Destruction of availability (exergy) due to combustion processes: A parametric study

Abstract

An analytical examination of the destruction of availability was completed for constant pressure, constant volume, and constant temperature combustion processes for isooctane vapour and air mixtures. The variation of the percentage destruction of availability was determined as a function of temperature, pressure, and equivalence ratio. The percentage destruction of availability decreased with increasing reactant temperatures (from ∼30 per cent at 300 K to ∼5 per cent at 4500 K for constant pressure and constant volume combustion processes). The effect of the reactant pressure on the percentage availability destroyed was less pronounced - for example, for a 500 K initial temperature, a change from 50 to 5000 kPa changed the percentage availability destroyed from 26 per cent to 22 per cent for constant pressure adiabatic combustion. For changes in the equivalence ratio, the lowest destruction of availability was for mixtures near stoichiometric. In addition, the contribution of the various components (e.g. chemical and thermo-mechanical) of the mixture availability to the total availability was quantified for a range of conditions. Also, the effect of the decomposition of the reactant species for high reactant temperatures (greater than 3000 K) was determined.