Experimental investigations over the thermo hydraulic behavior of the metal oxide nanofluids flowing through polygonal ducts

Abstract

The newlineresearch newlinework newlinefocuses newlineon newlinethe newlinemeasurement newlineof newlinethe newlinethermo-physical properties of the TiO2/DI water and Al2O3/DI water nanofluids before newlinewere measured under varying volume concentration (and#966;=0.05, 0.1, 0.2%) and newlinetemperature (25 oC to 60 oC) and comparing them with existing correlations before newlineusing them for convective heat transfer experiments. newlineThe thermo-physical properties such as density, viscosity, specific heat and newlinethermal conductivity were measured using Anton Paar Density meter DMA 79 512 newlineP/60, Brookfield viscometer DVI+PRIME C/P, Differential Scanning Calorimeter DSC newline200F3-Maia and KD2 Pro analyser, which were calibrated by measuring the thermo newlinephysical properties of DI water and comparing it with ASHRAE data. The nanofluids newlinewere found to be stable at pH 5 and pH 12 which was confirmed by the zeta potential newlinevalues existing around and#61617;40 mV. newlineConvective experiments on these nanofluids are performed to determine the newlinethermal performance of 0.05, 0.1 and 0.2% volume concentrated TiO2/DI water newlinenanofluids flowing through an equilateral triangular duct, square duct, hexagonal duct newlineand compared with the results obtained from a circular tube. The results are compared newlinewith the performance of Al2O3/DI water nanofluids under constant heat flux conditions newlinewithin the Reynolds number limit between 5000 and 10000. newlineThe experimental outcome reveals that the maximum Nusselt number of 78, newline74, and 71 were achieved when 0.2% Al2O3/DI water flowed through hexagonal, newlinesquare, and triangular ducts, respectively. Similarly, the desired lowest friction factor newlineof 0.03692, 0.03688, and 0.03686 was achieved by the same nanofluid through those newlineorientations, which ensured that the Al2O3/DI water performed better than TiO2/DI newlinewater. The Performance Evaluation Factor (PEF) was evaluated by considering two newlinebase references, first by the same orientation and second by considering the circular newlinetube. The performance of ducts with nanofluids fared well than with water. newline