Thesis (PhD) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: With increasing environmental concerns and the drive for a greener economy comes an increased desire to improve turbine engine fuel efficiency and reduce emissions. Unfortunately weight reduction techniques used increase the blade loading, which in turn increases the losses. Non-axisymmetric endwall contouring is one of several techniques being investigated to reduce loss in a turbine. An investigation at Durham University produced a non-axisymmetric endwall design for a linear cascade. An adaption of the most promising endwall was investigated in an annular rotating test rig at the CSIR using steady state instrumentation. The current investigation extends those investigations into the unsteady time domain. Previous investigations found that a generic rotor endwall contour improved efficiency by controlling the endwall secondary flow vortex system in both a linear cascade and an annular 1½ stage rotating test turbine. The current research was aimed at determining if there were any unsteady effects introduced by the contoured endwall. The approach was unique in that it investigated the unsteady effects of an endwall contour originally designed for a linear cascade both experimentally and numerically at three incidence angles (positive, zero and negative to represent increased load, design load and decreased load respectively), the results of which are openly available. Unsteady experimental hotfilm results showed that the endwall contour made the velocity profile more radially uniform by reducing the strength of the endwall secondary flow vortex system. The fluctuations in the velocity were also reduced producing a more temporally uniform velocity profile. The FFT magnitude of the velocity at the blade passing frequency below midspan was also reduced. It was found that the reduction in the endwall secondary flow vortex system due to the contour increased with increasing loading. Numerical results showed that the oscillations in the flow were small and did not penetrate the boundary layer. The contoured rotor was forward and aft loaded when compared to the annular rotor, resulting in a weaker cross passage pressure gradient which allowed the endwall secondary flow vortex system to be less tightly wrapped. Numerical results did not show a significant difference in the oscillations observed in the annular and contoured rotor. A new objective function for use in the endwall optimisation process was proposed that acts as a proxy for efficiency, but is less prone to uncertainty in the results. When used on the current results it shows the same trend as efficiency. It remains to be used to design an endwall for full validation. / AFRIKAANSE OPSOMMING: Met ’n toenemende omgewingsbesorgdheid en die strewe na ’n groener ekonomie kom ’n toenemende behoefte om turbine enjin brandstofdoeltreffendheid te verbeter en vrystellings te verlaag. Ongelukkig het gewigsbesparingstegnieke wat gebruik is die lemlading verhoog, wat op sy beurt die verliese verhoog. Nie-assimmetriese endwandprofilering is een van verskeie tegnieke wat ondersoek word om verliese in ’n turbine te verminder. ’n Ondersoek by die Universiteit van Durham het ’n nie-assimmetriese endwandontwerp vir ’n lineêre kaskade gelewer. ’n Aanpassing van die mees belowende endwand is in ’n annulêre roterende toetsopstelling by die WNNR getoets, deur gebruik te maak van bestendige toestand instrumentasie. Die huidige ondersoek brei daardie ondersoeke uit na die nie-bestendige verwysingsraamwerk . Vorige ondersoeke het bevind dat die generiese rotor endwandprofiel doeltreffendheid verbeter as gevolg van die beheer van die endwand sekondêre vloei draaikolkstelsel in beide ’n lineêre kaskade sowel as ’n annulêre 1½ stadium roterende toetsturbine. Die huidige navorsing was daarop gemik om vas te stel of die endwandprofiel enige onbestendige effekte tot gevolg gehad het. Die benadering was uniek in die sin dat dit die onbestendige effekte ondersoek het van ’n endwandprofiel wat oorspronklik ontwerp is vir ’n lineêre kaskade beide eksperimenteel en numeries op drie invalsshoeke (positief, nul en negatief om onderskeidelik verhoogde lading, ontwerplading en verlaagde lading te verteenwoordig), waarvan die resultate algemeen beskikbaar is. Onbestendige eksperimentele warmfilm resultate het getoon dat die endwandprofiel die snelheidsprofiel meer radiaal uniform gemaak het deur die vermindering van die sterkte van die endwand sekondêre vloei werwelstelsel. Die skommelinge in die snelheid is ook verminder wat ’n meer tyduniforme snelheidsprofiel gelewer het. Die FFT (Fast Fourier Transform) grootte van die snelheid van die lem verbygaan frekwensie onder lem midbestek het ook verminder. Daar was bevind dat die vermindering in die endwand sekondêre vloei draaikolkstelsel as gevolg van die endwandprofiel toeneem met toenemende lading. Numeriese resultate het getoon dat die ossilasie in die vloei klein was en nie die grenslaag binnegedring het nie. Die rotor met gevormde wand het ’n voor- en agterlading gehad in vergelyking met die rotor met annulêre wand, wat tot ’n laer drukgradient dwarsop die vloeirigting gelei het, die endwand sekondêre vloei draaikolkstelsel minder beperk het. Numeriese resultate het nie ’n beduidende verskil in die ossilasies tussen die annulêre en gevormde rotorwand getoon nie. ’n Nuwe doelwitfunksie vir gebruik in die endwand optimersproses is voorgestel wat dien as ’n plaasvervanger vir doeltreffendheid, maar minder geneig is tot onsekerheid in die resultate. Wanneer dit gebruik word op die huidige resultate toon dit dieselfde tendens as doeltreffendheid. Dit moet nog gebruik word in die ontwerp van ’n endwand vir volledige bevestiging.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering, 2016 / Global climate change is among the major challenges the world is facing today, and can be attributed to enhanced concentrations of Greenhouse Gases (GHG), such as carbon dioxide (CO2), in the atmosphere. Therefore, there is an urgent need to mitigate CO2 emissions, and carbon capture and storage (CCS) is amongst the possible options to reduce CO2 emissions. Against this background, this work investigated the synthesis and performance evaluation of Polyaspartamide (PAA) adsorbent for CO2 capture. In particular, the effect of the presence of water-soluble amines in the amine-grafted poly-succinimide (PSI) (referred to as Polyaspartamide (PAA) adsorbent), was investigated. Methyl Amine (MA) and Mono-Ethanol Amine (MEA) were employed as water-soluble amines and the effect of changes in their concentration on CO2 adsorption capacity was investigated as well. Water-soluble amines were incorporated to allow water solubility of the adsorbent paving the way for freeze-drying to improve the geometric structure (surface area, pore volume and pore size) of the adsorbent. Initially, the PSI was loaded with Ethylenediamine (EDA), forming PSI-EDA. The water-soluble amines were grafted to PSI-EDA, with the EDA added to improve the chemical surface of the adsorbent for CO2 capture. NMR and FTIR analyses were performed and confirmed the presence of MA and MEA amine groups in the PAA, thereby indicating the presence of the grafted amines on the backbone polymer. BET analysis was performed and reported the pore volume, pore size and surface area of the freeze-dried material. It was observed that the physical properties did not change significantly after the freeze-drying compared to literature where freeze-drying was not employed. An increase in adsorption capacity with an increase in MA and MEA concentrations in MA-PAA and MEA-PAA samples was observed. At low amine concentrations (20% amine and 80% EDA grafted), MEA-PAA was observed to exhibit higher adsorption capacity compared to the MA-PAA samples. At high amine (100% amine grafted) concentrations, MA-PAA samples displayed higher adsorption capacity. Three runs were performed on each sample and the results obtained were reproducible. The best adsorption capacity obtained was 44.5 g CO2/kg Ads. Further work was then performed to understand the effects of operating variables on CO2 adsorption as well as the interactive effect using the Response Surface Methodology approach. The experiments were done by use of CO2 adsorption equipment attached to an ABB gas analyzer. A central composite design of experiment method with a total of 20 experiments was employed to investigate three factors, namely, temperature, pressure and gas flow rate. Six regression models were drawn up and mean error values computed by use of Matlab, followed by response surfaces as well as contours, showing the influence of the operating variables on the adsorption capacity as well as interaction of the factors were then drawn up. The results obtained displayed that each of the factors investigated, temperature, pressure and gas flowrate had an incremental effect on the adsorption capacity of PAA, that is, as each factor was increased, the adsorption capacity increased up to a point where no more increase occurred. Adsorption was seen to increase for both an increase in gas flowrate and adsorption pressure to a maximum, thereafter it starts to decrease. A similar trend was observed for the interaction between temperature and pressure. However, the interaction between gas flowrate and temperature was such that, initially as the temperature and the gas flowrate increase, the adsorption capacity increases to a maximum, thereafter, the temperature seizes to have an effect on the adsorption capacity with a combined effect of decreasing temperature and increasing gas flowrate resulting in a further increase in adsorption capacity. It was confirmed that the operating variables as well as the flow regime have an effect on the CO2 adsorption capacity of the novel material. The highest adsorption capacity was obtained in the pressure range 0.5 bar to 1.7 bar coinciding with the temperature range of 10 oC to 45 oC. The interaction of gas flowrate and adsorption pressure was such that the highest adsorption capacity is in the range 0.8 bar to 1.5 bar which coincides with the gas flowrate range from 35 ml / min to 60 ml / min. In conclusion, the best adsorption capacity of 44.5 g / kg via the TGA and 70.4 g / kg via the CO2 adsorption equipment was obtained from 100 % MA grafted PSI. / GR2016

As managers of extensive vehicle fleets and transportation infrastructures, public transit agencies present unique opportunities for reducing greenhouse gas (GHG) emissions from the transportation sector. To achieve substantial and cost-effective GHG emissions reductions from their activities, public transit agencies need tools and resources that enable effective GHG emissions management. This research thesis presents the background, methodology, and results of the author's development of a public transit agency-level life cycle GHG emissions calculator. The development of the calculator involved a series of research efforts aimed at identifying and addressing the needs of transit agency GHG emissions management: a review of background information on climate change and public transit's role in mitigating climate change; a review of existing GHG emissions calculators for public transit agencies, a review of the methodologies for life cycle GHG emissions analysis; integration and adaption of existing calculation resources; development of calculator spreadsheets for estimating relevant lifecycle GHG emissions and quantifying GHG emission reduction cost-effectiveness; application of the developed calculator to a carbon footprint analysis for a typical mid-size to large-size transit agency; and application of the developed calculator to the evaluation of the cost-effectiveness of various potential strategies for reducing transit agency GHG emissions. The developed calculator provides an integrative resource for quantifying GHG emissions and costs of public transit agency activities, including GHG emission reduction strategies. Further research is needed to calibrate the estimation of upstream life cycle GHG emissions, particularly for vehicle manufacture and maintenance.

The dependency on fossil fuels faces resource limitations and sustainability concerns. This situation requires new strategies for greenhouse gas emission management and the development of new sources of energy. This thesis explores fundamental concepts related to carbon geological storage, including CO2-CH4 replacement in hydrate-bearing sediments. In particular it addresses the following phenomena: - Interfacial tension and contact angle in CO2-water-mineral and CH4-water-mineral systems. These data are needed to upscale pore phenomena through the sediment porous network, to define multiphase flow characteristics in enhanced gas recovery operations, and to optimize the injection and storage CO2 in geological formations. - Coupled processes and potential geomechanical implications associated to CH4-CO2 replacement in hydrate bearing sediments. Results include physical monitoring data gathered for CH4 hydrate-bearing sediments during and after CO2 injection. - Performance of cap rocks as trapping structures for CO2 injection sites. This study focuses on clay-CO2-water systems and CO2 breakthrough through highly compacted fine-grained sediments. Long term experiments help evaluate different sediments according to their vulnerability to CO2, predict the likelihood and time-scale of breakthrough, and estimate consequent CO2 leaks.

Transportation in the United States is responsible for a disproportionate amount of global greenhouse gas emissions, which contribute to climate change. To address the issue, strategies that seek to mitigate transportation-related greenhouse gas emissions and adapt transportation systems to the threats of a more inhospitable climate should be developed through the transportation planning process. The transportation plans and related documentation of 60 metropolitan planning organizations, 13 domestic cities, and 27 large international cities were reviewed to ascertain if climate change considerations are being incorporated into transportation planning. The review of transportation plans revealed that climate change considerations are often not incorporated into the planning process, especially in regard to adapting transportation systems to the effects of climate change due to the inherent uncertainties in climate data and risk analysis. On the other hand, greenhouse gas mitigation is more frequently included in the planning process, when compared to climate change adaptation, because the required data collection techniques and analysis tools are better developed and already in place within many planning organizations. This research has shown that there is much room for improvement in terms of including climate change into transportation planning through a variety of recommendations presented in the body of this thesis. Many of the identified mitigation and adaptation recommendations could be worked into existing transportation planning requirements, processes, and strategies at the metropolitan and local level. However, due to the influence by federal and state governments on the planning process, completely addressing climate change through transportation systems will require these high levels of government to redefine transportation regulations and planning requirements in addition to partnering with metropolitan planning organizations and local governments to develop more reliable climate data and increase its availability.

Thesis (M.E.S.)--The Evergreen State College, 2007. / Title from title screen viewed 1/17/2008. Includes bibliographical references (p. 123-126).

Thesis (M.E.S.)--The Evergreen State College, 2007. / Title from title screen (viewed 1/24/2008). Includes bibliographical references.

Orientadores: Antonio Carlos Moretti, Luis Gustavo Barioni / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matemática Estatística e Computação Científica / Made available in DSpace on 2018-08-23T21:29:50Z (GMT). No. of bitstreams: 1 Silva_RafaeldeOliveira_M.pdf: 1266731 bytes, checksum: c7c072db6adf998a52f0d31e791f3996 (MD5) Previous issue date: 2013 / Resumo: O Brasil e um dos primeiros países em desenvolvimento a se comprometer com metas de redução das emissões de gases de efeito estufa (GEE). As metas estabelecidas requerem uma redução entre 36,1% a 38,9% relativos as emissões estimadas para 2020. Focando na regiao central do Cerrado, responsavel por cerca de 35% da producao total de carne bovina do Brasil, este estudo estima as emissoes totais de GEE de 2006 a 2030. O estudo tambem identifica o custo efetivo do potencial de reducao das emissoes. A analise foi feito por meio da construcao de um modelo de programacao linear, batizado de "EAGGLE" (Analise Econômica dos Gases de Efeito Estufa das Emissoes da Pecuária), que representa um sistema de producao de gado de corte a pasto, com e sem suplementação, e confinamento. Um segundo modelo foi desenvolvido para estimar os estoques de carbono no solo sob pastagens com diferentes níveis de produtividade. Neste modelo e simulado o efeito da degradação, manutenção, recuperação, e dinâmica de mudança de uso da terra nos estoques de carbono. Os resultados mostraram que, no cenário de referencia, a regiao vai emitir cerca de 1,2 Gt de CO2 entre 2010 a 2020, o que equivale a 8% das emissoes liquidas totais do pais. Um conjunto de tecnologias de mitigação de GEE, foram analisados através da construcao de Curvas de Custo de Abatimento Marginal (CCAM). Os resultados indicam que ate 2030, a regiao e capaz de reduzir as emissoes em 24,3 Mt de CO2 equivalente por ano (CO2e/yr), utilizando tecnologias com custo efetivo negativo, enquanto que o potencial de reducao total apresentado pelas CCAM e 24.7MtCO2e.yr-1. Uma analise de sensibilidade foi feita para avaliar o potencial de mitigação da recuperação de pastagens em função de variações na demanda por carne. Ao contrario do que poderia se esperar, os resultados mostraram que, se as projeções de demanda diminuírem em 10%, 20% ou 30 %, ate 2030, as emissoes totais para o período aumentam em 1%, 4% e 5%, em GWP, respectivamente. Em contrapartida, considerando que as projeções de demanda cresçam em 10%, 20%, ou 30%, ate 2030, haverá uma reducao de 2%, 3 % e 4% do total das emissoes de GEE, respectivamente. Isto sugere que a recuperação de pastagens e capaz de compensar as emissoes diretas de CH4 e N2O pelo gado brasileiro, devido ao aumentando das taxas de seqüestro de carbono do solo / Abstract: Brazil is one of the first major developing countries to commit to a national emissions target that requires a reduction of between 36.1% and 38.9% relative to baseline emissions by 2020. Focusing on the Cerrado core (Central Brazilian Savanna), responsible for about 35% of the country's beef production, this study estimates the region GHG emissions from 2006 to 2030. This work also investigates the cost-effectiveness of the GHG abatement potential. The analysis was made by means of a construction of linear programing (LP) model, coined EAGGLE (Economic Analysis of Greenhouse Gases for Livestock Emissions). The LP model represents a beef production system under grazing and feedlot finishing. A second model was developed to estimate the C stocks under pastures soils with different dry-matter productivity. In this model it is simulated the effects of degradation, maintenance, restoration end the land use change dynamics over the C stocks. As a baseline, the region is going to emit 1.2 Gt from 2010 to 2020, the equivalent of 8% of the country's total liquid emissions. A set of mitigation measures, applicable to Brazil, were analyzed by constructing a marginal abatement cost curve (MACC). The results show that by 2030 the region could reduce emissions by 24.3 MtCO2e.yr-1 with negative costs; while total abatement potential shown by the MACC is 24.7MtCO2e.yr-1. Pasture restoration, involving avoided deforestation, offers the largest contribution to these results. Sensitivity analysis is used to evaluate the abatement potential of pasture restoration against variations in beef demand. Counterintuitively, the results showed, if demand projections decreases by 10%, 20% or 30% until 2030, the total liquid emissions for the period increases 1%, 4%, and 5%, in GWP, respectively. Whereas increasing demand projections by 10%, 20%, and 30% until 2030, there will be a reduction of 2%, 3% and 4% in total liquid GHG emissions for the period. This suggests that PR is able to offset the cattle direct emissions of CH4 and N2O by boosting carbon soil sequestration rates / Mestrado / Matematica Aplicada / Mestre em Matemática Aplicada

M.Sc.(Eng.), Faculty of Engineering and the Built Environment, University of the Witwatersrand, 2011

Thesis (Ph.D. Administration (Development Planning and Management)) -- University of Limpopo, 2021 / The study aims to evaluate the effectiveness in planning for and management of urbanisation towards climate change mitigation at the City of Polokwane, Polokwane Local Municipality in the Limpopo Province. In Africa, various studies have demonstrated that unplanned urbanisation has resulted in increasing Greenhouse Gas emissions, which has contributed to the intensification of climate change. Although every country has contributed to climate change, African countries have blamed the current climatic conditions (floods, drought, changing precipitation patterns, sea-level rise, heatwaves and high temperature) on the excessive development alternatives that are highly polluting from the developed countries. In South Africa, the Spatial Planning Land Use Management Act (SPLUMA) is an important planning instrument to plan and manage urbanisation. Although there has been a transformation of legislative framework in South Africa, its implementation remains unreformed. The study adopted a mixed method approach to integrate the strengths of both the qualitative and quantitative methods. The study was undertaken at four areas around the City of Polokwane, namely Legae le Batho, Serala View, Emdo Park and Flora Park by engaging with the local communities on their perceptions regarding the planning and management practices within the municipality. The findings of the study indicate that there is a gap between the municipality and the local communities in the planning and management of urbanisation. The collaboration between the communities and Polokwane Local Municipality in planning serves as a strategy for efficient climate change mitigation. The use of solar systems for street lights, solar geysers, hybrid system (solar and batteries) and gas application can significantly reduce electricity consumption, which is currently generated from the combustion of fossil fuels. Therefore, the study recommends implementation of bio-digesters and solar plants to mitigate climate change. The study recommends proper alignment between the Polokwane Local Municipality and Capricorn District Municipality in terms of climate change mitigation to ensure effective implementation of project initiatives such as bio digesters (for gas generation) and solar plants for electricity generation.