Abstract
The starting is a critical stage of diesel engine operation with respect to pollutant emissions (HC, CO and particulate matter), specific fuel consumption and stability of the combustion process, among others. Additionally, the starting is a very common transient process of the engine operation, which has been incorporated into the European certification cycle of light duty vehicles (NEDC). In this work, a turbocharged, direct injection (DI), diesel engine equipped with common rail injection system and EGR strategy has been tested during the starting. The engine was tested at two different starting modes: “cold start” mode (temperature of cooling water and lube oil were around ambient temperature ~20ºC) and “warm start” (the engine was previously warmed up). Pollutant emissions (HC, CO, NOx and smoke opacity) and operating parameters such as rotation speed, torque, air and fuel mass flow rates and EGR ratio were registered during the tests. The engine was fueled with a low sulfur diesel fuel and with biodiesel fuels. Biodiesel fuels were tested pure and blended with 70% v/v of diesel fuel. Biodiesel fuels tested were obtained from rapeseed, sunflower and soybean oils. The results show that biodiesel fuels lead to a reduction of smoke opacity during cold and warm engine start with similar nitrogen oxides (NOx) emissions.
KEYWORDS: Diesel, biodiesel, engine starting, pollutant emissions.