Characterization of the evaporation rates of complex hydrocarbon mixtures under environmental conditions

Abstract

AbstractThe characterization of the evaporation rate of complex hydrocarbon mixtures, such as commercial oil fractions, under environmental conditions is discussed. It is shown that the relevant thermodynamic quantity is the total volume of vapour (per unit of initial oil mass) removed under isothermal differential distillation conditions (V m3/kg) as a function of the mass fraction of the oil remaining (F). Plots of F versus V for various isothermal conditions can be used to estimate evaporation rates since it is shown that V is equivalent to the group KsAsτs/Ms where Ks is the evaporation mass transfer coefficient (m/s), As is the spill area (m2), τs is the evaporation time (s) and Ms is the spill mass (kg). The basis of a methodology for estimating environmental evaporation rates is thus outlined. Methods of obtaining V versus F data are discussed, with calibrated wind tunnel evaporations being preferred. The estimation of evaporation rates under spreading and non‐isothermal conditions and the analogous dissolution process are discussed briefly.