Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 13 of 13 for “"hydrofluorocarbons"”.
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Sustainable design of hydrocarbon refrigerants applied to the hermetic compressor
… applications were initially replaced with hydrofluorocarbons (HFCs) such as R134a which has a zero ozone depletion potential (ODP). The use of HFCs has also come under scrutiny as they have high global warming potential (GWP) and inferior thermodynamic and lubricating properties and have …
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Evaluation of unsaturated fluorocarbons for dielectric Etch applications
… have been investigated to date, including hydrofluorocarbons (HFCs), iodofluorocarbons (IFCs), and NF3/hydrocarbons. One class of chemistries that have shown considerable promise is the unsaturated fluorocarbons (UFCs). The research documented herein uses the UFCs to assess etch process and …
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Analysis of Ethoxyquin and its Oxidation Products using Supercritical Fluid Extraction and High Performance Liquid Chromatography with Chemiluminescent Nitrogen Detection
… during the extraction. Methanol modified hydrofluorocarbons provided more complete extractions over pure hydrofluorocarbon fluids. Methanol modified 1,1,1,2-tetrafluoroethane was used in the extraction of ethoxyquin from lean beef and beef fat, and provided a quantitative extraction at the …
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Creating an effective and equitable legal carbon taxing regime for South Africa
… (CO₂), Methane (CH₄), Nitrous oxide (N2O), Hydrofluorocarbons (HFCs), Perfluorocarbons (PFCs), and Sulphur hexafluoride (SF₆). The most notable of these gasses is Carbon Dioxide (CO₂), this gas is released into the atmosphere in vast amounts and is primarily responsible for the human …
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Impact of two potential policy options on atmospheric chemistry and climate: hydrogen economy and low-GWP alternatives to ozone depleting substances
… (Global Warming Potential) alternatives to hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs), on the composition of the atmosphere, on environment, on climate and on stratospheric ozone. This research is accomplished by using state-of-the-art numerical models that represents …
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Design, Testing And Controls For Air Source Heat Pump System In Cold Climates Using Natural & Conventional Refrigerants
… heat pump technologies use various types of hydrofluorocarbons (HFC) refrigerants which are also responsible for greenhouse gas emissions. Therefore, natural refrigerant such as which is naturally available, eco-friendly, non-toxic, non-flammable, and non-corrosive can be a good alternative …
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On potential effects from the aviation and refrigeration sectors on ozone and climate
… in refrigeration to replace long-lived hydrofluorocarbons (HFCs), which are of concern for climate. Iodine atoms from CF3I and CH3I, once released into the atmosphere, can react catalytically to destroy ozone and potentially add to stratospheric ozone depletion if the iodine gets into …
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Understanding Drivers of Stratospheric Ozone Change and Fingerprinting its Recovery
… for various hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), which are chemical constituents that have been used to replace CFCs. Once these man-made ODSs reach the stratosphere, they are photolyzed to chlorine reservoir species (e.g., HCl and ClONO2), which, through heterogeneous …
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Scuffing and wear of engineering materials under different lubrication regimes in the presence of environmentally friendly refrigerants
… alternative refrigerants for the replacement of hydrofluorocarbons (HFCs) due to environmental regulations. HFCs refrigerants have been widely used in the refrigeration industry since the early 1990’s as replacement to chlorofluorocarbon (CFCs) refrigerants that were non-flammable and non-toxic, …
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Assessment of the environmental acceptability of refrigerants by discrete mathematics: cluster analysis and Hasse diagram technique
… mooted were hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs), which contribute to the global warming, quantified by the global warming potential (GWP). ODP and GWP are related to the atmospheric lifetime (ALT), a third indicator. Hence, the environmental impact of a refrigerant may …
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Development of novel alternative chemistry processes for dielectric etch applications
… families of modified fluorocarbon molecules: hydrofluorocarbons (HFCs), iodofluorocarbons (IFCs), and unsaturated fluorocarbons (UFCs). In addition, other chemistries, namely trifluoroacetic anhydride (TFAA), oxalyl fluoride, and octafluorotetrahydrofuran, were also examined. The focus of much …
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Toxicity and biotransformation of 1,1,1,3,3-Pentafluoropropane, 3,3,3-Trifluoropropionic acid and 1,1,1,3-Tetrachloropropane
The biotransformation of 1,1,1,3,3-pentafluoropropane was investigated in rats and in in vitro systems. First, the metabolites were identified in vivo using GC/MS and 19F NMR analysis. The main metabolite was identified as trifluoroacetic acid, the minor metabolite as 3,3,3-trifluoropropionic acid …
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Phase Equilibria and Transport Properties of Gas-Saturated Ionic Liquids
… of high global warming potential (GWP) F-gases. Hydrofluorocarbons (HFCs), a particularly potent class of F-gases widely used in refrigeration and other industries, are often found in azeotropic mixtures that make their separation challenging. Extractive distillation with ionic liquids (ILs) as …