Abstract: A mechanistic model is presented to describe the enhancement of convective heat transfer due to particle impact in gas-solid two-phase flow.In order to analyze the heat transfer enhancement mechanism,the boundary layer charcteristics and the heat conduction between particle and heated surface during particle impactive process are both taken into account in this model.Effects of gas velocity,particle concentration and particle size on particle residence characteristic,boundary layer characteristics and h_(c2)/h_(conp) are investigated by means of model calculation.In addition,the enhancement of heat transfer in gas-solid flow predicted by this model have been compared with experimental results and a good agreement is observed.Finally,a correlation equation for heat transfer enhancement of gas-solid cross flow in a tube is presented.