Effect of nano-fluid types on the improvement of heat transfer in a micro-channel with regular hexagonal pattern

Micro channels are widely used in different industries. The investgations on heat transfer improvments of these instruments are of significant inportance. At hte present study, the influence of different nano-fluids and geometrical charectrestics on the thermal performance of a heat sink which is especially for for micro-channels are investigated. In the present study, the authors investigated the Nusselt number and pressure drop in differential geometries and Reynolds numbers (Re). Then the micro-channel was investigated with different heat flux (q).In the first step, the micro-channel was examined and the final numerical results showed that the hexagonal cross-section can improve heat transfer about 9%. At the second step and after selecting appropriate parameters, the effect of three nano-particles (Al2O3 - CuO- TiO2) were studied. The results presented that aluminum oxide (Al2O3) has the best heat transfer rate among the mentioned nano-fluids. With the presence of nano-particles (Al2O3, φ = 4%) an increment of 40% in heat transfer rate, for the hexagonal cross section was achieved compare to rectangular cross section with water as working fluid.

Recirculation Flow of Nanofluid Through Periodic Nanotube with Hexagonal Cross-Section

In this paper, we have investigated the recirculation flow of a nanofluid in the developed flow zones of an infinite periodic nanotube with a hexagonal cross-section. A numerical analysis is commenced to identify the existence of single and double recirculation zones for various geometric parameters. The boundary element method (BEM) has been formulated for an unbound interim nanotube for solving the governing equations. We have developed the codes for the BEM method in FORTRAN 90, and the graphs have been plotted in MATLAB 2016. We have various geometric parameters to inaugurate circumstances for the onset of recirculation. We have found recirculation flow through this type of periodic tube for a set of geometric parameters such as amplitude, wavelength and throat radius etc. Firstly recirculation flow in the expansion region of the nanotube is prophesied to arrive beyond a critical amplitude and second order recirculation zone is also predicted for still higher amplitudes. The recirculation flow has great importance in the application, for example, it can be used in the particle separation process.

Tolerance in superstructures formed from high-quality colloidal ZnO nanoparticles with hexagonal cross-section

The order of periodic arrays of hexagonal ZnO nanoplates has been investigated in terms of polydispersity. A continuous transition from a crystalline to a glassy state has been found.