The design and simulation of a two-stroke free-piston compression ignition engine for electrical power generation

Free-piston engines are under investigation by a number of research groups worldwide due to their potential advantages in terms of fuel efficiency and engine emissions. Some prototypes have emerged, mainly aimed for vehicle propulsion, and have reported favourable performance compared to conventional technology. This paper describes the design of a modular compression ignition free-piston engine generator, applicable to electric power generation in large-scale systems. The development of a full-cycle engine simulation model is described, and extensive simulation results are presented, giving insight into engine operating characteristics and performance. The operating characteristics of the free-piston engine was found to differ significantly from those of conventional engines, giving potential advantages in terms of fuel efficiency and emissions formation due to fast power stroke expansion. Effects of varying engine stroke length and compression ratio were not found to give any large advantages.