Experimental and model development of lead-bismuth eutectic solidification phenomenon flowing inside the tube

Abstract

Lead-bismuth fast reactor may solidify under accident conditions due to overcooling in components such as steam generators, waste heat exhaust heat exchangers, etc. In order to investigate the impact of the solidified layer adhering to the wall surface on the transient flow heat transfer and pressure drop characteristics of lead-bismuth eutectic, an experimental study of lead-bismuth eutectic solidification phenomenon flowing in a vertical circular tube was conducted. Moreover, a rapid prediction model for lead-bismuth eutectic solidification phenomenon was developed and verified with experimental results. The experimental results demonstrate that the formation of solidification layer results in a reduction in time-averaged Nu by approximately 43%, while concurrently exhibiting a sustained increase in pressure drop of the fluid flow. Additionally, the maximum thickness of the solidification layer on one side is 6.4 mm (inner diameter of the round tube is 20 mm), while the average thickness is 1.97 mm. The findings demonstrate that the formation of the solidification layer not only markedly diminishes the heat transfer efficiency between the lead-bismuth eutectic fluid and the wall but also augments the flow resistance.