Tanet Aroonsrisopon

Expanding the HCCI Operation With the Charge Stratification

A single cylinder CFR research engine has been run in HCCI combustion mode at the rich and the lean limits of the homogeneous charge operating range. To achieve a variation of the degree of charge stratification, two GDI injectors were installed: one was used for generating a homogeneous mixture in the intake system, and the other was mounted directly into the side of the combustion chamber. At the lean limit of the operating range, stratification showed a tremendous improvement in IMEP and emissions. At the rich limit, however, the stratification was limited by the high-pressure rise rate and high CO and NOx emissions. In this experiment the location of the Dl injector was in such a position that the operating range that could be investigated was limited due to liquid fuel impingement onto the piston and liner.

Robust Common-Rail Pressure Control for a Diesel-Dual-Fuel Engine Using QFT-Based Controller

Despite promising future, the diesel-dual-fuel engine, with diesel as pilot and natural gas as main, abounds with challenges from high NOx emission and knock especially at high speed and low load. To cope with these challenges, variation of common-rail pressure provides another desirable degree of freedom. Nevertheless, crippling with complicated dynamics, pressure wave inside the transporting rail, disturbance from varying of injections, engine speed variation, and actuator limitation, common-rail pressure control has relied on the simple PID to deliver only marginally satisfactory result. Some attempts to achieve better control have resulted in either too complicated or not too robust control system. We devise a controller from the quantitative feedback theory. Besides being able to quantitatively enforce specifications such as tracking, plant input and output disturbance rejections, and stability margin, the controller is designed from a simple model, whose parameters are allowed to be uncertain, hence robustness. The resulting controller has low order and is readily implementable. Experiment with a common-rail system in a Ricardo Hydra engine, modified to run dual fuel, shows the controller’s effectiveness over the PID.