A numerical investigation of natural convection heat transfer of copper-water nanofluids in a rectotrapezoidal enclosure heated uniformly from the bottom wall.

The present article numerically investigates the effects of natural convection of Cu-water nanofluid in a two-dimensional rectotrapezoidal enclosure used in application of absorber plate fin. The inclination angle of rectotrapezoidal enclosure, region φ is chosen as 60°. The left and right vertical walls of the enclosure are maintained at a local cold temperature Tc (heat sink) while the bottom wall is kept at a high temperature of T_h, respectively. The top wall of the enclosure is adiabatic. After non-dimensionalising the necessary governing controlling equations, the finite element strategy is adopted for solving the same. We present here the results in form of stream line contour, isotherm contours, local and average heat transfer rate (...) adopting a specific gamut of Rayleigh numbers i.e 10³≤Ra≤10⁶. The solid volume fraction range of Cu-water nanoparticles adopted for the present study is (0 ≤ φ ≤ 0.1). The Prandtl number of the numerical simulation is maintained at 6.2. From the results it is observed that the higher stream line intensity is reported at a higher Rayleigh number for higher values of φ and also it is found that with an increase of solid volume fraction φ, of copper water nanoparticles, average heat transfer rate (...) enhancement occurs. Accordingly, heat transfer enhancement greater than 20% as observed for higher Ra =10⁶, whereas 30% heat transfer enhancements are reported using Cu-water nanofluid with Ra=10³. [ABSTRACT FROM AUTHOR]