A model for the effective thermal conductivity of nanofluids

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mme.modares.ac.ir

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model for the effective thermal conductivity of nanofluids–effect of interfacial layer and non-uniform size distribution of nanoparticles

Zohreh Shams

^1*

,Mohammad Moghiman

²

1- Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran 2- Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran

*P.O.B. 9177948944, Mashhad, Iran, [email protected]

A RTICLE I NFORMATION A BSTRACT

Original Research Paper Received 23 September 2014 Accepted 14 October 2014 Available Online 22 November 2014

This work presents model for calculating the effective thermal conductivity of nanofluids. In this method, the effect of non-uniform sizes of nanoparticles and interfacial layer is investigated simultaneously. The developed model for the thermal conductivity of nanofluids takes into account the effects of thermal conductivity of base fluids, thermal conductivity, volume fraction and the size of nanoparticles, the interfacial layer, non-uniform sizes of nanoparticles, Brownian motion and temperature. Hence, this model has the capability of offering both analytical and numerical predictions.The accuracy of the proposed model for the effective thermal conductivity of water-Al O ethylene glycol-Al O water-CuO ethylene glycol-CuO ethylene glycol-Al,water- TiOis investigated. The effect of temperature, size of nanoparticles and volume fraction of nanoparticles are determined. Results show that the interfacial layer at the nanoparticle-liquid interface and non-uniform sizes of nonparticles are the most important parameters for calculating the thermal conductivity of nanofluids. Comparison between the result and available experimental data of several types of nanofluids indicates that the proposed model provides accurate results with maximum error of 5%.

Keywords:

Nanofluid Nanoparticle

Effective thermal conductivity,Non-uniform size

Interfacial layer

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