In-cylinder combustion visualization of Jatropha straight vegetable oil and mineral diesel using high temperature industrial endoscopy for spatial temperature and soot distribution

Endoscopic optical visualization technique is reliable for investigations in harsh environments such as IC engine combustion chambers. In this study, high temperature industrial endoscopy was employed to a production grade diesel engine for optical diagnostics of in-cylinder combustion. Engine cylinder-head was suitably modified for visual access of combustion. Combustion characteristics such as in-cylinder pressure, heat release rate (HRR), start of combustion (SoC), combustion duration (CD), etc., for Jatropha straight vegetable oil (SVO) and mineral diesel were investigated using Industrial endoscope, which can withstand such harsh environment. In-cylinder combustion images were recorded using a high-speed charge coupled device (CCD) camera. Recorded images were corrected using calibration tool to remove endoscopic lens distortions (spherical aberration). Spatial soot and flame temperature distributions were analysed from the corrected combustion images using soot analysis and correlated colour temperature (CCT) methods. Spatial soot and temperature distributions for the test fuels indicated that luminous regions in the combustion chamber were the prime locations for soot formation. These regions also indicated peak temperature zones in the field of view. This study is unique, where in-situ combustion characteristics were determined for SVO and baseline diesel using endoscopic visualization. This study generated valuable information about in-cylinder spatial combustion of SVO, which can be utilized for combustion and emission optimization of SVO fuelled engines.