Experimental Study of Thermophysical Properties and Nanostructure of Self-Assembled Water/Polyalphaolefin Nanoemulsion Fluids

Published

July 15, 2015

Author(s)

Jiajun Xu, Boualem Hammouda, Fangyu Cao, Bao Yang

Abstract

In this study, the nanostructures and thermophysical properties (thermal conductivity, viscosity and specific heat) of one new type of nanostructured heat transfer fluid: Water/polyalphaolefin (PAO) nanoemulsion fluid is investigated. The water/polyalphaolefin nanoemulsion fluids are thermodynamically stable containing dispersed water nanodroplets formed by self-assembly. It has been found that the nanostructure inside nanoemulsion fluids may affect their thermophysical properties, especially their boiling heat transfer characteristics. The small-angle neutron scattering (SANS) technique has been used to help identify the nanostructure inside the water/PAO nanoemulsion fluids. Using the 3-region Guinier-Porod model, we show that there is a nonlinear variation of the nanodroplets¿ size and shape with water concentration/molar ratio, which also happens to coincide with the trend of its viscosity and specific heat. On the other hand, the thermal conductivity increases linearly with increasing volume fraction of water nanodroplets which appears to be insensitive to its nanostructure change. While the water nanodroplets inside can increase the thermal conductivity by 16 %, the effective specific heat can be enhanced by upto 90 % when the water nanodroplets undergo a liquid-solid phase change.

Citation

Advances in Mechanical Engineering

Volume

7

Issue

4

Pub Type

Journals

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Keywords

Phase change, Nanoemulsion fluid, Small-angle neutron scattering, Thermophysical properties

Citation

Xu, J. , Hammouda, B. , Cao, F. and Yang, B. (2015), Experimental Study of Thermophysical Properties and Nanostructure of Self-Assembled Water/Polyalphaolefin Nanoemulsion Fluids, Advances in Mechanical Engineering, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=915996 (Accessed December 1, 2024)