Thermal Analysis Of Mono and Hybrid Nanofluids

Abstract

ABSTRACT newlineIn the past, extensive research works have been carried out by researchers and engineers to augment the heat transfer rate in different mechanical and industrial processes via various active or passive techniques such as extended surfaces, vortex generators, multiphase cooling, mini and microchannels, porous media, and natural convection techniques. Even though the above methods have provided a considerable heat transfer augmentation, an important issue of the low thermal conductivity of working fluid (e.g., water, ethylene glycol) limits their heat transfer capability. This major pitfall led to the generation of precious thoughts in the minds of researchers and scientists so as to improve thermophysical properties of the working fluid that can greatly augment the heat transfer. Hamilton and Crosser (1962) introduced the concept of ameliorating the thermal conductivity of base fluid by dispersing the micro-sized solid particles. It is clear that micron-size particles mixed with base fluids lead to poor stability and sedimentation of the micron-size particles, erosion, clogging of the channels, and the enhanced fluid pumping power in heat transfer systems. The coagulation condition associated with the micro-sized particles has deterred its usage in practical applications. Later, Choi and Eastman (1995) introduced nanofluids in which the nanoparticles (nanometer-sized particles of diameter 1 100 nm) are dispersed in base fluid making a colloidal suspension to prevent agglomeration and augment thermal conductivity. Adding surfactants in nanofluids can significantly emaciate the agglomeration condition. In nanofluids preparation, single nanoparticles (e.g., Au, Ag, Cu, Al2O3, CuO, TiO2, SiO2, Fe3O4, SiN, SiC, CNT, MWCNT, graphite, diamond) are dispersed in base fluid (e.g., water, ethylene glycol, a mixture of water and ethylene glycol, transformer oil, Polymer solutions). This type of fluid is referred to as mono nanofluid (MNF). A further investigation of various nanoparticles reveals that the metal part