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The evaluation of some photochemical smog reaction mechanisms—I. Temperature and initial composition effects

1992; Elsevier BV; Volume: 26; Issue: 4 Linguagem: Inglês

10.1016/0960-1686(92)90174-j

1878-2124

GLENN HESS, F. Carnovale, M.E. Cope, Graham Johnson,

Vehicle emissions and performance

Four popular photochemical reaction mechanisms, Caltech, CB-III, CB-XR and CB-IV, are evaluated using a major, newly available set of outdoor smog chamber data. The smog chamber experiments were carried out under conditions representative of urban air. Sixteen experiments with various temperature and initial HC/NOx ratios are used to test model performance. In general the four photochemical smog models are found to give results in good agreement with experiment, particularly at moderate temperatures (15–25°C) and HC/NOx ratios of 7–16 and when the initial organic composition included gasoline vapour, synthetic exhaust and solvents. At higher temperatures (30–45°C) and at lower HC/NOx ratios (<5) the agreement is not as good. For HC/NOx = 3.5 the CB-XR and CB-IV mechanisms underestimate the final O3 concentration by up to 82%. When solvent emissions are omitted from the initial composition the Caltech and CB-III models overestimate the final O3 concentration by up to 59%.