This paper presents a computational investigation of heat transfer, especially the direct particle-particle heat transfer between different particle classes in a dense gas-solid fluidized bed of binary particles using a computational fluid dynamics (CFD) method. A particle-particle heat transfer model between different particle classes is proposed in a gas-solid fluidized bed. By incorporating it into the multi-fluid model, a Eulerian-Eulerian CFD model is established. The heat transfer in a fluidized bed containing binary particles is thus investigated. The results indicated that particle-particle heat exchange coefficient between different particle classes increases with increasing large particle size and superficial gas velocity. However, it first increases and then decreases with increasing the large particle content in the fluidized bed. Gas-particle heat transfer is still the dominant heat transfer mode in the fluidized bed of binary particles. The ratios of particle-particle heat transfer to gas-particle heat transfer range from 1.27% to 3.09% for various operating conditions. (C) 2011 Elsevier B.V. All rights reserved.