Combustion and Emissions Characterization of Biodiesel Blends in a City-Car Engine

Abstract

Increasing attention has been devoted to the use of biodiesel fuel in internal combustion diesel engine due to its positive attributes as compared to the other types of fuel: e.g., being a renewable source, non-petroleum-based, with lower carbon monoxide, hydrocarbon, and particulate matter emissions. This work investigates the performance and the air emission of a small displacement engine fueled with blends of distilled biodiesel (from this point forward biodiesel only) and ultralow-sulfur diesel fuel up to 40% by volume. The considered engine plays a leading role in city cars and urban vehicles; the urban congestion and the antipollution regulations for urban vehicles make this kind of engine very attractive in the near future, especially if it will be fueled with biodiesel blends for their potential of reducing the pollutant emissions in urban areas. The first part of this work aims at comparing the results obtained with biodiesel blends and those determined using diesel fuel as a reference under various operating regimes without any modification to the injection process. The impact of biodiesel blend fuels on the engine's power, specific fuel consumption, and emissions is analyzed. The second part of this work aims at investigating the influence of a variation of the injection parameters on the performance and emissions of the engine using biodiesel blends (20% and 40%). Five engine operation modes are considered, in which the engine is tested with split injection (preinjection and main injection) and various preinjection and main injection timings and durations. ■ INTRODUCTIONThe continuous tightening of regulations on engine exhaust emissions has led to new solutions capable of reducing nitrogen oxides (NO x ) and particulate matter (PM) and also limiting fuel consumption and related costs.It is well-known that performance and emission characteristics are strongly governed by injector design that has a key role in the atomization and spray development. 1,2 A number of researchers have investigated the effects of the injection parameter settings on diesel engine performance and emission characteristics. 3−6 According to these authors, NO x emissions are affected by injection timing and pressure. The increase of pressure and the advanced injection timing cause the gas temperatures to rise during the combustion process. A more homogeneous mixture is therefore realized, with an increase of NO x emissions due to the kinetic constants and oxygen concentration of the Zeldovich mechanism. Soot formation is enhanced by heterogeneous fuel/air mixtures and fuel droplets size. The increase of injection pressure and the advanced injection timing determines a decrease of soot emission. 7 In order to reduce harmful diesel engine emissions, considerable attention has been devoted to the investigation of the impact of fuel composition on diesel emissions.Numerous types of fuels have been alternatively proposed, and many studies have demonstrated the suitability of renewable nature fuels made from agricultural products to b...

Emission Performance of a Diesel Engine Fuelled with Petrol Diesel, Green Diesel, and Waste Cooking Oil Blends

“…The results highlight a modest increase of fuel consumption with the WCO content in the blend, which is ascribed to the reduction of the energy content in biodiesel as compared to ULSD and green diesel and to some improvements in the combustion process due to the oxygenate nature of WCO. This is in agreement with a previous experimentation of WCO in blends with ULSD [12] and with results from literature related to the investigation of biodiesel from many feedstock types [16,17]. Figure 4 shows the variation of brake thermal efficiency (BTE) with engine speed at a constant value of load condition.…”

“…It was established that 40% of WCO in the blend is the highest quantity of biodiesel that can be tested, since higher percentage of biodiesel in the blend may not be compatible with certain metals causing corrosion, and elastomers and seals may swell or harden, according to previous experimental tests [12]. The experimentation was thus performed with a biodiesel from WCO percentage lower than 40% by volume; this allowed the investigated blends to be ready for use in actual engine.…”

“…The resulting raw biodiesel, coming from poor raw material, was distilled in order to comply with the reference specifications of biodiesel (EN 14214). Details of the procedure may be found in [12]. Table 2 reports the composition of the obtained biodiesel.…”

Effect of Waste Cooking Oil Biodiesel Blends on Performance and Emissions from a CRDI Diesel Engine

“…Details of the procedure may be found in Ref. [31]. The properties of the biodiesel and ultralow-sulfur diesel (ULSD) are listed in Table 2.…”

Impact on Combustion and Emissions of Jet Fuel as Additive in Diesel Engine Fueled with Blends of Petrol Diesel, Renewable Diesel and Waste Cooking Oil Biodiesel

“…The oxygen in the fuel results in HC, CO, and particulate matter (PM) reduction; a general increase of nitrogen oxides (NO x ) emission is also observed, due to the higher oxygen available in biodiesel. However, biodiesel has a lower caloric value as regarding diesel oil, which thus results in engine power losses when it is blended with conventional diesel fuel [10][11][12][13][14].…”