Experimental and Simulation Study of Diesel Engine for Lower Exhaust Emissions

The objective of this work is to study the effect of different control parameters viz. EGR, fuel injection pressure, swirl ratio, nozzle hole diameter, spray included angle and start of injection timing on exhaust emissions from diesel engine. A single cylinder, water cooled engine has been selected for experiments and AVL FIRE 3D CFD software was used for simulation study. The basic idea of the simulation study is to find the suitable EGR ratio to run the engine so as to avoid any damage to the engine during testing. From simulation study, it was observed that the optimum EGR at 1500 rpm is approximately 30%. The trends of in cylinder pressure and ROHR are closely matching with the experimental results. The experiments were conducted at different loads and at 1500 rpm and EGR was varied from 0% to 50%. With increased swirl ratio from 1.8 to 2.1, brake power reduced by 1.5% and soot by 3.5%. For the nozzle hole diameter of 0.181 mm, bsfc decreased by 1.5% and BP increased by 1.4%. At a spray included angle of 146o BSFC decreased by 2.3%, NOx decreased by 4.3% and smoke increased by 5%. At injection pressure of 220 bar and fuel injection timing of 8o bTDC and high EGR ratio of 30%, BP decreased by 0.9% and NOx decreased by 6.7%. Detailed experiments were conducted at 1500 rpm to study simultaneous reduction of NOx, SOOT, UHC and CO emissions from diesel engine.