Comparative Strategies for Nox Reduction in Diesel Engines
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This study investigates the reduction of nitrogen oxide (NOx) emissions in diesel engines using computational simulations performed with Diesel-RK. Three in-cylinder control strategies were evaluated: exhaust gas recirculation (EGR), direct water injection, and variations in combustion chamber depth. Simulations were conducted on a six-cylinder, four-stroke diesel engine at engine speeds ranging from 1000 to 3000 rpm. The results show that increasing EGR lowers NOx emissions by reducing peak combustion temperatures through oxygen dilution and enhanced mixture heat capacity. Water injection was found to be the most effective strategy, reducing NOx to nearly negligible levels across all speeds by combining evaporative cooling, heat absorption, and oxygen displacement. Changes in combustion chamber depth had a moderate influence, with shallower chambers improving swirl and mixing, thereby lowering local temperature peaks and suppressing NOx formation. Overall, the findings highlight water injection as the most effective standalone strategy, while combining it with optimized chamber geometry and moderate EGR offers a promising integrated approach for NOx control in diesel engines.
Akinpelu, A., et al., Greenhouse gas emission dynamics of Saudi Arabia: potential of hydrogen fuel for emission footprint reduction. Sustainability, 2023. 15(7): p. 5639.
Heywood, J.B., Combustion engine fundamentals. 1ª Edição. Estados Unidos, 1988. 25: p. 1117-1128.
Park, J., Y. Lim, and S. Park, NOx reduction scenarios under real-world driving conditions for light-duty diesel vehicles. Transportation Research Part D: Transport and Environment, 2024. 136: p. 104467.
Abdelhameed, E. and H. Tashima, EGR and emulsified fuel combination effects on the combustion, performance, and nox emissions in marine diesel engines. Energies, 2022. 16(1): p. 336.
Deng, B., et al., A comprehensive investigation of EGR (exhaust gas recirculation) effects on energy distribution and emissions of a turbo-charging diesel engine under World Harmonized transient cycle. Energy, 2025. 316: p. 134506.
Hu, H., et al., Study of EGR strategy for marine two-stroke methanol-diesel dual-fuel engines: Combustion, performance, and emission analysis across full operating range. Thermal Science and Engineering Progress, 2025: p. 104058.
Saravanan, S., Effect of exhaust gas recirculation (EGR) on performance and emissions of a constant speed DI diesel engine fueled with pentanol/diesel blends. Fuel, 2015. 160: p. 217-226.
Nurtanto, M., et al. The use of water injection on performance and emission in diesel engine: A review. in AIP Conference Proceedings. 2025. AIP Publishing LLC.
Ithnin, A.M., et al., Combustion performance and emission analysis of diesel engine fuelled with water-in-diesel emulsion fuel made from low-grade diesel fuel. Energy Conversion and Management, 2015. 90: p. 375-382.
Sun, X., et al., Effect of direct water injection on combustion and emissions characteristics of marine diesel engines. Fuel, 2022. 309: p. 122213.
Chen, Z., et al., Experimental study on the effect of water port injection on the combustion and emission characteristics of diesel/methane dual-fuel engines. Fuel, 2022. 312: p. 122950.
http://www.diesel-rk.bmstu.ru/Eng/index.php?page=History.
Gaurav Paul, A.D., Bijan Kumar Mandal, An Experimental and Numerical Investigation of the Performance, Combustion and Emission Characteristics of a Diesel Engine Fueled with Jatropha Biodiesel. Energy Procedia, 2014. 54: p. 455-467.
Shrivastava, P. and T.N. Verma, Effect of fuel injection pressure on the characteristics of CI engine fuelled with biodiesel from Roselle oil. Fuel, 2020. 265: p. 117005.
Agrawal, A.K., et al., Effect of EGR on the exhaust gas temperature and exhaust opacity in compression ignition engines. Sadhana, 2004. 29(3): p. 275-284.
De Serio, D., A. de Oliveira, and J.R. Sodré, Effects of EGR rate on performance and emissions of a diesel power generator fueled by B7. Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2017. 39(6): p. 1919-1927.
Hansen, A.C., Q. Zhang, and P.W. Lyne, Ethanol–diesel fuel blends––a review. Bioresource technology, 2005. 96(3): p. 277-285.
Turns Stephen, R., An introduction to combustion: concepts and applications. Boston: McGraw-Hill, 2000: p. 158.
Ladommatos, N., et al., The dilution, chemical, and thermal effects of exhaust gas recirculation on diesel engine emissions-Part 3: effects of water vapour. 1997, SAE Technical Paper.
Stone, R., Introduction to internal combustion engines. Vol. 3. 1999: Springer.
Payri, F., et al., CFD modeling of the in-cylinder flow in direct-injection Diesel engines. Computers & fluids, 2004. 33(8): p. 995-1021.
Şahin, Z., M. Tuti, and O. Durgun, Experimental investigation of the effects of water adding to the intake air on the engine performance and exhaust emissions in a DI automotive diesel engine. Fuel, 2014. 115: p. 884-895.
Saravanan, P., et al., Effect of exhaust gas re-circulation on performance, emission and combustion characteristics of ethanol-fueled diesel engine. Case Studies in Thermal Engineering, 2020. 20: p. 100643.
Jaichandar, S. and K. Annamalai, Influences of re-entrant combustion chamber geometry on the performance of Pongamia biodiesel in a DI diesel engine. Energy, 2012. 44(1): p. 633-640.
