The temperature and pressure correlations for the volume of gas hydrates forming crystal structures sI and sII developed in previous study [Fluid Phase Equilib. 427 (2016) 268-281], focused on the modeling of pure gas hydrates relevant in CCS (carbon capture and storage), were revised and modified for the modeling of mixed hydrates in this study. A universal reference state at temperature of 27...

Understanding the thermal and mechanical properties of CH4 and CO2 hydrates is essential for the replacement of CH4 with CO2 in natural hydrate deposits as well as for CO2 sequestration and storage. In this work, we present isothermal compressibility, isobaric thermal expansion coefficient and specific heat capacity of fully occupied single-crystal sI-CH4 hydrates, CO2 hydrates and hydrates of ...

Quantum path-integral simulations of the hydrate solid structures have been performed using the recently proposed TIP4PQ/2005 model. By also performing classical simulations using this model, the impact of the nuclear quantum effects on the hydrates is highlighted; nuclear quantum effects significantly modify the structure, densities, and energies of the hydrates, leading to the conclusion that...

Chloride-based salt hydrates form a promising class of thermochemical materials (TCMs), having high storage capacity and fast kinetics. In the charging cycles of these hydrates however hydrolysis might appear along with dehydration. The HCl produced during the hydrolysis degrades and corrodes the storage system. Our GGA-DFT results show that the enthalpy charge during proton formation (an impor...

The Michelsen stability and multiphase flash calculation by direct minimization of Gibbs free energy of the system at constant temperature and pressure, was used for systems containing gas hydrates. The solid hydrate phase was treated as a solid solution. The fugacities of all components of the hydrate phase were calculated as a function of compositions by the rearranged model of van der Wa...

Oceanic gas hydrates have been measured near the seafloor for the first time using a seagoing Raman spectrometer at Hydrate Ridge, Oregon, where extensive layers of hydrates have been found to occur near the seafloor. All of the hydrates analyzed were liberated from the upper meter of the sediment column near active gas venting sites in water depths of 770– 780 m. Hydrate properties, such as st...

Pyrimidine hydrates are products of ultraviolet irradiation of DNA. We have already demonstrated the formation of both cis-thymine hydrate and trans-thymine hydrate (6-hydroxy-5,6-dihydrothymine) in irradiated poly(dA-dT):poly(dA-dT). These are released from DNA as free bases by bacterial or human glycosylases. Thymine hydrate stabilities were studied in irradiated DNA substrates using purified...

Gas Hydrates Markup Language (GHML) has been under development since 2003 by the CODATA Task Group “Data for Natural Gas Hydrates” as an international standard for data storage and transfer in the gas hydrates community. We describe the development of this evolving communication protocol and show examples of its implementation. In describing this protocol, we concentrate on the most recent upda...

The first aspect is the problem of how to gain a better understanding of the distribution and abundance of gas hydrates in continental slope sediments at the present day. Mark Maslin (University College London) and Nick Langhorne (Office of Naval Research, USA) both emphasized that while the potential distribution of hydrates can be defined, based on the pressure and temperature limits of their...

We report molecular simulation studies of the diffusion processes in ice and CO2 clathrate hydrates performed using classical potential models of water ~SPC/E! and carbon dioxide ~EPM2!. The diffusivity of H2O in ice is calculated to be 1.3310 218 m s at 200 K using molecular dynamics simulations, a result in good agreement with experimental data. We also computed the diffusivity of H2O and CO2...