Thermodynamic investigation of performance and emission study of miller cycle-type engine with the novel eccentric drive mechanism

Improvement in fuel conversion efficiency in an internal combustion engine increases power and reduces fuel consumption. The efficiency of an engine increases either by the increase in compression ratio or expansion ratio. This paper presents a new concept for a higher expansion process in comparison to compression process stroke on the base of the Miller cycle, rather than early or late closing inlet valves. The proposed mechanism works with eccentric crankshaft movement around the eccentric-derived path to achieve a shorter compression process and longer over-expansion process stroke. The theoretical simulation results of SI engine were obtained using thermodynamic quasi-dimensional combustion (burned and unburned zone) power cycle integrated with the intake and exhaust system. The best result of over-expansion (OE) system over non-OE has been observed at 1500–2000 rpm, and the corresponding results are: increment in indicated thermal efficiency from 36 to 38.5%, brake torque from 32 to 46 N-m, brake power from 6.52 to 9.46 kW and indicated power from 7.36 to 10.89 kW, and maximum BSFC decrement 5.42% at 1500 rpm. OE system has a higher value of CO concentration throughout the speed range; however, the NO concentration in ppm decreased by 1.62% at 1500 rpm at the same EVO crank angle. Thus, this mechanism offers significant benefits in thermal efficiency, fuel consumption, and NO emission. And, it is highly beneficial at 1500–2000 rpm engine run, which shows most suitable for engine-integrated electric power generation.