Analysis of Exhaust Gas Recirculation (EGR) effects on exergy terms in an engine operating with diesel oil and hydrogen

Despite the fact that the high diffusivity of hydrogen in air leads to the fast mixing and homogeneous premixed mixture, it is not suitable for operation as a single fuel because it needs a high temperature to reach self-ignition; moreover, its operation results in knocking. In this study, a Deutz dual fuel (operation with diesel oil and hydrogen) was used and from the view point of second law the effects of EGR introduction was investigated. The fuel injection amount and gas fuel-air ratio were kept constant in 6.48 mg/cycle and øH2 = 0.3, respectively. For combustion simulation and exergetic analyses, the Extend Coherent Flame Model-Three Zone model (ECFM-3Z) and a FORTRAN-based code were used, respectively. For four EGR mass fraction cases (i.e. 0%, 10%, 20%, and 30%) the rate and accumulation of various exergy terms were calculated. The results showed that as EGR introduction increases from 0% to 30%, the exergy efficiency decreases from 42.4% to 14.1%. Furthermore, the value of exhaust loss exergy increases from 14.9% to 56.7% of the mixture fuel chemical exergy. The results of the current study were compared with those existing in the relevant literature, and an acceptable behavior was observed.