Date of Award

2016

Document Type

Open Access Master's Thesis

Degree Name

Master of Science in Mechanical Engineering (MS)

Administrative Home Department

Department of Mechanical Engineering-Engineering Mechanics

Advisor 1

Mahdi Shahbakhti

Committee Member 1

Bo Chen

Committee Member 2

David D. Wanless

Abstract

Low Temperature Combustion (LTC) has got widespread attention over the past two decades in the field of Automotive Research and Development due to it’s potential for achieving higher efficiencies with near-zero engine out NOx and soot emissions. Among all the LTC strategies Reactivity controlled compression ignition (RCCI) has shown the most promising results due to it’s precise control over combustion phasing and heat release rate. However, RCCI being a dual-fuel stratified combustion, precise control over the injection timing of direct injected fuel and in-cylinder fuel reactivity of the mixture needs to be controlled effectively in order to achieve gross indicated thermal efficiencies as high as around 60%.

This thesis focuses on developing real-time, model-based controller for controlling combustion phasing of an RCCI Engine. Optimum combustion phasing can be achieved by varying mixture reactivity and injection timing of higher reactive fuel. An experimental study was performed to study the effects of these variables on combustion phasing. Next,a mean-value and dynamic control-oriented model (COM) was developed to predict combustion phasing during steady-state and transient operating conditions. The validation results have shown that the COM was able to capture the experimental trends with minimal error. Next, for implementing in real time, a PI controller was developed using the COM to track the desired combustion phasing by adjusting duel-fuel premixed ratio and start of injection timing. The PI controller is then implemented on the engine plant. The validation results proved that the designed controller can follow the desired combustion phasing with an average error of 2 crank angle degrees and rise time of 3 engine cycles.

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