Power Curve of Gas Engine Beyond Max Power Point - Effect of Gas System

Natural gas engines are finding wider applications in automobiles due to environmental and operating economics reasons. These applications include add on fitment in gasoline vehicles as well as replacement of diesel engines. In case of replacement of diesel engines, the gas engines are expected to have matching power curve. Typically the performance of an engine is characterized by following three parameters- Max Power, Max Torque, Low end Torque. Through engine design and optimization of engine these parameters can be matched to diesel engine. Then fly-up speed of the engine remains under consideration, which means the second half of engine power curve that is between Max Power speed point and fly-up speed. The present article deals with shaping of the Power-torque curve of an engine beyond Max Power point.

The technique used here for Power Curve shaping is controlled leaning operation. The engine is made to run at lean air fuel ratio and there by reducing engine power and finally a fuel cut. This paper describes technique that can be implemented for Power curve shaping in venturi and gas injection system. The experimental results obtained on a Multipoint Sequential Gas Injection engine (MPSGI) are also discussed.