Vapour cloud dispersion and the evaporation of volatile liquids in atmospheric wind fields—II. Wind tunnel experiments

Abstract

Rates of evaporation from free surfaces of toluene and pentane have been measured in a wind tunnel as a function of wind velocity, wind tunnel surface roughness and liquid temperature. For smooth boundary layer flows, the experimental data are found to be in very good agreement with predictions from the diffusion model of the preceding article. The earlier proposed semi-empirical procedure for taking transitions in surface roughness into account turns out to work satisfactorily for describing measured evaporation data at different upwind surface roughnesses. Neglect of the roughness transition from land to liquid is shown to yield very erroneous results. The influence of the liquid temperature on the evaporation turns out to be quite important, especially near the boiling point of the liquid. An adequate description of the observed effects is given by the effective diffusivity approach, described in Part I.