Since about four to five years car manufacturers are concerned with measurements of particulate matter in the diesel exhaust gas and with possible measures to control and re duce these substances. This paper discusses the technical approaches to the problems of sampling and determination of the diesel particulates on a mass basis.
In detail the paper includes 1) results from experiences with the instrumentation for sampling and weighing particulate matter: manual sampling set-up, automatic sampling apparatus, filter holder., filter material, and microbalance; 2) results of the investigation of the main test parameters: sample flow rate, background particulate level, filter conditioning and efficiency.
Further, a specific area of concern was the uncertainty of the measurements especially the variability and correlation of test results.
The emission testing program, the basis of this study, comprised the determination of the particulate rates from a number of VW and Audi diesel vehicles with a displacement between 1.5 and 2.4 1 including 4-, 5-, and 6-cylinder engines. These measurements were per formed on a chassis dynamometer in accordance with the specifications of three transient driving cycles including that used in emissions certification, sulfate testing, and highway fuel economy.