An investigation into the free-piston engine concept and its potential for high efficiency and low emissions power generation

Abstract

An investigation into the feasibility of the free-piston engine concept and its potential for high efficiency and low emissions power generation has been conducted using computational modelling and simulation. A thorough background study and literature review was carried out covering previously reported experience with free-piston engines, particular features of this technology, and potential advantages and challenges associated with their design. A single piston free-piston engine generator was proposed as a result of the background study and a design strategy for this engine configuration was formulated. Detailed simulation models for the free-piston engine were developed and extensive simulation studies conducted to investigate the performance and operating characteristics of such an engine. Engine performance indicators, such as fuel efficiency, power to weight ratio, and exhaust gas emissions formation, were studied along with engine operational control issues. The results were directly compared to those of equivalent conventional crankshaft engines in order to investigate potential differences in engine performance. It was found that the free-piston engine has potential advantages over conventional technology in the areas of mechanical efficiency, exhaust gas emissions formation, and operational flexibility. The main challenge lies within the area of piston motion control and further research into engine control issues are required. A more detailed study of engine emissions formation is also recommended in order to fully understand the influence of the particular operating characteristics of the free-piston configuration on engine performance.