Search Results

Investigation of operating parameters have been carried out for an FTIR system dedicated for emission analysis. Discussions are focused on the key parameters, such as spectral resolution, gas cell dimensions, quantification algorithm, and sample gas treatment. The spectral resolution has to be determined so that the scan rate is high enough to make transient analysis, the minimum detection limit is low enough to carry out high sensitivity measurement, and no cross sensitivity can be recognized. A trade-off relationship between the response and the sensitivity exists for the gas cell design. Small volume of the cell is desirable when gas replacement is considered. On the other hand, the sensitivity can be increased by enlarging the cell volume to obtain long optical path. Both quantification algorithm and the sample gas treatment have to be well arranged to obtain accurate concentration values of the gas compounds sampled from the tailpipe.

Measurements of soot and SOF emitting from automobile engines by conventional gravimetric method and soxhlet extraction method are difficult and time-consuming processes. The composition in the filter substrate may change during time-consuming analysis. Therefore an accurate and real time measurement method for particulate matter is the key demand for automobile industry. This paper describes a new concept for analyzing PM, which includes measurement of soot and SOF separately, as well as the total PM emission from automobile engine continuously. The concept comprises of the real-time measurement of soot emission with a diffusion charger (DC) combined with a specific dilution system. A differential flame ionization detector with separate sample line temperatures (47°C and 191°C), have been applied for the SOF measurement. The total PM is then expressed as the sum of soot and SOF mass.