ON-ROAD SAMPLING TECHNIQUE FOR VEHICLE EMISSION MEASUREMENTS

There has been a considerable amount of published work in the literature on the influence of the dilution conditions on the size distribution of emitted aerosols (Maricq et al., 1999) (Kittelson et al., 2000), (Khalek et al., 2000). During dynamometer tests the vehicle remains stationary while a controlled load is applied to the driving wheels and the exhaust is diluted artificially. Such tests are expensive and time consuming and the ability to reproduce dilution processes and driving conditions occurring when a vehicle is driving on the road has been questioned. On the other hand field sampling where measurements focus on the overall exhaust plume from a busy road are relatively inexpensive and can only provide averages based on the entire vehicle fleet. Such data cannot be analyzed in terms of vehicle or fuel type. The main concept of the newly developed design is that samples are collected from individual vehicles under real world road conditions, and diluted under real atmospheric conditions.