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ISSN Online: 2379-1748

ISBN Flash Drive: 978-1-56700-518-9

5th Thermal and Fluids Engineering Conference (TFEC)
April, 5-8, 2020, New Orleans, LA, USA

Theoretical Investigation of Thermal Conductivity and Viscosity of Nanofluids

Get access (open in a new tab) pages 747-775
DOI: 10.1615/TFEC2020.nma.032014

Abstract

Working fluids are used every day in a plethora of applications ranging from electronics, automotive, aerospace and many more. With increasing demands for more efficient design and operation in electrical and mechanical components the criteria for cooling has consequently increased. We are at a point in design optimization where the thermal conductivity of working fluids has become a limiting factor in the design process. Cooling systems are imperative to the functionality of these components which is why it has become a modern challenge to manufacture working fluids with higher thermal conductivities, this is where nanofluids become a major point of interest. A nanofluid is a mixture of nanoparticles within a base fluid. Nanoparticles change the physical properties of the working fluids including the thermal conductivity and viscosity. This research was focused on expressing the effects of concentration and characteristics of nanoparticles including size and material on the nanofluids thermal conductivity and viscosity. It was also explained different thermal conductivity theoretical models that fall into three categories. These categories are the Effective Medium, Nanolayer and Brownian motion approaches for approximating nanofluid thermal conductivity. As well as theoretical models approximating viscosity of nanofluids. The level of accuracy of existing theoretical models was also examined through comparison to experimental data by calculating the average percent error. Observations have been made on the impact of temperature, concentration and size on viscosity and thermal conductivity. Generally, as the concentration was increased, the viscosity and thermal conductivity both increased. This research was focused to explain how to minimize the negative side effects of nanoparticles on viscosity of nanofluid. Indeed, the temperature can be raised to effectively reduce the viscosity while retaining the enhanced thermal conductivity of the nanofluid.