A model to estimate radiative heat transfer in particle beds is developed for use in the Discrete Element Method (DEM). Monte Carlo ray tracing simulations are run to find the Radiation Distribution Factor (RDF) between pairs of particles and between particles and a wall, in particle beds with random packing. Curves are found to express the average RDF as a function of distance, and within DEM these aims arc used to estimate particle-particle and particle-wall radiative transfer. The resulting Distance Based Approximation model is computationally efficient and simple to implement. RDF-distance curves are given as a set of tables covering two particle emissivitics (0.65, 0.86), four wall emissivities (0.4, 0.6, 0.8,1.0), and five solid fractions (0.25, 035, 0.45, 0.55, 0.64). The accuracy of the model is investigated, with accuracy sufficient for many engineering applications shown. An initial implementation is demonstrated for a heat exchanger with a dense granular flow. (C) 2020 Elsevier B.V. All rights reserved.