Ambient temperature field and energy consumption analysis of air channel construction ventilation in high-geotemperature tunnels

Air channel construction ventilation (ACCV) provides an effective solution for extra-large air flow rate supply in tunnels with high-geotemperatures, thereby facilitating the simultaneous excavation of multiple working faces in inclined shafts. To investigate the distribution and development law of temperature fields in ACCV and analyze the system’s energy consumption, this study proposes a Coupled Convective-Conductive Heat Transfer Model (CCM) for calculating the temperature field, and the model’s reliability is validated through field tests. Using the CCM model, this study analyzes the impact of various air flow rates, inlet air temperatures, and partition thermal conductivity on the temperature field and energy consumption in ACCV. The findings are as follows: The temperature in the air channel shows a linear upward trend under different air flow rates, yet the heating rate decelerates as the air flow rate increases. Considering the ambient temperature of the inclined shaft, the air flow rate in air channel of tunnel should not be less than 100 m3/s, regardless of the required air flow rate for the working face. When the air flow rate is between 200 and 500 m3/s, the outlet air temperature decreases by roughly 0.2 °C for every 50 m3/s increase in air flow rate if the inlet air temperature drops by 5 °C. Partition thermal conductivity should be below 0.21 W/m/K to ensure effective insulation. As the inlet air temperature rises, the air flow rate’s impact on cooling power growth strengthens. Conversely, as the air flow rate declines, the inlet air temperature’s influence on cooling power growth weakens. Calculated with COP = 5.0, using insulated partitions can reduce energy consumption by 8,760,000 kW·h annually and decrease carbon emissions by 7,884 t/year.