Numerical simulation of rapid phase transition caused by LNG spills into water and results interpretation

In order to quantitatively predict the Rapid Phase Transition (RPT), a two-fluid Euler-Euler multiphase numerical model was established to simulate RPT. A typical Rapid Phase transitions experiment conducted by Clarke H. was modeled and the simulation results greatly matched the experiment results, thus the model was proven to be accurate. By simulating RPT in the open space with the model, the RPT's dynamic process underwater was reached, as well as local overpressure and the distribution of methane concentration horizontally and vertically. The results showed that RPT is essentially the rapid transformation of forced convection, film boiling, explosive boiling and nucleate boiling between LNG and water. Besides, the duration of RPT was extremely short and last for about a second. The local overpressure can be up to 97 kPa in typical cases, which will cause brick wall collapse, visceral injury and even lead to death. RPT will not only cause overpressure hazards but may also cause fire and asphyxia hazards downwind and downstream. Overall, this study could serve as theoretical foundation for safety protection in waterway transportation of LNG.