Effects of Environmental Parameters on Real-World NOx Emissions and Fuel Consumption for Heavy-Duty Diesel Trucks Using an OBD Approach

OBD (On-Board Diagnostic) test system is applied to research influences of environmental parameters (altitude and environment temperature) on real-world NOx emission and fuel consumption for heavy-duty diesel trucks in this paper. The research results indicate that altitude and environment temperature have great influence on NOx emission rate and fuel consumption. High altitude in range of 3000~4000 m results in NOx emission rate is lower than low and moderate temperature because of air intake amount decreasing. However the fuel consumption rate is higher than lower altitude because altitude influences real-time changes of air inflow and combustion conditions in the cylinder of the engine. NOx emission rate and fuel consumption is more stable at different vehicle speed, VSP and RPM at high altitude, and NOx emission rate fluctuate dramatically at low and moderate altitude. The fuel consumption rate is higher at 10~20 °C than that at lower and higher temperature. The environment temperature of 20~35 °C provides beneficial conditions for NOx production and deteriorates emission, and the environment temperature of −10~10 °C provides oxygen enrichment environment because of low temperature and high air density, so increases in production amount of NOx. Effects of altitude and environment temperature on NOx emission rate and fuel consumption rate show an opposite tendency. Compared with fuel consumption rate, NOx emission rate is more sensitive to vehicle speed, VSP and rotating speed.