Liquefied Natural Gas (LNG) hazards include LNG flammable vapor dispersion and LNG pool fire thermal radiation. A large LNG pool fire emits high thermal radiation thus preventing fire fighters from approaching and extinguishing the fire. One of the strategies used in the LNG industry and recommended by federal regulation National Fire Protection Association (NFPA) 59A is to use expansion foam to suppress LNG vapors and to control LNG fire by reducing the fire size. In its application, expansion foam effectiveness heavily depends on application rate, generator location, and LNG containment pit design. Complicated phenomena involved and previous studies have not completely filled the gaps increases the needs for LNG field experiments involving expansion foam. In addition, alternative LNG vapor dispersion and pool fire suppression methodology, Foamglas® pool fire suppression (PFS), is investigated as well. This dissertation details the research and experiment development. Results regarding important phenomena are presented and discussed. Foamglas® PFS effectiveness is described. Recommendations for advancing current guidelines in LNG vapor dispersion and pool fire suppression methods are developed. The gaps are presented as the future work and recommendation on how to do the experiment better in the future. This will benefit LNG industries to enhance its safety system and to make LNG facilities safer.

Liquefied Natural Gas (LNG) is flammable when it forms a 5 – 15 percent volumetric concentration mixture with air at atmospheric conditions. When the LNG vapor comes in contact with an ignition source, it may result in fire and/or explosion. Because of flammable characteristics and dense gas behaviors, expansion foam has been recommended as one of the safety provisions for mitigating accidental LNG releases. However, the effectiveness of foam in achieving this objective has not been sufficiently reported in outdoor field tests. Thus, this research focused on experimental determination of the effect of expansion foam application on LNG vapor dispersion and pool fire. Specifically, for evaluating the use of foam to control the vapor hazard from spilled LNG, this study aimed to obtain key parameters, such as the temperature changes of methane and foam and the extent reduction of vapor concentration. This study also focused on identifying the effectiveness of foam and thermal exclusion zone by investigating temperature changes of foam and fire, profiles of radiant heat flux, and fire height changes by foam. Additionally, a schematic model of LNG-foam system for theoretical modeling and better understanding of underlying mechanism of foam was developed. Results showed that expansion foam was effective in increasing the buoyancy of LNG vapor by raising the temperature of the vapor permeated through the foam layer and ultimately decreasing the methane concentrations in the downwind direction. It was also found that expansion foam has positive effects on reducing fire height and radiant heat fluxes by decreasing fire heat feedback to the LNG pool, thus resulting in reduction in the safe separation distance. Through the extensive data analysis, several key parameters, such as minimum effective foam depth and mass evaporation rate of LNG with foam, were identified. However, caution must be taken to ensure that foam application can result in initial adverse effects on vapor and fire control. Finally, based on these findings, several recommendations were made for improving foam delivery methods which can be used for controlling the hazard of spilled LNG.

High expansion foam (Hi-Ex) is a firefighting technology that has been widely used for fire suppression in underground locations. Hi-ex foam can be applied remotely through boreholes from the surface reducing firefighter exposure to fires. Despite the experimental studies that have been carried out there are still some uncertainties about foam behavior in underground locations. For this reason, the main objective of this thesis was to estimate Hi-Ex foam flow behavior in different underground configurations using computational fluid dynamics (CFD) simulations. An experimental apparatus was built to study the foam rheology in order to determine the rheological model parameters to simulate foam as a continuous Non-Newtonian fluid. Furthermore, numerical and experimental results of Hi-Ex foam flowing in a pipe were compared with the objective of validating numerical results. Results of this study show that Hi-Ex foam with an expansion ratio between 1:250 and 1:1280 behaves as a shear thinning fluid represented by the power law model. Numerical simulations results were between 0.06% and 14% of experimental results for Reynolds numbers between 200 and 1700. Finally, numerical simulations of Hi-Ex foam in different mine entry slopes were carried out and compared with qualitative results of prior field work. This work generates some of the necessary numerical parameters for the simulation of Hi-Ex foam flow in mines. Furthermore, results of this work and the methodology used can allow for improved predictions of foam flow in in underground mine fires, while improving safety for mine workers / Master of Science / High expansion foam (Hi-Ex) is a firefighting technology that has been widely used for fire suppression in underground locations. Hi-Ex foam can be applied remotely through boreholes from the surface reducing firefighter exposure to fires. Despite the experimental studies that have been carried out there are still some uncertainties about foam behavior in underground locations. For this reason, the main objective of this thesis was to predict Hi-Ex foam flow in different underground configurations using computational fluid dynamics (CFD) simulations. An experimental apparatus was built to study the foam rheology in order to determine the rheological model parameters to simulate foam as a continuous Non Newtonian fluid. Furthermore, numerical and experimental results of Hi-Ex foam flowing in a conduit pipe were compared with the objective of validating numerical results. This work generates some of the necessary numerical parameters for the simulation of Hi-Ex foam flow in mines. Furthermore, results of this work and the methodology used can allow for improved predictions of foam flow in in underground mine fires, while improving safety for mine workers.