Abstract

The present work in nanofluids isfocusing into using the electrokinetic phenomenal occurring around nanoparticles immersed in a basefluid as a method to stabilize a nanofluid and enhance its thermal conductivity. The electro-kinetic physic establishes, that when an electrolyte solution is in contact with a solid, an electric double layer (EDL) is produced on the solid surface. Due to the high concentration of ions with the same charge around of the particle surface, "it is possible to stabilize a nanofluid by the action of an electro repulsive force caused by ions over the nanoparticle surface and enhance its thermal conductivity as the concentration ofthe solutions increases". The nanofluid samples were prepared by the two-step method and a continuous ultrasonication, lwt% and 3wt% concentration (mass fraction) of Titanium oxide, Anatase (7O2) nanoparticles, is added in an electrolyte solution (base fluid) made of different concentration ofPotassium Chloride (KCI), and deionized water The pH ofthe base fluid is maintained constant adding HEPES as a buffering agent. To measure the different level ofstabilityfor the nanofluid we used the thermal conductivity enhancement of the base fluid by nanoparticles. The experimental results under controlled temperature condition show that an electrolyte solution with nanoparticles after 20 days of preparation, presents a higher thermal conductivity with respect to the base fluid with an improvement rate ranging from 0.43+0.12% to 0.72+0.12% for lwt%, and 2.15+0.17% to 3.03+0.21% for 3wt% of nanoparticles added respectively. The higher improvement shows sign ofa major level ofhomogeneity of the nanofluid, and this behavior seems to be directly proportional to the KCl concentration.