On-board monitoring of hazardous exhaust emissions in passenger cars (category M1)

摘要

A fibre-optic sensor for the monitoring of hazardous exhaust gases based on absorption in the ultra-violet region is described. The loss of light through a gas cell across the UV/VIS spectrum was utilised to determine the level of absorption for three of the exhaust gases present in an exhaust. The measured absorption specific to each of these test gases Nitrogen Dioxide (NO2), Sulphur Dioxide (SO2) and Nitric Oxide (NO) was used in a variation of the Beer-Lambert law to determine the absorption line intensities for each of the gases. Theoretical absorption line intensities for each of the exhaust gases compared favorably with our measured results. A Lab VIEW program was created and utilised to interrogate the highest absorbing wavelength for each of the gases and absorption recorded at these specific absorbing wavelength were then input along with our measured absorption line intensities into the Beer-Lambert law to determine the concentrations of each of the gases present in the test cell. In this manner the concentrations were calculated immediately and then output to the user eliminating the need for processing the data after testing. A lower detection level of lppm for both NO2 and SO2 and in the order of 26ppm for NO was achieved.