Influences of spray angle and bowl center depth on power and exhaust emissions in a dual fuel direct injection engine

Abstract

Injection strategy and piston bowl geometry play a very effective role in engine design. Hydrogen fuel in liquid or gaseous form is high in energy, and engine that burns pure hydrogen produces almost no exhaust emissions. In this article, influences of spray angle and bowl center depth on engine performance (indicated power and efficiency), fuel economy, and exhaust emissions (CO, CO 2 , NO, soot, and hydrocarbon) are investigated for a hydrogen (6%) + diesel dual fuel engine under 1500, 2000, and 3000 r/min speeds. Numerical simulation was performed using computational fluid dynamics code. To ensure validity of simulation, calculated in-cylinder mean pressure and rate of heat release were compared to experimental data, and the results specified a good accordance (for 1200 r/min and 70% load). The results of studies show that 160°spray angle is the best to achieve balanced emissions and more power and efficiency in comparison to other spray angles (120°, 130°, 140°, and 180°spray angles). It is found that taking into account the 160°spray angle in comparison to 120°spray angle, indicated power and efficiency increase by 25%, and the amount of exhaust CO, soot, and hydrocarbon reduces approximately by 76%, 71%, and 95%, respectively. It is determined that a deep bowl center depth leads to higher temperature (further NO emissions) and lower brake-specific fuel consumption. Three bowl center depths (5, 10, and 20 mm) were chosen for further investigation, and the 10-mm depth showed a suitable balance between exhaust emissions and power generated.

Experimental and Numerical Investigation of Methane Combustion Combined with Biodiesel in Dual Fuel Mode

“…During the phase of the diffusion combustion in particular at 20°V we have a cylinder pressure of 47.18 bars for the combustion of biodiesel and 45.80 bars in the combustion of diesel for a difference of 3.01%. This difference is in agreement with the results of several researches such as Hossain et al [17] and other scholars [30][31][32][33][34][35][36], who made the same observation on the study of the combustion and the emissions with biofuels. The difference in premix phase would reflect a relatively short auto-ignition time for biodiesel increasing the cylinder pressure because of its oxygenated character and high cetane number.…”

“…In general, the combustion in dual fuel mode reduces by 48.32% and 26.65% respectively in biodiesel and diesel operation. This finding has also been the subject of several studies such as that of Papagiannakis et al [36][37][38][39]. The author reports that this decrease in NOx and state variables is due to the reduction in the amount of oxygen intake compensated by the primary fuel input during the intake phase.…”

“…The difference between the peak cylinder pressures in dual fuel mode and in single mode is 5.54 bars, i.e., a reduction of 8% for biodiesel and a difference of 1.4 bars, i.e., 1.84% bars for diesel. During the premix and diffusion phases the curves are closer together but around the top dead center they diverge more, this would mean that the dual fuel mode is dominant [34][35][36][37]. During the premixing phase, the dual fuel biodiesel methane presents after -10°V a deviation of 3% higher than the diesel methane.…”