The Calculation of Chemical and Thermophysical Properties in Process of Natural Gas Combustion

Abstract

The presented paper features the mathematical model of computing the chemical and thermophysical properties in process of natural gas combustion.. To identify the parameters of state of combustion products their composition has to be known, which may be determined from chemical equilibrium. The computation is performed by the use of chemical potentials and use of statistical thermodynamics. The paper features all important molecular contributions (translation, rotation, vibration, and intermolecular potential energy) The thermal equation of state with two virial terms is used. The reality of the gas mixture is considered with four components: carbon dioxide, nitrogen, carbon monoxide and water. Virial coefficients are dependent on temperature and mole fractions of the real components. Mixed terms are considered. The caloric equation of state is based on ideal gas statistical thermodynamics. Considered are corrections according to the second law of thermodynamics and thermal equation of state. As the whole computation is based on matrix algebra the expansion of the component number under consideration does not represent any problem. We tested our model in high pressure region (100 bar) and low pressure region (1bar), between temperatures 500-6000K. Our analytic model is compared with other analytical models presented in the literature and show relatively good agreement. At the some time we tested the influence of reality on chemical and thermophysical properties of combustion products.