scholarly journals Volumetric Measurements of Methane-Coal Adsorption and Desorption Isotherms—Effects of Equations of State and Implication for Initial Gas Reserves

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 2022 ◽  
Author(s):  
Jamiu M. Ekundayo ◽  
Reza Rezaee
Keyword(s):  
Bituminous Coal ◽  
Equations Of State ◽  
Hysteresis Loops ◽  
Desorption Isotherm ◽  
Model Parameters ◽  
Adsorbed Gas ◽  
Desorption Isotherms ◽  
Compressibility Factors ◽  
Gas Compressibility ◽  
Adsorption Curve

This study presents the effects of equations of state (EOSs) on methane adsorption capacity, sorption hysteresis and initial gas reserves of a medium volatile bituminous coal. The sorption experiments were performed, at temperatures of 25 °C and 40 °C and up to 7MPa pressure, using a high-pressure volumetric analyzer (HPVA-II). The measured isotherms were parameterized with the modified (three-parameter) Langmuir model. Gas compressibility factors were calculated using six popular equations of state and the results were compared with those obtained using gas compressibility factors from NIST-Refprop® (which implies McCarty and Arp’s EOS for Z-factor of helium and Setzmann and Wagner’s EOS for that of methane). Significant variations were observed in the resulting isotherms and associated model parameters with EOS. Negligible hysteresis was observed with NIST-refprop at both experimental temperatures, with the desorption isotherm being slightly lower than the adsorption isotherm at 25 °C. Compared to NIST-refprop, it was observed that equations of state that gave lower values of Z-factor for methane resulted in “positive hysteresis”, (one in which the desorption isotherm is above the corresponding adsorption curve) and the more negatively deviated the Z-factors are, the bigger the observed hysteresis loop. Conversely, equations of state that gave positively deviated Z-factors of methane relatively produced “negative hysteresis” loops where the desorption isotherms are lower than the corresponding adsorption isotherms. Adsorbed gas accounted for over 90% of the calculated original gas in place (OGIP) and the larger the Langmuir volume, the larger the proportion of OGIP that was adsorbed.

EQUATIONS OF STATE FOR FLUIDS: THE LIQUID-VAPOR EQUILIBRIUM (LVE)

2008 ◽  
Vol 22 (30) ◽  
pp. 5335-5347 ◽  
Author(s):  
JIANXIANG TIAN ◽  
YUANXING GUI
Keyword(s):  
Experimental Data ◽  
Equations Of State ◽  
Packing Fraction ◽  
Optimal Choice ◽  
Critical Conditions ◽  
Mechanics Model ◽  
Vapor Equilibrium ◽  
Pure Substances ◽  
Compressibility Factors ◽  
Liquid Vapor

Historically, the development of equations of state for fluids has almost invariably followed the lead of the van der Waals (vdW) equation which includes an attraction term and a repulsion term. In this paper, using a simple statistical mechanics model, we introduce a parameter σ as both the power and a coefficient of the packing fraction y which locates at the numerator of the vdW attraction term. Then nine equations of state are constructed to solve the critical conditions and the main thermodynamic properties of pure substances at liquid-vapor equilibrium. As a result, the correct critical compressibility factors of Nitrogen, Argon, Carbon dioxide, Ethene, Methane, Oxygen, Propene, Water and Hydrogen, are obtained with an optimal choice of parameter σ. Good predictions of these equations to the liquid-vapor equilibrium properties below critical temperature are reported and compared with experimental data.

Variation in Pore Structure Characteristics with Composition in the High Volatile Bituminous Coal of Binchang Area

2014 ◽  
Vol 962-965 ◽  
pp. 890-898
Author(s):  
Jin Ping Li ◽  
Da Zhen Tang ◽  
Ting Xu Yu ◽  
Gang Sun
Keyword(s):  
Low Temperature ◽  
Pore Structure ◽  
Parallel Plate ◽  
Bituminous Coal ◽  
Nitrogen Adsorption ◽  
Bet Surface Area ◽  
Test Results ◽  
Structure Characteristics ◽  
Desorption Isotherms ◽  
Adsorption Desorption

Pore structure characteristics and the effect of lithotype and maceral on pore for three types of high-volatile bituminous coals from Binchang area were investigated by combined low-temperature nitrogen adsorption/desorption, nuclear magnetic resonance (NMR), scanning electron microscope (SEM) and maceral analysis. The low temperature N2 adsorption/desorption test results show that: micropores are more abundant than transitional pores with high BET surface area; two types of pore structures can be identified by adsorption/desorption isotherms; Pore morphology is mainly represented by well-connected, ink-bottled, cylindrical and parallel plate pores. NMR T2 distributions at full saturated condition are apparent or less obvious trimodal and three types of T2 distributions are identified; Seepage pores are better developed when compared with the middle-high rank coal. Further research found that the three coal lithotypes are featured by remarkably different pore structure characteristics and maceral contents of coal are linearly correlated to some of pore structure parameters.

Desorption Isotherm of Mango Soy Fortified Yoghurt

2005 ◽  
Vol 1 (5) ◽  
Author(s):  
Pradyuman Kumar ◽  
H. N. Mishra
Keyword(s):  
Water Activity ◽  
Goodness Of Fit ◽  
Static Method ◽  
Desorption Isotherm ◽  
Percentage Error ◽  
Typical Type ◽  
Sigmoid Curve ◽  
Relative Percentage Error ◽  
Desorption Isotherms ◽  
Residual Plots

Desorption isotherms of three yoghurt samples viz. plain yoghurt, mango soy fortified yoghurt (MSFY) and MSFY containing 0.4 % gelatin stabilizer (MSFYG) were determined by gravimetric static method at 20, 30, 40 and 50 °C in the range of 0.11 – 0.81 water activity. It was found that desorption isotherm of yoghurt samples follow a typical type III sigmoid curve. Experimental data were fitted to five mathematical models i. e. modified Henderson, modified Chung Pfost, Oswin, Smith and Guggenheim-Anderson-deBoer (GAB). Equations were developed for the prediction of the GAB constants as a function of temperature and these equations were used during modeling. Standard error of estimate (SE), mean relative percentage error (P), percent root mean square (% RMS) and trend of residual plots were used to compare the goodness of fit. It was found that the GAB models were acceptable in describing equilibrium moisture content – water activity relationships for yoghurt samples over the entire experimental temperature range.

Modeling of Magnetoelastic Materials for Force and Torque Sensors

2008 ◽  
Vol 144 ◽  
pp. 124-129 ◽  
Author(s):  
Roman Szewczyk ◽  
Jacek Salach ◽  
Adam Bieńkowski
Keyword(s):  
Amorphous Materials ◽  
Magnetic Hysteresis ◽  
Compressive Force ◽  
Hysteresis Loops ◽  
Evolutionary Strategies ◽  
Model Parameters ◽  
Extended Model ◽  
Gradient Optimization ◽  
Magnetoelastic Materials ◽  
Experimental Findings

The paper presents a new idea of extension of the Jiles-Atherton-Sablik model for modeling of the influence of mechanical stresses on magnetic hysteresis loops of amorphous alloys. In the extended model changes of parameter k are considered during the magnetization and the influence of stresses on eight parameters of the Jiles-Atherton-Sablik model is taken into account. Verification of the model was carried out on the base of experimental results obtained for Fe40Ni38Mo4B18 amorphous alloy subjected to both stress from external compressive force as well as shearing stresses from torque. In the experiment uniform stress distribution was achieved in both cases due to special mechanical system of backings. Evolutionary strategies were used in conjunction with gradient optimization for calculation of the model parameters. Results of simulation are in good agreement with experimental findings. As a result the extended Jiles- Atherton-Sablik model enables modeling of the magnetoelastic characteristics of amorphous materials for mechatronic inductive components such as compressive stress and torque sensors.

scholarly journals Bayesian Analysis for Extracting Properties of the Nuclear Equation of State from Observational Data Including Tidal Deformability from GW170817

Universe ◽  
2019 ◽  
Vol 5 (2) ◽  
pp. 61 ◽  
Author(s):  
Alexander Ayriyan ◽  
David Alvarez-Castillo ◽  
David Blaschke ◽  
Hovik Grigorian
Keyword(s):  
Equation Of State ◽  
Bayesian Analysis ◽  
Quark Matter ◽  
Equations Of State ◽  
Compact Star ◽  
String Tension ◽  
Model Parameters ◽  
Analysis Method ◽  
Hybrid Stars ◽  
Limiting Case

We develop a Bayesian analysis method for selecting the most probable equation of state under a set of constraints from compact star physics, which now include the tidal deformability from GW170817. We apply this method for the first time to a two-parameter family of hybrid equations of state that is based on realistic models for the hadronic phase (KVORcut02) and the quark matter phase (SFM α ) which produce a third family of hybrid stars in the mass–radius diagram. One parameter ( α ) characterizes the screening of the string tension in the string-flip model of quark matter while the other ( Δ P ) belongs to the mixed phase construction that mimics the thermodynamics of pasta phases and includes the Maxwell construction as a limiting case for Δ P = 0 . We present the corresponding results for compact star properties like mass, radius and tidal deformabilities and use empirical data for them in the newly developed Bayesian analysis method to obtain the probabilities for the model parameters within their considered range.

scholarly journals Study on Desorption Experiment and Desorption Model of Deep Shale Gas Containing Water

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Zuping Xiang ◽  
Yangyang Ding ◽  
Xiang Ao ◽  
Zehua Cheng ◽  
Qianhua Xiao ◽  
...  
Keyword(s):  
Water Content ◽  
Shale Gas ◽  
Desorption Process ◽  
Pressure Drops ◽  
Adsorbed Gas ◽  
Desorption Hysteresis ◽  
The Impact ◽  
Adsorption Curve ◽  
Desorption Model ◽  
Water Contents

In this work, the methane desorption isothermal curves at different water contents on deep sampled from Western Chongqing of China were measured at pressures up to 65 MPa and at 130°C by the volumetric method. In the first instance, the desorption increases with the decrease of pressure, the adsorbed gas desorbs slightly with decreasing pressures from 65 to 30 MPa. When the pressure drops to 30–20 MPa, the desorption rate increases rapidly with the decrease of pressure and the desorption curve begins to separate from the adsorption curve, resulting in desorption hysteresis. At last, when the pressure is lower than 20 MPa, the desorption increases almost linearly with the further decrease of pressure, but eventually there will be some adsorbed gas which cannot be desorbed to form residual adsorbed gas. After that, the isotherm desorption data of CH4 was fitted using the improved desorption model. The fitting results showed that the improved desorption model can be used to describe the desorption process of deep shale gas containing water and has a strong applicability. In addition, the critical desorption pressure increases with increasing water content. When the water content is lower than 1%, the effect of the water content on the desorption of deep shale gas increases rapidly with increasing water content, as well as when the water content is greater than 1%, the impact changes slowly.

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