Comparison of real-time NOx emission measurements from two heavy-duty diesel engines

This study investigated the real-time NOx emissions from a heavy-duty diesel truck and a bulk carrier ship. The test road vehicle was driven on a combination of a flat and hilly route from Brisbane to Toowoomba that covered urban, rural and motorway driving. On-board ship emissions were measured on the sea from the port of Gladstone to Newcastle. NOx emissions from both engines were compared and analysed to understand the influence of engine parameters as well as route variables and power transmission on NOx emissions. Results from these measurements show that truck NOx emissions increased with the engine power and speed however a significant NOx emission can be seen during the idling condition while producing low power. On the other hand, ship NOx emissions followed an approximate cubic relationship as a function of engine RPM that is completely different from that of the truck.