Abstract: The dispersion of immiscible liquids is of great importance in many chemical engineering processes.In a turbulent dispersion,the breakup and coalescence of drops usually take place continuously.These rate processes determine the drop size distribution,which is an equilibrium property,and the interfactial area is availrable for mass transfer.The coalescence between drops in an isotropic turbulent dispersion is examined in this investigation.Whith this result,a new model without any adjustable or empirical parameters is developed to predict the minimum drop size free from coalescence both in surfactant systems and pure systems.The drop size distribution and coalescence efficiency are also discussed.