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Turbulent acidic discharges into seawater

This thesis analyses the chemistry and physics behind acidic jets and plumes. The research was motivated from the discussions between industry and regulatory bodies concerning the dispersion of highly acidic discharges from exhaust gas scrubbers on ships into seawater. The industrial problem is simplified in an analytical model for acidic jets and plumes, which is then validated through an experimental study. The analytical model allows for the construction of an optimisation tool that considers the acidity of the discharge, the alkalinity of local seawater and the required scrubber flow rate to propose optimal discharge pipe configurations. This tool can be used for designing discharge pipe configurations in compliance with regulation MEPC 59/24/Add.1 Annex 9. The analytical model was then extended to also take into account the effects of ambient flow and buoyancy on the discharge trajectory. Existing regulatory compliance tests for scrubber discharges assume that no deflection occurs, however, the experimental study shows that an offset of one jet radius leads to an overestimation of pH recovery by one unit. Simplified expressions are developed to improve the accuracy of regulatory compliance tests by taking into account the effects of buoyancy and ambient flow. A general purpose computational fluid dynamics code was written to study the dispersion of contaminants in the wake of a ship. The study suggests that rapid dilution occurs in the near field as a result of the turbulence generated by propulsion, and further dilution occurs more slowly through the widening of the ship wake. Different velocity profiles are generated when the ship is either decelerating, accelerating or moving at a steady pace, but the widening of the wake is relatively insensitive to these factors in the near field.

Identiferoai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:654627
Date January 2015
CreatorsÜlpre, H.
PublisherUniversity College London (University of London)
Source SetsEthos UK
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation
Sourcehttp://discovery.ucl.ac.uk/1467269/

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