Parametric study on cavity formation during in-situ burning of oils in ice

Abstract

A parametric experimental study on melting of ice adjacent to liquids exposed to heat flux from above was conducted in order to understand the role of liquid properties in formation of cavities in ice. During in-situ burning of crude oil contained in an ice cavity (a probable situation in the Arctic) the convective motion in the fuel layer is enhanced because of strong temperature gradients imposed by the hot fuel and the cold ice-wall. This sideways movement of hot oil causes lateral melting of the ice, leading to pockets where the oil ultimately deposits. As a result, the burning efficiency, which is a key success criterion, decreases. Furthermore, mechanical recovery of oil after combustion is almost impossible with the formation of such lateral cavities. An experimental setup was designed to measure the melting rate of the ice and penetration speed of the liquid as it recounted the cavity formation problem. Experiments were conducted in a transparent glass pan (7cm×7cm×4.5cm) with a 2 cm thick ice cuboid (7cm×5cm×2cm) on one side of the pan. The liquids used in this study included water, Pentane, Dodecane, n-Octane, m-Xylene, and 1-Butanol – all carefully chosen based on their thermo-physical properties, as thermally driven buoyancy and surface tension driven Marangoni flows are altered with a change in these properties. Fundamental insight on the primary controlling parameters responsible for lateral cavity formation was obtained from the parametric experimental study. For example, the melting rate of ice with m-Xylene (with higher surface tension) was found to be greater than that of Dodecane. The results can be applied towards improved guidelines on when to ignite and how to ignite an oil spill confined in an ice cavity, so as to minimize formation of lateral cavities.