Integrated Control Strategies of Egr System and Fuel Injection Pressure to Reduce Emissions and Fuel Consumption in a Di Engine Fueled with Diesel-Wcome Blends and Neat Biodiesel

A wide experimental campaign was developed on an automotive turbocharged diesel engine, using two blends between diesel oil and waste cooking oil methyl esters (WCOME) and neat biodiesel. A conventional B7 diesel oil was considered as reference fuel. The two blends respectively included 40 and 70% of WCOME, on a volumetric basis. The influence of biodiesel was analyzed testing the engine in two part load operating conditions, applying proper control strategies to the exhaust gas recirculation (EGR) circuit and rail pressure, in order to assess the interactions between the engine management and the tested fuels. Variable nozzle turbine (VNT) was controlled to obtain constant level of intake pressure in the two experimental points. Referring to biodiesel effects at constant operating mode, higher WCOME content generally resulted in better efficiency and soot emission, while NOX emission was negatively affected. EGR activation allowed for limited NO formation but with penalties in soot emission. Furthermore, interactions between EGR circuit and turbocharger operations and control led to higher fuel consumption and lower efficiency. Finally, the increase of rail pressure corresponded to better soot emission and penalties in NOX emission. Combining all these effects, the selection of EGR rate and rail pressure values higher than the standard levels resulted in better efficiency, NOX and soot emissions when comparing blends and neat biodiesel to conventional B7, granting for advantages not only referred to Green House Gas emissions. Combustion parameters were also assessed, showing that combustion stability and combustion noise were not negatively affected by biodiesel use. Combustion duration was reduced when using WCOME and its blend, even if centre of combustion was slightly shifted along the expansion stroke.