Heat Transfer Analysis Of Tunnel Ventilaton-Theoretical And Numerical Study Of Heat Transfer In Underground Tunnel Of Jing-hong And Nuo-zha-du Hydropower Station

With people's increasing living level and economical development, building energy consumpution is growing year after year in P.R. China and accounts for up to 30% of total energy consumpution. While the petrochemical energy, including coal, oil, gas etc, as nonrenewable energy sources is further declining. So it is urgent to find an energy conservation, environment protection and sustainable development air conditioning method to reduce building energy consumption. The soil, which has tremendous thermal storage capacity, is a natural, renewable and environment protection energy source so that underground tunnel ventilation has wide application prospect in ventilation and air conditioning design of hydropower station for its simplity, energy conservation and low costing.This paper makes a systematical theoretical analysis and numerical simulation about heat transfer in underground tunnel of hydropower station. It establishes a physical model about air flowing through underground tunnel according to practical problems in Jing-hong and Nuo-zha-du hydraulic power stations and studies heat transfer characteristics in the tunnel. It puts forward a theoretical calculation procedure toghther with a numerical prediction method, which are both quite validated against experimental data.The result shows an obvious temperature drop or up according to season variations occurs during air runs through the underground tunnel. It also testifies the great cooling/heating effect of underground tunnel as a natural colding/heating source for the heat transfer between flowing air and tunnel wall. Outlet air temperature of underground tunnel can meet ventilation design demand of hydropower house. Tunnel ventilation can provide a comfortable working environment for the house.All the results indicate the good agreement of the theoretical equation and numerical simulation which are developoed in this paper. Parametric analysis is conducted to determinethe effect of wall temperature, air velocity, tunnel hydraulic diameter, inlet air temperature etc. on the heat transfer between tunnel wall and air inside.