Authors: E. Park, I. Bang, H. Park
Affilation: Ulsan National Institute of Science and Technology(UNIST), Korea
Pages: 353 - 356
Keywords: nanofluids, electrical explosion of wire in liquids (EEWL), critical heat flux (CHF)
Nanofluids, dispersed nanoparticles in base fluid, have been drawing the attention as heat transfer fluid for enhancement of critical heat flux (CHF). The enhancement of CHF contributes to increase the safety margin of thermal system. In Pool boiling experiment, the CHF enhancement is explained by changing the morphology of the heated surface during boiling. The property of heated surface after pool boiling experiment is dependent on many factors such as materials, concentration and size of particles, thermophysical properties and dispersibility of nanofluids. In this study, the Ag, Cu, and Al2O3 nanofluids were produced by the electrical explosion of wire in liquids (EEWL). The EEWL as physical method has many advantages such as high-purity nanofluids production without surfactants (non-toxic, in contrast to chemical method), control of oxidation of nanoparticles surface, and spherical nanoparticle production. The greatest advantages are the simple evaporation and condensation processes, short production times, and the possibility of mass production. And we were performed pool boiling experiements to characterize the CHF enhancement using Ag, Cu and Al2O3 nanofluids. The surface of the heating wire was observed using TEM and AFM after pool boiling. The heater surface contained deposited nanoparticles that formed nano/microstructures with different uniformity according to the dispersion state. Build-up of the nanoparticles on the heater surface occurred during nucleate boiling, which decreased the contact angle of heater surface. The improving of surface wettability contributed to the CHF enhancement.