Compression Ignition Linear Engine Design Variable Effects

A linear engine/alternator was simulated and designed, and a prototype was built at West Virginia University. This paper describes the engine and presents original operational data. The linear engine was a two-cylinder, two-stroke, common rail direct injection, compression ignition engine. The engine was built using off the shelf components to reduce cost where it was possible. Engine control, injection duration and timing, were achieved using a microcontroller with piston position as a control input. Experiments on the engine were performed to study its behavior. The studied variables included mass of the translator, amount of fuel injected, injection timing, load, and stroke with operating frequency and mechanical efficiency as the basis of comparison. At this point of development, the engine was far from optimized; however, the trends in engine behavior were clear. Increasing the translator mass resulted in decreased operating frequency. Increasing the stroke length also resulted in decreased operating frequency. Overcharging and increased fueling rate, both, resulted in increased power output, efficiency, and operating frequency. Advancing injection timing resulted in increased frequency, efficiency and power output, and decreased stalling frequency. This suggests that the engine operated in an HCCI-like fashion.