Experimental and numerical study on heat transfer enhancements of concentric tube heat exchanger using water based nanofluids

Nanofluid is mixture between nanoparticle and base fluid, this mixture is used to enhance the heat transfer process inside heat exchangers. In this work, three alternatives of nanofluid based on CuO and TiO2 were studied inside concentric tube heat exchanger. Different volume fractions (0.05 % and 0.2 %) and mass flow rates (0.05 kg/sec and 0.25 kg/sec) were tested. 3-D numerical simulation was performed using computational fluid dynamic (CFD) for all nanofluid types under the same volume fraction (0.2 %). The numerical results showed that CuO nanofluid has the highest enhancement heat transfer ratio among the others two types where these augmentation ratios were 47% and 61 % for TiO2 and CuO respectively, while experimental results showed that these augmentation ratios were 48% and 50 % for TiO2, and CuO respectively at volume fraction 0.05 % and 30% and 62% for TiO2 and CuO respectively at volume fraction 0.2 %.