In the present paper, simulation for shell and tube heat exchanger investigated using CFD techniques. Numerical simulations of the turbulent, three-dimensional fluid flow and heat transfer are performed using Ansys Fluent 6.3. The effect of friction characteristics on the model of heat exchanger is discussed. A RNG κ-ε turbulence model with non-equilibrium wall function and 2nd order upwind is used. The present model is validated with the experimental literature and show a good agreement. The numerical results of the present study predict reasonably agree well with available correlations. Finally the present study model can be used to model a shell and tube heat exchanger with a satisfactory accuracy level in predictions