Exergy losses of n-butanol constant volume combustion by simulation with detailed chemical kinetics

Combustion of n-butanol was simulated using detailed chemical kinetics under adiabatic premixed constant volume conditions. The exergy losses during n-butanol combustion were studied by calculating the changes in chemical potentials during all chemical reactions. Results show that the history of overall exergy loss rate has two peaks. The first peak is caused by the reactions of n-butanol decomposition into the small molecules (named as stage1) together with the reactions related to the H2O2 loop (named as stage 2). The second peak involves the oxidation reactions of CO, H, and O to CO2 and H2O (named as stage 3). Increasing the initial temperature or equivalence ratio rises temperature rapidly. In stage 1, the low temperature reactions with high exergy losses are replaced by high temperature reactions with low exergy losses. In stages 2 and 3, significant shorter duration of exergy loss plays a decisive role, resulting in the reduction of exergy loss to the main exergy loss sources. However, higher initial temperature and equivalence ratio increase the dissociation reaction rates, leading to the increase of incomplete combustion. Increasing initial pressure or decreasing oxygen concentration can inhibit the dissociation and decrease the incomplete combustion. Total losses are decreased from 30.7%, to 18.7%, by the combined effects of combustion initial conditions with advanced engine technologies by preheating and boosting the inlet charge, lean combustion, exhaust gas recirculation, higher compression ratio. © 2016, Chinese Society for Internal Combustion Engines. All right reserved.