Abstract: For a single dodecane droplet in the thermal environment of combined convection and radiation,the evaporation characteristics were investigated numerically.The internal absorption model of thermal radiation and the surface absorption one was separately combined with the limited conductivity model of droplet.The transient dependence of thermal properties on temperature and components was taken into account along with the transient relative velocity of gas flow to the droplet.The evolvements of droplet radius,temperature and evaporating rate under various convective conditions and various temperatures of thermal radiation were presented.The differences between the predicted results by the two thermal radiation models were compared,and the effect of thermal radiation on droplet evaporation was analyzed.The results show that,the predicted values of droplet lifetime by the two thermal radiation models are relatively less different.But the internal absorption model can reveal the characteristics of energy supply to droplet surface.The effect of thermal radiation on the droplet evaporation is small when the temperature of thermal radiation equals to that of the gas flow,but it becomes very significant at a temperature higher than that of gas flow.