HYDROTHERMAL PERFORMANCE IMPROVEMENT OF MICROSCALE BACKWARD-FACING STEP CHANNEL BY EMPLOYING VORTEX GENERATORS AND NANOFLUIDS

Fluid flow and convective heat transfer in a microscale backward-facing step (MBFS) with vortex generators are simulated numerically using computational fluid dynamics. The finite volume method is used to discretize the governing equations. Different arrangements of vortex generators at the top and bottom of the channel are employed to evaluate hydrothermal performances. Five different working fluids, including various nanofluids and three multiphase models, are used to study the proposed physic comprehensively. The hydrothermal performance of MBFS with vortex generators is analyzed by looking at Nu/ f and J/f factors to indicate the heat transfer improvement and pressure drop at the same time. The obtained results reveal some valuable facts about the performance enhancement in the MBFS models. For instance, the best hydrothermal performance is achieved where the single-phase model and nanofluid#1 (Ethylene Glycol-SiO2) is employed with no top vortex generator (VG) and bottom VG with full length. Also, it is observed that the increment of the aspect ratio of bottom VG and Re number results in higher hydrothermal performances.