Thermodynamic description of the process of gas liberation from a coal bed

A Model for Surface Diffusion of Adsorbed Gas in Nanopores of Shale Gas Reservoirs

“…For simple calculations, the isosteric adsorption heat is distributed uniformly (19) Influence of isosteric adsorption heat It is assumed that isosteric adsorption heat does not vary with temperature and can be calculated through different adsorption isothermal curves under different temperature. 13,28,43,54,55 According to the calculation and experimental results of Nodzeriski (1998), 28 the isosteric adsorption heat and gas coverage have a linear relationship and can be shown as (21) where ␥ is a fitting coefficient of isosteric adsorption heat, which is usually negative, J/mol, and ⌬H(0) is the isosteric adsorption heat when gas coverage is "0", J/mol. 13,28,43,54,55 According to the calculation and experimental results of Nodzeriski (1998), 28 the isosteric adsorption heat and gas coverage have a linear relationship and can be shown as (21) where ␥ is a fitting coefficient of isosteric adsorption heat, which is usually negative, J/mol, and ⌬H(0) is the isosteric adsorption heat when gas coverage is "0", J/mol.…”

“…The relationship between temperature and an adsorbed gas volume can be expressed as 28,55 The relationship between temperature and an adsorbed gas volume can be expressed as 28,55 …”

Sorption of methane on lignite from Polish deposits

“…For the description of the aforementioned isotherms, the thermal sorption equation (Czepirski and Jagiełło, 1989;Jagiełło et al, 1992) was applied. The virial form of the equation was used:…”

Energetic effects of adsorption of C6-C8hydrocarbons on hard coal samples of different metamorphism

“…The attempt for a formal description of the experimental isotherms using the thermal sorption equation isotherms was performed along with preparation of calculated isotherms. Thermal adsorption equation, which author used to describe the adsorption equilibrium, was derived from Jagiello and co-authors [22,23]. The experimental data were governed by the thermal equation of sorption based on an empirical fact that isosteric heat of sorption is in fact temperature-invariant in a wide range of temperatures.…”

“…Presented dependencies were of declining character, with increasing values of sorption once the values of isosteric heat of sorption decrease, however values were not reaching the heat of condensation. Isosteric heat values may indicate the physical nature of the hydrocarbons molecules interaction with hard coal [22]. Isosteric heat of sorption curves as a function of filling the surface may suggest energy heterogeneity of the studied coal adsorbents.…”