Combustion and emission characteristics of a heavy-duty diesel engine at different altitudes

Using a mobile test bench and portable emission measurement system, the combustion and emission characteristics of an Euro III turbocharged heavy duty diesel engine were experimentally investigated at three altitudes. The effect of altitude on combustion and emissions of diesel engine was analyzed. Results show that with increasing the altitude, peak combustion pressure is decreased, start of combustionis postponed, combustion duration is decreased, and peak combustion temperature is increased. CO emission is increased at higher altitudes, while a certain decrease was observed at middle loads of rated speed. PM emission is increased when altitude is increased, especially at maximum torque speed. Trend of NO_x emission was not obvious and its variation is small.