Numerical investigation of SWCNT–H₂O nanofluid and core topology effects on the thermal and moisture performance of sandwich panels

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Chinese explanation / 中文解读

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Original abstract

This study presents a numerical analysis of the combined influence of SWCNT–H₂O nanofluid concentration and core topology on thermal performance, using ANSYS Fluent and the Finite Volume Method (FVM). Five core materials—Polyurethane (PU), Unplasticized Polyvinyl Chloride (UPVC), Extruded Polystyrene (XPS), Expanded Polystyrene (EPS), and Glass Wool (GW)—were analyzed under laminar flow and constant heat flux conditions ranging from 35 to 350 kW/m². The continuity, momentum, and energy equations were discretized using a second-order upwind scheme, with convergence thresholds of 10⁻⁷ for the continuity and momentum equations and 10⁻⁹ for the energy equation. This study presents a coupled multi-physics numerical analysis of SWCNT–H₂O nanofluid-cooled sandwich panels, simultaneously evaluating thermal transport, hydraulic behavior, and moisture diffusion within a unified finite volume framework. Unlike conventional investigations focusing on isolated thermo-hydraulic or hygrothermal effects, the present work quantifies the interacting mechanisms governing convective heat-transfer enhancement, conductive insulation resistance, and moisture stability across multiple core materials. Furthermore, entropy generation and Bejan number analyses are incorporated to reveal thermodynamic trade-offs and irreversibility characteristics, providing deeper insight into performance optimization. The study reveals a non-intuitive trade-off: materials providing higher thermal insulation do not always deliver superior thermo-hydraulic efficiency under nanofluid cooling, highlighting the competing roles of conduction resistance and convective enhancement. The increase in pressure drop between φ = 1.5% and φ = 4.5% remained below 12% in all cases, which is modest compared to the 39.8–55.4% improvement in heat transfer. However, this finding is specific to the single-phase homogeneous nanofluid model employed; real SWCNT–water nanofluids at 4.5% concentration would likely exhibit larger viscosity increases and higher pressure penalties. Overall, the findings confirm that SWCNT–H₂O nanofluids significantly enhance thermal conductivity and convective heat transfer, particularly at higher Reynolds numbers (Re = 200–600). Among the tested materials, the UPVC panel exhibited the highest thermo-hydraulic efficiency—surpassing the other cores by up to 42.7%—whereas PU proved to be the most cost-effective option, offering a balanced combination of thermal and structural performance.

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