The Baseline Design of The UiS Subsea Glider for Cargo and Liquid Carbon Dioxide Transportation
Master thesis
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https://hdl.handle.net/11250/3020280Utgivelsesdato
2022Metadata
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Sammendrag
This dissertation presents the baseline design of the UiS subsea-freight glider (USFG) for cargoand liquid carbon dioxide transportation. The USFG is a cutting-edge autonomous vesseldeveloped to be an alternative to active transportation technologies and satisfy the demands ofsmall-scale fields for CO2 transportation. Usually, these smaller fields fail to economicallyjustify the costs of large tanker or cargo ships or underwater pipelines on the seabed, as thetransport volume is nominal compared to larger fields. The USFG can travel underwater at anoperational depth of 200 meters, allowing the glider to carry freight operations withoutconsidering ideal weather windows. The length of the USFG is 5.50 meters, along with a beamof 50.25 meters, which allows the vessel to carry 518 m3 of CO2 while serving the storageneeds of the carbon capture and storage (CCS) ventures on the Norwegian continental shelf. Itcan maneuver itself underwater by monitoring the flow between the ballast tanks. During theentire mission of the USFG, from capturing to injection locations, it follows a pre-laid routewhile experiencing transient loads from the ocean current. A planar mathematical model forthe analysis of equilibrium glide paths of the USFG is presented. The model is developed usingSimscape Multibody in MATLAB/Simulink to study the volatile dynamics of the glider.Subsequently, the gliding paths of USFG in the vertical plane are analyzed along with theobservability and controllability of the steady equilibrium glides. Along with the controlgliding design of the USFG, the mechanical design is also presented in this work. Themaneuvering model of the USFG is presented along with two operational case studies: theequilibrium glide and the -38° dive. The extreme motion along the surge direction affects therange of the glider (vital for battery design) and the dynamic controller parameters concerningmaneuverability. Finally, the averaged conditional exceedance rate (ACER) is employed toscrutinize the extreme motion (surge direction) of the USFG while gliding to a defined depth.This analysis is done when the glider is exposed to an average current velocity of 0.5 m/s and1.0 m/s. The presented ACER method efficiently uses the available data points and accuratelypredicts the extreme surge responses precisely and accurately.