The influence of EGR to performance and emissions of a CI engine fuelled with jatropha-based biodiesel blend

Abstract

Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.

The depletion of fossil fuel and the impact of environmental pollution from mobile vehicles have led the search for alternative fuels. Vegetable oils have very similar properties with conventional diesel fuel and therefore, they are quite promising as alternative fuels for diesel engines. Since 1900s, over 30 different types of vegetable oils have been used to fuel compressed ignition (CI) engines. Straight vegetable oils are known to pose various long-term operational and durability problems in CI engines, such as poor fuel atomization, piston ring-sticking, fuel injector coking and deposits, fuel pump failure, and lubricating oil dilution. These problems are due to the vegetable oil high viscosity, low volatility, and polyunsaturated characters. Transestetification, which produces biodiesel, is the most effective process to treat all those problems associated with vegetable oils. Biodiesel productions follow the primary country feedstock. Hence, countries like Malaysia utilize Coconut oil, Palm oil, Jatropha oil and other vegetable oils as the feedstock. Production of biodiesel from edible oil is very expensive than diesel fuel and has caused fuel-food conflicts. In the current study, the focus is on jatropha-based biodiesel (JBD) and previous studies have reported that JBD was found to emit higher nitrogen oxides (NOx) and lower soot emissions compared to conventional diesel fuel. Other researchers have also achieved to decrease the NOx. emission from JBD by using exhaust gas recirculation (EGR), at the expense of higher soot. As a result, there exists difficulty in reducing both soot and NOx emissions and a trade­ off between them is essential. The aim of the present research was to investigate the engine performance and soot emission by using different blends of JBD with different EGR rates. A 4- eylinder, water-cooled, turbocharged, indirect injection diesel engine was used for the experiments. Data collection and analysis have been carried out on exhaust emission and other engine performance parameters such as thermal efficiency, brake specific fuel consumptioo (BSFC) and brake specific energy consumption (BSEC). The focal finding will verify the need of trading off between soot and NOx emissions, for CI engine running using JBD fuel.