Regular Article

Experimental and theoretical analysis of nanofluids based on high temperature-heat transfer fluid with enhanced thermal properties^*

¹ Department of Physical Chemistry, Cádiz University, Cádiz E-11510, Spain
² Department of Physical Chemistry, Seville University, Seville E-41012, Spain
³ Department of Chemical Engineering, Seville University, Seville E-41012, Spain

^a e-mail: javier.navas@uca.es
^b e-mail: antsancor@us.es

Received: 5 October 2016
Revised: 16 March 2017
Accepted: 3 April 2017
Published online: 28 April 2017

Abstract

In this work, nanofluids were prepared using commercial Cu nanoparticles and a commercial high temperature-heat transfer Fluid (eutectic mixture of diphenyl oxide and biphenyl) as the base fluid, which is used in concentrating solar power (CSP) plants. Different properties such as density, viscosity, heat capacity and thermal conductivity were characterized. Nanofluids showed enhanced heat transfer efficiency. In detail, the incorporation of Cu nanoparticles led to an increase of the heat capacity up to 14%. Also, thermal conductivity was increased up to 13%. Finally, the performance of the nanofluids prepared increased up to 11% according to the Dittus-Boelter correlation. On the other hand, equilibrium molecular dynamics simulation was used to model the experimental nanofluid system studied. Thermodynamic properties such as heat capacity and thermal conductivity were calculated and the results were compared with experimental data. The analysis of the radial function distributions (RDFs) and the inspection of the spatial distribution functions (SDFs) indicate the important role that plays the metal-oxygen interaction in the system. Dynamic properties such as the diffusion coefficients of base fluid and nanofluid were computed according to Einstein relation by computing the mean square displacement (MSD).