In a recent article published in Case Studies in Thermal Engineering, researchers developed a comprehensive thermal comfort evaluation model tailored to the unique characteristics of hot and humid mines. The research provides a theoretical foundation for improving miner safety and productivity by focusing on the factors influencing heat dissipation and comfort levels.
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Background
The underground mining environment is characterized by elevated temperatures and humidity levels, which pose serious risks to miners' health and performance. Previous studies have identified various thermal comfort indices, such as the Wet Bulb Globe Temperature (WBGT) and the Predicted Mean Vote (PMV), but these indices often fail to accurately assess comfort in high-temperature mines.
The metabolic rate of miners is significantly higher than that of individuals in less strenuous environments, leading to increased heat production and difficulty in heat dissipation. Air temperature, humidity, wind speed, and clothing thermal resistance are crucial in determining thermal comfort.
The Current Study
The methodology identifies key parameters influencing miners' thermal comfort, including metabolic rate, skin temperature, clothing thermal resistance, and environmental conditions. The metabolic rate is critical as it represents the heat generated by the body during physical activity. Skin temperature is calculated based on various environmental factors, including ambient air temperature, partial pressure of water vapor, air velocity, and the thermal resistance of clothing.
The thermal resistance of clothing is also a crucial factor in determining how well heat can dissipate from the body. The study introduces the concept of dressing rate, which quantifies the extent of clothing coverage and its impact on heat loss. The ambient conditions of the underground environment, characterized by high humidity levels and elevated temperatures, are considered essential in assessing the overall thermal comfort of miners.
The methodology's core involves constructing a mathematical model that integrates the identified parameters to evaluate thermal comfort. This model is based on the principles of heat balance, which considers the heat produced by the body, the heat lost through various mechanisms, and the heat gained from the environment.
The heat balance equation is formulated to represent the change in thermal energy, incorporating metabolic heat production, work done by the body, convective heat loss, radiative heat loss, and evaporative heat loss from the skin. Modifications to the parameters affecting thermal balance are made to reflect the specific conditions of hot and humid mines, ensuring that the model accurately represents the thermal dynamics experienced by miners.
A software system was developed to facilitate the practical application of the thermal comfort evaluation model. This software allows users to input various parameters related to the mining environment and the miners' physiological conditions. It performs real-time calculations based on the established mathematical model, providing immediate feedback on thermal comfort levels.
Results and Discussion
The study's results indicate that the newly developed thermal comfort model significantly improves the accuracy of evaluations in hot and humid mining environments. The model provides a more realistic representation of miners' thermal comfort levels by incorporating the dressing rate and other relevant factors.
The findings reveal that miners' metabolic rate, influenced by their high labor intensity, plays a pivotal role in heat production. As the metabolic rate increases, dissipating heat becomes increasingly challenging, leading to discomfort and potential health risks. The study also highlights the importance of airflow and its impact on convective heat transfer, noting that the airflow rates in underground tunnels often deviate from comfortable levels due to safety constraints.
The evaluation model's application in the Shoushan mine demonstrates its effectiveness in assessing thermal comfort across various working points. The results underscore the necessity of considering environmental factors, such as temperature and humidity, alongside physiological parameters when evaluating miners' comfort. The research contributes to the existing body of knowledge by providing a more nuanced understanding of thermal comfort in extreme conditions, paving the way for future studies and practical applications in mine safety management.
Conclusion
In conclusion, the article presents a significant advancement in evaluating thermal comfort for miners working in hot and humid environments. The research enhances the accuracy of thermal comfort assessments by developing a tailored model that incorporates the dressing rate and other critical factors.
The findings emphasize the need for a comprehensive understanding of the interplay between environmental conditions and human physiology in mining settings. The proposed evaluation model and accompanying software system offer valuable tools for improving miner safety and well-being, ultimately contributing to more effective management of underground operations. The study lays the groundwork for future research to refine thermal comfort evaluations and implement practical solutions to mitigate the risks associated with extreme thermal conditions in mining environments.
Source:
Zhao W., Liu J., et al. (2024). Evaluation and application research on thermal comfort of mining face in hot and humid mines. Case Studies in Thermal Engineering 59, 104493. DOI: 10.1016/j.csite.2024.104493, https://www.sciencedirect.com/science/article/pii/S2214157X24005240?dgcid=api_sd_search-api-endpoint