Experimental and Numerical Investigation Into the Heat Transfer Study of Nanofluids in Microchannel

Abstract

There are very few detailed experimental investigations about the heat transfer behavior of nanofluids in microchannel. The heat transfer behavior of nanofluids in microchannel is investigated. Two microchannels with hydraulic diameters 218 and 303 μm are fabricated by wet etching process on silicon wafer. An experimental set-up having provision of flow in the channel and temperature measurement along with bottom wall temperature is built-up. Alumina nanofluids with concentrations of 0.25 vol. %, 0.5 vol. %, and 1 vol. % with 45 nm are prepared, stabilized, and characterized by standard methods. The thermal conductivity and viscosity used in the study were measured and analyzed. The base fluids used are water and ethylene glycol. The effect of volume fraction, channel size, particle size, and base fluids are presented and analyzed. An important phenomenon of dispersion is observed. In addition, numerical modeling is carried out by using discrete phase approach. Shear induced particle migration is identified to be the reason of difference for dispersion of particles. The Brownian and thermophoretic forces are responsible for major changes in particle concentration and their movement. Also, it was found that better heat transfer characteristics can be obtained by higher concentration of nanofluids and by low viscous base fluids.