A two-phase simulation for analyzing thermohydraulic performance of Cu-water nanofluid within a square channel enhanced with 90° V-shaped ribs

A numerical investigation is conducted by implementing a two-phase model based on the mixture theory with the aim of assessing the attributes associated with the thermohydraulic performance of the Cu-water nanofluid through a square channel equipped by the 90 degrees V-shaped ribs. The ribs are attached on the top and bottom walls of the channel with different rib heights and rib pitches. It is observed that the average heat transfer coefficient significantly enhances with the volume fraction increment such that it enhances around 22.7% with increasing the volume fraction from 1 to 2% at rib pitch of 100 mm and rib height of 2.5 mm. The presence of the ribs considerably intensifies the flow mixing and disrupts the thermal boundary layer by means of generating the four counter-rotating vortices. In addition, employing the ribs with greater heights as well as smaller pitches augments the heat transfer coefficient as well as Nusselt number, such that the Nusselt number increases about 28.3% when the rib height increases from 2.5 to 7.5 mm in the condition in which the rib pitch is 50 mm. The Figure of Merit (FoM), which shows the fraction of the convective heat transfer coefficient ratio to the pumping power ratio for the case of using the nanofluid compared to the water, is much higher than 1, which demonstrates the benefit of employing the nanofluid rather than the water. Furthermore, increasing the volume fraction results in a greater FoM, which manifests the greater merit of using the nanofluid at higher concentrations. (C) 2019 Elsevier Ltd. All rights reserved.