TRANSIENT BEHAVIOUR OF PARTICLE EMISSIONS FROM DIESEL, GASOLINE AND CNG PASSENGER CARS

Among various regulatory pollutants particles emitted are gaining special attention due to it’s size particularly in the nano and ultrafine range cause serious health concerns in the modern society especially in the urban areas. This research paper focuses on the transient behaviour of particle number concentrations measured by EEPS from diesel, gasoline and CNG vehicles. Tests in various transient and steady state phases on driving cycle showed considerable differences in size distributions and particle number concentrations from vehicles operating on diesel are different from gasoline and also from CNG vehicles. However, dynamic behavioural pattern of PN emission for both the diesel vehicles is more or less same and no significant impact observed due to difference in their mileage accumulation, similarly, dynamic behaviour of both the gasoline vehicles has similar pattern. For diesel vehicles particle number size distributions have an arithmetic mean diameter between 60 and 70 nm, for gasoline vehicles it is between 19 and 20 nm and for CNG vehicle it is 32 and 33 nm. For all the vehicles major PN concentration peaks appear within nano size range between 7 to 20 nm. Experimental investigation show that for all diesel, gasoline and CNG vehicles almost 94% of the total particles over MID cycle are below 200 nm and out of this 90% are ultrafine and around 50% are of nano size. Transient behaviour for port fuel injection gasoline vehicles over driving cycle shows that PN emissions are very dynamic throughout the cycle and large numbers of peaks observed over entire driving cycle without any specific pattern and no relation to operating phases. However, transient behaviour of both diesel vehicles shows that the particle number concentrations follow the vehicle speed trend.