An experimental analysis of quenching of continuously heated vertical rod with aqueous Al2O3 nanofluid

Quenching characteristics of metallic vertical rod with an internal heater has been investigated in pure water and water-based nanofluid with alumina nanoparticles of 0.001% by volume. Initial temperature of the testing rod (12 mm diameter and 1000 mm length) ranges from 200 °C to 250 °C. The internal heater may be used to simulate the decay heat generated by the nuclear fuel rod after the power plant shutdown. Tests have been performed with varied range of experimental conditions of decay heat, constant water and nanofluid flow rates. The cooling curves follow a general trend of a rapid temperature drop up to almost 100 °C of the rod surface temperature irrespective of the operating parameters and the location of the thermocouple. The obtained results during quenching process indicated that HTC (heat transfer coefficient) for nanofluids are more than de-ionized water. It was also observed that in identical circumstances, the quenching time of the specimen in Al₂O₃ nanofluid considerably decreased as compared to water. The results exhibit that nanofluids can enhance the reflood heat transfer performance in terms of quenching rate for a long vertical rod causing liquid-droplets-induced depositions of nanoparticles resulting in making a pre-coating effect characterized by higher wettability.