Investigation into particulate size distributions in the exhaust gas of diesel engines fuelled with biodiesel blends

Particulate matter (PM) size distributions in the exhaust gas of biodiesel blend fuelled diesel engines have been studied by experimenting firstly on a single cylinder equipped with a pump-line-injector injection system and secondly for comparison on a V6 DI engine equipped with a common rail fuel injection system. Both engines were operated with a biodiesel (RME) blend of B30 and ultra low sulphur diesel fuel (ULSD). Several engine load conditions with and without exhaust gas recirculation (EGR) were selected. Particulate number concentrations vs. the electrical mobility equivalent diameter were examined using a fast differential mobility spectrometer. The effect of engine operating conditions including EGR rates on particulate emissions has been investigated. It is found that PM sizes from combustion of B30 without EGR operation are generally smaller than those from ULSD while number concentrations are higher. This can result in lower PM mass estimates for the B30 case if due care is not taken. When EGR is applied to control nitrogen oxides emissions, both the total PM number and mass are increased and shifted toward the larger sizes for both fuels used in the test. The calculated total PM mass from B30 combustion is lower than in the ULSD case for all the tested engine operating conditions.