This paper investigates heat transfer between particles during particle-particle and particle-wall collisions in fluid-solid flows. A model is described, which is based on the work by Sun and Chen (1988) [27], who described heat conduction between elastic, non-cohesive particles. The model of Sun and Chen is, in this work, extended to investigate how cohesion and viscoelasticity, elements that are always present in real systems, of the colliding particles influence the process of heat transfer. This was done by adopting three different soft-sphere models. At the end of the paper dimensional analysis is applied and, by fitting relations between the resulting dimensionless groups to numerical simulations using the models developed, "empirical" relations for the heat transfer during particle-particle and particle-wall collisions are derived. These empirical relations are suitable for use with hard-sphere collision models. (c) 2012 Elsevier Ltd. All rights reserved.