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Abstract

The coal matrix can expand after gas adsorption, thus reducing the permeability of coal reservoirs and further affecting the coalbed methane production. Whether the heat released by coal adsorbing gas is a cause of the coal expansion has not yet been determined. Therefore, the anthracite coal with high gas adsorption capacity was used; under the conditions of 35°C and 1-6 MPa, the adsorption capacity and the adsorption heat of coal adsorbing CO₂ and CH₄ were tested. The specific heat capacity and thermal expansion coefficient of coal at 35°C were tested. The temperature change of the coal after being heated was calculated by combining the absorption heat and specific heat capacity; also, the thermal expansion rate was calculated by combining the temperature change and expansion coefficient. In addition, the cube law was used to calculate the permeability change of coal before and after the adsorption expansion. The results show that the changes in the gas adsorption capacity and adsorption heat of the coal obey the Langmuir equation, and those to CO₂ are both higher than to CH₄. The temperature of coal increases after the heat is released in the process of CO₂ and CH₄ adsorption, and the temperature change of coal adsorbing CO₂ and CH₄ reaches 102°C and 72°C, respectively, at 6 MPa. The thermal expansion rate of coal adsorbing CO₂ and CH₄ reaches 5.40% and 3.81%, at 6 MPa, respectively. It is found that a higher gas pressure could lead to a higher temperature change, a higher thermal expansion rate, as well as a higher thermal expansion and coal deformation. After the adsorption of CO₂ and CH₄, the coal permeability is reduced by 20.43% and 14.66%, respectively, at 6 MPa. Both the thermal expansion rate and the permeability change with the gas adsorption pressure obey the Langmuir equation. Therefore, the adsorption expansion of coal may be thermal expansion caused by the heat released by coal adsorbing gas.

1. Introduction

Coal is a typical dual-porosity rock with matrix pores and fractures, in which matrix pores are the main space for the storage of coalbed methane (CBM), and fractures are the main channels for CBM to migrate [1, 2]. The gas adsorption and desorption of coal can cause the expansion and shrinkage of the coal [3, 4], leading to the change in fracture width and so does the permeability, affecting the production efficiency of CBM [5–7].

Previous studies have found that the coal expansion caused by gas adsorption refers to different mechanisms [8–10]. Specifically, during the gas adsorption process, the pressure drives the gas molecules into the pores and fractures of the coal, prompting the sorption layer to wedge microfissures with similar diameters of gas molecules, thereby causing the coal to expand [11]. Also, the interaction between the gas molecules adsorbed on the coal surface and the coal molecules may lead to expansion [12]. In addition, the van der Waals force on the coal fracture surface is weakened during the gas adsorption process, causing a decrease in the internal attraction energy of the coal and an increase in the expansion energy, which could also result in the expansion [13, 14]. Note that the heat change caused by gas adsorption/desorption would lead to the change in coal temperature [15–18], while coal has the property of thermal expansion, which means thermal expansion during the gas adsorption/desorption process could also be a cause of coal deformation. However, there is no sufficient evidence to prove this.

Some publications have studied the temperature change of coal during the adsorption/desorption process through contact thermometers or sensors [19–23]. They found that the coal is accompanied by energy conversion, which indicates that there will be a temperature change in the coal. The gas adsorption in coal will release heat, which will increase the coal temperature. While gas desorption is reversible, it will absorb heat and reduce the coal temperature [24, 25]. Also, the change range of coal temperature is related to multiple factors, such as the pressure, gas adsorption characteristics, and coal metamorphism degree. Generally, the higher gas pressure, gas adsorption ability, and the coal metamorphism degree could lead to greater temperature change in the coal during the gas adsorption/desorption process [26, 27].

In this paper, experiments were conducted to determine the isothermal adsorption capacity and adsorption heat of coal samples to CO₂ and CH₄, the specific heat capacity, and the expansion coefficient of coal. On this basis, the temperature change and thermal expansion rate of the coal after being heated were calculated, and the relationship between the temperature change and the deformation of the coal was analyzed. The cubic law was used to determine the coal permeability change, and the influence of thermal expansion on permeability was investigated, which could provide a theoretical basis for further research on the CBM production law and the geological storage of carbon dioxide in coal reservoirs.

2. Experiments and Methods

2.1. Coal Sample Collection and Preparation

In this study, coal samples from Zhongma Mine in Jiaozuo, Henan Province, were collected as experimental samples, and the coal characteristics are shown in Table 1. Some coal samples were pulverized and sieved to 60-80 mesh for the tests of isothermal adsorption, adsorption heat, and specific heat capacity. In addition, some coal was made into cubic coal blocks with the size of $10 \times 5 \times 5 mm$ , and the prepared samples were vacuum-dried in a DHG-9055A electrothermal vacuum dryer at 100°C for 6 h and sealed for the thermal expansion coefficient test.

Table 1

Vitrinite reflectance and proximate analysis of the coal sample.

Sample name	$R$ o (%)	Proximate analysis
Sample name	$R$ o (%)	$M$ ad (%)	$A$ ad (%)	$V$ ad (%)	$F$ Cad (%)
ZM	4.2	0.43	9.64	8.28	81.65

$R$ o: vitrinite reflectance; $M$ ad: moisture; $A$ ad: ash yield; $V$ ad: volatile matter; $F$ Cad: fixed carbon.

2.2. Isothermal Adsorption Test and Adsorption Heat Test

The ISO-300 isothermal adsorption instrument was used to measure the isothermal adsorption capacity of coal samples to CO₂ and CH₄ at 35°C. Under the conditions of 35°C and 1-6 MPa, the heat released by the adsorption of CO₂ and CH₄ in the coal samples was measured by the French Setaram C80 calorimeter.

2.3. Test of Coal-Specific Heat Capacity and Thermal Expansion Coefficient

The specific heat capacity of coal samples at different temperatures was measured by Naichi DSC 200F3 specific heat capacity instrument. The linear expansion coefficient of the coal samples at different temperatures was determined by DIL402C NETZSCH thermal expansion coefficient device.

3. Results and Discussion

3.1. Variation of Gas Adsorption Capacity and Adsorption Heat

The results of the isothermal adsorption test and the heat of adsorption test are shown in Table 2 and Table 3, respectively.

Table 2

Isothermal adsorption of CO₂ and CH₄ to coal samples under different pressures.

	CO₂						CH₄
Pressure (MPa)	0.44	1.34	2.27	3.23	4.35	5.49	0.81	1.57	2.60	3.90	5.53	7.46
Adsorption capacity (m³/t)	33.13	47.89	53.09	56.39	58.17	59.38	19.41	25.04	29.30	31.05	32.45	33.23

Table 3

Adsorption heat of coal samples to CO₂ and CH₄ under the pressure of 1-6 MPa.

Pressure (MPa)	Adsorption heat (J/g)
Pressure (MPa)	CO₂	CH₄
1	33.585	16.110
2	42.805	34.530
3	72.516	42.310
4	87.786	50.897
5	94.750	60.210
6	103.274	72.980

Through Equation (1), the isotherm data of coal to CO₂ and CH₄ were fitted, and the curve of the isotherm adsorption of the coal to the two gases was obtained (Figure 1). With the increase of pressure, the adsorption capacity of coal samples for both gases showed a trend of rapid increase at first and then gradually stabilized. The adsorption capacity of CO₂ is always greater than that of CH₄. The Langmuir volume $V_{L}$ and Langmuir pressure $P_{L}$ for CO₂ adsorption of coal samples are 64.103 m³/t and 0.436 MPa, respectively, and those for CH₄ adsorption are 36.364 m³/t and 0.684 MPa, respectively (Table 4). $\begin{matrix} (1) & V = \frac{V_{L} p}{P_{L} + p}, \end{matrix}$ where $V$ is the adsorption capacity, m³/t, $V_{L}$ is the Langmuir volume, m³/t, $p$ is the pressure, MPa, and $P_{L}$ is the Langmuir pressure, MPa.

Figure 1

Adsorption isotherms of CO₂ and CH₄ on the coal samples.

Table 4

Parameters related to the adsorption capacity and adsorption heat and temperature change of coal to CO₂ and CH₄.

	Parameters related to adsorption capacity			Parameters related to adsorption heat			Parameters related to temperature change
	$V_{L}$ (m³/t)	$P_{L}$ (MPa)	$R^{2}$	$q_{L}$ (J/g)	$p_{L}$ (MPa)	$R^{2}$	$t_{L}$ (°C)	$p_{L}$ (MPa)	$R^{2}$
CO₂	64.103	0.436	0.999	217.37	6.41	0.982	213.93	6.41	0.985
CH₄	36.364	0.684	0.999	195.92	10.71	0.990	192.85	10.71	0.992

Through Equation (2), the adsorption heat data of coal to CO₂ and CH₄ were fitted, and the curve of the adsorption heat of the coal to the two gases was obtained (Figure 2). The results show that the adsorption heat of the two gases increases with the increase of the pressure, which conforms to the Langmuir equation and is consistent with the variation law of adsorption capacity. Also, it can be seen that the heat released by adsorption is positively correlated with the adsorption capacity. The adsorption heat parameter $q_{L}$ and pressure parameter $p_{L}$ of coal samples for CO₂ are 217.37 J/g and 6.41 MPa, respectively, and for CH₄, they are 195.92 J/g and 10.71 MPa (Table 4). $\begin{matrix} (2) & q = \frac{q_{L} p}{p_{L} + p}, \end{matrix}$ where $q$ is the adsorption heat, J/g, $q_{L}$ is the adsorption heat parameter, J/g, and $p_{L}$ is the pressure parameter, MPa.

Figure 2

Variation of adsorption heat of CO₂ and CH₄ by coal with pressure.

The gas molecules adsorbed on the coal surface interact with the coal surface molecules and generate intermolecular forces with previously adsorbed gas molecules to release heat. With the continuous gas adsorption process, the intermolecular forces become dominant, and the greater the adsorption pressure, the greater the gas intermolecular force and the heat released. In addition, consistent with the results of the adsorption capacity, the adsorption heat of the coal samples to CO₂ is greater than that of CH₄, which is because the physical adsorption force is the van der Waals force including the dispersion force and the inductive force. The greater the polarizability and ionization potential of the molecule, the greater the dispersion force and inductive force, and therefore, the larger the adsorption heat. The polarizability and ionization potential of CO₂ are 7.344 C·m²·V^-1 and 15.6 eV, respectively, which are greater than those of CH₄ of 6.541 C·m²·V^-1 and 13.79 eV [26]. Therefore, the adsorption heat of CO₂ is greater than CH₄.

3.2. Coal Sample Temperature Change

The results of the specific heat capacity and the thermal expansion coefficient test of coal at different temperatures are shown in Table 5. In this paper, the specific heat capacity and thermal expansion coefficient of coal at 35°C is selected.

Table 5

Specific heat capacity and linear expansion coefficient of coal samples at different temperatures.

Temperature (°C)	Specific heat capacity (J·g^-1·°C^-1)	Linear expansion coefficient (K^-1)
20	0.9070	$0.29 \times 10^{- 4}$
25	0.9402	$0.02 \times 10^{- 4}$
30	0.9740	$0.76 \times 10^{- 4}$
35	1.0161	$1.77 \times 10^{- 4}$
40	1.0570	$2.98 \times 10^{- 4}$

The temperature change of a unit mass coal after gas adsorption and heat release can be calculated by $\begin{matrix} (3) & Δ Τ = \frac{q}{c}, \end{matrix}$ where $Δ T$ is the temperature change of the coal samples, °C, $q$ is the adsorption heat, J/g, and $c$ is the specific heat capacity, J·g^-1·°C^-1.

The gas adsorption/desorption process is accompanied by the temperature change of the coal. If the adsorption system is adiabatic and does not exchange heat with the outside environment, the temperature change of the coal can be calculated by the adsorption heat and the specific heat capacity (Table 6). Equation (4) was used to fit the temperature change of coal samples to CO₂ and CH₄ under different pressures, and the fitting result is shown in Figure 3. The temperature change parameter $t_{L}$ and the pressure parameter $p_{L}$ of the coal samples are 213.93°C and 6.41 MPa for CO₂ and 192.85°C and 10.71 MPa for CH₄ (Table 4). $\begin{matrix} (4) & Δ Τ = \frac{t_{L} p}{p_{L} + p}, \end{matrix}$ where $t_{L}$ is the temperature change parameter, °C.

Table 6

The temperature change of the coal samples under the pressure of 1-6 MPa due to the adsorption of CO₂ and CH₄.

$P$ (MPa)	$C$ (J·g^-1·°C^-1)	$Δ T$ (°C)
$P$ (MPa)	$C$ (J·g^-1·°C^-1)	CO₂	CH₄
1	1.0161	33.05	15.85
2		42.13	33.98
3		71.37	41.64
4		86.40	50.09
5		93.25	59.26
6		101.64	71.82

Figure 3

Variation of temperature change with pressure on coal adsorption of CO₂ and CH₄.

It can be seen from Figure 3 that the temperature change of the coal samples increases with the gas pressure and obeys the Langmuir equation (Equation (4)). Since the adsorption heat of coal to CO₂ is larger than that of CH₄, the temperature change of CO₂ adsorption by coal is always larger than that of CH₄, and the change law of its curve is similar to that of adsorption heat. At 6 MPa, the temperature changes of the coal samples adsorbing CO₂ and CH₄ reach 102°C and 72°C, respectively, which has not been found in previous studies. In the gas adsorption/desorption process under the in-situ conditions of the reservoir, since the environment cannot be adiabatic, the temperature change of coal will not be so severe. According to the statistics of changes in reservoir temperature during CBM development in Qinshui Basin [28], it is found that with the progress of drainage, the reservoir temperature generally decreases.

3.3. Thermal Expansion Rate and Permeability Change

3.3.1. Thermal Expansion Rate

Objects have expansion and contraction due to temperature changes [9]. Through the positive and negative values of the coal thermal expansion rate, we can intuitively observe whether the increase in coal temperature will cause the expansion of the coal matrix. That is, the value of the coal thermal expansion rate is positive, which proves that the increase in coal temperature will lead to the expansion of the coal matrix. So, the thermal expansion rate in this section is calculated.

By measuring the linear expansion coefficient of the coal samples, the volume expansion coefficient can be obtained as $\begin{matrix} (5) & β = 3 α, \end{matrix}$ where $β$ is the volume expansion coefficient, K^-1, and $α$ is the linear expansion coefficient, K^-1.

From Equation (5), the thermal expansion rate of the coal can be obtained: $\begin{matrix} (6) & k = β Δ Τ \times 100 %, \end{matrix}$ where $k$ is the thermal expansion rate, %, $β$ is the volume expansion coefficient, K^-1, and $Δ T$ is the temperature change of the coal samples, °C.

The volume expansion coefficient of the coal was obtained according to Equation (5), and the thermal expansion rate was obtained by substituting the volume expansion coefficient and the temperature change of the coal samples into Equation (6), as shown in Table 7. The thermal expansion rate of coal adsorption of CO₂ and CH₄ under different pressures was fitted by Equation (7), which shows the similar trends of the Langmuir equation (Figure 4), and the thermal expansion rate of CO₂ is always greater than that of CH₄, and the thermal expansion coefficient $k_{L}$ and pressure parameter $p_{L}$ of the coal samples are 11.34% and 6.39 MPa for CO₂, and 10.27% and 10.76 MPa for CH₄ (Table 8), where $k_{L}$ and $p_{L}$ are the parameters derived from nonlinear curve fitting of the curve of thermal expansion rate changing with adsorption pressure through Origin drawing software. According to the results, at 6 MPa, the thermal expansion rate of the coal samples adsorbing CO₂ and CH₄ reaches 5.40% and 3.81%, respectively, indicating that the coal will expand when it is heated. $\begin{matrix} (7) & k = \frac{k_{L} p}{p_{L} + p}, \end{matrix}$ where $k_{L}$ is the thermal expansion coefficient parameter, %.

Table 7

The thermal expansion rate and permeability change of coal matrix adsorbing CO₂ and CH₄ under the pressure of 1~6 MPa.

$P$ (MPa)	$Α$ (K^-1)	$Β$ (K^-1)	$K$ (%)		$Δ K$ (%)
$P$ (MPa)	$Α$ (K^-1)	$Β$ (K^-1)	CO₂	CH₄	CO₂	CH₄
1	$1.77 \times 10^{- 4}$	$5.31 \times 10^{- 4}$	1.76	0.84	-6.91	-3.33
2			2.24	1.8	-8.76	-7.07
3			3.79	2.21	-14.59	-8.65
4			4.59	2.66	-17.52	-10.36
5			4.95	3.15	-18.82	-12.2
6			5.40	3.81	-20.43	-14.66

Figure 4

Variation of thermal expansion rate and permeability change of coal adsorbing CO₂ and CH₄ with pressure.

Table 8

Parameters related to the thermal expansion rate and permeability change of coal to CO₂ and CH₄.

	Parameters related to the thermal expansion rate			Parameters related to permeability change
	$k_{L}$ (%)	$p_{L}$ (MPa)	$R^{2}$	$Δ k_{L}$ (%)	$p_{L}$ (MPa)	$R^{2}$
CO₂	11.34	6.39	0.985	40.59	5.72	0.985
CH₄	10.27	10.76	0.992	36.74	9.57	0.992

3.3.2. Permeability Change

The coal will absorb the gas to release heat and cause thermal expansion, while desorb the gas to absorb heat and cause shrinkage, resulting in the change of the reservoir fracture width (Figure 5). Cubic law can be used to characterize the relationship between fracture width and reservoir permeability, which treats the fracture as a parallel plate with a certain degree of opening. Under the action of a stable equilibrium pressure gradient, the cubic law expression can be derived from the Navier-Stokes equation and expressed as follows [29–31]: $\begin{matrix} (8) & Q_{v} = \frac{_{{l b}^{3}}}{12 μ} \times \frac{d p}{d l}, \end{matrix}$ where $Q_{v}$ is the flow rate, m³/s, $b$ is the crack opening, m, $p$ is the pressure, Pa, $l$ is the length of the parallel plate, m, and $μ$ is the dynamic viscosity coefficient of the fluid, mPa·s. Substitute the fracture porosity $φ_{f} = b l / A$ (single fracture porosity $φ_{f} = 1$ , $A$ is the cross-sectional area of the sample, m²) into Equation (8): $\begin{matrix} (9) & Q_{v} = \frac{_{φ_{f} A b^{2}}}{12 μ} \times \frac{d p}{d l} . \end{matrix}$

Figure 5

Variation of crack width before and after coal matrix expansion.

Assuming the equivalent permeability of the fractured coal samples is $K$ (m²), then Darcy’s law can be expressed as $\begin{matrix} (10) & Q_{v} = \frac{K A}{μ} \times \frac{d p}{d l} . \end{matrix}$

Comparing Equation (9) and Equation (10), the relationship between equivalent permeability and fracture width can be obtained as $\begin{matrix} (11) & Κ = \frac{b^{2}}{12} . \end{matrix}$

According to Equation (11), the permeability of the coal before and after the thermal expansion can be obtained, and then, the permeability change $Δ K$ of the coal after thermal expansion can be obtained (Table 7). The curve of the permeability change of CO₂ and CH₄ with pressure was obtained by fitted in Equation (12), as shown in Figure 4. The thermal expansion rate of coal to CO₂ is always greater than that of CH₄. With the increase of pressure, the permeability decrease of coal adsorption of CO₂ and CH₄ increases, which also obeys the Langmuir equation [32], and the permeability change parameter $Δ k_{L}$ and pressure parameter $p_{L}$ of coal samples are 40.59% and 5.72 MPa for CO₂ and 36.74% and 9.57 MPa for CH₄ (Table 8). At 6 MPa, the permeability change of coal after the adsorption of CO₂ and CH₄ is 20.43% and 14.66%, which are lower than that before gas adsorption and are consistent with the changing trend of adsorption capacity and adsorption heat. It shows that the thermal expansion of the coal will occur when it is heated and cause the fracture width to become smaller, further leading to the decrease of coal reservoir permeability. $\begin{matrix} (12) & Δ k = \frac{Δ k_{L} p}{p_{L} + p}, \end{matrix}$ where $Δ k_{L}$ is the change parameter of coal sample permeability, %.

4. Conclusions

In this paper, the relationship among adsorption capacity, adsorption heat, coal temperature change, thermal expansion rate, and permeability change was obtained by analysis. The cubic law is used to characterize the relationship between the permeability and the coal fracture width.

It was found that the adsorption capacity and adsorption heat of coal to CO₂ and CH₄ showed a trend of rapid increase at first and then gradually stabilized with the increase of pressure, and the adsorption capacity and adsorption heat of coal to CO₂ were both larger than of CH₄. The coal temperature change, thermal expansion rate, and permeability change have the same variation law as the adsorption heat and all obey the Langmuir equation.

The heat released by the coal-adsorbed gas increases the temperature of the coal. The greater the adsorption heat, the greater the temperature change and the greater the thermal expansion rate, that is, the greater the degree of expansion deformation of the coal. It shows that the expansion caused by coal-adsorbed gas may be caused by the thermal expansion caused by the increase in coal temperature. The expansion deformation of the coal will compress the fracture channels of the coal, which leads to a decrease in permeability. This study can provide an experimental basis for realizing the dual benefits of CBM production increase and carbon dioxide sequestration in the process of engineering application.

Footnotes

Data Availability

The data used to support the findings of this study are available from the corresponding author upon request.

Disclosure

A preprint of this manuscript is at the following link: .

Conflicts of Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This work was supported by the National Natural Science Foundation of China (42072193), Natural Science Foundation of Henan Province for Young Scientists of Henan Province, China (222300420173), and the Science and Technology Major Project of Shanxi Province (20191102001).

References

Luo

Y. F.

Xia

B. W.

H. L.

H. R.

M. Y.

K. N.

Fractal permeability model for dual-porosity media embedded with natural tortuous fractures

Fuel 2021 295, article 120610

5201794

10.1016/j.fuel.2021.120610

Min

Bai

S. G.

Factors influencing the gas adsorption thermodynamic characteristics of low-rank coal

Fuel 2019 248

5201794

5 117 126

10.1016/j.fuel.2019.03.064

2-s2.0-85063010193

Guo

Wang

Z. M.

Zhao

Y. L.

A comprehensive model for the prediction of coal swelling induced by methane and carbon dioxide adsorption

Journal of Natural Gas Science and Engineering 2016 36, Part A

5201794

563 572

10.1016/j.jngse.2016.10.052

2-s2.0-84994479765

Pan

J. N.

M. M.

Hou

Q. L.

Han

Y. Z.

Wang

Coal microcrystalline structural changes related to methane adsorption/desorption

Fuel 2019 239

5201794

5 13 23

10.1016/j.fuel.2018.10.155

2-s2.0-85056197099

Zhang

Tang

D. Z.

Gan

Niu

Wang

Shen

Coal pore size distributions controlled by the coalification process: an experimental study of coals from the Junggar, Ordos and Qinshui basins in China

Fuel 2017 206

5201794

352 363

10.1016/j.fuel.2017.06.028

2-s2.0-85020712334

Yang

J. H.

Pan

Tong

Nanoscale pore structure and mechanical property analysis of coal: an insight combining AFM and SEM images

Fuel 2020 260, article 116352

5201794

10.1016/j.fuel.2019.116352

Qiang

Harpalani

Liu

A simplified permeability model for coalbed methane reservoirs based on matchstick strain and constant volume theory

International Journal of Coal Geology 2011 85

5201794

1 43 48

10.1016/j.coal.2010.09.007

2-s2.0-78650678998

Connell

L. D.

Detournay

Coupled flow and geomechanical processes during enhanced coal seam methane recovery through CO₂ sequestration

International Journal of Coal Geology 2009 77

5201794

1-2 222 233

10.1016/j.coal.2008.09.013

2-s2.0-57649156362

Pan

Connell

L. D.

A theoretical model for gas adsorption-induced coal swelling

International Journal of Coal Geology 2007 69

5201794

4 243 252

10.1016/j.coal.2006.04.006

2-s2.0-33846404468

10.

Pan

Z. J.

Connell

L. D.

Modelling of anisotropic coal swelling and its impact on permeability behaviour for primary and enhanced coalbed methane recovery

International Journal of Coal Geology 2011 85

5201794

3-4 257 267

10.1016/j.coal.2010.12.003

2-s2.0-79951549862

11.

Larsen

J. W.

The effects of dissolved CO₂ on coal structure and properties

International Journal of Coal Geology 2004 57

5201794

1 63 70

10.1016/j.coal.2003.08.001

2-s2.0-1642504703

12.

Ozdemir

Morsi

B. I.

Schroeder

CO₂ adsorption capacity of argonne premium coals

Fuel 2004 83

5201794

7-8 1085 1094

10.1016/j.fuel.2003.11.005

2-s2.0-1342302116

13.

F. H.

Yuan

Y. Y.

Chen

X. J.

Expansion energy of coal gas for the initiation of coal and gas outbursts

Fuel 2019 235

5201794

551 557

10.1016/j.fuel.2018.07.132

2-s2.0-85051490093

14.

Liang

W. G.

Zhang

B. N.

Z. W.

Experimental study on swelling deformation characteristics of coal bodies of different ranks by adsorption and storage of CO₂

Journal of China Coal Society 2018 43

5201794

5 1408 1415

10.13225/j.cnki.jccs.2017.1138

2-s2.0-85053628903

15.

Liu

Z. X.

Feng

Z. C.

Zhang

Q. M.

Zhao

Guo

H. Q.

Heat and deformation effects of coal during adsorption and desorption of carbon dioxide

Journal of Natural Gas Science and Engineering 2015 25

5201794

5 242 252

10.1016/j.jngse.2015.04.024

2-s2.0-84929160367

16.

Feng

Z. C.

Cai

T. T.

Zhou

Zhao

Y. S.

Wang

Temperature and deformation changes in anthracite coal after methane adsorption

Fuel 2017 192

5201794

27 34

10.1016/j.fuel.2016.12.005

2-s2.0-85002702076

17.

Kang

Zhu

Wang

Zhou

Liu

Dynamical modeling of coupled heat and mass transfer process of coalbed methane desorption in porous coal matrix

International Journal of Heat and Mass Transfer 2022 183, Part C, article 122212

5201794

10.1016/j.ijheatmasstransfer.2021.122212

18.

Nodzeński

Sorption and desorption of gases (CH₄, CO₂) on hard coal and active carbon at elevated pressures

Fuel 1998 77

5201794

11 1243 1246

10.1016/S0016-2361(98)00022-2

2-s2.0-0032166893

19.

Wang

Z. F.

Tang

Yue

G. W.

Kang

Xie

X. J.

Physical simulation of temperature influence on methane sorption and kinetics in coal: benefits of temperature under 273.15K

Fuel 2015 158

5201794

207 216

10.1016/j.fuel.2015.05.011

2-s2.0-84930640583

20.

Meng

Z. P.

Liu

S. S.

G. Q.

Adsorption capacity, adsorption potential and surface free energy of different structure high rank coals

Journal of Petroleum Science & Engineering 2016 146

5201794

856 865

10.1016/j.petrol.2016.07.026

2-s2.0-84989855497

21.

Zhu

C. J.

Ren

Wan

J. M.

Lin

B. Q.

Yang

Methane adsorption on coals with different coal rank under elevated temperature and pressure

Fuel 2019 254, article 115686

5201794

10.1016/j.fuel.2019.115686

2-s2.0-85067691294

22.

Liu

J. K.

Wang

C. X.

X. Q.

S. G.

Infrared measurement of temperature field in coal gas desorption

International Journal of Mining Science and Technology 2014 24

5201794

1 57 61

10.1016/j.ijmst.2013.12.010

2-s2.0-84892442910

23.

Guo

L. W.

Jiang

C. L.

Analysis of factors affecting temperature change during coal and gas outburst

Journal of China Coal Society 2000 4

5201794

401 403

10.13225/j.cnki.jccs.2000.04.015

24.

Sunil

Harish

J. P.

Rajwardhan

N. A.

Bhasakar

Lalit

Study of adsorption characteristics of Au(III) onto coal particles and their application as radiotracer in a coal gasifier

Applied Radiation and Isotopes 2017 122

5201794

127 135

10.1016/j.apradiso.2016.12.059

2-s2.0-85010655321

28160715

25.

Meng

Z. P.

Experimental comparisons of gas adsorption, sorption induced strain, diffusivity and permeability for low and high rank coals

Fuel 2018 234

5201794

5 914 923

10.1016/j.fuel.2018.07.141

2-s2.0-85050880680

26.

H. J.

Research on the Thermal Effect of Coal Adsorbing Gas 2019

China University of Mining and Technology

27.

Kang

Elsworth

Liang

Chen

Contribution of thermal expansion on gas adsorption to coal sorption-induced swelling

Chemical Engineering Journal 2022 432

5201794

15, article 134427

10.1016/j.cej.2021.134427

28.

Han

S. J.

Sang

S. X.

Duan

P. P.

Zhang

J. C.

Xiang

W. X.

The effect of the density difference between supercritical CO₂ and supercritical CH₄ on their adsorption capacities: an experimental study on anthracite in the Qinshui Basin

Petroleum Science 2022 19

5201794

4 1516 1526

10.1016/j.petsci.2022.03.003

29.

Y. Y.

Chen

X. Y.

H. L.

Tang

J. R.

Zhou

Han

An improved cubic law for shale fracture considering the effect of loading path

International Journal of Oil, Gas and Coal Technology 2021 26

5201794

1 25 39

10.1504/IJOGCT.2021.111871

30.

Zhou

C. B.

Xiong

W. L.

Generalized cubic theorem of seepage in rock joints

Rock and Soil Mechanics 1996 17

5201794

4 7

10.16285/j.rsm.1996.04.001

31.

C. L.

Reservoir Engineering Principles 2017

Beijing

Petroleum Industry Press

32.

Wang

X. B.

S. Y.

Wang

L. N.

Experimental investigation of the thermal expansion characteristics of coal induced by gas adsorption

2022 https://ssrn.com/abstract=4134164

10.2139/ssrn.4134164

Experimental Investigation of the Thermal Expansion Characteristics of Anthracite Coal Induced by Gas Adsorption

Abstract

1. Introduction

2. Experiments and Methods

2.1. Coal Sample Collection and Preparation

2.2. Isothermal Adsorption Test and Adsorption Heat Test

2.3. Test of Coal-Specific Heat Capacity and Thermal Expansion Coefficient

3. Results and Discussion

3.1. Variation of Gas Adsorption Capacity and Adsorption Heat

3.2. Coal Sample Temperature Change

3.3. Thermal Expansion Rate and Permeability Change

3.3.1. Thermal Expansion Rate

3.3.2. Permeability Change

4. Conclusions

Footnotes

Data Availability

Disclosure

Conflicts of Interest

Acknowledgments

References