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, CO₂, 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.