An empirical study on forced convective heat transfer and flow thermal properties of a nanofluid consisting of three various concentrations of ZnO nanofluids (0.09, 0.2 and 0.44%) and water which flows in a cooling coil made of copper pipe (heat exchanger) under laminar flow conditions are investigated. The ZnO nanoparticles of 40 nm diameter are used in this study. Working fluid flow rate of 0.5 lpm to have the fully laminar regime (Re< 1325). The results prove that the heat transfer coefficient of ZnO/water nanofluid when concentration 0.44 % is higher than that of other concentrations and also the water at same conditions (temperature and velocity).
