This thesis is related to the experimental investigation of forced convective heat transfer through noncircular annular and square channels. For this purpose we examined Newtonian nanofluids with water and ethylene glycol as base fluids and Non-Newtonian nanofluids with base 0.5 wt% carboxymethyl cellulose solution base fluid using aluminum oxide and titanium dioxide nanoparticles. Experiments were done under constant wall temperature boundary condition with both laminar and turbulent flow regimes. Based on the experimental results, both Newtonian and Non-Newtonian nanofluids have better heat transfer performance in comparison with the base fluids through noncircular channels. Heat transfer coefficient and Nusselt number of nanofluids are higher than those of the base fluid. Heat transfer coefficient is enhanced for both employed nanofluids and the enhancement increases with increase of nanparticle concentration. According to the results, nanofluids containing aluminum oxide nanoparticles possess better heat transfer performance in comparison to the nanofluids containing titanium dioxide nanoparticles. Furthermore we found that thermal performance of Newtonian nanofluids in both channels is higher than that of non-Newtonian nanofluids. Comparison of the performance of nanofluids through square and annular channels shows that there is a higher increase in convective heat transfer coefficient and Nusselt number in square duct for both turbulent and laminar flows. Based on the experimental results of this research, some equations have been developed for nanofluid usselt number in square and annular channels. Keywords Nanofluid, Convective heat transfer coefficient, Nusselt number, Non-circular channel.
