The dispersion of polydisperse droplets in a pulsating air stream has been analyzed. The grouping and segregation of droplets in both steady and oscillating flow field has been studied. The effect of evaporation on the grouping process has also been investigated. Eulerian-Eulerian multiphase framework has been used to model the polydisperse drop phase. The model is employed to study the dynamics in a 1D plug flow evaporator. The variation in dispersion process of the droplets along the channels has been observed both without and with presence of evaporation of the droplets. It has been found that the larger size droplets responses weekly with the oscillating flow field whereas, the smaller size droplets clustered differently at different locations depending upon the phase angles of the oscillating flow field.