Combined impact of EGR and injection pressure in performance improvement and NOx control of a DI diesel engine powered with tamarind seed biodiesel blend.

In the process of creating eco-friendly environment and conserving fossil fuels for the future generations, biodiesel has been chosen as a good substitute for diesel. It is a proven fact that biodiesel operated diesel engine can deliver comparable results with diesel. The present work focuses on TSME20 (tamarind seed methyl ester 20% + diesel 80%) as a renewable fuel, and its performance and emission results are analyzed at different exhaust gas recirculation rates and various injection pressures. The process is done in two stages. Firstly, experiments are conducted on TSME20 operated diesel engine at three injection pressures (180, 200, and 220 bar), and the results are analyzed. From the experimental results, improved efficiency by 2.29% and reduced emissions, such as hydrocarbon, smoke, and carbon monoxide, by 53.84, 56.25, and 75.15% are observed at the peak load for the increased injection pressure (220 bar) over 200 bar except NOx levels, which are found high by 11% compared to 200-bar injection pressure. Secondly, tests are again performed at the optimal condition of 220-bar injection pressure with the exhaust gas re-circulation (EGR) rates at different levels, i.e., 10 and 20%. The test results reveal that the addition of 10% EGR to the engine operating at 220 bar counteracts the release of NOx levels, which are found reduced by 80.5% over standard conditions without much compromise in engine performance. Also, the combustion characteristics of diesel engine at 220-bar fuel injection pressure of tamarind biodiesel blend showed enhancement when compared to other fuel injection pressures.