AN EXPERIMENTAL STUDY OF BIOETHANOL HCCI

Abstract

ABSTRACT Bioethanol has been successfully used in conventional spark ignition (SI) internal combustion engines. Homogeneous charge compression ignition (HCCI) combustion, a novel combustion method, has shown the potential for low nitric oxides (NOx) emissions with no particulate matter formation. This paper explores two different approaches to achieve HCCI with bioethanol; namely, trapping of internal residual gas and intake temperature heating with a high compression ratio. For naturally aspirated HCCI operation with residual gas trapping on a spark ignition engine, although the NOx emissions were low, the load range was unacceptably small. When inlet manifold pressurisation was employed, a substantial increase in the upper load boundary could be achieved without any substantial increase in NOx emissions. With forced induction, the feasibility of using boost control as the main method of load control for higher engine loads during HCCI operation has been explored with possible methods of utilizing boost control. One possible strategy is a map based strategy where fuelling rates are correlated versus boost pressure and trapped residual amounts. A proof of concept using this strategy showed that transient operation from a low load to a much higher load, using boost control might be possible without engine misfire.