Search Results (15)

The implementation of a decentralized blue–green infrastructure (BGI) is a key strategy in climate adaptation and stormwater management. However, the integration of urban trees into the multifunctional infrastructure remains insufficiently addressed, particularly regarding rooting space in dense urban environments. Addressing this gap, the BoRSiS project developed the soil-pipe system (SPS), which repurposes the existing underground pipe trenches and roadway space to provide trees with significantly larger root zones without competing for additional urban space. This enhances tree-related ecosystem services, such as cooling, air purification, and runoff reduction. The SPS serves as a stormwater retention system by capturing excess rainwater during heavy precipitation events of up to 180 min, reducing the pressure on drainage systems. System evaluations show that, on average, each SPS module (20 m trench length) can store 1028–1285 L of water, enabling a moisture supply to trees for 3.4 to 25.7 days depending on the species and site conditions. This capacity allows the system to buffer short-term drought periods, which, according to climate data, recur with frequencies of 9 (7-day) and 2 (14-day) events per year. Geotechnical and economic assessments confirm the system stability and cost-efficiency. These findings position the SPS as a scalable, multifunctional solution for urban climate adaptation, tree vitality, and a resilient infrastructure. Full article

To address ventilation challenges in the working face of metal mine excavation, an equal-scale physical model was established with a mine section as the test site, combined with field-measured data and relevant parameters of spent air reuse equipment. Numerical simulations were carried out using Fluent 2020 R2 software to analyse the characteristics of the airflow field, temperature field, and dust distribution in the excavation roadway. The results show that when the cold air outlet temperature (T₀) is 22 °C, the temperature within the cooling zone does not exceed 26.3 °C, thereby demonstrating effective cooling. The equipment parameters significantly impacted cooling and dust removal. When the distance from the cold air outlet to the heading face was set to Z_m = 8 m, the air outlet temperature was T₀ = 22 °C, and the ventilation circulation rate was F = 40%, the working area achieved better cooling and dust removal effects. On-site application showed that within 15 m of the working face, temperatures dropped by 3–3.5 °C, reaching a low of 25.1 °C. The relative humidity at a point 1 m away from the working face decreased from 90.6% to 70.2%, and the average dust removal efficiency was 44.9%, which significantly improved the comfort and safety of the working environment at the heading face. Full article

This study establishes a numerical simulation model based on heat and mass transfer theory to reflect the variations in temperature and humidity conditions within a tunnel. It analyzes the impact of high-temperature fissure water, humid porous media, and drainage methods on the temperature and humidity distribution in a tunnel. The results indicate the following: (1) When the area of the humid porous media increases from 150 m² to 300 m², the relative humidity (RH) of the air in the tunnel rises from 52.7% to 55.8%, but the impact on air temperature (T_a) is minimal. (2) The heating and humidification effects of hot water in a drainage ditch on the airflow cannot be overlooked. Meanwhile, the hot water transfers heat to the surrounding rock, with heat transfer predominantly driven by the surrounding rock convection. Compared to a drainage pipe, the heat transfer amount increases by 44.9%, and RH rises by 9.3%. (3) For every increase of 5 °C in water temperature (water volume of 90 m³/h), the ventilation outlet T_a linearly increases by 0.15 °C, and the rate of increase in RH accelerates with rising water temperature. (4) Covering a drainage ditch with a cover plate can reduce RH by 12.3%, while spraying a 10 cm insulation layer on the tunnel walls can significantly lower T_a by 0.66 °C. These findings provide a potential solution for the application of insulation materials in reducing the thermal hazards of deep high temperatures. Full article

Electric vehicle (EV) proliferation is accelerating, characterized by the rising quantity of electric automobiles on global roadways. The electric machine is a crucial component of an EV, and the heat generated within the motor requires consideration as it impacts performance and longevity. A prevalent form of machine in EV is the in-wheel motor (IWM), which is notable for its compact size. However, it presents more significant cooling challenges. This research offers a new cooling method to cool the IWM. The system consists of wafters mounted on the housing of the IWM. Testing was conducted to determine the effect of wafters on the thermal properties and performance of IWMs. The machine used in this research is a brushless direct current (BLDC) motor featuring an outer rotor configuration and a peak power output of 1.5 kW. Testing was carried out experimentally and by simulation, and the simulation used Ansys Motor-CAD software. The research results show that applying wafers to IWM reduces the temperature of IWM components by up to 13.1%. IWM with wafters results in a torque increase of 0.14%, a power increase of 0.64%, and an efficiency improvement of 0.6% compared to IWM without wafters. Full article

With the increasing depletion of shallow resources, mining has gradually shifted to deeper levels, and the high-temperature problem of deep mining has restricted the efficient and safe development of mining. In this study, five types of thermal insulation materials for surrounding rocks with different ratios were produced using tailings, P.O.32.5 clinker, aluminum powder, glass beads, quick lime, and slaked lime as test materials. Based on the uniaxial compression test, the thermal constant analysis test, and numerical simulation analysis technology, the change rule of mortar compressive strength and thermal conductivity was analyzed, and the cooling effect of surrounding-rock thermal insulation materials with different ratios was discussed. The results showed that the compressive strength of the surrounding-rock thermal insulation materials ranged from 0.39 to 0.53 MPa, and the thermal conductivity ranged from 0.261 to 0.387 W/(K·m), with the compressive strength of ratio E being the largest and the thermal conductivity of ratio A being the lowest. In the numerical simulation analysis results, the thermal insulation layer thickness was taken as a value of 10 cm when, at this time, the best thermal insulation effect and economic benefits involved a temperature reduction of 0.9 K. In the case of changing the thermal conductivity and inlet wind speed, the original temperature of the rock temperature reduction was also very clear, with maximum reductions of 0.92 K, 0.92 K, and 1.42 K. Full article

With the continuous development of the mining industry and advancements in deep mining technology, mine environment optimization has become key to ensuring safety and improving the efficiency of mining. The high-temperature environment, particularly in deep mines, not only poses a serious threat to miners’ health but also significantly reduces operational efficiency. These issues have been determined based on the current application status and development trends of mine cooling technology, including traditional mechanical and non-mechanical cooling technologies, as well as emerging roadway insulation materials and mine cooling clothing applications. By comparing the advantages and disadvantages of each technology, the main challenges related to the use of current mine cooling technologies are pointed out, including the low energy efficiency ratio, high cost, and difficult implementation. Finally, this paper looks forward to the future development directions of mine cooling technologies, emphasizing the importance of intelligent, energy-saving, and environment-improving comprehensive system management and, in turn, promoting the progress and application of mine environment optimization technology and supporting safe and efficient deep mining. Full article

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 $T_{f_{out}}$ and humidity ${RH}_{out}$ at the end of the water trickling roadway. The importance scores (ISs) indicate that $T_{f_{out}}$ is mainly influenced by the surrounding rock temperature (IS 0.661) and the inlet air temperature (IS 0.264). While ${RH}_{out}$ 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. Full article

Semiclosed tunnels are very common in engineering construction. They are not connected, so they easily accumulate heat. Once a fire breaks out in a semiclosed tunnel, the route for rescue workers to enter is limited, so it is tough to get close to the fire source. In this paper, taking a mine excavation roadway with local pressure ventilation as an example, the temperature field distribution and water spray fire prevention characteristics of the excavation roadway face were studied using numerical simulation and theoretical analysis. This paper provides an explanation of a dynamics-based smoke management method for water spraying in a semiclosed tunnel as well as the equilibrium relationship between droplet drag force and smoke buoyancy. A method was first developed to calculate the quantity of smoke blockage based on the thickness of the smoke congestion. The local ventilation and smoke movement created a circulating flow in the excavation face, which was discovered by investigating the velocity and temperature fields of the excavation face. The size of the high-temperature area and the pattern of temperature stratification varied due to this circulating flow. When local ventilation and sprinkler systems were operating simultaneously, when the volume of smoke was small, the smoke avoided the majority of the water spray effect with the circulation flow; however, when the volume of smoke was large, the effect of the circulation flow decreased and the smoke gathered close to the sprinkler head. At this time, the blocking effect of the water spray was significant. The mean square error analysis revealed that activating the sprinkler had the most significant cooling impact on the wall on one side of the air duct. Full article

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. Full article

This paper takes the bottom pumping roadway of 33190 machine roadway in the No.10 mine of China PingMeiShenMa Group as the engineering background. This mine is a hydrothermal mine, with strong heat conduction and thermal convection activities between the surrounding rock and geothermal water. This forms a geothermal anomaly area, making the overall temperature of the surrounding rock temperature field increase and affecting the mine thermal environment. According to the measured field data and the engineering geological conditions of the roadway, a roadway seepage-heat transfer model is constructed using the comsol numerical simulation software, emulating the effect of geothermal water upwelling to the roadway through random cracks in the surrounding rock at different temperatures and pressures, which has an impact on the airflow temperature field of the roadway. The study shows that the evolution law of the airflow temperature field in the roadway under different water upwelling temperatures and pressures is roughly the same, and the temperature at the entrance of the roadway is almost unchanged: the heating rate is 0, and then increases linearly. The variation in the airflow outlet temperature is analyzed, both under the conditions of same temperature but different pressure, and under the same pressure but different temperature. The water upwelling temperature and the cooling efficiency are positively correlated, and the overall growth rate of the airflow temperature is positively correlated with the water upwelling temperature and pressure; however, the effect of temperature is far greater than that of pressure. The upwelling temperature of geothermal water is the main influencing factor on the temperature field of the airflow in the roadway. Therefore, it is possible to reduce the temperature of upwelling water by laying heat insulation materials on the bottom plate, evacuating geothermal water and circulating cold-water by injection, so as to improve the thermal environment of water-heated mines and increase their production efficiency. Full article

The urban heat island (UHI) phenomenon is caused by the anthropic alteration of the natural environment by urban expansion, its impermeable surfaces, and anthropic activities. In addition, urban morphology can also contribute to the increase in temperature in cities. The UHI effect can be described as an urban climate that is generally characterized by higher temperatures in densely built-up areas compared to surrounding areas. This effect impacts the environmental stress of the city and directly affects the health and quality of life of its inhabitants. Therefore, it is necessary to allocate resources to understand the UHI mechanism in cities in order to propose appropriate mitigation measures that will reduce energy consumption and improve living conditions. In this context, this research was aimed at analyzing the behavior of urban heat islands by replacing asphalt with cool paving materials (concrete) in roadways. Through computer simulations, using the ENVI-met software, the thermal variations of urban heat islands were examined. The city of Cuenca (Ecuador) was selected as the study area. The day of the analysis was 22 January 2020, which was recorded as the warmest day of the year, registering an average temperature of 16 °C. The findings of this research evidenced that, by replacing asphalt pavements with concrete pavements in the analyzed zones, land surface temperature (LST) could be reduced by 8 °C and the global LST of the studied areas could be reduced by approximately 3 °C. Consequently, the mean air temperature of the study areas reflected a decrease of up to 0.83 °C. Full article

A steady and proper thermal environment in deep underground is imperative to ensure worker health and production safety. Understanding the thermal performance in the roadway is the premise of temperature prediction; ventilation design; and improvement in cooling efficiency. A full coupled model incorporated with a moving mesh method was adopted; reflecting the dynamic condition of roadway construction. This study revealed the characteristics of the thermal performance and its evolution law in an excavating roadway. Several scenarios were performed to examine the designs of the auxiliary ventilation system on thermal performance in the roadway. The results show that there is a limitation in the cooling effect by continuously increasing the ventilation volume. Reducing the diameter of the air duct or distances between the duct outlet and the working face will aggravate the heat hazard in the roadway. The heat release from the roadway wall increases with the increase of the advance rate of the working face or roadway section size. Furthermore; an orthogonal experiment was conducted to investigate the effect of major factors on the average air temperature and local heat accumulation in the roadway Full article

The mining process in deep mines occurs at elevated temperatures and thus is significantly jeopardized by the thermal damage. In this study, the main factors causing high-temperatures under particular mining geological and prevailing conditions of coal mine production, namely for the Longgu Coal Mine (LCM) in Shandong Province of China, were specified and analyzed in detail. This included exothermic heat from the surrounding rock of an underground roadway, inflow of high-temperature water, seasonal temperature rise, mechanical and electrical equipment operation, and airflow compression in the mine. The integrated artificial cooling mode was implemented on the basis of the original normal ventilation and cooling facilities of the LCM, which involved cooling by mobile refrigeration units, water source heat pump refrigeration units, and a ground centralized ice-cooling radiation system, as well as the underground centralized cooling system provided by Wärme-Austausch-Technik (WAT) GmbH. Eventually, a comprehensive set of measures for the overall control and reduction of high-temperature-induced damage was realized, which ensured more effective cooling of the LCM. Thus, the average temperature of the main operation sites was reduced by 8 K, while that of the underground working faces was maintained at 299.15 K. These measures also resulted in excellent technical and economic benefits: the total three-year increase in revenue and savings reached 76.3 million USD, hence relevant findings of the study are expected to provide technical guidance on the treatment of high-temperature-induced damage in deep mines. Full article

Heat damage in deep mines is severe and can lead to adverse health effects. The existing refrigeration schemes for the heading face in excavation roadways aim to cool the whole cooling region. However, the ratio of the area occupied by workers to that of the cooling region is quite small. A great quantity of energy for refrigeration is doomed to waste. In this study, a new cooling strategy for building a non-uniform environment in the heading face was developed. A certain quantity of well-designed tracking air coolers were distributed in the excavation roadway near the heading face. The air cooler tracked the constantly moving workers and blew cold air to them. Economic analysis based on estimation of the cooling load for this cooling strategy was conducted. The airflow in the excavation roadway was numerically simulated to estimate the cooling effect. An average energy saving of approximately 30% could be realized. The thermal environment for the workers whether near the heading face or in the roadway improved. This cooling strategy should be considered in all of mine cooling. Full article

The high-temperature environment is a major factor that affects deep mining. Cooling has become a major expense, accounting for up to 25% of the total energy consumption of such mines. To address methods of cooling and the cooling cost, this paper studies the influence of the ventilation duct layout on the cooling effect. Six models were created in ICEM-CFD (3D modeling software), and the influence of cold airflow diffusion on the temperature of the mine environment was numerically simulated using ANSYS Fluent. Under the condition of the same ventilation volume, two models utilizing single pipe and double pipe scenarios were established, and six points were selected as the pipeline suspension position, forming six ventilation duct models. The cooling effect of each model was evaluated by analyzing the average temperature of the roadway section, the three-dimensional distribution of the roadway temperature and the velocity streamline of the whole roadway. The results show that the double-tube model has greater advantages than the single-tube model does, due to its superior local temperature, average temperature of the cross-section, range below 303 K, temperature uniformity and local wind speed. Among the models, model 4 (diameter of 0.5 m, 1.9 m away from the bottom of the roadway and 2.4 m away from the center of the circle) is the best pipeline layout scheme for comprehensive temperature values, roadway temperature uniformity and other factors. The average temperature is 299.3 K within 8 m from the mining face, which is 1.66 K lower than that of the single tube model. This configuration will increase the comfort of the mining environment and reduce cooling costs. These results can provide a reference for ventilation duct layouts of roadways in high temperature mines. Full article