The Effect of Injection Timing, Enhanced Aftercooling, and Low-Sulfur, Low-Aromatic Diesel Fuel on Locomotive Exhaust Emissions

An experimental study was performed to demonstrate the fuel economy and exhaust emissions implications of retarding fuel injection timing, enhancing charge air aftercooling, and using low-sulfur, low-aromatic diesel fuel for locomotive engines. Steady-state gaseous and particulate emissions data are presented from two 12-cylinder diesel locomotive engines. The two laboratory engines, an EMD 645E3B and a GE 7FDL, are each rated at 1860 kW (2500 hp) and represent the majority of the locomotive fleet in North America. Each engine was tested for total hydrocarbons (HC), carbon monoxide (CO), oxides of nitrogen (NO_x), and particulate. Emissions were measured at three steady-state operating conditions: rated speed and load, idle, and an intermediate speed and load. Test results on the EMD engine indicate that a 4 deg injection timing retard, along with a low-sulfur, low-aromatic fuel and enhanced aftercooling, was effective in reducing NO_x from 10.5 g/hp-h to 7.2 g/hp-h; however, particulates increased from 0.15 g/hp-h to 0.19 g/hp-h, and fuel efficiency was 4.3 percent worse. Similar observations were made with the GE engine. This paper gives details on the test engines, the measurement procedures, and the emissions results.