Influence of Fuel Injection Pressure on Combustion and Gas Emissions in a TBC Diesel Engine Fuelled with Pongamia Bio-Fuel Blends for Sustainable Environment

Abstract

The objective of this research work was to investigate the environmental aspects of Pongamia bio-fuel blends and diesel in a Thermal Barrier Coated (TBC) diesel engine with the influence of fuel injection pressure. The combustion chamber components including inlet and exhaust valves, cylinder head and piston crown were coated with yttria stabilized zirconia ceramic material over nickel aluminium alloy bond coat for 300 μm thickness. Biodiesel obtained by Transesterification process from non-edible Pongamia pinnata oil was blended with diesel in various proportions from 0–30% in steps of 5% by volume. Injection pressure was varied from 210 bar to 240 bar in steps of 10 bar by means of adjusting the injector spring tension. The effect of fuel injection pressure for specified biodiesel blends and diesel at full load are studied. Experimental results confirmed that in coated engine biodiesel blend 15% by volume (B15) with diesel showed significant reduction in emissions carbon monoxide (CO) of about 50%, unburnt hydrocarbon (UHC) of 26.5%, smoke of 20% with slightly higher values of 2.37% oxides of nitrogen (NOx) and 5.17% of carbon di oxide (CO2) at 230 bar injection pressure in full load condition compared with uncoated engine. Increase of injection pressure improved heat release rate of about 5.21%, 4.65% for diesel and blend B15 in coated engine and the occurrence of peak heat release rate is earlier around 2°CA before diesel fuel in coated engine at 230 bar pressure for blend B15. From the test results, it was found that blend B15 causes better atomization with improved emission characteristics at 230 bar injection pressure.