Energy and exergy viability analysis of nanofluids as a coolant for microchannel heat sink

Abstract

The present paper aims to provide a theoretical analysis of energy, exergy loss and pumping power demand of water-based Al2O3, TiO2, CuO, SiC nanofluids flow through rectangular microchannel heat sinks under constant heat flux condition. The weight fraction of nanoparticles was varied from 0% to5%. Thermal resistance decreased with particle inclusion in the base fluid. Decease in thermal resistance and increase in microchannel efficiency was observed with the application of nanofluids. However, reduction in thermal resistance and rise in efficiency is more with Al2O3 -water and CuOwater nanofluids rather than TiO2-water and SiC-water nanofluids. Addition of nanoparticles in base fluids was found suitable for reducing thermal resistance and increasing efficiency of microchannel but at the same time, an increase in pumping power with the rise in weight fraction was also observed. The maximum reduction in thermal resistance with a simultaneous increase in thermal efficiency was observed using CuOwater nanofluids at 5% wt. fraction. The estimated exergy loss is relatively higher in CuOwater and Al2O3-water nanofluids than TiO2-water and SiC-water nanofluids. The rise in ambient temperature effectively reduces the exergy loss. Maximum exergy loss was obtained with CuO nanofluids at 5% wt. fraction while the minimum was observed with water. The effect of substrate thickness on efficiency and exergy loss was also estimated.