Laminar flow heat transfer in circular tube with internal solidification of a binary mixture of paraffin is investigated numerically. The problem of the solidification process is formulated using the enthalpy-porosity based method. The influence of various parameters such as: wall temperature, inlet maximal velocity, initial temperature and initial concentration of the binary mixture, on the solidification process is analyzed in detail. It is found that the initial temperature has less important effect on the solidification progress than the wall pipe temperature, the initial concentration and the inlet velocity of the binary mixture. (C) 2014 Elsevier Ltd. All rights reserved.