Chapter 2 - Chemical Kinetics

Abstract

This chapter reviews the essential features of chemical kinetics, which occur frequently in combustion phenomena. From the standpoint of combustion, the interest in chemical kinetic phenomena has generally focused on the conditions under which chemical systems undergo explosive reaction. All chemical reactions, whether of the hydrolysis, acid–base, or combustion type, take place at a definite rate and depend on the conditions of the system. The most important of these conditions are the concentration of the reactants, the temperature, radiation effects, and the presence of a catalyst or inhibitor. In most chemical reactions the rates are dominated by collisions of two species that may have the capability to react. Thus, most simple reactions are second order. Other reactions are dominated by a loose bond-breaking step and thus are first-order. Most of these latter type reactions fall into the class of decomposition processes. Isomerization reactions are also found to be first-order. For systems with large numbers of species and reactions, the dynamics of the reaction and the interactions between species can become quite complex. To analyze the reaction progress of species, various diagnostic techniques have been developed. Two of these techniques are reaction rate-of-production analysis and sensitivity analysis. A sensitivity analysis identifies the rate limiting or controlling reaction steps, while a rate-of-production analysis identifies the dominant reaction paths.