Document Type : Article
Department of Mechanical Engineering, Science and Research Branch, Islamic Azad University, Tehran, P.O. Box 14515-775, Iran
In this paper, the heat transfer characteristics of nanofluids nucleate and film boiling is studied experimentally. For this purpose, Al2O3 and SiO2 deionized water-based nanofluids prepared with three volumetric concentrations of 0.1%, 0.3% and 0.5%. The boiling experiments were conducted on a circular and polished copper surface with a diameter of 25 mm. The results showed that the addition of nanoparticles to the base fluid reduced the heat transfer coefficient of nucleate boiling. The boiling of nanofluids increased the surface wettability and the critical heat flux was significantly higher than that of pure deionized water. The Al2O3 deionized water-based nanofluid with a volumetric concentration of 0.5% had the best performance, with a critical heat flux of 44.56% higher than that of pure deionized water. The presence of nanoparticles in the deionized water-based nanofluid improved the heat transfer coefficient of film boiling. The results showed that the stable film boiling for nanofluids starts at higher wall superheat temperature difference than pure deionized water. Among the investigated concentrations, volumetric concentration of 0.5% had best performance for both nanofluids, so that the minimum heat flux of Al2O3 and SiO2 deionized water-based nanofluids were increased 35.01% and 34.40% compared to pure deionized water, respectively.