A numerical investigation of a laminar forced convection of different working fluids including pure water, various volume concentrations of a nanofluid (${\mathrm{Al}}_2{\mathrm{O}}_3$ nanoparticles dispersed in water), and a hybrid water-based suspension of ${\mathrm{Al}}_2{\mathrm{O}}_3$ and Cu nanoparticles (which is a new advanced nanofluid with two kinds of nanoparticle materials) in a uniformly heated circular tube is accomplished. In this paper, the effect of using hybrid water-based suspension on thermal behavior and hydrodynamic performance in a range of Reynolds number in the laminar regime is investigated. Then, a comparison is made between the thermal and hydrodynamics behavior of the hybrid suspension with those of the nanofluid (with the same concentration) and the conventional one. It is observed that, for all Reynolds numbers studied, employing the hybrid suspension improves the heat transfer rate compared to pure water and the nanofluid. Nevertheless, it reveals an adverse effect on the wall shear stress and friction factor due to the presence of nanoparticles. However, the average increase of overall Nusselt number (rather to pure water) in hybrid suspension is 7.20%, whereas is is 10.94% for the average increase of the friction factor.

Nanostructured microporous surfaces were electrodeposited at various electrolyte temperatures on copper substrate to investigate the saturated pool boiling enhancement of distilled water at atmospheric pressure. Surface structure topography and wickability were analyzed to investigate their relation to critical heat flux. Scanning electron microscope showed that the micro-clusters have nanostructures from cubic at 5°C to dendritic at 60°C electrolyte temperature. Rate-of-rise experiments demonstrated that dendritic copper structure has the best capillary performance. The experimental results of pool boiling heat transfer indicate that the critical heat flux increased with surface wickability. Electrodeposited porous surface in hot electrolyte showed the highest critical heat flux and heat transfer coefficient of the 124 W/cm² and 17 W/cm²K, respectively, which is 50% and 270% higher than that of plain surface. However, the two-step electrodeposition and annealing were used in fabrication of surfaces, but the mechanical strength of layer needs more improvement by changing the electrochemical process parameters.