Comparative analysis of CuO-water and ZnO-water nanofluids in the turbulent regime for enhanced performance in double-pipe heat exchanger

In order to reduce size and cost, the heat transfer (HT) capacity of conventional heat exchanger (HE) must be increased. Addition of nanoparticles (NPs) into parent fluids is a potentially effective method of improving HT at a manageable pressure drop. The present study was focused on the comparative analysis of thermal performance factor (TPF) between CuO-water nanofluid (NF) and ZnO-water nanofluids on double-pipe heat exchanger (DPHE) at four volume fractions (0.005%, 0.02%, 0.04%, and 0.07%) in the Reynolds number (Re) range of 5500-15000. The experiment was performed for single-phase fully developed flow in turbulent regime. The maximum enhancement in Nusselt number (Nu) for CuO-water NF was observed as 12.58% higher than ZnO-water NF for volume fraction (VF) of 0.07% at Re = 5000. Maximum augmentation in friction actor was recorded for CuO-water NF as 14.55% superior than ZnO-water NF for VF of 0.07% at lowest Re of 5500. At a Re of 5500, the maximum TPF value for CuO-water NF was found to be 2.61% greater than ZnO-water NF for 0.07% of VF. In order to develop better understanding of the behaviour of NFs, ZnO and CuO-NPs were characterized in the laboratories using XRD, HRTEM, EDS, and FTIR analysis. An empirical correlation for both Nu and friction factor (& fnof;) has been developed within the range of given parameters using regression analysis.