Develop a CFD Heat Transfer Model for Using High Expansion Foam in an LNG Spillage

To effectively store and transport natural gas, liquefied natural gas (LNG) is widely used in the industry. However, a LNG spill can result in a vapor cloud, which can potentially cause fire and explosion. The National Fire Protection Association (NFPA) 11 recommends using high expansion (HEX) foam to effectively mitigating the vapor hazard and controlling LNG pool fire. In the experiments, the liquid nitrogen pool was used to simulate LNG leakage, because the boiling point of liquid nitrogen is close to methane, which is the main component of LNG. A lab-scale foam generator was used to produce HEX foam and carry out experiments to evaluate the temperature profile in the foam. Based on these experimental results, the heat balance among HEX foam and vaporized gas was discussed, and a heat transfer model using ANSYS Fluent^® was developed to estimate minimum HEX foam height that should be applied in the LNG spillage risk mitigation. Finally, we performed a sensitivity analysis on the effect of vaporization rate, the diameter of the vapor channel, and the heat transfer coefficient on the required minimum height of the HEX foam. It can be observed that at least 1.2 m HEX foam in height is needed to ensure the risk mitigation under the common situation. The simulation result can be used not only for understanding the heat transfer mechanism when applying HEX foam but also for effectively formulating HEX foam related standard by the policymaker.