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Numerical Study on Effects of Airflow Parameters on the Air Temperature the at Mechanized Longwall of Mongduong Coal Mine

Nguyen Hong Thi, Nguyen Quang Van

Inżynieria Mineralna

2023

no. 2, vol. 1

89--96

The increasing depth of extraction and the degree of mechanization leading to the risk of workers working in poor microclimate conditions has become one of the major safety issues in coal mines. During the survey of the current microclimate in Mongduong coal mine, it showed that the temperature of the mechanized longwall exceeded the permissible regulations (t°≤ 30°C), the air humidity is about 95–100%. The reason for the increase of air temperature in longwall is due to geothermal, heat radiated from the longwall equipment and the inlet wind high temperature. To improve the thermal environment in the mechanized longwall area, Vietnam's coal mines open use ventilation, but the efficiency is not high. Therefore, the paper evaluated the influence of airflow on the temperature of the longwall, 7 models with different air flow velocities and 3 models with inlet air temperature have been created in ICM-CFD and simulated by Ansys CFX software. The environment temperature of each model was evaluated by analyzing the average temperature of the roadway section, the cross-section distribution of the roadway temperature and the velocity streamline of the whole roadway. As a result, the air flow rate increases leading to the air temperature in the longwall decreases, however the wind speed is limited. The inlet temperature of the gas stream is an important factor that affects the thermal environment in the longwall. The results of the article are the basis for making solutions to improve the thermal environment suitable for high-temperature longwall.

Some Effects on the Temperature of the Mine Air at the Heading Face

Nguyen Van Quang, Nguyen Van Thinh, Nguyen Cao Khai, Pham Van Chung

Inżynieria Mineralna

2021

no. 2

423--432

Currently, with the increase in mining output leading to deeper mining levels, the volume of heading face serving production has also increased. The thermal environment tends to worsen when digging deep due to the geothermal's effect, which increases the air temperature at the heading face. According to QCVN01/2011-BCT, the temperature at the heading face is not allowed to exceed 300C. To ensure this, in Vietnam today, mainly forced ventilation method uses local fans to provide a clean amount of air to ensure a favorable environment for workers. With the forced ventilation method, the duct position is usually arranged on the side, and the distance from the duct mouth to the heading face is determined to ensure that l < 6√s. In this study, a numerical simulation method by Ansys CFX software is applied to study the influence of several factors such as duct position, air temperature of duct, and roughness characteristics of roadway on the temperature of the mine air at the heading face. The models are set up with six duct positions and four air temperature of duct parameters. Model 1 (y =1.1 m) is better than models 2 to 6 in terms of temperature distribution and the lowest temperature values. Four models have different wind temperatures, and we can see the significant influence of the inlet air temperature of the duct on the thermal environment of the heading face. The results show that with the model T = 297.15K, the temperature value on the roadway length is guaranteed as specified < 303K. The result is a reference for determining the duct position and cool for the high-temperature heading face.