Performance, Combustion and Emission Studies of A Single Cylinder Diesel Engine By Dual Fuel Mode Propelled with Biogas Derived From Food Waste

Abstract

Reduction in petroleum products, ever increasing rate of fossil fuels consumption, environment concern and strict emission norms have directed researchers, policy makers to focus on alternative energies to meet the energy demand for various applications. Present research work emphasizes on the application of biogas derived from food waste on the diesel engine operated by dual mode to enhance the performance and mitigate the emissions. Generalized studies on the diesel engine characteristics using biogas (BG) by dual fuel mode with the different ratios ranging from 20% to 60% with a step of 10% are explored. To understand the nature of combustion, the concept of cycle by cycle variation and return map in terms of maximum cylinder pressure (Pmax) is studied for diesel and dual mode for 100 cycles. The nature of stability and instability in the combustion is measured by coefficient of variation (COV), such that BG20 showed lower COV of Pmax by 2.3% and BG30 showed slightly higher COV of Pmax by 1.89% than diesel. Return map, indicated that BG20 and BG30 showed greater combustion stability compared to other biogas proportions. Next objective was to study the effect of injection timing (25.5° bTDC - 29.5° bTDC) on the diesel engine for dual mode of operation. Overall, 27.5° bTDC injection timing showed optimum results compared to other injection timings as well BG50 is optimized compared to other biogas with respect to better engine performance and less emissions. To enhance the engine performance, oxygen enrichment (21% to 27% v/v) is implemented to the engine along with BG50. The thermal efficiency for BG50 with 27% oxygen concentration was improved by 18.37% compared to BG50 without oxygen induction. But NOx emission increased drastically compared to diesel, which is the foremost disadvantage of the oxygen enrichment process and hence the oxygen level is optimized to 25%. The work is extended to study the effect of vaporized water-methanol (MVI) induction to bring down the NOx emission intensity for BG50 with 25% O2 as well to enhance the performance of the dual engine. Using the shell and tube heat exchanger, the water-methanol is vaporized using the heat from the waste exhaust gas and it is inducted into the intake manifold. Engine efficiency improved for BG50 at 25% O2 with 20% MVI compared to BG50 at 25% O2 without vapor induction by 9% and NOx emission improved significantly for BG50 at 25% O2 with 30% MVI compared to BG50 at 25% O2 without vapor induction by 86.82% at full load. The final outcome of the current research work is, use of BG50 operated at 27.5° bTDC injection timing with 25% oxygen enrichment and 20% vaporized water-methanol induction rate is superior iv alternative for modified single-cylinder CI engine for enhanced engine performance and emission characteristics. To conclude, the aim of the present research work was to examine the potential of using the higher proportions of biogas in the dual fuel diesel engine. Also, to replace the diminishing fossil fuels to meet the energy demand and for various applications. Moreover, to work towards the efficient conversion of heat into energy without compromising the performance and emissions of the engine. The investigation was also well planned by focusing on the new techniques to improve the performance and implement on the engine to stabilize the operation practically. The study also deals with the emission reduction techniques to reduce the exhaust emissions and to implement the methods practically on the automobiles ranging from small to heavy vehicles. Overall agenda of the research was to provide an affirmative solution to the complex issues faced by the transportation sectors with reasonable expenditure.