Chitralkumar Naik

Publications (42) View all

• Article: Modeling the Detailed Chemical Kinetics of NOx Sensitization for the Oxidation of a Model fuel for Gasoline

  Chitralkumar V Naik, Karthik Puduppakkam, Ellen Meeks
  SAE International Journal of Fuels and Lubricants 01/2010; 3(1):556-566.
• Source

  Available from: mines.edu

  Article: Detailed modeling of the reaction of C2H5 + O2.

  Hans-Heinrich Carstensen, Chitralkumar V Naik, Anthony M Dean
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  ABSTRACT: Modeling of low-temperature ethane oxidation requires an accurate description of the reaction of C(2)H(5) + O(2), because its multiple reaction channels either accelerate the oxidation process via chain branching, or inhibit it by forming stable, less reactive products. We have used a steady-state chemical-activation analysis to generate pressure and temperature dependent rate coefficients for the various channels of this system. Input parameters for this analysis were obtained from ab initio calculations at the CBS-QB3 level of theory with bond-additivity corrections, followed by transition state theory calculations with Wigner tunneling corrections. The chemical-activation analysis used QRRK theory to determine k(E) and the modified strong collision (MSC) model to account for collisional deactivation. This procedure resulted in a C(2)H(5) + O(2) submechanism which was either used directly (possibly augmented with a few C(2)H(5) generating and consuming reactions) or as part of a larger extended mechanism to predict the temperature and pressure dependencies of the overall loss of ethyl and of the yields of ethylene, ethylene oxide, HO(2), and OH. A comparison of the predictions using both mechanisms allowed an assessment of the sensitivity of the experimental data to secondary reactions. Except for the time dependent OH profiles, the predictions using the extended mechanism were in good agreement with the observations. By replacing the MSC model with master equation approaches, both steady-state and time dependent, it was confirmed that the MSC assumption is adequate for the analysis of the C(2)H(5) + O(2) reaction. The good overall performance of the C(2)H(5) + O(2) submechanism developed in this study suggests that it provides a good building block for an ethane oxidation mechanism.
  The Journal of Physical Chemistry A 04/2005; 109(10):2264-81. · 2.95 Impact Factor
• Source

  Available from: Chitralkumar Naik

  Article: Modeling and experimental investigation of methylcyclohexane ignition in a rapid compression machine

  W.J. Pitz, C.V. Naik, T. Ní Mhaoldúin, C.K. Westbrook, H.J. Curran, J.P. Orme, J.M. Simmie
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  ABSTRACT: A new chemical kinetic reaction mechanism has been developed for the oxidation of methylcyclohexane (MCH), combining a new low temperature mechanism with a recently developed high temperature mechanism. Predictions from this kinetic model are compared with new experimentally measured ignition delay times from a rapid compression machine. Computed results were found to be particularly sensitive to isomerization rates of methylcyclohexylperoxy radicals. Three different methods were used to estimate rate constants for these isomerization reactions. Rate constants based on comparable alkylperoxy radical isomerizations corrected for the differences in the structure of MCH and the respective alkane, predicted ignition delay times in very poor agreement with the experimental results. The most significant drawback was the complete absence of a region of negative temperature coefficient (NTC) in the model results using this method, although a prominent NTC region was observed experimentally. Alternative estimates of the isomerization reaction rate constants, based on the results from previous experimental studies of low temperature cyclohexane oxidation, provided much better agreement with the present experiments, including the pronounced NTC behavior. The most important feature of the resulting methylcyclohexylperoxy radical isomerization reaction analysis was found to be the relative rates of isomerizations that proceed through 5-, 6-, and 7-membered transition state ring structures and their different impacts on the chain branching behavior of the overall mechanism. Theoretical implications of these results are discussed, with particular attention paid to how intramolecular H atom transfer reactions are influenced by the differences between linear alkane and cycloalkane structures.
  Proceedings of the Combustion Institute.
• Article: Detailed chemical kinetic reaction mechanisms for soy and rapeseed biodiesel fuels

  C.K. Westbrook, C.V. Naik, O. Herbinet, W.J. Pitz, M. Mehl, S.M. Sarathy, H.J. Curran
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  ABSTRACT: A detailed chemical kinetic reaction mechanism is developed for the five major components of soy biodiesel and rapeseed biodiesel fuels. These components, methyl stearate, methyl oleate, methyl linoleate, methyl linolenate, and methyl palmitate, are large methyl ester molecules, some with carboncarbon double bonds, and kinetic mechanisms for them as a family of fuels have not previously been available. Of particular importance in these mechanisms are models for alkylperoxy radical isomerization reactions in which a CC double bond is embedded in the transition state ring. The resulting kinetic model is validated through comparisons between predicted results and a relatively small experimental literature. The model is also used in simulations of biodiesel oxidation in jet-stirred reactor and intermediate shock tube ignition and oxidation conditions to demonstrate the capabilities and limitations of these mechanisms. Differences in combustion properties between the two biodiesel fuels, derived from soy and rapeseed oils, are traced to the differences in the relative amounts of the same five methyl ester components.
  Combustion and Flame. 158(4):742-755.
• Source

  Available from: Chitralkumar Naik

  Conference Proceeding: Reaction Rate Representation Using Chebyshev Polynomials

  Chitralkumar V. Naik, Hans-Heinrich Carstensen, Anthony M Dean
  WSS 2002 Spring Meeting of the Combustion Institute;