Theoretical and experimental study of heat loss and ice accretion of large structures on marine vessels and offshore structures

Dehghanisanij, Alireza (2017) Theoretical and experimental study of heat loss and ice accretion of large structures on marine vessels and offshore structures. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Sea spray icing, or marine icing, is one of the most significant problems for the operation of marine vessels and offshore structures in cold regions and the Arctic. This phenomenon risks the stability of marine vessels and structures as well as the safety of human activities onboard. In this thesis, several issues related to the spray icing phenomena are investigated. Chapter 1 briefly reviews sea spray icing models, along with various experimental, theoretical and numerical approaches, which are used for modeling and prediction of the accumulated ice on marine platforms located in cold seas and ocean regions. In chapter 2, several topics, such as droplet trajectories, flux of seawater spray, liquid water content (LWC), heat balance at the phase interface, and freezing equations are formulated and examined. The trajectory and cooling process of droplets during flight over marine platforms are investigated and analyzed theoretically in chapter 3. The solidification process of a saline water droplet is studied using semi-analytical techniques in chapter 4. The theoretical prediction of ice accumulation on horizontal and vertical surfaces of marine vessels in cold regions is investigated in chapter 5. An experimental study to measure ice accumulation on vertical marine platform surfaces under various conditions is conducted in chapters 6 and 7. Summary and recommendations for future research are presented in chapter 8. Chapters 3 to 7 represent the original research in this thesis. Previously, no comprehensive evaluation of ice accumulation on the vertical marine platform surfaces under harsh environmental conditions via empirical measurements had been conducted. To fill the knowledge gap, a number of parameters, such as the weight and thickness of ice accumulation on the plate, relative humidity, the temperature at the front and back of the vertical plate, and the water temperature inside the pipe during the spray icing event for various conditions, as well as the spray mass flux that impacts on the vertical plate for the duration of the spray event were measured (chapter 7). The cooling and freezing processes of water droplets during flight over marine platforms in cold weather conditions were investigated and analyzed. The originality of this study was in the use of a semianalytical technique to solve an inward moving boundary problem (chapter 4).

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