Global ETD Search

41	Concentrated solar chemistry: design stage theoretical thermodynamic analysis of an iron-ethylene production process Sheline, William Robert 09 May 2013 (has links) Although concentrated solar power can be used to produce power using traditional electricity generation, energy storage has become a problem due to the intermittent supply of solar energy. By using solar energy in chemical production processes, the solar energy can be stored in a useful chemical product. The purpose of this thesis will be to examine the possibilities of a new solar chemical cycle the produces iron and ethylene from hematite (a form of iron oxide) and ethane using concentrated solar power. These two products are important stepping stones in the production of steel and polymers. This process could allow for the current process of steel production to move away from processes using coal and towards a more sustainable process using the hydrogen formed from the ethane cracking process and solar energy. The thesis will include: (1) the development of a new solar powered iron and ethylene combined cycle, (2) a feasibility study of a Concentrated Solar Heat Supply System (CSHSS) being developed at Georgia Tech, and (3) an assessment of the proposed cycle. The assessment will include an estimate of production including a thermodynamic ASPEN model, assessment of research to realize actualization of the theoretical cycle, an exergy analysis, and a heat exchanger analysis for the exchange of heat between the CSHSS and the chemical process. Solar energy Sustatinability Renewable energy Exergy Concentrated solar power Chemical reformation Ethylene production Iron production Solar fuels Solar energy Photochemistry Energy storage Iron Ethelyne Hematite Ethanes
42	Carbon molecular sieve dense film membranes for ethylene/ethane separations Rungta, Meha 07 November 2012 (has links) The current work focused on defining the material science options to fabricate novel, high performing ethylene/ethane (C₂H₄/C₂H₆) separation carbon molecular sieve (CMS) dense film membranes. Three polymer precursors: Matrimid®, 6FDA-DAM and 6FDA:BPDA-DAM were used as precursors to the CMS membranes. CMS performances were tailored by way of tuning pyrolysis conditions such as the pyrolysis temperature, heating rate, pyrolysis atmosphere etc. The CMS dense film membranes showed attractive C₂H₄/C₂H₆ separation performance far exceeding the polymeric membrane performances. Semi-quantitative diffusion size pore distributions were constructed by studying the transport performance of a range of different penetrant gases as molecular sized probes of the CMS pore structure. This, in conjunction with separation performance data, provided critical insights into the structure-performance relationships of the CMS materials. The effects of testing conditions, i.e. the testing temperature, pressure and feed composition on C₂H₄/C₂H₆ separation performance of CMS dense films were also analyzed. These studies were useful not just in predicting the membrane behavior from a practical stand-point, but also in a fundamental understanding of the nature of CMS membrane separation. The study helped clarify why CMS membranes outperform polymeric membrane performance, as well as allowed comparison between CMS derived from different precursors and processing conditions. The effects on C₂H₄/C₂H₆ separation in the presence of binary gas mixture were also assessed to get a more realistic measure of the CMS performance resulting from competition and bulk flow effects. The current work thus establishes a framework for guiding research ultimately aimed at providing a convenient, potentially scalable hollow fiber membrane formation technology for C₂H₄/C₂H₆ separation Entropic selectivity Testing conditions Pyrolysis Diffusion size pore distribution Carbon molecular sieve membrane Ethylene/ethane Gas separation membranes Molecular sieves Ethylene Ethanes
43	Conceptual design of gasification-based biorefineries using the C-H-O ternary diagram Litheko, Lefu Andrew 10 1900 (has links) This dissertation develops a systematic targeting method based on the C-H-O ternary diagram for the conceptual design of gasification-based biorefineries. The approach is applied using dimethyl ether (DME) as case study. A stoichiometric equilibrium model is presented for calculation of the C-H-O chemical equilibria to evaluate and predict equilibrium syngas composition, operating temperature, type and amount of oxidant required in biomass gasification. Overall atomic species balances are developed and process targets are plotted on the C-H-O ternary diagram. Sustainability metrics are incorporated to provide useful insights into the efficiency of biorefinery process targets. It was found that syngas at 1200 and 1500 K is predominantly H2 and CO. Moreover, DME biorefineries have two main process targets, based on the indirect and direct synthesis routes. Gasification at 1200 K and 1 atm. using H2O/CO2 = 2.642 (w/w) and H2O/CH4 = 1.645 (w/w) achieved syngas composition targets for the direct and indirect methods respectively. Comparatively, the integrated biorefinery based on indirect route was more efficient, producing 1.903 ton of DME per ton of biomass feedstock. The process is 100% carbon-efficient and recycles 1.025 tons of H2O. / Civil and Chemical Engineering / M. Tech. (Chemical Engineering) Biorefinery Gasification C-H-O ternary diagram Chemical equilibria Dimethyl ether (DME) Process targets Sustainability metrics 547.411 Biomass gasification Ethanes Molecular structure Molecular dynamics
44	Spartial distribution and environmental compartmentalization of DDT and its metabolites in different environmental media (soil, water and plants) in Tshilamusi Area, Mutale district in Limpopo Province, South Africa Makoni, Tonderai 10 February 2016 (has links) MEnvSC / Department of Ecology and Environmental Science DDT Metabolite Spatial distribution Soil Water Plants 632.95170968257 Ethanes -- South Africa -- Limpopo Insecticide -- South Africa -- Limpopo
45	Destruction of chlorinated hydrocarbons by zero-valent zinc and bimetallic zinc reductants in bench-scale investigations Cushman, Christopher Scott 09 May 2014 (has links) No description available. Chemistry Environmental Engineering Environmental Geology Environmental Management Environmental Science Environmental Studies Organic Chemistry Sustainability Water Resource Management chlorinated hydrocarbons zero-valent zinc ZVZ zero-valent iron ZVI bimetallic reductants copper Cu-Zn palladium Pd-Zn nickel Ni-Zn chlorinated methanes chlorinated ethanes chlorinated ethenes chlorinated propanes 1,2,3-TCP

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