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ISSN Online: 2688-7231

ISBN Online: 978-1-56700-478-6

Proceedings of the 24th National and 2nd International ISHMT-ASTFE Heat and Mass Transfer Conference (IHMTC-2017)
December, 27-30, 2017, BITS Pilani, Hyderabad, India

ANALYSIS OF THERMAL EFFECTS ON FRAGMENTATION OF SODIUM SPRAY DROPLETS IN INERT GAS ENVIRONMENT

Get access (open in a dialog) DOI: 10.1615/IHMTC-2017.830
pages 593-600

Abstract

Analysis of postulated sodium fire events is essential in the safety evaluation of Sodium cooled Fast Reactors (SFR). In the event of sodium leak from the reactor systems, sodium fire can take place in two major modes i.e. spray fire and pool fire depending on the scenario of leak. As spray fire involves sodium combustion in droplets form, evaluation of proper droplet size distribution is essential for the realistic assessment of consequences of various postulated spray fire events. The experimental evaluation of sodium spray droplet size distribution has to be carried out in the inert atmosphere to avoid the oxidation reactions of sodium. However, under this condition, the spray formation could be affected by the simultaneous heat transfer process between the hot liquid sodium and the inert gas. Especially, if cooling and solidification of sodium droplets happen quickly, it can hamper their secondary fragmentation process, which may lead to poor representation of droplet size distribution. Hence, in the present work analysis has been carried out to evaluate thermal effects on secondary fragmentation of sodium droplets in the inert gas atmosphere. Due to the coupled hydrodynamic and thermal interactions between molten sodium droplets and the inert gas, two representative time scales have been considered in this analysis, i.e., time scales for droplet breakup and solidification. Based on these time scale values, the effect of solidification on the sodium droplet breakup in the inert gas has been brought out. Present analysis results are useful for the evaluation of sodium spray droplet size distribution, which is an important parameter determining the consequences of spray fire events.