Abstract:
This study explores the impact of reduced flow rates and exhaust gas recirculation (EGR) on the combustion process in methane (CH4)-fueled engines, with a focus on their potential to reduce hazardous emissions such as CO and NOx. Through detailed simulations using ANSYS Fluent, the study investigates how variations in flow rates (5e-6, 4.5e-6, and 4e-6 m³/s) and EGR percentages (0%, 5%, 10%, and 15%) influence the combustion dynamics and emission characteristics. The analysis considers the interaction between CH4 and air or EGR gases, evaluating the resulting temperature distributions and emission indices. The geometry of the fluid domain is modeled using CATIA, and the accuracy of the computational results is ensured through rigorous mesh convergence studies, identifying the optimal mesh size for precise predictions. The study’s approach enables a detailed understanding of how different operating conditions influence the combustion process, making it possible to optimize engine performance while minimizing harmful emissions.
A key finding of the study is that EGR significantly reduces combustion temperatures and pollutant concentrations, particularly in the presence of lower flow rates. As EGR is introduced into the combustion system through air and CH4 streams, the temperatures within the combustion chamber decrease, resulting in lower concentrations of CO and NOx emissions. These benefits are amplified when lower flow rates are used, demonstrating how a combination of these two factors can work synergistically to achieve cleaner combustion. The results offer valuable insights into emission control strategies, suggesting that modifications in flow rate and the application of EGR can be effectively used in real-world combustion systems to meet stringent environmental regulations. By highlighting the feasibility of these strategies, the study provides critical information for future engine design and optimization efforts aimed at reducing environmental impact while maintaining performance.
Aim:
This study examines the NOx and emission characteristics of CNG-air non-premixed flames by utilizing an exhaust gas recirculation (EGR) model within a 2D Computational Fluid Dynamics (CFD) simulation framework. The simulation focuses on analyzing emission levels and NOx generation patterns, providing detailed insights into how non-premixed combustion influences pollutant formation. By simulating the combustion dynamics of the flame, the study explores the interaction between the fuel and air, including the impact of EGR on reducing NOx emissions. The results shed light on the complex processes involved in non-premixed combustion, highlighting how various factors, such as temperature distribution and recirculation, contribute to the production of pollutants. This information is crucial for understanding the environmental impact of CNG combustion and for developing strategies to mitigate harmful emissions.
Objectives:
This study addresses the critical issue of reducing NOx and other harmful emissions from combustion engines, particularly those powered by traditional fossil fuels, by focusing on non-premixed CNG-air flames and the impact of exhaust gas recirculation (EGR) in mitigating these emissions. The research uses a 2D CFD simulation framework to analyze combustion dynamics, temperature distributions, and pollutant generation, while systematically varying EGR rates, CNG injection levels, and burner configurations to identify optimal strategies for emission reduction. By assessing the balance between fuel economy and NOx reduction, the study aims to develop efficient emission control techniques that do not compromise combustion performance. Through this comprehensive approach, the study not only advances our understanding of how EGR influences CNG-air flame emissions but also provides valuable insights for improving combustion engine designs, promoting the use of cleaner fuels, and supporting environmental regulations. The findings contribute to the development of sustainable combustion technologies, offering solutions that can reduce the environmental and public health impact of emissions in the transportation and industrial sectors.
