Heat transfer in gas-solid flows has been numerically investigated via an immersed boundary-thermal lattice Boltzmann method. Stationary random assemblies of spheres are adopted in the simulations. The effect of particle velocity fluctuations whose magnitude is represented by the so-called granular temperature is accounted for by implementing velocity fluctuations obeying the isotropic Maxwellian distribution on spheres. It is found that particle fluctuations enhance the heat transfer between the gas and solid phases. This enhancement increases with increasing granular temperature-based Reynolds number and becomes less significant as the particle Reynolds number and the solid volume fraction increase. It is also found that the Nusselt numbers on individual particles follow the Log-Normal distribution at both zero and finite granular temperature conditions. The long tail of this distribution is caused by the existence of a non-negligible portion of the domain with fast local gas velocities that could significantly promote heat transfer. (C) 2019 Elsevier Ltd. All rights reserved.