An analytical model to predict the temperature in subway-tunnels by coupling thermal mass and ventilation

Sun, Tingting; Luo, Zhiwen; Chay, Tim

doi:10.1016/j.jobe.2021.102564

Cited by 6 publications

(4 citation statements)

References 36 publications

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“…(4) Time duration to solve flow field continuously To model turbulence, it is essential to identify two quantities that characterize turbulent flow: the specific turbulent kinetic energy, k , and the turbulent kinetic energy dissipation rate, ε , or the energy-specific dissipation rate, ω . These quantities are defined in equations ( 4), ( 5), (6) as shown below:…”

Section: Governing Equationsmentioning

confidence: 99%

“…Song and Chen [5] analyzed the temporal variations of soil temperature fields and tunnel wall temperatures. Sun et al [6] established a mathematical model describing the thermal processes in deeply buried subway tunnels and pointed out that due to global warming and increasingly severe climate change, active cooling or heat recovery systems will soon become essential in subway tunnels.…”

Section: Introductionmentioning

confidence: 99%

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Cooling performance study of a new cooling system in subway tunnel based on field measurement and CFD simulation

Wang,

Zhang,

et al. 2024

IOP Conf. Ser.: Earth Environ. Sci.

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Some cities’ subways were constructed early and have been in operation for a long time. A large amount of heat accumulates in the rocks around the subway tunnels, causing the phenomenon of heat accumulation. This situation leads to the inadequate cooling capability of train air-conditioning systems, which, may even cease to function under extreme conditions. Currently, few solutions are available to address this issue. Therefore, this study proposes a new cooling system in subway tunnel. Considering the dusty environment inside the tunnel, the terminal equipment mainly consists of natural convection copper tube finless heat exchangers and a self-flushing device without fans, which cool using piston wind. By comparing field measurements of two tunnels with and without the cooling system in similar locations, the results show that the air temperature in the tunnels is reduced after the cooling system is installed. The results indicate that the average temperature in the tunnels decreases from 30.93 °C to 19.80 °C, marking a reduction of 11.13 °C after the cooling system runs for 24 hours. The temperature change in the tunnel is a long-term process, and actual measurements require significant time consumption. In this study, the long-term effect is predicted using CFD simulation in tunnels. The accuracy and credibility of the CFD simulation have been confirmed through its reasonable agreement with experimental data, with the final temperature after 24 hours achieving a relative error of less than 0.26%. Through the simulation, the temperature at a depth of 10 cm inside the tunnel wall after 24 hours is determined to be 27.56 °C, indicating a reduction of 3.44 °C compared to the initial temperature of 31 °C. This study can provide a reference for other subway tunnel cooling systems and serves as a basis for CFD simulations to verify cooling effects.

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Section: Governing Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cooling performance study of a new cooling system in subway tunnel based on field measurement and CFD simulation

Wang,

Zhang,

et al. 2024

IOP Conf. Ser.: Earth Environ. Sci.

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“…Xu et al [12] took into account the impacts of groundwater flow and buoyancy on tunnel ventilation heat transfer laws in order to make tunnel thermal environment prediction more accurate. Sun et al [13] studied how complex heat transfer affected the air temperature of subway tunnels by building a numerical model, and their findings revealed that the air temperature was positively and linearly related to the internal heat source and ambient temperature. Wang et al [14] constructed a scale model tunnel and considered the temperature distribution under natural ventilation in a closed tunnel, and then they proposed a temperature correction prediction model including factors such as blockage and heat release rate.…”

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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“…Its formation mechanism and heat migration law have been deeply studied both in China and abroad [13][14][15]. In theoretical analysis, the analytical solution for the heat transfer equations of the soil mass was derived [16][17][18][19][20][21], but the complexity of the solution expression greatly limits its application in engineering. In addition, due to the rapid development of numerical calculation methods, the heat transfer rules of the soil mass surrounding the tunnel have been widely studied from various perspectives, such as mechanical ventilation systems [22][23][24][25], heat absorption ratio [26], capillary heat exchange [27], tunnel temperature assessment [28], heat storage effects [29], seasonal heat storage characteristics [30][31][32][33][34][35], and thermal physical parameters [36][37][38][39][40][41].…”

Section: Introductionmentioning

confidence: 99%

Research on the Influence of Subway Tunnel Depth on Heat Storage Characteristics of the Surrounding Soil Mass

Song,

Li,

et al. 2023

Applied Sciences

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With the long-term running of the subway, the soil layer around the tunnel takes on the thermal deposition effect, which can lead the air in the tunnel to heat up and pose a serious threat to the safety operation of trains. Through taking some subway tunnels from typical zones as an example, the influence of tunnel depth on the heat storage characteristics of the surrounding soil mass was analyzed in the paper. The results indicate that the temperature field of the surrounding soil mass was thermally disturbed by both the ground air temperature and the tunnel air temperature, and there was a significant coupling point ‘O’ located at the center of the tunnel overburden. With the extension of the heat-exchange time, the shape of the cooling ring around the tunnel gradually changed from a circle to an oval. For the analysis of cases, from the space aspect, when the tunnel depth was less than 30 m, the wall temperature increased gradually with the increase of tunnel depth. From the time aspect, over time, the wall temperature gradually rose and finally reached a fixed value. From the region aspect, the heat absorption capacity of different areas decreased gradually with the increase of tunnel depth. When the depth exceeded 45 m, the heat absorption capacity of certain cities became negative. In addition, three typical boundaries were discussed, and the optimal method for evaluating the heat absorption capacity of the tunnel soil was ultimately determined. This study has important reference value for temperature control and positioning problems in the process of tunnel construction and operation.

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An analytical model to predict the temperature in subway-tunnels by coupling thermal mass and ventilation

Cited by 6 publications

References 36 publications

Cooling performance study of a new cooling system in subway tunnel based on field measurement and CFD simulation

Cooling performance study of a new cooling system in subway tunnel based on field measurement and CFD simulation

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

Research on the Influence of Subway Tunnel Depth on Heat Storage Characteristics of the Surrounding Soil Mass

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