Scheme: Newton International Fellowships
Organisation: University of Oxford
Dates: Aug 2009-Aug 2011
Summary: There is currently a considerable interest in developing accurate chemical kinetic models for technologically important systems, including combustion, pyrolysis, and atmospheric oxidation of organic compounds. Kinetic models are used to predict quantitatively the time evolution in a reaction medium (ignition delays, species concentration profiles under different reactor conditions etc.). As an input data, these models use the rate coefficients of elementary reactions involved in the process and solve the system of differential equations that describes it. Construction of a reliable kinetic model is a very challenging task as the number of possible reactions rises super linearly with the number of species in a reacting mixture. As a result, hundreds of reaction intermediates and thousands of reactions between them can be involved in typical kinetic mechanisms. Efficient reduced kinetic models could be often proposed to lessen the computational cost. Sensitivity analysis of different reactor models reveals key intermediate chemical reaction channels important for accurate modelling. Unfortunately, direct experimental measurements of the corresponding rates are usually problematic due to complex chemistry involved. But advances over last 10-15 years in the development of quantum chemistry techniques and reaction rate theory approaches demonstrate that theoretical calculations of rate coefficients are becoming accurate enough to provide quantitative kinetic predictions and thus are able to substitute lacking experimental data.
The main goal of my current research is to generate the accurate theoretical estimates of the rate coefficients using state-of-art techniques of quantum chemistry and rate theory for reactions controlling concentrations of the H.O2 radical. H.O2 is one of the key chemical intermediates in various combustion and atmospheric oxidation processes. Sensitivity analysis indicates that reactions involving H.O2 drive the output uncertainty of various combustion kinetic models. Specifically, I focus on several important reactions of the H.O2 radical with (i) biofuel radical and (ii) biofuel molecules for which direct experimental measurements and/or accurate theoretical calculations of the rate coefficients are not available. Because of a different nature of the intermolecular interactions (open shell-open shell, open shell-closed shell), these two classes of reactions will require the development and use of different theoretical methodologies.