Effects of exhaust gas recirculation on exergy destruction due to isobaric combustion for a range of conditions and fuels

This study was directed at examining the effects of exhaust gas recirculation (EGR) on the exergy destroyed due to combustion in a simple constant pressure combustion system. Both cooled and adiabatic cases of EGR were studied. Hi-her 'cooled FGR' fractions lead to higher exergy destruction for reactant temperatures less than 2000 K. For the base case, the percentage of the reactant exergy destroyed for 0.20. and 40% EGR at 300 K was found to be 28, 32, and 36%, respectively. Neglecting the chemical exergy in the products, the equivalence ratio and reactant temperature that corresponded to the lowest exergy destruction varied from 0.9 to 1.0 and 800-1300 K, respectively, depending on the EGR fraction. The Fraction of the reactant exergy destroyed increased with increase in the molecular mass of the fuel For the alkanes examined. The exergy destroyed due to combustion was the least for acetylene and the highest for the alcohols. The trends stayed the saint for the different EGR fractions For the eight Fuels that were analyzed. For the adiabatic EGR' case, the percentage destruction of exergy decreased with increase in the EGR fraction with a 40% adiabatic FGR' fraction corresponding to a destruction of exergy of 14%. Copyright (C) 2008 John Wiley & Sons, Ltd.