Hydrate Thermodynamics

Acetylene, clathrate in hydroquinone, 7 hydrate thermodynamic data and lattice constants, 8 Acrylamides, polymerization of, 181 Acrylonitrile, 155 Activity coefficients, 125... 

Projections, linearly independent, 293 Propagation, of polymerization, 158 Propane, hydrate, 10, 33, 43, 46, 47 hydrate thermodynamic data and lattice constants, 8 + iodoform system, 99 Langmuir constant, 47 water-hydrogen sulfide ternary system, 53... 

Sulfur dioxide hydrate, thermodynamic data and lattice constants, 8 Sulfur hexafluoride (SFa), hydrate, 22, 47... 

Kang, S.P. Lee, H. (2000). Recovery of C02 from flue gas using gas hydrate Thermodynamic verification through phase equilibrium measurements. Environ. Sci. Technol., 34(20), 4397-4400. 

Plodinec, M. J. 1984. Stability of radioactive waste glasses assessed from hydration thermodynamics. In McVay, G. L. (ed) Scientific Basis for Nuclear Waste Management VII. Materials Research Society Symposia Proceedings, 26, 755-762. 

With the determination of hydrate structure, more rigorous predictive methods were formulated for hydrate thermodynamic property predictions. Barrer and Stuart (1957) initially suggested a statistical thermodynamic approach to determining gas hydrate properties. In a similar yet more successful approach,... 

The time-dependent phenomena of hydrate nucleation and growth are challenging to both measure and model. This is in contrast to hydrate thermodynamics that... 

Makogon (1981, p. 134) and Berecz and Balla-Achs (1983, p. 102) indicated that methanol can increase the temperature of hydrate formation at concentrations less than 5 mass% (presumably due to the clustering effect), but higher concentrations inhibit formation. Nakayama and Hashimoto (1980) also suggested that several of the alcohols could form hydrates yet further study by Nakayama et al. (1997) caused the opposite opinion. Further measurements by Svartas (1988) also indicated that small methanol amounts do not increase hydrate thermodynamic stability. 

Chapters 4 and 5 were concerned with the fitting and prediction of hydrate thermodynamic data. Those two chapters indicate how hydrate theoretical developments have dramatically changed over their history, particularly due to advances in knowledge of molecular structure, statistical thermodynamics, kinetics, and computing capability. Yet the powerful tools provided by all of these predictive methods are only as good as the measurements upon which they are based. 

In addition to the change in the theoretical methods applied to hydrates, there have been significant advancements and widespread use of meso- and microscopic tools in hydrate research. Conversely, the typical static experimental apparatus used today to measure macroscopic properties, such as phase equilibria properties, is based on the same principles as the apparatus used by Deaton and Frost (1946). In part, this is due to the fact that the simplest apparatus is both the most elegant and reliable simulation of hydrate formation in industrial systems. In Section 6.1.1 apparatuses for the determination of hydrate thermodynamic and transport macroscopic properties are reviewed. 

For quick reference, Tables 6.1 through 6.3 provide a summary of the key features, capabilities, limitations, and advantages of different experimental apparatuses for macro- (Table 6.1), meso- (Table 6.2), and molecular-level (Table 6.3) measurements of hydrate thermodynamic and kinetic properties. 

This section will outline the developments and significance of applying mesoscopic and molecular-level methods to measure hydrate thermodynamic and kinetic properties. The characteristics of these different techniques are also listed in Tables 6.2 and 6.3. 

Structure identification and relative cage occupancies. The hydration number and relative cage occupation for pure components and guests were measured by Sum et al. (1997), Uchida et al. (1999), and Wilson et al. (2002). Raman guest spectra of clathrate hydrates have been measured for the three known hydrate crystal structures si, sll, and sH. Long (1994) previously measured the kinetic phenomena for THF hydrate. Thermodynamic sl/sll structural transitions have been studied for binary hydrate systems (Subramanian et al., 2000 Schicks et al., 2006). 

While accurate thermodynamic predictions (as in Chapters 4 and 5) enable avoidance via use of inhibitors such as methanol, risk management is enabled by operating experience and by kinetic predictions. Hydrate thermodynamic predictions can provide avoidance techniques, but kinetic predictions are required to provide techniques of risk management. 

A new computer program CSMGem, for hydrate thermodynamic calculations... 

S. N. Timasheff, Protein hydration, thermodynamic binding, and preferential hydration, Biochemistry 2002, 41, 13473-13482. 

Res. Inst. Tokyo Univ.) 3, 17-19 (1948). IR chloral hydrates, thermodynamic properties. 

After their discovery and attendant interest, hydrate thermodynamic advances have been driven by practical concerns. In this section, motivating factors are shown with... 

In retrospect, the discovery of hydrates blocking energy flowlines motivated significant advances in clathrate hydrate thermodynamics, which may be typical of knowledge advances for many new compounds, with the following stages ... 

Due to limitations of space, this section emphasizes only two major aspects of hydrate thermodynamics - namely the phase diagram and the hydrate prediction method. For examples of several counter-intuitive spectroscopic measurements results that impact the thermodynamic perspective, the reader is referred to a recent review, presented with an overview of the 2002 Fourth International Hydrate Conference. 

The major advance in hydrate thermodynamics was the generation of the van der Waals and Platteeuw model bridging the normal macroscopic and microscopic domains. Only a brief overview is given here to provide a basis for model improvements the reader interested in more details should refer to another source. The essence of the van der Waals and Platteeuw model is the equation for the chemical potential of water in the hydrate phase ... 

The above three errors can be seen as second-order corrections to a theory that has served the hydrate thermodynamics community well. To account for these second-order changes. Equation (1) must be slightly modified as follows ... 

Over the last decade or so, many research efforts have been focused on developing what are termed low-dosage hydrate inhibitors , or LDHIs, that potentially can kinetically inhibit hydrate formation/ LDHIs operate via a much different mechanism than thermodynamic inhibitors such as methanol. They are often effective at concentrations as low as 0.5 wt% and act by delaying the onset of hydrate formation, while thermodynamic inhibitors are effective only at much higher concentrations and act by changing the conditions of hydrate thermodynamic stability, thus shifting the phase diagram. 

Marky, L.A., Rentzeperis, D., Luneva, N.P., Cosman, M., Geadntoy, N.E., and Kupke, D.W. (1996) Differential hydration thermodynamics of stereoiso-meric DNA-benzo[a]pyrene adducts derived from diol epoxide enantiomers with different tumorigenic potentials. 

These have been the backbone of studies on hydrophobic hydration. Thermodynamic functions such as AG, LH and AA extrapolated to infinite dilution give information about solute-solvent interactions whereas the same functions studied over a range of concentrations give information on solute-solute interactions (see Sections 1.7.1 and 1.9). Results at infinite dilution will give information on hydrophobic hydration. 

Hess, B., van der Vegt, N.F.A. Hydration thermodynamic properties of amino acid analogues A comparison of biomolecular force fields and water models, J. Phys. Chem. B 2006,110,17616-26. 

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