Application of thermodynamic analysis in reducing detailed hydrogen combustion mechanism

Abstract

A set of programs has been created; it allows to carry out the thermodynamic analysis and kinetic computation of complex chemical reactions. A minimum mechanism describing the combustion kinetics of hydrogen is determined; the mechanism was used to solve an inverse task of finding parameters describing the experimental data of Kowalski at pressures of 7.4, 7.1, 6.8, 6.4 and 6.1 mm Hg. All obtained constants of direct and inverse reactions are interrelated by thermodynamic equilibrium constants. The parameters obtained for the maximum hydrogen combustion mechanism make it possible to describe well the ignition limits in Lewis and Egerton experiments. In carrying out further thermodynamic analysis, a minimal mechanism M-I is identified that corresponds to the maximum mechanism and with good accuracy describing the critical conditions of hydrogen combustion in the pressure interval 1 ÷ 200 mm Hg and temperatures of 400°C ÷ 600 °C. From the analysis of critical conditions, an analytical equation is obtained; roots of the equation give ignition limits close to the experimental ones.