energies Article Dynamic Viscosity, Surface Tension and Wetting Behavior Studies of Paraffin–in–Water y Nano–Emulsions David Cabaleiro 1,2,3,* , Samah Hamze 1, Filippo Agresti 4 , Patrice Estellé 1,* , Simona Barison 4, Laura Fedele 2 and Sergio Bobbo 2 1 Université Rennes 1, LGCGM, EA3913, F-35704 Rennes, France 2 Institute of Construction Technologies, National Research Council, I–35127 Padova, Italy 3 Departamento de Física Aplicada, Universidade de Vigo, E–36310 Vigo, Spain 4 Institute of Condensed Matter Chemistry and Technologies for Energy, National Research Council, I–35127 Padova, Italy * Correspondence:
[email protected] (D.C.);
[email protected] (P.E.); Tel.: +33-(0)23234200 (P.E.) This article is an extended version of our paper published in 1st International Conference on Nanofluids y (ICNf) and 2nd European Symposium on Nanofluids (ESNf), Castellón, Spain, 26–28 June 2019; pp. 118–121. Received: 23 July 2019; Accepted: 24 August 2019; Published: 29 August 2019 Abstract: This work analyzes the dynamic viscosity, surface tension and wetting behavior of phase change material nano–emulsions (PCMEs) formulated at dispersed phase concentrations of 2, 4 and 10 wt.%. Paraffin–in–water samples were produced using a solvent–assisted route, starting from RT21HC technical grade paraffin with a nominal melting point at ~293–294 K. In order to evaluate the possible effect of paraffinic nucleating agents on those three properties, a nano–emulsion with 3.6% of RT21HC and 0.4% of RT55 (a paraffin wax with melting temperature at ~328 K) was also investigated. Dynamic viscosity strongly rose with increasing dispersed phase concentration, showing a maximum increase of 151% for the sample containing 10 wt.% of paraffin at 278 K.