An improved correlation for the estimation of drag coefficient in the flow of solid particle in the solar receiver is being presented. Drag coefficient on free falling particles is of considerable importance. In this work, typical evaluations of widely used correlation have been performed. The analysis of these correlations are based on sphericity, void fraction, particle diameter and Reynolds number ranging from 0.6 to 0.98, 0.25 to 0.95, 400 to 650 and 10-2