Magnetic fields and equilibrium combustion characteristics

Abstract

The impact of a uniform magnetic field on equilibrium combustion characteristic has been explored. An expression for the Gibbs free energy that includes a magnetic field contribution has been developed. Using the method of Lagrange multipliers, changes in the Gibbs free energy for a mixture of paramagnetic and diamagnetic ideal gases is minimized. A model reaction of methane in air is used to quantitatively examine the changes in equilibrium compositions in the presence of a uniform magnetic field. Plots are presented showing the equilibrium mole fractions as a function of temperature and magnetic induction for all the product species. In general, the results indicate that within a certain temperature range a magnetic field decreases the mole fraction of major product species and increases the mole fraction of minor product species at a specified temperature. The maximum equilibrium mole fraction of NO; however, was observed to decrease an order of magnitude for an increase in magnetic induction of 0 to 0.04 Tesla. aii B 4 G C F G z H I M n nc Nomenclature atoms of element j in product i magnetic induction atoms of element j in reactants Curie-Weiss constant damping constant Lagrange multiplier function Gibbs free energy molar specific reference Gibbs free energy magnetic field strength enthalpy intensity of magnetization number of moles number of constituent elements ’ Assistant Professor, Dept. of M&ME, Member AIAA + Professor, Dept. of ME, Member AIAA Copyright Q 1999, The American Institute of Aeronautics and Astronautics Inc. All right reserved. “, nT P Pi R” s T u V Yi e 4 PO x number of product species total number of moles pressure partial pressure of species i universal gas constant entropy temperature internal energy volume mole fraction of species i CurieWeiss constant Lagrange multiplier of species i permeability of free space magnetic susceptibility Suoerscrim 0 reference conditions Subscript i respective specie