Fatty Alcohol Nanoemulsions as Latent Functional Thermal Fluids for Energy Management

This work presents an experimental study on the preparation and characterization of thermal and physical properties of fatty alcohol nanoemulsions based on an ethylene glycol: water mixture (20%:80% in mass) as potential latent functional thermal fluids for energy management. Concentrations from 2 to 8% in mass of cetyl alcohol (with a melting transition at 48 °C) were dispersed by means of a solvent-assisted emulsification method using a mixture of anionic and non-ionic surfactants. The size of dispersed droplets was monitored through time and after samples were subject to several cooling-heating cycles to rule out possible destabilization issues. Phase change transitions were characterized in terms of temperature and latent heat, and sub cooling was reduced to a few Celsius when eicosyl alcohol (melting point at 64 °C) was used as a nucleating agent. Even if emulsions showed thermal conductivities larger than that of the bulk-cetyl alcohol, this transport property reduced with increasing concentration of dispersed phase. Finally, samples exhibited desirable Newtonian viscosities or slight shear thinning behavior.