Numerical Investigation on Nanofluid Mixed Convection in Triangular Ducts Heated by a Uniform Heat Flux

Heat transfer enhancement technology covers a very important role in designing efficient heating and cooling equipments. This goal can be achieved by means of different techniques. Convective heat transfer can be improved actively or passively, for example, by adopting special surfaces or by increasing the thermal conductivity of the working fluids. Thus, the use of suspended solid nanoparticles in the working fluids can be taken into account. In this paper a numerical investigation on laminar mixed convection with Al₂O₃/water based nanofluids in a triangular channel is presented. A uniform and constant heat flux on the channel surfaces is assumed and the single-phase model approach has been employed in order to describe the nanofluid behaviour. The analysis has been performed in the steady state regime for particle size in nanofluids equal to 30 nm. The CFD code Fluent has been employed in order to solve the three-dimensional numerical model and different Richardson number values and nanoparticle volume fractions have been considered. Results are presented for the fully developed regime flow. The increase of average convective heat transfer coefficients and Nusselt number values for increasing values of Richardson number and particle concentration is observed by analyzing the obtained results. However, also wall shear stress and required pumping power profiles increase as expected.