications receiving 1360 citations. Previous affiliations of Preeti Aghalayam include University of Delaware & University of Massachusetts Amherst.


Papers
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Journal ArticleDOI
01 Nov 2007-Energy
TL;DR: In this article, the potential for UCG in India is studied by comparing the properties of Indian coals with those of coal that are utilized by various UCG trials, which will help to motivate both applied and theoretical research on UCG sites in India and after detailed analysis it will provide basic data to interested industries.

195 citations

Journal ArticleDOI
TL;DR: In this article, a multistep methodology was applied to construct a C1 surface reaction mechanism for methane oxidation on platinum, which is capable of capturing the physics of methane oxidation over a wide range of operating conditions.

123 citations

Journal ArticleDOI
TL;DR: The role of wall quenching of radicals in ignition, extinction and autothermal behavior of premixed H2-air flames impinging on a flat surface was studied using numerical bifurcation techniques, with detailed gas-phase chemistry and surface radical recombination reactions.
Abstract: The role of wall quenching of radicals in ignition, extinction and autothermal behaviour of premixed H2–air flames impinging on a flat surface was studied using numerical bifurcation techniques, with detailed gas-phase chemistry and surface radical recombination reactions. Quenching out of radicals was found to retard the system at ignition due solely to the kinetics of the surface reactions. While kinetically extinction is also retarded, the thermal feedback from the wall recombination of radicals can render the flame more stable and lead to a higher wall heat flux as a function of wall temperature compared to an inert surface under some conditions. It is also shown that the combined kinetic and thermal effects of wall radical quenching can expand the autothermal regime. Implications for estimating flammability limits near reactive surfaces of tubes are finally discussed. M This article features multimedia enhancements available from the abstract page in the online journal; see http://www.iop.org.

93 citations

Journal ArticleDOI
TL;DR: In this article, a multistep methodology for the quantitative determination of rate constants of a detailed surface-reaction mechanism was proposed, where thermodynamically consistent, coverage-dependent activation energies and heats of reactions were derived from the application of the unity bond index-quadratic exponential potential formulation, and initial estimates of the preexpontentials were obtained from transition-state theory or available experiments.
Abstract: A multistep methodology for the quantitative determination of rate constants of a detailed surface-reaction mechanism is proposed. As a starting point, thermodynamically consistent, coverage-dependent activation energies and heats of reactions were derived from the application of the unity bond index-quadratic exponential potential formulation, and initial estimates of the preexpontentials were obtained from transition-state theory or available experiments. Important feature identification analysis was performed to determine key kinetic parameters for various experiments. Model responses were parameterized in terms of these important parameters by polynomials and factorial design techniques, and these parameterized responses were subsequently used in simultaneous optimization through simulated annealing against different sets of experimental data to obtain a quantitative reaction mechanism that is valid over a wide range of operating conditions. The technique was successfully applied to the development of a comprehensive reaction mechanism for H 2 /air mixtures on polycrystalline Pt.

89 citations

Journal ArticleDOI
TL;DR: In this article, a new methodology is presented for calculating parameters of complex surface reaction mechanisms, which combines an extension of the unity bond index−quadratic exponential potential theory, reactor scale modeling, important feature identification, and model validation.
Abstract: A new methodology is presented for calculating parameters of complex surface reaction mechanisms. This approach takes into consideration adsorbate−adsorbate interactions along with their influence on the activation energies of surface reactions as a function of operating conditions. It combines an extension of the unity bond index−quadratic exponential potential theory, reactor scale modeling, important feature identification, and model validation. The H2 oxidation over platinum has been chosen as a model system to test this methodology. Comparison with a variety of available experimental data in the literature, such as catalytic ignition temperature, laser-induced fluorescence OH desorption measurements, catalytic autotherms, and species profiles, shows that the proposed surface mechanism is capable of quantitatively capturing all the important features of the published experiments. Our approach offers the potential of quantitative modeling of catalytic reactors exhibiting complex surface reaction proces...

80 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, the authors presented a new formula for calculating when fossil fuel reserves are likely to be depleted and developed an econometrics model to demonstrate the relationship between fossil fuel reserve and some main variables.

1,744 citations

Journal ArticleDOI
TL;DR: In this article, an extensive table on contributions to catalytic partial oxidation of methane over transition metal catalysts in the literature is provided, and both theoretical and experimental evidence pointing to inherent differences in the reaction mechanism over transition metals.
Abstract: Catalytic partial oxidation of methane has been reviewed with an emphasis on the reaction mechanisms over transition metal catalysts. The thermodynamics and aspects related to heat and mass transport is also evaluated, and an extensive table on research contributions to methane partial oxidation over transition metal catalysts in the literature is provided. Presented are both theoretical and experimental evidence pointing to inherent differences in the reaction mechanism over transition metals. These differences are related to methane dissociation, binding site preferences, the stability of OH surface species, surface residence times of active species and contributions from lattice oxygen atoms and support species. Methane dissociation requires a reduced metal surface, but at elevated temperatures oxides of active species may be reduced by direct interaction with methane or from the reaction with H, H2, C or CO. The comparison of elementary reaction steps on Pt and Rh illustrates that a key factor to produce hydrogen as a primary product is a high activation energy barrier to the formation of OH. Another essential property for the formation of H2 and CO as primary products is a low surface coverage of intermediates, such that the probability of O–H, OH–H and CO–O interactions are reduced. The local concentrations of reactants and products change rapidly through the catalyst bed. This influences the reaction mechanisms, but the product composition is typically close to equilibrated at the bed exit temperature.

697 citations

Journal ArticleDOI
TL;DR: In this article, a review of the development of micro-power generators by focusing more on the advance in fundamental understanding of microscale combustion is presented, and the conventional concepts of combustion limits such as flammability limit, quenching diameter, and flame extinction and heat recirculation are revisited.

621 citations

Journal ArticleDOI
TL;DR: Various spatial and temporal multiscale KMC methods, namely, the coarse-grained Monte Carlo (CGMC), the stochastic singular perturbation approximation, and the τ-leap methods are reviewed, introduced recently to overcome the disparity of length and time scales and the one-at-a time execution of events.
Abstract: The microscopic spatial kinetic Monte Carlo (KMC) method has been employed extensively in materials modeling. In this review paper, we focus on different traditional and multiscale KMC algorithms, challenges associated with their implementation, and methods developed to overcome these challenges. In the first part of the paper, we compare the implementation and computational cost of the null-event and rejection-free microscopic KMC algorithms. A firmer and more general foundation of the null-event KMC algorithm is presented. Statistical equivalence between the null-event and rejection-free KMC algorithms is also demonstrated. Implementation and efficiency of various search and update algorithms, which are at the heart of all spatial KMC simulations, are outlined and compared via numerical examples. In the second half of the paper, we review various spatial and temporal multiscale KMC methods, namely, the coarse-grained Monte Carlo (CGMC), the stochastic singular perturbation approximation, and the τ-leap methods, introduced recently to overcome the disparity of length and time scales and the one-at-a time execution of events. The concepts of the CGMC and the τ-leap methods, stochastic closures, multigrid methods, error associated with coarse-graining, a posteriori error estimates for generating spatially adaptive coarse-grained lattices, and computational speed-up upon coarse-graining are illustrated through simple examples from crystal growth, defect dynamics, adsorption–desorption, surface diffusion, and phase transitions.

428 citations

Journal ArticleDOI
TL;DR: In this article, a two-dimensional elliptic, computational fluid dynamics (CFD) model of a micro-burner is solved to study the effects of microburner dimensions, conductivity and thickness of wall materials, external heat losses, and operating conditions on combustion characteristics and flame stability.

398 citations