Modal Measurement of Raw Exhaust Volume and Mass Emissions by SESAM

The System for Emission Sampling And Measurement (SESAM), an analyzing system for exhaust gas mass emissions based on a Fourier Transform Infrared (FTIR) analyzer and a gas flow measurement device VVS (Vortex Volume System) based on a Vortex sensor, is described in this paper. The Vortex sensor works on the principle that the frequency of vortices generated on a bar in a flowing medium is proportional of the flowing speed of the medium. SESAM is designed to measure the concentrations from up to 30 different automotive exhaust gas components. With the complete system the modal and integral mass emissions with a time resolution of one second can be calculated. After the systems have been optimized and tested at Volkswagen for several years, an overview of the experiences and advantages of modal mass calculation compared to the integral CVS (Constant Volume Sampler) procedure is given in examples of simultaneous pre- and post catalyst tests. The results of limited and unlimited components measured with SESAM and conventional methods are presented. It was found that SESAM is a valuable tool for engine and catalyst development work.