Date of Award
Master of Science in Mechanical Engineering (MS)
College, School or Department Name
Department of Mechanical Engineering-Engineering Mechanics
Reactivity controlled compression ignition (RCCI) is a novel combustion strategy introduced to achieve near-zero NOx and soot emissions while maintaining diesel-like efficiencies. Meanwhile, precise control of combustion phasing is a key in realization of high fuel conversion efficiency as well as meeting stringent emission standards. Model-based control of RCCI combustion phasing is a great tool for real-time control during transient operation of the engine, which requires a computationally efficient combustion model that encompasses factors such as, injection timings, fuel blend composition and reactivity. In this thesis, physics-based models are developed to predict the combustion metrics of an RCCI engine. A mean value control-oriented model (COM) of RCCI is then developed by combining the auto-ignition model, the burn duration model, and a Wiebe function to predict combustion phasing. Development of a model-based controller requires a dynamic model which can predict engine operation, i.e., estimation of combustion metrics, on a cycle-to-cycle basis. Hence, the mean-value model is extended to encompass the full-cycle engine operation by including the expansion and exhaust strokes. In addition, the dynamics stemming from the thermal coupling between cycles are accounted for, that results in a dynamic RCCI control-oriented model capable of predicting the transient operation of the engine. This model is then simplified and linearized in order to develop a linear observer-based feedback controller to control the combustion phasing using the premixed ratio (the ratio of the PFI fuel to the total fuel injected) of the gasoline/diesel fuel. The designed controller depicts an accurate tracking performance of the desired combustion phasing and successfully rejects external disturbances in engine operating conditions.
Khodadadi Sadabadi, Kaveh, "MODELLING AND CONTROL OF COMBUSTION PHASING OF AN RCCI ENGINE", Master's Thesis, Michigan Technological University, 2015.