By means of the concept of void fraction, a homogeneous flow model for boiling heat transfer is established from the change of void fraction in the tiny hexahedral element of the flow field. The model is based on the assumption that the boiling liquid field is a single phase flow in which vapor and liquid are homogeneously mixed, with void fraction being calculation basis to reflect boiling heat transfer, therefore, the concept of single phase flow can be used to calculate boiling heat transfer problems. After validated with the reported experimental results, as a calculation instance, the numerical simulation of boiling heat transfer process of engine cooling water-jacket in cylinder head is carried out, which indicates the void fraction distribution in cooling passage. The result shows that heat transfer coefficient considering boiling factor is evidently different from that of pure heat convection, and the maximum deviation can be more than 50%. (C) 2009 Published by Elsevier Ltd.