Abstract

MBARAWA, M.. A Correlation for Estimation of Ignition Delay of Dual Fuel Combustion Based on Constant Volume Combustion Vessel Experiments. R&D j. (Matieland, Online) [online]. 2003, vol.19, pp.17-22. ISSN 2309-8988.

One method of using alternative fuels in diesel engines is by adopting a mixed combustion process called dual-fuelling where alternative fuel such as natural gas (NG) is induced into the cylinder as a primary fuel with air and is subsequently ignited with a pilot injection of diesel fuel. The ignition delay in a dual fuel (DF) engine is different from that in a diesel engine because the primary fuel alters the properties of the charge, reduce oxygen available and undergoes pre-ignition reactions during compression. Various conclusions of DF ignition delay have been reached using different engines. In the present work a constant volume combustion vessel (CVCV) has been used to study the ignition delay of a DF combustion process. Experiments have been performed to investigate the ignition delay period at different initial temperatures and pressures. The results obtained were used to modify the Hu and Milton 's⁵ DF ignition delay correlation. The proposed correlation predicts a delay period for a wide range of initial temperatures and pressures. The trends exhibited by the correlation are consistent with DF ignition delay engine tests data from other researchers¹². In particular, it explains why some reported tests results show that ignition delay is always rising while others show that it decreases temporarily before rising again to very high values. The rising of ignition delay occurs with low pilot diesel quantities and the latter with high ones.

        · text in English     · English ( pdf )