Integrated energy–exergy modeling and fleet-level decarbonization potential of dual-fuel LPG/diesel engines validated using AVL-BOOST

Abstract

Retrofitting conventional diesel engines for LPG/diesel dual-fuel operation offers a near-term decarbonization option for fleets that cannot yet transition to full electrification. This study develops an integrated engine-to-fleet framework that combines AVL-BOOST-based combustion modeling, experimental validation, energy–exergy analysis, emission trade-off assessment, and fleet-level CO₂ mitigation. The model was calibrated and validated on two representative platforms, a common-rail AVL 5402 engine and a mechanically injected D1146TI engine, using brake torque, specific energy consumption (SEC), in-cylinder pressure, combustion phasing, and gaseous and smoke emissions. The predicted torque and SEC showed high agreement with experiments, with MAPE below 5%, R² values of 0.992 and 0.948, respectively, and peak-pressure deviations below 3%. At LPG substitution ratios of 20–30%, brake power was maintained, SEC remained near the diesel baseline, exergy efficiency increased by 1.5–2.8%, and smoke decreased markedly, although NOx, CO, and HC remained sensitive to combustion phasing and low-load mixture oxidation. Fleet-scale analysis indicates that 30% retrofit penetration at an average 25% LPG substitution ratio can reduce TTW CO₂-equivalent emissions by approximately 6–9%; the corresponding WTW benefit remains dependent on the upstream LPG supply pathway. The framework provides a physics-informed basis for evaluating LPG/diesel retrofit as a transitional decarbonization pathway.