Optimization of thermal and hydraulic performance of nanofluids in a rectangular miniature-channel with various fins using response surface methodology

Abstract

In the present work, optimization of the thermal and hydraulic performances of various nanofluids inside a rectangular miniature-channel heat sink with different longitudinal fins was studied. Response surface methodology was used to obtain optimal condition of miniature-channel. The selected cross sections for fins were semi-circular, quadrant (bi-directional) and rectangular. Gamma alumina–water and silicon oxide–water nanofluids were utilized as working fluids. The thermal conductivity, viscosity, convective heat transfer coefficient and pressure drop of working fluids are measured. The test facility provided experimental conditions to measure the heat transfer coefficient and pressure drop at different Reynolds numbers ranged between 400 and 1200. KD2 pro property analyzer for thermal conductivity and Brookfield DV3T rheometer for viscosity of nanofluids were applied. Experimental results showed that the efficiency of miniature-channel increases when nanofluid and extended surface are both employed. The highest and lowest values for the heat transfer enhancement belonged to the case of silicon oxide–water and for a miniature-channel with a rectangular fin. The highest thermal–hydraulic performance belonged to the miniature-channel with quadrant-2, rectangular, quadrant-1 and semi-circular fin with silicon oxide/water nanofluid, which was 1.27, 1.26, 1.16 and 1.11, respectively. According to statistical analysis, new correlations are also proposed to predict the Nusselt number and friction factor of various finned miniature-channel. The results of the proposed models are in good agreement with experimental data.