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(2006)Journal ArticleThe sequestration of CO2 as a greenhouse mitigation option is becoming an increasingly important priority for industry. Theoretically membrane based CO2 removal systems have the potential to provide a cost effective, low maintenance approach for removing CO2 from gas streams. This study examines the effect of membrane characteristics, operating parameters and system design on sequestration costs for any source-sink combination. The total sequestration cost per tonne of CO2 avoided for separation, transport and storage are compared for the separation of CO2 from a black coalfired power plant in Australia. The results show that the membranes currently available have a total sequestration cost of US$55-61/tonne CO2 avoided. Lower costs for CO2 avoided can be achieved using an MEA amine based absorption separation system. Gas separation membranes would require significant improvements in CO2 permeability and selectivity, together with reductions in the cost of membranes and changes to the process configurations and operating pressures to be competitive against MEA systems for the purposes of geo-sequestration.
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(2004)Conference PaperThe capture and storage of CO2 (CCS) as a greenhouse mitigation option is becoming an increasingly important priority for Australian industry. Membrane based CO2 removal systems can provide a cost effective, low maintenance approach for removing CO2 from gas streams. This study examines the effect of membrane characteristics and operating parameters on CCS costs using economic models developed by UNSW for any source-sink combination. The total sequestration cost per tonne of CO2 avoided for separation, transport and storage are compared for the separation of CO2 from coal fired power plants and natural gas processing. A cost benefit analysis indicates that sequestration of gases of high purities are dominated by compression costs which can be off-set by utilising membranes of higher selectivity coupled with higher permeability to reduce the required transmembrane pressure.
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(2011)Journal ArticleThick anatase films were fabricated on graphite substrates using a method of anodic aqueous electrophoretic-deposition using oxalic acid as a dispersant. Thick films were subsequently fired in air and in nitrogen at a range of temperatures. The morphology and phase composition were assessed and the photocatalytic performance was examined by the inactivation of Escherichia coli in water. It was found that the transformation of anatase to rutile is enhanced by the presence of a graphite substrate through reduction effects. The use of a nitrogen atmosphere allows higher firing temperatures, results in less cracking of the films and yields superior bactericidal performance in comparison with firing in air. The beneficial effects of a nitrogen firing atmosphere on the photocatalytic performance of the material are likely to be a result of the diffusion of nitrogen and carbon into the TiO2 lattice and the consequent creation of new valence band states.
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(1989)ThesisIn this project the preparation of the electrolyte for the all vanadium redox flow battery was investigated using both chemical and electrolytic reduction of ^O,- powder. Oxalic acid and SO^ reduction were found to be unsuitable as only the V(IV) state could be produced directly. With suspended powder hydrolysis, however, vanadium sulphate of any oxidation state, in this case 50% V(IV) plus 50% V(III) in sulphuric acid can readily be prepared from V^O^ powder, thus allowing a significant reduction in the cost of the vanadium battery electrolyte. Results from conductivity and electrolyte stability tests at elevated temperature have led to modification of the electrolyte composition for the vanadium redox cell, from the 2 M V plus 2 M H^SO^, originally employed, to the use of 3 M H^SO^, much higher energy efficiencies and greater electrolyte stability was demonstrated with the 3 M H^SO^ supporting electrolyte. Spectroscopy and electrolyte conductivity have been demonstrated as suitable techniques for state-of-charge monitoring. A number of electrode materials were also evaluated and a Toray graphite bonded to a carbon plastic electrode was selected for further prototype development. Energy efficiencies of between 83 and 86% were obtained for a current density of 30 mA/cm for a temperature range 5 to 45'C, and between 0 and 100% state-of-charge. A wide range of construction materials was tested for long term stability in the vanadium redox electrolyte.
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(1998)ThesisThe optimization of the spiral wound module design generally refers to the optimization of feed channel spacers, which is investigated in this thesis. The feed channel spacers serve to improve the mass transfer by promoting turbulence and provide passage for the fluid. However, the presence of spacers also significantly increases the channel pressure drop and consequently increases the energy costs of the process. The spacer design could therefore have a significant effect on process economics. The main aim of this work was to study spacer characteristics and test its major geometrical characteristics. To achieve this, custom designed spacers were developed in the laboratory and CFD simulations were used to visualize the flow management that spacer can achieve. Through experiments and CFD simulation, it was found that the transverse filament was one of the dominating factors in spacer design. Most of the pressure drop in the spacer filled channel was caused by the form drag introduced by the transverse filaments. The variation in transverse filament distance can greatly affect the number of transverse filaments in the channel and consequently affect the pressure drop and mass transfer in the channel. The experimental results showed that the diameter of the transverse filament also had a significant effect on channel pressure drop and mass transfer, especially at high flow rates. Increasing transverse filament diameter may result in a rapid increase in pressure drop and mass transfer caused by increased from drag and enhanced turbulence. Voidage alone was found not to be efficient for quantifying the geometrical properties of spacer filled channels. Two ratios, transverse filament diameter/channel height and transverse filament diameter/transverse distance, were established for quantifying the performance of the spacer filled channels. Novel spacers were developed as the result of this research. They provide similar mass transfer performance to the benchmark commercial spacer with lower pressure drop. Optimal novel spacer design was analysis based on economics analysis.
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