A control strategy analysis for clean and efficient combustion in compression ignition engines

In this work, the pathways and challenges for enabling the clean and efficient combustion are first identified with extensive engine tests on a high compression ratio single-cylinder diesel engine. The engine load and emission trade-offs are analyzed for different fuel injection strategies, intake boost, injection pressure and exhaust gas recirculation. The identified challenges are then analyzed to define the requisite control strategies for improving the stability and combustion efficiency of such clean combustion processes. Moreover, the critical issue of switching in multi-mode combustion on-the-fly is also addressed and empirically demonstrated for the seamless transition from the single-injection to multi-injection modes in 3 consecutive engine cycles without leaving low temperature combustion. To further demonstrate the robustness of the control system, the use of ethanol in a dual-fuel configuration with a diesel pilot-injection is demonstrated to extend the load limit of clean combustion. This research intends to advance the control methodologies for application of the clean combustion modes over the engine operating regime. Copyright © 2012 by the Japan Society of Mechanical Engineers.