Numerical investigation of the effects of ammonia energy share on power, torque, and emission characteristics of an ammonia–diesel dual-fuel engine

Abstract

This study investigates the effects of ammonia energy share on power, torque, and emissions of an ammonia–diesel dual-fuel engine using an AVL BOOST simulation model. The DESSUN 4DSP-75 diesel engine model was developed and validated under baseline diesel operation. The validated model was then converted to dual-fuel operation by supplying ammonia through the intake pipe, while diesel was directly injected into the cylinder as the pilot fuel. Ammonia energy shares of 5%, 10%, 15%, and 20% were investigated over the engine speed range of 1400-3000 rpm. The results show that increasing ammonia energy share decreases engine power and torque, while brake specific fuel consumption increases. This is mainly attributed to ammonia’s lower heating value, higher auto-ignition temperature, and lower burning velocity compared with diesel. Soot emissions decrease significantly because ammonia contains no carbon, whereas CO and NOx emissions increase due to slower combustion, incomplete oxidation, and possible fuel-NOx formation.