Diesel engine performance and emissions analysis with four different combinations of diesel-soybean biodiesel blends

Abstract

The increasing interest in renewable resources as a replacement for fossil fuels has placed biofuels in the forefront. Therefore, a comprehensive exhaust emission analysis was performed on a MWM International S4T Diesel engine fuelled with 100% Diesel (D100), 75% Diesel and 25% soybean biodiesel (B25), 50% Diesel and 50% soybean biodiesel (B50) and 100% soybean biodiesel (B100) at 980, 1270, 1820 and 2420 revolution per minute (RPM) for assessing human health and air quality. Additionally, fuel density, engine strength and power, torque and specific fuel consumption were also calculated. 80 L Teflon chambers, the solid phase micro-extraction(SPME) technique and gas chromatography coupled to mass spectrometry (GC-MS) were employed for VOCs analysis. In addition, O2, CO2, CO, NO and NOx concentration and volumetric flow rate from the exhaust pipe were measured. Up to 1270 RPM, a slight increase in power and torque was detected for biodiesel fuels for the higher oxygen content and density of the soybean biodiesel. Therefore, the specific fuel consumption slightly increased with the addition of biofuel, whereas no significant variations in CO2 and O2 concentrations were observed. However, NOx concentrations significantly increased and CO emissions decreased at 1270 and 1820 RPM from D100 to B100. Regarding VOCs, a drop in the chromatographic areas for alkanes and aromatics and a higher proportion of oxygenated compounds and alkenes were observed with biofuel blends. C9-C14 alkanes, benzene and 1,2-dimethylbenzene, and 1-heptanol, 6-methyl-1-heptanol and 1-octanol were the compounds with the highest ARCA values. The origin and properties of biofuels, engine type and the operating mode are the mainfactors with most influence in exhaust emissions. Consequently, the risks to human health and the impact on the air pollution needs to be considered, and therefore biofuels are a highly debated field of research.