(47cm) Characterization Of Vaporization Rates Of Liquid Nitrogen On Water and Ice

One of the key steps in Liquefied Natural Gas (LNG) source term modeling is the characterization of heat transfer taking place between substrate and cryogenic liquid. The convective and conductive mechanisms of heat transfer of cryogenic liquid released on water and ice is studied. The boiling of cryogenic liquid on water exhibits a special immiscible liquid-liquid heat transfer phenomenon where heat transfer parameters change rapidly in a short duration of time. The boiling process starts on film boiling regime owing to the large temperature difference and may evolve to transition and nucleate boiling regime as the temperature difference between water and cryogen decreases. Similarly, when cryogenic comes in contact with ice, it undergoes rapid vaporization due to the difference in temperature between the ice and cryogenic liquid. This process is different from the heat transfer between water and cryogenic, as ice is a solid and the heat transfer through the solid is characterized by conduction phenomena instead of convection, as in water. A small scale experimental study was conducted to characterize the heat transfer behavior of liquid nitrogen spilled on water and ice. Liquid Nitrogen was used as a safe analog for LNG. The amount of liquid nitrogen spilled was varied in both the scenarios. The initial water temperature was varied in release on water experiment to see its effect on vaporization rate .The boiling regimes of liquid nitrogen on water were determined from experimental data and validated with correlations for convective boiling. The vaporization rate was determined directly from the mass loss monitored during the experiment. The experimental results were also compared with past experiment data obtained from literature.