MHD Natural Convection and Entropy Generation of Variable Properties Nanofluid in a Triangular Enclosure

Natural convection heat transfer has many applications in different fields of industry; such as cooling industries, electronic transformer devices and ventilation equipment; due to simple process, economic advantage, low noise and renewed retrieval. Recently, heat transfer of nanofluids have been considered because of higher thermal conductivity coefficient compared with those of ordinary fluids. In this study; natural convection and entropy generation in a triangular enclosure filled by Al۲O۳ –water nanofluid affected by magnetic field considering Brownian motion is investigated numerically. Two inclined walls are maintained at constant cold temperature (Tc) while the bottom wall is kept at constant high temperature (Th) with (Th>Tc). In order to investigate natural convection, a computer program (FORTRAN language) based on finite volume method and SIMPLER algorithm has been used. Analyses is performed for volume fraction of nanoparticles ۰, ۰.۰۲, ۰.۰۴, Hartmann number ۰, ۵۰,۱۰۰, Rayleigh numbers ۱۰۳,۱۰۴,۱۰۵ and angle of inclined walls ۴۵۰. In investigated angles and Rayleigh numbers; average Nusselt number is increased by enhancement of volume fraction of nanoparticles in a fixed Hartmann number. It is also observed that total entropy generation variations by increasing volume fraction of nanoparticles is similar to that of Nusselt number. By the results; effect of friction is always insignificant on generated entropy. It is observed that natural convection of nanofluid is decreased by enhancement of Hartmann number and its behavior is close to thermal conduction. It is also concluded that average Nusselt number and total generated entropy are decreased.

Keywords:

Bejan Number , Brownian motion , Entropy generation , Hartman Number , Nanofluid , Triangular Enclosure