Bio diesel against petroleum diesel : assessment of internal combustion engine performance and emissions

This study investigates the need for bio-diesel and analyse bio-diesel against its counterpart being petroleum diesel. Both, performance and emissions of an internal combustion engine (ICE) using bio-diesel and bio-diesel blends are experimentally measured for two types of bio-diesel, type A - 80% tallow (beef, pork and sheep) and 20% canola oil methyl ester and type B - 70% chicken tallow and 30% waste cooking oil methyl ester. The test was done according to the ISO 8178 standard for emissions analysis of off-road engines. Kubota V3300 indirect injection, four cylinders naturally aspirated ICE was used to evaluate the performance and emissions of test fuels. Bio-diesel blends of B5, B10, B20, B50 and B100 are analysed. Bio-diesel properties such as density, viscosity, calorific value, and cetane number, etc have significant impact on performances and emissions. This study found that the performance of both biodiesel fuels reduces with increasing blend ratio, with a torque decrease of 5% for both biodiesels, and a fuel consumption increase of 7-10% over the ISO 8178 test cycle. This can be attributed to the lower energy content of biodiesel when compared with petroleum diesel. The emissions results were varied for the biodiesels, as some emissions were found to be higher than petroleum diesel, while some were lower. NOx emissions decreased by 14% for biodiesel A, but increased by 17% for biodiesel B. CO emissions were significantly reduced for both biodiesel A and B, with reductions of 58% and 27% respectively. Hydrocarbon (HC) emissions were found to increase with increasing blend ratio for both biodiesels, with an increase of 10% for biodiesel A and 80% for biodiesel B. Lastly, CO2 emissions were found to increase, with an increase of 6% for biodiesel A and 18% for biodiesel B. The study clearly found that each of the biodiesels has different scale ofeffect on ICE performance and emissions and hence, it is essential to test biodiesels before it can be recommended for commercial use in ICE. However, the study indicates that although performance is reduced when using biodiesel fuels the two major pollutant gas emissions are generally reduced when using biodiesel, therefore biodiesel can be considered as more environmentally friendly, secure and renewable approach of obtaining energy in the long run.