Examining the effect of air-fuel atomization on the performance and emission of heavy duty trucks : a case study of Mercedes-benz actros engine model 3340-ls

Abstract

Internal Combustion Engines (ICEs) are facing criticism for their role in greenhouse gas emissions and air pollution. Despite technological advancements in air-fuel atomization, optimizing air-fuel atomization to enhance performance and reduce emissions in heavy-duty diesel engines such as the Mercedes-Benz Actros 3340-LS remains a challenge. A comprehensive assessment of air-fuel atomization mechanisms is therefore important to enhance engine efficiency while simultaneously holding back harmful emissions to ensure sustainability and competitiveness of heavy-duty trucks engines in modern transportation. This research examined the effects of air-fuel atomization on engine performance and emissions using Computational Fluid Dynamics (CFD) simulations in Ricardo Wave 2019.1. It specifically aimed at characterizing the design parameters of Mercedes Benz Actros 3340-LS engine, developing a validated Ricardo Wave CFD simulation engine model, and analyzing the impact of key injection parameters specifically nozzle hole diameter, injection pressure, Air-Fuel Ratio (AFR), and engine speed on performance and emissions. The engine model was replicated in Ricardo Wave and subjected to a series of simulations with varying nozzle hole diameters from 0.194 mm to 0.278 mm and engine speed from 700 rpm to 2500 rpm. Performance indicators such as brake power, torque, brake-specific fuel consumption (BSFC), volumetric efficiency, and emissions like Nitrogen oxides (NOx), Carbon monoxides (CO), Hydrocarbons (HC), and Smoke were evaluated under standardized test cycles. Model validation was conducted by comparing simulation trends with experimental findings from related heavy-duty engines, including MAN D2676LF, Volvo D13C, Cummins ISX12G, and various GDI engines. Results show that smaller injector nozzle diameters (0.194 mm - 0.203 mm) produced finer sprays with reduced Sauter Mean Diameter (SMD) and breakup length, leading to improved brake torque, brake power, volumetric efficiency, and lower Brake Specific Fuel Consumption (BSFC), NOx, CO, HC, and smoke emissions. Larger injector nozzles diameters (above 0.24mm) yielded coarser sprays, higher emissions, and reduced efficiency. The study also found a correlation between nozzle hole size and smoke emissions, with diameters above 0.25 mm leading to increased smoke and hydrocarbon emissions. The study also found that injection parameters, particularly nozzle hole diameter and injection pressure, significantly affect air-fuel atomization quality. The optimal nozzle hole diameter of 0.203 mm yielded the most balanced trade-off between fuel efficiency, power output, and emission levels. The results closely aligned with published experimental findings, confirming the model’s predictive capability. The research recommends that for further research and practical applications, manufacturers should implement adjustable injector designs, fleet operators should maintain regular injector calibration, and policymakers should encourage the adoption of precision fuel injection technologies through emissions regulation frameworks and incentives for low-emission heavy-duty vehicles, and integrating 1D with 3D CFD tools like ANSYS fluent and Coverage to get insights on spray behavior, turbulence and flame propagation which are not fully resolved in 1D models, and employing advanced wear-resistant materials. Future research should focus on adaptive injection systems, atomization optimization under varying engine loads and speeds, the impact of alternative fuels and nozzle hole geometry, real-world driving conditions, long-term durability, and integrating variable geometry turbocharging for performance and emissions reduction.