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