Estimation of nitrogen oxides emissions from petrol and diesel passenger cars by means of on-board monitoring: Effect of vehicle speed, vehicle technology, engine type on emission rates

NOX emission rates of 13 petrol and 3 diesel passenger cars as a function of average speed from 10 to 120 km/h, emission class (pre-Euro 1 - Euro 5), engine type were investigated by on-board monitoring on roads and highways of St. Petersburg using a portative Testo XXL 300 gas analyzer. The highest level of NOX emission 0.5-2.5 g/km was inherent to old pre-Euro 1 petrol cars without a catalytic converter. NOX emissions rates of Euro 1 and Euro 2 petrol cars changed within 0.15-0.9 g/km, Euro 3 - 0.015-0.27 g/km, Euro 4 - 0.013-0.1 g/km, Euro 5 - 0.002-0.043 g/km. Euro 3 - Euro 4 petrol cars generally satisfied corresponding NOX Emission Standards (ES), except cold-start period, Euro 5 petrol cars did not exceed ES. Warmed, stabilized engines of Euro 3 - Euro 5 petrol cars showed 5-10 times lower NOX emission rates than corresponding ES in the range of speed from 20 to 90 km/h. NOX emission rates of diesel Euro 3 and Euro 4 cars varied from 0.45 to 1.1 g/km and from 0.31 to 1.1 g/km, respectively. Two examined diesel Euro 3 and one Euro 4 passenger vehicles did not satisfy NOX ES at real use. Euro 3 diesel cars showed 28.9 times higher NOX emissions than Euro 3 petrol cars and Euro 4 diesel car demonstrated 17.6 times higher NOX emissions than Euro 4 petrol cars at warmed and stabilized engine at a cruise speed ranging from 30 to 60 km/h.