Investigation of laminar convective heat transfer and pressure drop of SiO2 nanofluid in ducts of different geometries.

摘要

Engineers are seeking alternatives to conventional heat transfer fluids and in an attempt to improve their thermal transport properties, they added thermally conductive solids into the conventional fluids resulting in a fluid called nanofluid. Nanofluid was suggested as an alternative solution to the problem and many publications reported its potential for heat transfer enhancement. This thesis describes the experimental study of 9.58% by vol. silica/water nanofluid flow through different flow geometries which are circular, hexagonal and rectangular ducts of close hydraulic diameter. The experiments are performed at uniform heat flux condition. The aim of this thesis is to determine experimentally the best duct geometry for optimal thermal performance in nanofluids.;The effect of the cross-section of the flow geometry on the enhancement capability of nanofluid is the focus of this research and four different geometries of relatively equal hydraulic diameters were studied. This study compares the result from the different duct geometries in order to identify the best flow channel for optimal heat transfer using nanofluids. Based on the test data, the thermal performance comparisons are made under three constraints (similar mass flow rate and Reynolds number). It was observed from the comparisons that the rectangular duct showed the highest heat transfer capability through a higher Nusselt number and heat transfer coefficients at for the silica/water nanofluid flow. The circular duct was next to the rectangular duct in thermal performance. There was no significant change in friction factor between the ducts for both water and nanofluid flow.