Abstract
The photochemical reactivities of non-methane hydrocarbons in vehicle exhaust were evaluated by linear summation method and ultra violet irradiation test. As the linear summation method, Altshuller's reactivity scale, Rs, and OH radical reaction rate constant, KOH, were used with the analytical results of non-methane hydrocarbons.
The bellows type smog chamber of 6.64 m3 was used for irradiation test. The test conditions were as follows: ultra violet intensity 7 mw/cm2(k1=0.41 min-1), temperature 30°C, relative humidity 50%, initial concentration HC 10 ppmC, NO 1 ppm, irradiation time 4 hr. The NMHC complexes for evaluation, having approximately the exhaust compositions of the running condition, were prepared by standard gas and reagents. The vehicle for the test was the typical passenger car which was equipped with 3 way catalyzer and exhaust gas ecirculation system and was drived on a chassis dynamometer.
The results of the linear summation method showed good correlativity with the irradiation test results, especially the correlativity between KoH method and the irradiation test was fairly good and the correlation coefficients were about over 0.9. As the result, it was clarified that the linear summation method by KoH was very effective for the evaluation of photochemical reactivities of NMHC in vehicle exhaust gas. Actually, as the result of the evaluation of some vehicle exhaust gases, which were drived under the various running conditians, it was found that the photochemical reactivities of NMHC in exhaust gas varied with the running conditions.
