An Experimental Investigation And Modelling Into Viscosity Of Nanofluids

Abstract

Nanofluid is the suspension of nanoparticles (1 – 100 nm) in traditional heat transfer fluids called base fluids. Nanofluids are supposed to have better heat transfer properties than traditional heat transfer fluids which make it useful in cooling application. The coolant is circulated by pump in most of the cooling systems. Thus pumping power requirement is an important issue in the selection of coolant. This pumping power requirement is based on the viscosity of fluid. Moreover the heat transfer coefficient of a fluid is also influenced by the viscosity of the fluid. In the present work, the accuracy of existing theoretical models and empirical models has been evaluated by using them to predict the experimental values of viscosity. It has been found that none of the model could predict the exact value of viscosity. The error in predicting the experimental values comes out to be in the range of 8.27 to 71.87%. The effects of various parameters like sonication time, settling time and temperature on the viscosity of ZnO-water, ZnO- ethylene glycol, SWCNT – water and aqueous silver-water nanofluid is evaluated. It has been found that the viscosity of nanofluid decreases with the increase in the sonication time. The viscosity of ZnO-EG nanofluid decreases by 7% for a sonication of 6 hours. The viscosity of nanofluid is found to be increasing with the increase in settling time. The viscosity of SWCNT – water nanofluid for a volume fraction of 1% increases by 8% for a settling time of 6 hours. The viscosity of nanofluid is found to be decreasing with the increase in temperature. An empirical model has been prepared for the viscosity measurement of nanofluid by using the experimental data of ZnO-water and ZnO- EG. This empirical model has been validated for different experimental values of viscosity and it has been found that the error in predicting the experimental values of viscosity is in the range of 1.561 to 8.28%.