Heat transfer enhancement technologies play an important role in research and industrial fields; thus, they have been widely applied to many applications as in refrigeration, automotive, aerospace, process industry, etc. For example, heat transfer can be passively enhanced by increasing the thermal conductivity of the working fluids, adopting nanofluids, or actively by employing impinging jets. In this paper a numerical analysis on confined impinging slot jets working with pure water or water/Al2O3 based nanofluids is presented. The flow is laminar and a constant uniform temperature is applied on the target surface. The single-phase model approach has been adopted in order to describe the nanofluid behaviour and different particle volume concentrations have been considered. Moreover, simulations have been performed for different geometric ratios in order to take into account the confining effects and Reynolds numbers. The behaviour of the system have been analyzed in terms of average and local convective heat transfer coefficient, Nusselt number, and required pumping power profiles. Correlations for stagnation point and average Nusselt number for 100<Re<400, 0%<fi<5% and 4<H/W<10 are provided.

Thermal and fluid dynamic behaviors of confined laminar impinging slot jets with nanofluids

MANCA, Oronzio;NARDINI, Sergio;
2016

Abstract

Heat transfer enhancement technologies play an important role in research and industrial fields; thus, they have been widely applied to many applications as in refrigeration, automotive, aerospace, process industry, etc. For example, heat transfer can be passively enhanced by increasing the thermal conductivity of the working fluids, adopting nanofluids, or actively by employing impinging jets. In this paper a numerical analysis on confined impinging slot jets working with pure water or water/Al2O3 based nanofluids is presented. The flow is laminar and a constant uniform temperature is applied on the target surface. The single-phase model approach has been adopted in order to describe the nanofluid behaviour and different particle volume concentrations have been considered. Moreover, simulations have been performed for different geometric ratios in order to take into account the confining effects and Reynolds numbers. The behaviour of the system have been analyzed in terms of average and local convective heat transfer coefficient, Nusselt number, and required pumping power profiles. Correlations for stagnation point and average Nusselt number for 100
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11591/329722
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