Impact of straight slot impingement jets on heat transfer enhancement of TiO<sub>2</sub>/H<sub>2</sub>O nanofluid flow in a square channel: CFD analysis.

Abstract

This study presents a computational fluid dynamics (CFD) analysis of heat transfer and pressure drop in a straight slot impingement jet, utilizing [Formula: see text] nanofluid within a square duct. The working fluid comprises [Formula: see text] nanoparticles (diameter d_p = 25 nm) suspended in water at a volume fraction (ϕ) of 2.5%. The investigation of different values of Reynolds numbers (Re) from 8,000 to 17,000, with variations in different geometrical parameters such as slot jet height ratio ([Formula: see text]: 0.3-0.6), spanwise pitch ratio ([Formula: see text]: 0.18-0.45), and streamwise pitch ratio ([Formula: see text]: 0.88-1.30). Three-dimensional numerical simulations are conducted using the ANSYS CFD module, incorporating the RNG k-ε turbulence model to solve governing equations in a turbulent regime. The CFD results show strong agreement with both the experimental results and empirical correlations results with similar geometrical configurations and flow conditions for a plain-wall square duct. The deviations are around 6% for the Nusselt number ([Formula: see text]) and 3% for the friction factor ([Formula: see text]), demonstrating the reliability of the CFD model. The [Formula: see text] nanofluid exhibits a notable enhancement in heat transfer performance compared to pure water. Variations in [Formula: see text], [Formula: see text] and [Formula: see text] significantly influence [Formula: see text], with the optimal configuration ([Formula: see text] = 0.5, [Formula: see text] = 0.3, [Formula: see text] = 0.97) yielding the highest heat transfer enhancement across most Reynolds numbers. The thermohydraulic performance parameter (THPP) ranges from 0.97 to 1.04, reaching its peak at Re = 8,000 for [Formula: see text]= 0.5, [Formula: see text] = 0.3, [Formula: see text]= 0.97. These findings highlight the potential of impingement jet cooling with nanofluids for thermal management in industrial applications, offering enhanced heat transfer efficiency through direct fluid impact on target surfaces.