.ThermalSeparation.HeatAndMassTransfer.InterfacialArea.SprayColumn.DropletSurface .ThermalSeparation.HeatAndMassTransfer.InterfacialArea.SprayColumn.DropletSurfaceThe interfacial area is calculated by multiplying the surface of the droplets (assuming them to be perfect spheres) by the number of droplets in one stage.