Search Results

Sensory studies have described diesel exhaust odor in terms of two major odor character groups-oily-kerosene and smoky-burnt. The odorous compounds have been identified in a detailed analytical chemistry-odor study. The oily-kerosene odor group is associated with the aromatic portion of the unburned fuel-principally, the alkyl substituted benzenes, indans, and tetralins. The smoky-burnt odors arise from partial combustion products of the paraffin and aromatic fuel components. Our studies have shown a good correlation between exhaust odor intensity and abundance of the partial combustion products. An analytical method has been developed, based on liquid chromatography, for the quantitative expression of exhaust odor intensity by measurement of the smoky-burnt odor group. Initial survey studies show the method to be applicable over a wide odor emission range. Fuel variation has little effect, whereas injector variables do influence odor intensity.

The odor profile method has been applied to the measurement and analysis of diesel exhaust odor. The human sensory panel has described the odor of diluted exhaust and analytical fractions isolated from the exhaust in terms of total intensity of aroma (TIA), and individual odor character notes. For convenience, diesel exhaust odor can be described in two character groups-oily-kerosene and smoky-burnt odor. The odorous species were determined by detailed chemical analyses supported by comparative data from reference compounds. To achieve reliable quantitative odor intensity measurements, it was necessary to present the odor panel with a series of concentrations (dilutions) of exhaust in air over a wide range. The odor intensity at a given exhaust concentration is computed from a least squares analysis of the entire panel data. The results demonstrate an odor intensity range of slight to moderately strong for diesel exhaust at 1000:1 dilution.