Modeling of frost growth and fog generation at ultra-low temperatures

Abstract

When liquefied natural gas (LNG) is vaporized by an ambient air vaporizer (AAV), frost and fog appear, which reduce energy efficiency and cause environmental issues. A model for simulating frost growth behavior and fog formation was developed for evaluating an AAV. The mechanisms of frost and fog formation and their mass transfer rates were defined, and they were characterized numerically. Experimental tests were performed at ultra-low temperatures (below −100°C) to quantitatively verify the frost thickness and density and qualitatively verify the fog formation. Despite the irregular characteristics of the fog, it was found that fog generation was dominantly influenced by the frost surface temperature. Therefore, the period of fog formation could be predicted through frost and fog modeling, and the model would be useful in managing AAVs.