Effects of gasoline–diesel and n-butanol–diesel blends on performance and emissions of an automotive direct-injection diesel engine

Abstract

In the present paper, results of an experimental investigation carried out in a modern diesel engine running at different operating conditions and fuelled with blends of gasoline–diesel and n-butanol–diesel, are reported. The exploration strategy was focused on the management of injection pressure and timing to achieve a condition in which the whole amount of fuel was delivered before ignition. The aim of the paper is to evaluate the effects of fuel blends, which have low cetane number (CN) and are more resistant to auto-ignition than diesel fuel, on performance and engine-out emissions. Blends were mixed by the baseline diesel (D00) with 40% of commercial unleaded gasoline (G40) and 40% of n-butanol (B40). Fuel consumption and engine-out gaseous and smoke emissions from fuel blends were measured and compared to the neat diesel fuel. The investigation was performed on a turbocharged, water-cooled, direct-injection diesel engine, equipped with a common-rail injection system. The engine equipment included an exhaust gas recirculation system controlled by an external driver, a piezo-quartz pressure transducer to detect the in-cylinder pressure signal and a current probe to acquire the energizing current to the injectors. Engine tests were carried out at two engine operating conditions: 2000 r/min at 0.5 MPa and 2500 r/min at 0.8 MPa brake mean effective pressure, exploring the effect of start of injection, O2 concentration at intake and injection pressure on combustion behaviour and engine-out emissions. Taking advantages of the higher resistance of G40 and B40 to auto-ignition, it was possible to extend the range in which a partial premixed combustion was achieved. The management of injection pressure, O2 concentration at intake and injection timing allowed partial premixed combustion to be obtained by extending the ignition delay, both for diesel fuel and blends. The longer ignition delay and the better mixing before combustion made more advanced injection timings, which reduced smoke and nitrogen oxide emissions, possible. The joint effect of higher resistance to auto-ignition and higher volatility of n-butanol and gasoline improved the emissions of the blends compared to the neat diesel fuel, with a low penalty on fuel consumption.

Experimental study on the two stage injection of diesel and gasoline blends on a common rail injection system

“…The well-maintained combustion temperature could avoid the combustion deterioration as in the conventional LTC mode. Some researchers considered using blends of diesel and gasoline instead of diesel in advanced compression ignition (CI) engine combustion modes, and remarkable advantages in emissions control and fuel efficiency improvements were observed due to the extended ignition delay and improved in-cylinder fuel/air distribution [5][6][7][8][9][10]. Meanwhile, compared to gasoline LTC, using blends of diesel and gasoline does not cause combustion instability problems at low load and low speed conditions, as reported by Weall and Collings [11,12].…”

Autoignition response of n-butanol and its blends with primary reference fuel constituents of gasoline

“…Moreover, there have been several applied studies investigating the effect of butanol addition to conventional transportation fuels in spark ignition [66][67][68][69][70][71][72][73][74], compression ignition [70,[75][76][77][78][79][80][81][82][83][84][85][86][87][88][89][90][91][92], and homogeneous charge compression ignition (HCCI) engines [17,70,81,[93][94][95]. By comparison, fundamental combustion studies on blends of n-butanol and a representative hydrocarbon component for transportation fuels are meager.…”

Experimental investigation of hydraulic effects of two-stage fuel injection on fuel-injection systems and diesel combustion in a high-speed optical common-rail diesel engine

“…In recent years, advancement in the design of such versatile and flexible systems has led to the development of alternative combustion modes including low temperature combustion (LTC) [8][9][10][11][12][13][14], homogeneous charge compression ignition (HCCI) [14][15][16][17][18][19][20][21][22], premixed charged compression ignition (PCCI) [23][24][25][26][27][28][29] and partially premixed combustion (PPC) [30][31][32][33] through the application of sophisticated fuel injection strategies. The results revealed the potential for simultaneous reduction of NOx and PM emissions through the application of such fuel injection and combustion modes.…”