Unregulated and Regulated Emissions from Biodiesel Fuelled CRDI SUV Engine
Abstract
Use of biodiesel from non-edible vegetable oil as an alternative fuel to mineral diesel is attractive economically and environmentally. Diesel engines emit several harmful gaseous emissions and some of them are regulated worldwide, while countless others are not regulated. These unregulated species are associated with severe health hazards. Karanja biodiesel is a popular alternate fuel in South Asia and various governments are considering its large-scale implementation. Therefore it is important to study the possible adverse impact of this new alternate fuel. In this study, unregulated and regulated emissions were measured at varying engine speeds (1500, 2500 and 3500 rpm) for various engine loads (0%, 20%, 40%, 60%, 80% and 100% rated load) using 20% Karanja biodiesel blend (KB20) and diesel in a 4-cylinder 2.2L common rail direct injection (CRDI) sports utility vehicle (SUV) engine. Concentrations of regulated emissions namely CO, CO2, HC and NOX, in the engine exhaust were measured using raw exhaust gas emission analyzer. CO and THC emissions were emitted only at lower engine loads. Higher NOX emissions were seen for KB20 compared to diesel, particularly at higher engine loads. Fourier transform infrared (FTIR) emission analyzer measured various unregulated emission species to gauge their possible environmental and health impact. Alkanes, ethylene, acetylene and propylene, aldehydes were found only at lower engine loads and with increasing load, almost negligible concentrations were detected. Most unregulated emissions such as n-butane, n-octane, ethylene, aldehydes (formaldehyde and acetaldehyde), formic acid, benzene, toluene, SO2 etc. were observed to be lower for KB20 biodiesel blend compared to mineral diesel.