Unsteady heat transfer in a gassolid fluidized bed of Geldart D particles was simulated with the help of EulerianEulerian fluid dynamic method.6 gasparticle heat transfer coefficient models were compared and analyzed.According to the simulation of a twodimensional bed,it is found that the mean wall heat transfer coefficient of the whole bed is in good agreement with that based on the reported experimental correlative expression.However,the gasparticle heat transfer coefficient based on local conditions in the bed is found to be varied obviously when different models are used.A thorough numerical simulation was conducted with Gunn model to investigate the twophase flow and heat transfer in the Geldart D particle bed.Relatively stable fluidization can be observed,although more or less bubbling exists.Uniform temperature distribution is easily reached when fluidization initialization has finished.