A new model for three-dimensional (3D) global simulation of heat transfer in a unidirectional solidification furnace with square crucibles was proposed. Convective, conductive and radiative heat transfers in the furnace are solved together in a coupled way by using a finite volume method. An efficient algorithm for view factor calculations in modeling radiative heat transfer and a mixed 2D/3D space discretization technique were developed. With coupling a 2D transient global simulation, the proposed 3D global model can be used to investigate 3D features of heat transfer in the entire furnace throughout a whole solidification process with moderate requirement of computation resources. Some typical results of 3D features of a unidirectional solidification furnace for producing multi-crystalline silicon used for solar cells were presented as a case study. (c) 2007 Elsevier B.V. All rights reserved.