Highly accurate density data is required for engineering calculations to make property estimations in natural gas custody transfer through pipelines. It is also essential to have accurate pressure-volume-temperature (PVT) data for developing equations of state (EOS). A highly accurate, high pressure and temperature, compact single sinker magnetic suspension densimeter has been used for density measurements. First, the densimeter is calibrated against pure component densities for which very reliable data are available. After validating its performance, the densities of four light natural gas mixtures that do not contain components heavier than hexane and two heavy gas mixtures containing hexane and heavier components having fractions more than 0.2 mole percent were measured. The light mixtures were measured in the temperature range of 250 to 450 K and in the pressure range of 10 to 150 MPa (1450 to 21,750 psi); the heavy mixtures were measured in the range of 270 to 340 K and in the pressure range of 3 to 35 MPa (500 to 5,000 psi). Out of those, the data for only four light natural gas mixtures have been presented in the dissertation due to confidentiality agreements that are still in force. A force transmission error and uncertainty analysis was carried out. The total uncertainty was calculated to be 0.11%. Data calculated in this work is compared with the current industry standard EOS for natural gas systems (AGA8-DC92 EOS) and GERG EOS, which is the most recently developed EOS for natural gas systems. The data measured as a part of this research should be used as reference quality data, either to modify the parameters of AGA8-DC92 EOS and GERG EOS or to develop a more reliable equation of state with wider ranges of pressure and temperature.

Understanding protein stability and folding is of central importance in chemistry, biology, and medicine. Despite its importance, a molecular level understanding of protein stability still remains illusive due to the complexity of the system. In this study, we employed protein-like polypeptides to study several aspects of protein stability in different aqueous environments. The model system employed here is elastin-like polypeptides (ELPs). First, the modulation of the lower critical solution temperature (LCST) of neutral ELPs was investigated in the presence of 11 sodium salts that span the Hofmeister series for anions. It was found that the hydrophobic collapse/aggregation of these ELPs generally followed the series. Specifically, kosmotropic anions decreased the LCST by polarizing interfacial water molecules involved in hydrating amide groups on the ELPs. By contrast, chaotropic anions lowered the LCST through a surface tension effect. Additionally, chaotropic anions showed salting-in properties at low salt concentrations that were related to the saturation binding of anions with the biopolymers. These overall mechanistic effects were also compared to the results previously found for the hydrophobic collapse and aggregation of poly(N-isoproplyacrylamide). A positively charged ELP, ELP KV6-112, was used as a next model system. We observed both inverse and direct Hofmeister effects on LCST with five chaotropic salts. Next, the solvent isotope effects on the LCST of ELPs were investigated as a function of ELP chain length and guest residue chemistry using D2O and H2O. Differences in the LCST values with heavy and light water were correlated with secondary structure formation of the polypeptide chains which was quantified by circular dichroism, FTIR, and differential scanning calorimetry measurements. It was found that there is a great change in the LCST values between H2O and D2O for those polypeptides which form the greatest amount of b-spiral structure. This study suggests that hydrogen bonding rather than hydrophobicity is the key factor in the stabilization of ELPs in D2O over H2O. The phase transition property of ELPs can also be applied to development of stimuli responsive biosensor system. In this study, we employed ELP-conjugate solid supported lipid bilayer as a size selective binding sensor.

This dissertation intends to provide new tuning techniques for several simple cubic equations of state (EOS) to improve their accuracy in calculating fluid phase equilibrium. It also provides graphical tools to predict some phase equilibrium phenomena from activity coefficient models. Finally, it presents simulation results for a new gas-to-liquids process. Saturation Properties for Fluids: By deriving a new identity linking the heat of vaporization for pure components to the EOS, we are able to find new expressions for the two constants a & b in the EOS. These new expressions then allow tuning of both constants a and b to experimental saturation properties at subcritical temperatures. These new tuning procedures prove effective to the point where the simpler Redlich-Kwong EOS provides better results with our procedure than does the usually superior Peng-Robinson EOS with conventional procedures. Activity Coefficient Models: This dissertation shows the flexibility of four activity coefficient models in the prediction of three fluid phase equilibrium phenomena. From these models we successfully developed new graphs that allow one to identify the presence of any of the three phenomena by visual inspection without performing a complex calculation as seen in current texts. Remote Natural Gas: This dissertation presents simulation results of a new gas-to-liquids process which converts natural gas to liquid transportation fuels. Based on the assumption of adiabatic reactions, our simulation results show that methane conversion increases with higher reaction temperature and longer residence times. Hydrogen can both inhibit methane decomposition and reduce coke formation. The rich components in the natural gas are found to decompose very fast and they have a vast quenching effect on the whole reactions. Recycling of unreacted methane also increases overall methane conversion. Finally, our simulator provides very close prediction of the experimental results from a pilot plant. Thus, we conclude that the simulation work is basically successful in fulfilling the goal of this research.

Thesis(M.S.)--Case Western Reserve University, 2009 / Title from PDF (viewed on 2010-01-28) Department of Materials Science and Engineering Includes abstract Includes bibliographical references and appendices Available online via the OhioLINK ETD Center

Promotionsarbeit--Eidgenössische Technische Hochschule, Zürich. / Lebenslauf.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2010. / Committee Chair: Mayor, James Rhett; Committee Member: Garimella, Srinivas; Committee Member: Jeter, Sheldon. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 270-290). Available also in a digital version from Dissertation Abstracts.

Not available / text

Melanoidin is responsible for the dark brown color of distillery wastewater. Discharge of colored wastewater has a major environmental impact on the biota of the receiving water body. Consequently, this study explores the removal of melanodin from aqueous solution. The equilibrium, kinetics and thermodynamics of melanoidin sorption are studied by varying initial solution pH, initial concentration, adsorbent dose and temperature. Kinetically, the melanoidin removal from solution by a surfactant modified zeolite is rapid and the amount adsorbed is dependent on pH, initial concentration, adsorbent dose and temperature. The equilibrium sorption data are fitted to the Freundlich and Langmuir models while the sorption kinetics are described by the Ho pseudo-second order and Elovich models. The thermodynamic analysis indicates that the sorption is spontaneous and endothermic in nature. The FTIR spectra analyses show no new peaks or shift in peaks after sorption indicating that the melanoidin sorption may have occurred by a physical process. The results from desorption studies showed that melanoidin eluted back easily to the solution using distilled water which corroborates the physical sorption mechanism.

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