Numerical Simulation Analysis of Unsteady Temperature in Thermal Insulation Supporting Roadway

Shu-guang, Zhang; Lu, Pingping; Wang, Hongwei

doi:10.1155/2019/6279164

Cited by 3 publications

(3 citation statements)

References 12 publications

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“…Previous studies gener ally treated the surrounding rock as zero thickness and set the rock wall temperature as constant, using either temperature-boundary conditions or convective-heat-transfer-coef ficient-boundary conditions [21,36]. However, as the ventilation time increased, hea transfer within the rock and convective heat transfer between the rock wall and the air flow were coupled [37]. Considering the interaction of heat transfer in solids and convec tion in fluids, solid structures were added to the model to significantly improve the accu racy of the simulation.…”

Section: Geometric Modeling and Meshingmentioning

confidence: 99%

Performance Test and Thermal Insulation Effect Analysis of Basalt-Fiber Concrete

Zhang

Song

2022

Materials

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This paper examines the feasibility of applying inorganic thermal-insulating concrete in high geothermal roadways in underground coal mines. This innovative material is based on a mixture of ceramsite, glazed hollow beads, cement, and natural sand, enhanced with varying degrees of basalt fibers. Fibers were used as a partial substitute in the mixture, in the following volumes: 0% (reference specimen), 5%, 10%, 15%, and 20%. Their compressive strength, permeability resistance, and thermal conductivity were studied. A high content of fibers tends to entangle into clumps during mixing, resulting in a significant reduction in the mechanical properties of compressive strength. The appropriate amount of fiber content can improve impermeability, and the permeability height of 5% fiber concrete was reduced by 22.5%. Experiments on thermal behavior showed that an increase of basalt fibers leads to a significant reduction in thermal conductivity. For concrete containing 20% fiber, the thermal conductivity for the reference specimen (0%) in the wet state was reduced from 0.385 W/(m∙°C) to 0.098 W/(m∙°C). There was a slight increase in thermal conductivity when the temperature increased from 30 °C to 60 °C. Despite the reduced mechanical strength, the resulting concrete is well-suited for use in the insulation of underground roadways, as numerical simulations showed that insulating concrete with optimal fiber content (15%) can reduce the average temperature of the wind flow in a high ground temperature roadway of 100 m in length in a mine by 0.3 °C. The final cost-benefit analysis showed that insulating concrete has more economic benefits and broad development prospects when applied to high geothermal roadway cooling projects.

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Section: Geometric Modeling and Meshingmentioning

confidence: 99%

Performance Test and Thermal Insulation Effect Analysis of Basalt-Fiber Concrete

Zhang

Song

2022

Materials

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“…However, each of these equations is typically a multivariate function, so when the application scope is beyond the statistical scope, the error will be relatively large. In recent years, the numerical calculation models (e.g., FEM and FVM) for a single line of surrounding rock-airflow heat transfer have been included in the scholars' discussion scope [21][22][23]; nevertheless, since the relationships between the air temperature and numerous influencing factors (e.g., wall roughness, thermal physical parameters of rock, and moisture content of airflow) are highly nonlinear, scholars find it extremely hard to figure out parameters in these models. In addition, the models are rarely applied to whole ventilation networks on engineering sites as a result of missing parameters, deficient validation, and insufficient an description of the heat and mass transfer mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Predicting Temperature and Humidity in Roadway with Water Trickling Using Principal Component Analysis-Long Short-Term Memory-Genetic Algorithm Method

Wu,

Jia,

Zhang

et al. 2023

Applied Sciences

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The heat dissipated from high geo-temperature underground surrounding rocks is the main heat source of working faces, while thermal water upwelling and trickling into the roadway will notably deteriorate the mine’s climate and thermal comfort. Predicting airflow temperature and relative humidity (RH) is conductive to intelligent control of air conditioning cooling and ventilation regulation. To accommodate this issue, an intelligent technique was proposed, integrating a genetic algorithm (GA) and long short-term memory (LSTM) based on rock temperature, inlet air temperature, water temperature, water flow rate, RH, and ventilation time. A total of 21 input features including over 200 pieces of data were collected from an independently developed modeling roadway to construct a dataset. Principal component analysis (PCA) was conducted to reduce features, and GA was used to tune the LSTM and PCA-LSTM architectures for best performance. The following research results were yielded. The proposed PCA-LSTM-GA model is more reliable and efficient than the single LSTM model or hybrid LSTM-GA model in predicting the air temperature Tfout and humidity RHout at the end of the water trickling roadway. The importance scores (ISs) indicate that Tfout is mainly influenced by the surrounding rock temperature (IS 0.661) and the inlet air temperature (IS 0.264). While RHout is primarily influenced by the rock temperature in the water trickling section (IS 0.577), the inlet air temperature (IS 0.187), and the trickling water temperature and flow rate (total IS 0.136), and it has an evident time effect. In addition, we developed relevant equipment and provided engineering practice methods to use the machine learning model. The proposed model, which can predict the mine microclimate, serves to facilitate coal and geothermal resource co-mining as well as thermal hazard control.

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“…The results showed that the insulation layer greatly reduced the rock wall temperature and the disturbance range of the surrounding rock temperature; The smaller the thermal conductivity of the thermal insulation layer, the greater the decrease in roadway wall temperature and the greater the rate of change of its decrease curve. Zhang et al [20] used numerical simulation method to simulate and analyze the temperature field of the thermal insulation supporting roadway. The results showed that the temperature field of the heat insulation support structure does change significantly, but it has the effect of weakening the convective heat transfer between the surrounding rock wall and the airflow.…”

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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Numerical Simulation Analysis of Unsteady Temperature in Thermal Insulation Supporting Roadway

Cited by 3 publications

References 12 publications

Performance Test and Thermal Insulation Effect Analysis of Basalt-Fiber Concrete

Performance Test and Thermal Insulation Effect Analysis of Basalt-Fiber Concrete

Predicting Temperature and Humidity in Roadway with Water Trickling Using Principal Component Analysis-Long Short-Term Memory-Genetic Algorithm Method

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

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