This review includes the current state of the art understanding and advances in technical developments about various fields of gas hydrates, which are combined with expert perspectives and analyses.

Over the past few decades, development of innovative techniques for carbon capture and storage (CCS) from power plant flue gas has become imperative due to substantial increase in the global atmospheric concentration of greenhouse gases, particularly anthropogenic CO2. In this regard, it is of utmost importance to have accurate thermodynamic experimental data along with reliable predictive models to be used in the novel CCS techniques such as hydrate-based geological storage methods. In this study, we introduced a new approach to accurately measure the solubility of three different types of simulated power plant flue gases, including coal-fired flue gas, gas-fired flue gas, and syngas, in water and aqueous solutions of NaCl. To mimic real operational conditions, the solubility measurements were carried out over a temperature range from 273.25 to 303.05 K and pressures up to 22 MPa with 5, 10, and 15 wt % NaCl. The experimental data were presented in conjunction with thermodynamic predictions. To predict the solubility of CO2 and N2 in water and brine, we applied three different equations of state, including CPA-SRK72, VPT, and PC-SAFT, with adjusted binary interaction parameters (BIPs) using a wide range of available experimental data. Good agreement between the predictions and the experimental results confirms the reliability of the thermodynamic model. We also performed a series of sensitivity analyses to identify the accuracy range of each EOS in terms of pressure, temperature, and salinity.

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In this work, we conducted a mechanistic study on pore-scale mechanisms controlling heat transfer in partially saturated porous media at unfrozen and frozen conditions. Experimental measurement of effective thermal conductivity (ETC) of simulated partially saturated sediments was carried out to explore the effect of different parameters including pore and overburden pressures, temperature, and water/ice saturation on the pore-scale mechanisms governing heat transfer in multiphase porous media. The experimental measurements show that the heat transfer is a complex phenomenon affected by several important pore-scale mechanisms such as particle-particle conduction and particle-fluid-particle conduction, which are governed by water content and distribution, packing structure, wettability characteristics of grains, coordination number, and physical contact among sediment particle. A numerical model was also developed for prediction of ETC using free-energy lattice Boltzmann model and a space renormalization method. The model predictions were in good agreement with the experimental data, showing that the model is able to reliably estimate ETC with average relative deviations of less than 10%, as it appropriately incorporates the pore-scale mechanisms influencing ETC. The numerical model predictions were also compared with those of six predictive models available in the literature, and root-mean-square errors were calculated to assess its accuracy against the existing models.