Evaporation of polydisperse multicomponent oil droplets

During machining, polydisperse mist droplets are generated from multicomponent oils used as metalworking fluids. As these droplets travel with an airstream, they are subject to evaporation. The resulting vapor will pass through mist collectors and enter factory air where it may recondense on particles or surfaces, be inhaled by workers, or be emitted to the atmosphere. Maxwell's equation for evaporation of an isolated drop can be used to model the evaporation of polydisperse multicomponent oil droplets at normal temperatures. Within each droplet size, relationships describing the change in mass with time for small droplets (diameter <20 μm) are numerically integrated over time for the most prevalent compounds in the oil. Decreases or increases in mass for individual droplets are linked by their combined influence oft vapor concentrations. Experiments conducted with mineral oil mist demonstrate that the model predicts evaporation accurately. The model indicates that under some conditions as much as 65% of the mass in a mineral oil mist can volatilize within 10 seconds. The amount of vaporization will depend on the initial concentration, size distribution, and composition of the mist. Substitution of an alternative oil as a machining fluid may decrease evaporation considerably.