In this paper, two phase heat transfer of a mixture of nanopaticles in air flow as a type of nanofluid is studied. Volume fraction of the dispersed phase is very low (less than 1%). Nanoparticles travel in the base fluid due to drag, brownian and gravity forces and are tracked according to lagrangian approach. Effect of reduced specific heat of nanofluid on heat transfer is considered. The results show an increase in heat transfer rate which is very much more than that predicted by the Maxwell model.