Theoretical Study of Equilibrium Compositions and Thermodynamic Properties of Combustion Reactions by Gibbs Free Energy Minimization: Application of Feasible Direction Method

ABSTRACT This paper presents the feasible direction (FD) method for calculating equilibrium compositions in combustion systems via Gibbs free energy minimization under mass balance constraints. The method was used to calculate the adiabatic flame temperature and the equilibrium composition of combustion products from combustion reactions of two types. The results of the present work are compared with those obtained using the Lagrange multipliers method. The proposed algorithm demonstrated robust convergence at the complicated multicomponent equilibrium calculation involving the condensed products as well as the simple chemical equilibrium problem. In addition, we simulated the equilibrium compositions and thermodynamic properties of combustion products depending on the temperature.