The paper presents an evaporation model for Heavy Fuel Oil (HFO) combustion studies. In the present work, HFO is considered as a mixture of a heavy and a light fuel component, with the thermophysical properties of the heavy component calculated from the recently introduced model of Kyriakides et al. (2009) [1]. The model proposes a proper treatment of convective heat transfer to the evaporating fuel droplets. Computational Fluid Dynamics (CFD) simulations of HFO spray combustion in constant volume chambers are performed, utilizing a modified characteristic time combustion model. The results are in good agreement with literature experimental data. Computational results for a two-stroke marine Diesel engine also compare favorably against experiments. The present development yields a basis for detailed CFD studies of HFO combustion in large marine Diesel engines. (C) 2013 Elsevier Ltd. All rights reserved.