Modeling and analysis of exhaust gas recirculation effects on performance and emissions of a single-cylinder agricultural diesel engine

This study investigates the effects of exhaust gas recirculation (EGR) on the performance and emission characteristics of a single-cylinder agricultural diesel engine using a one-dimensional simulation model developed in AVL Boost. The model is constructed based on engine specifications and validated against manufacturer data and experimental measurements, showing good agreement with deviations below 5%. After validation, the model is employed to analyze the influence of EGR under partial load conditions (75% load), which are representative of typical engine operation. The results indicate that increasing the EGR rate leads to a significant reduction in excess air ratio (λ), accompanied by a decrease in combustion temperature and indicated efficiency. Specifically, the peak combustion temperature decreases by approximately 10%, while the indicated efficiency drops by around 10–12% as the EGR rate increases from 0% to 30%. In terms of performance, engine torque decreases slightly (up to 2.65%), whereas brake specific fuel consumption (BSFC) increases by about 7–8%. From an emission perspective, NOₓ emissions are significantly reduced by over 90%, while soot emissions increase by approximately 15–18%, highlighting the well-known trade-off between NOₓ and particulate matter. An optimal EGR range of 5–15% is identified, where a substantial reduction in NOₓ can be achieved with moderate penalties in soot emissions and engine performance. The findings demonstrate that EGR is an effective strategy for NOₓ control in agricultural diesel engines; however, its application requires careful optimization to balance emission reduction and engine efficiency.