Despite a body of research carried out on thermally coupled processes in soils, understanding of thermo-osmosis phenomenon in clays and its effects on hydromechanical behavior is incomplete. This paper presents an investigation on the effects of thermo-osmosis on hydraulic behavior of saturated clays. A theoretical formulation for hydraulic behavior was developed, incorporating an explicit description of thermo-osmosis effects on coupled hydromechanical behavior. The extended formulation was implemented within a coupled numerical model for thermal, hydraulic, chemical, and mechanical behavior of soils. The model was tested and applied to simulate a soil heating experiment. It is shown that the inclusion of thermo-osmosis in the coupled thermohydraulic simulation of the case study provides a better agreement with the experimental data compared with the case in which only thermal expansion of the soil constituents was considered. A series of numerical simulations are also presented, studying the por...

An experimental campaign on the methane-oriented underground coal gasification (UCG) process was carried out in a large-scale laboratory installation. Two different types of coal were used for the oxygen/steam blown experiments, i.e., “Six Feet” semi-anthracite (Wales) and “Wesoła” hard coal (Poland). Four multi-day gasification tests (96 h continuous processes) were conducted in artificially created coal seams under two distinct pressure regimes-20 and 40 bar. The experiments demonstrated that the methane yields are significantly dependent on both the properties of coal (coal rank) and the pressure regime. The average CH₄ concentration for “Six Feet” semi-anthracite was 15.8%_vol. at 20 bar and 19.1%_vol. at 40 bar. During the gasification of “Wesoła” coal, the methane concentrations were 10.9%_vol. and 14.8%_vol. at 20 and 40 bar, respectively. The “Six Feet” coal gasification was characterized by much higher energy efficiency than gasification of the “Wesoła” coal and for both tested coals, the efficiency increased with gasification pressure. The maximum energy efficiency of 71.6% was obtained for “Six Feet” coal at 40 bar. A positive effect of the increase in gasification pressure on the stabilization of the quantitative parameters of UCG gas was demonstrated.