Jeyaseelan, T. and Mehta, P., "Reducing NO in a Biodiesel Fueled Compression Ignition Engine - An Experimental Study," SAE Technical Paper 2015-24-2483, 2015, doi:10.4271/2015-24-2483.
The replacement of fossil diesel with neat biodiesel in a compression ignition engine has advantage in lowering unburned hydrocarbon, carbon monoxide and smoke emissions. However, the injection advance experienced with biodiesel fuel with respect to diesel injection setting increases oxides of nitrogen emission. In this study, the biodiesel-NO control is attempted using charge and fuel modification strategies with retarded injection timing. The experiments are performed at maximum torque speed and higher loads viz. from 60% up to full load conditions maintaining same power between diesel and biodiesel while retarding the timing of injection by 3 deg. crank angle. The charge and fuel modifications are done by recycling 5% by volume of exhaust gas to the fresh charge and 10% by volume of methanol to Karanja biodiesel. The comparison of experimental results using the two NO control strategies show 35 to 45 % decrease in NO concentration at the load conditions specified above and 60 and 90% lower smoke respectively relative to diesel. Unlike using exhaust gas recirculation with biodiesel which reduces nitric oxide at an expense of increasing soot, the use of methanol blended biodiesel result in simultaneous reduction of both nitric oxide and smoke.