Experimental investigation toward obtaining nanoparticles' surficial interaction with basefluid components based on measuring thermal conductivity of nanofluids

摘要

In this study the effect of temperatures, the CuO and TiO2 nanoparticles' mass fraction, and basefluid types were studied on thermal conductivity of nanofluid. CuO and TiO2 nanoparticles were dispersed in ethanol and liquid paraffin model 107,160 separately by using ultrasonic waves. The stability of nanoparticles in basefluids was estimated by exploiting DLS and Zeta Potential analysis. The results showed that the thermal conductivity enhances with the increase in temperature; conversely, with the increase in temperature the thermal conductivity of the basefluid decreases. The results of this study showed that by increasing the mass fractions of metal oxides nanoparticles the thermal conductivity of nanofluid increases. Also, by increasing the concentration of oxides nanoparticles in liquid paraffin, the changes in the thermal conductivity of nanofluid at concentrations of 1% are insignificant, but by increasing the concentration of nanoparticles from 1% mass to 5%, the changes in the thermal conductivity of nanofluid are remarkable. The results of the calculation for the interaction parameter showed that in the low concentrations of metal oxides nanoparticles, the interaction effect between surfaces of metal oxide nanoparticles and ethanol molecules is greater than the liquid paraffin. The results also showed that the thermal conductivity of ethanol/CuO is greater than the other nanofluids (ethanol/TiO2, liquid paraffin/TiO2, and liquid paraffin/CuO) at various temperatures and nanoparticles' mass fraction. Finally an empirical equation including temperature, nanoparticles mass fraction, and physical properties of nanoparticles and basefluids was predicted by using hybrid GMDH-type neural network to estimate the interaction parameter between nanoparticles surface and basefluids molecules.