Field Test On Tunnel Ventilation Heat Exchange Efficiency And Research And Development Of New Air Duct

Underground tunnels have a natural heat storage capacity.Underground tunnel ventilation is often used in hydropower stations or other large underground projects.The outdoor air is directly sent to the underground powerhouse after cooling or heating through the tunnel wall.This kind of ventilation method can reduce the energy consumption of the air-conditioning system in the plant and achieve the effect of energy saving.In this paper,the dynamic heat transfer effect of underground tunnel ventilation is studied by field measurement and theoretical analysis.The application effect of special air duct instead of underground tunnel ventilation technology is studied by numerical simulation.The main contents are as follows:First of all,the field measurement of the ventilation heat transfer effect of the traffic holes in three hydropower stations is measured.Based on the measured data,the ventilation and heat transfer effect of the traffic hole in the hydropower station is evaluated,and the causes of fogging in the tunnel during the air intake were pointed out.Secondly,the process of heat and moisture exchange between the air and the surface of underground tunnel is calculated and analyzed.The mathematical model of heat and moisture exchange between air and underground tunnel surface is established.and the expressions of air temperature and moisture content in different positions of underground corridors are obtained.Mathematical formulas were used to analyze the effects of factors such as outdoor air temperature,air flow velocity,corridor structure size,and wall surface temperature on the heat transfer effect between air and tunnel walls.Finally,the author points out the problems existing in the underground tunnel ventilation and tries to find the cause of fog in the underground tunnel.Based on this,a new ventilation technology is put forward,which is dedicated to air supply along the side walls of underground tunnels.For deep-buried underground projects,the use of dedicated air duct ventilation technology along the underground tunnel instead of the original ventilation method through underground tunnels can effectively increase the utilization efficiency of underground natural energy.In summer,the cooling and dehumidification effect of underground tunnels on the air can be enhanced,which can effectively reduce the load on the air-conditioning system in the plant,and can further reduce the moisture content of the air sent to the plant.In the winter,the preheating effect of underground tunnels on the air can be enhanced and the working environment in the factory can be improved.Taking the tunnel of Xianyou Pumped Storage Power Station as an example,the application effect of the new ventilation technology is verified by numerical simulation.The results show that the use of special air duct can solve the problem of fog in the tunnel,and can effectively enhance the cooling and dehumidifying effect on the air.For the tunnel of Xianyou Pumped Storage Power Station,the special air duct with a cross section size of 6×0.5m~2 is the best choice.