The impact of thermal insulation on cooling energy consumption and optimal insulation thickness for underground tunnel

Wang, Yijiang; Wang, Chaochao; Gao, Shang; Zheng, Xiaofeng; Darkwa, Jo

doi:10.1016/j.seta.2021.101495

Cited by 8 publications

(6 citation statements)

References 42 publications

(50 reference statements)

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“…For thermal insulation, it is a common practice to spray special concrete or to set up a thermal insulation layer (TIL). Wang et al [20] analyzed how the materials of thermal insulation affect heat transfer by building a mathematical model, and based on that, they found the optimum thickness for the insulating layer according to the economic cost and insulating effect. Liu et al [21] demonstrated the beneficial effects of the insulating layer covered on the building surface in underground tunnels by developing a mathematical model.…”

Section: Introductionmentioning

confidence: 99%

Performance Analysis and Optimization of Coupled Cooling System for Auxiliary Ventilation and Partial Thermal Insulation in High Geothermal Tunnels

Li,

Jia,

et al. 2024

Applied Sciences

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A high temperature is the key factor limiting the safe development of deep mine tunnels. By confronting the phenomenon of serious heat exchange between airflow and the surrounding rocks in the tunnel excavation area, a conceptual model of coupled cooling of auxiliary ventilation and partial thermal insulation is proposed. The performance of a coupled cooling system was investigated and optimized by using the scale model test with a 1:10 geometric scale and the orthogonal test. The results suggest that the average temperatures of the work zone and its central point decrease by 1.5 °C and 3.3 °C, respectively, while partial insulation layers are used. According to the sensitivity analysis for a single factor, as the ventilation duct outlet (VDO) moves away from the working face (WF), the temperature gradually increases, leading to a local high temperature area. When the ventilation duct height is arranged in the middle of the insulation layer, the cooling effect is optimal and the highest average temperature difference is 4.4 °C. The thermal equilibrium temperature can be further decreased by lengthening and thickening the insulation layer. In addition, the range analysis shows that the ventilation velocity has a greater impact on the thermal environment of the tunnel working area than the ventilation duct location and insulation layer length. The coupled cooling method can save on cooling capacity and effectively alleviate the high-temperature problems of the tunnel excavation area.

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Section: Introductionmentioning

confidence: 99%

Performance Analysis and Optimization of Coupled Cooling System for Auxiliary Ventilation and Partial Thermal Insulation in High Geothermal Tunnels

Li,

Jia,

et al. 2024

Applied Sciences

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“…China is the largest coal producer and consumer in the world, and the share of coal in primary energy consumption has been greater than 50% for a long time. − As the depth and intensity of coal mining increase, mining conditions have become more and more complex and dangerous. − Spontaneous coal combustion is one of the most important threats, which mainly occurs in the gob area of longwall mining face. , The interior of the gob area is full of rocks after the collapse of the roof, forming a complex porous medium structure. − In addition, a large amount of crushed coal is left in the gob area. The fresh air leaking into the gob area oxidizes with the crushed coal, and the heat released from the reaction gradually accumulates and eventually causes a fire, leading to huge human and property losses. , …”

Section: Introductionmentioning

confidence: 99%

“… 1 − 4 As the depth and intensity of coal mining increase, mining conditions have become more and more complex and dangerous. 5 − 7 Spontaneous coal combustion is one of the most important threats, which mainly occurs in the gob area of longwall mining face. 8 , 9 The interior of the gob area is full of rocks after the collapse of the roof, forming a complex porous medium structure.…”

Section: Introductionmentioning

confidence: 99%

Gas Dispersion Coefficient Test System and Dimensionless Inversion Method for Porous Media

Qin,

Guo,

Zhang

et al. 2023

ACS Omega

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Due to the complex porous media structure of the longwall gob area, it has been difficult to determine the gas dispersion coefficient of oxygen when studying spontaneous coal combustion in the gob area. In this work, we first designed an experimental device for testing the gas diffusion coefficient of porous media. Then, the distribution law of gas concentration in porous media under different particle size conditions was obtained by experiments. Subsequently, we established a dimensionless mathematical model of gas dispersion in porous media and developed a corresponding numerical simulator based on the finite volume method (FVM). The influence of the dimensionless gas dispersion coefficient on the gas concentration distribution was analyzed, and then a dimensionless inversion method of the gas dispersion coefficient was summarized and put forward. Finally, we obtained the values of the gas dispersion coefficient in the experimental device under different particle size conditions by inversion and discussed its effect on the gas dispersion behavior in porous media. The results show that (1) the distribution of gas concentration obtained from the experimental test and numerical simulation is consistent, which verifies the reliability of our work; (2) the dimensionless gas concentration is the highest near the injection point and gradually decreases along the depth and both sides of the test container; (3) with the increase of the dimensionless gas dispersion coefficient, the distance required for uniform gas mixing in the test container is gradually shortened and the gas dispersion coverage is wider; and (4) the larger pore space facilitates the dispersion behavior of the gas, and the gas dispersion coefficient shows a parabolic trend with the increase of porous medium particle size.

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“…Many factors cause thermal hazards in mines, among which the heat dissipation of the high-temperature surrounding rock is the primary heat source that considerably increases the temperature of the mine airflow [9,10]. The roadway thermal insulation cooling method in non-artificial cooling can isolate heat dissipation from hightemperature rock strata, and reduce the mine cooling demand, thereby reducing the cooling system power consumption [11]. Therefore, studying the thermal insulation technology of high-temperature roadway surrounding rock is significant for controlling the thermal environment of deep mines.…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer Model and Thermal Insulation Characteristics of Surrounding Rock of Thermal Insulation Roadway in a High-Temperature Mine

Gao,

Li,

et al. 2023

Sustainability

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The thermal insulation method is one of the effective methods for controlling the thermal environment of a high-temperature mine. In order to explore the thermal insulation mechanism and characteristics of thermal insulation roadways in high-temperature mines, a heat transfer model for the surrounding rock of the thermal insulation roadway was established based on the steady heat transfer theory. The temperature field of the surrounding rock of the thermal insulation roadway was studied, and the effects and sensitivities of thermal insulation layer thickness and thermal conductivity, convective heat transfer coefficient between roadway wall and airflow, and roadway radius on the thermal insulation performance of thermal insulation roadway were discussed. The results suggest the following: (1) The temperature gradient inside the thermal insulation layer is greater than that inside the surrounding rock. The thermal insulation roadway reduces the temperature difference between the original rock and the outside surface of the thermal insulation layer, thereby reducing the heat dissipation of the surrounding rock. (2) As the thermal insulation layer thickness increases, the thermal insulation capacity gradually increases, but its enhancement rate gradually weakens; as the thermal conductivity of the thermal insulation layer or the roadway radius increases, the thermal insulation capacity gradually decreases and its decline rate gradually weakens; and the convective heat transfer coefficient between the roadway wall and airflow has almost no effect on the thermal insulation capacity. (3) The thermal insulation performance of the thermal insulation roadway is highly sensitive or above the thickness and thermal conductivity of the thermal insulation layer, as well as the roadway radius. The sensitivity of thickness and thermal conductivity of the thermal insulation layer is greater than that of roadway radius. Therefore, the research results have guiding significance for the application of thermal insulation methods in the prevention and control of thermal hazards in mines.

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The impact of thermal insulation on cooling energy consumption and optimal insulation thickness for underground tunnel

Cited by 8 publications

References 42 publications

Performance Analysis and Optimization of Coupled Cooling System for Auxiliary Ventilation and Partial Thermal Insulation in High Geothermal Tunnels

Performance Analysis and Optimization of Coupled Cooling System for Auxiliary Ventilation and Partial Thermal Insulation in High Geothermal Tunnels

Gas Dispersion Coefficient Test System and Dimensionless Inversion Method for Porous Media

Heat Transfer Model and Thermal Insulation Characteristics of Surrounding Rock of Thermal Insulation Roadway in a High-Temperature Mine

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