This paper presents computational results on the effect of fixed or suspended cylindrical solid particles on heat transfer in a channel flow. The computational method is based on the solution of the lattice-Boltzmann equation for the fluid flow, coupled with the energy equation for thermal transport and the Newtonian dynamic equations for direct simulation of suspended particle transport. The effects of Reynolds number, particle-to-channel size ratio, and the eccentricity of the particle on heat transfer from the channel walls for single and multi-particles are presented. The multi-particle flow condition represents a case with solid particles suspended in the cooling medium, such as in micro/nanofluids, to augment heat transfer. The results provide insight into the mechanism by which suspended particles can change the rate of heat transfer in a microchannel.