Application of Spherical Copper Oxide (II) Water Nano-fluid as a Potential Coolant in a Boiling Annular Heat Exchanger

V. Nikkhah, M. M. Sarafraz and F. Hormozi

Abstract
Convective boiling heat transfer coefficient of spherical CuO (II) nanoparticles dispersed in water is experimentally quantified inside the vertical heat exchanger. Influence of different operating parameters including applied heat and mass fluxes, sub-cooling temperature and concentration of nano-fluid on forced convection and nucleate boiling heat transfer mechanisms is experimentally investigated and briefly discussed. Results show that by increasing heat and mass fluxes, the heat transfer coefficient considerably increases for both heat transfer regions, while by increasing the nanoparticle weight concentration, the heat transfer coefficient increases in convective heat transfer (about 35 % at the maximum concentration) and deteriorates the heat transfer coefficient (about 9 % at maximum concentration) in nucleate boiling region due to the formation of nanoparticle deposition on heating surface. Experimental results are then compared to well-known correlations. Results of comparisons reveal good agreement between experimental data and those obtained by some correlations. In addition, thermo-physical properties of CuO nano-fluid are experimentally measured and represented, which are a good reference for other nano-fluid-related studies.

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Keywords
convection, nucleate boiling, nano-fluids, heat transfer enhancement, heat transfer deterioration