Heat transfer enhancement in confined slot jets using water-based Cu core-shell and double-shell nanofluids under forced convection conditions

Abstract

Heat transfer from confined slot jets is important in several thermal engineering applications, including electronics cooling and turbine blade temperature control. This study presents a numerical investigation of a confined slot jet impinging on a heated wall under forced convection using core-shell nanofluids. The objective is to evaluate the influence of nanoparticle architecture on heat transfer performance. Several configurations are considered, including Cu@Ag, Cu@Au, Cu@Au@Ag, and Cu@Ag@Au. The flow and heat transfer are modeled by solving the Reynolds-Averaged Navier-Stokes equations with the Reynolds Stress Model (RSM) and enhanced wall treatment for Reynolds numbers between 10,000 and 25,000 and nanoparticle volume fractions up to 5%. The numerical approach is validated against data available in the literature. The performance of various core-shell nanofluids was evaluated in terms of heat transfer enhancement efficiency relative to the conventional Cu-water nanofluid. Among them, Cu@Au nanofluids demonstrated the highest improvement, ranging from 32.87% to 43.06%, ranking first. The results also indicate that heat transfer enhancement shows only a weak dependence on Reynolds numbers. These findings suggest that significant heat transfer enhancement is possible with low nanoparticle concentrations, providing practical advantages by minimizing stability and agglomeration issues.