Experimental Investigation Of The Cooling Effect Of Tailrace Tunnel Ventilation Process In Hydropower Stations

In recent years,there has a rapid development in hydropower station construction. And the ventilation in Hydropower Plant must be sure enough important.In hydropower station project,it can achieve the application of natural cool source in ventilating and air conditioning system of workshop by using air handled by tailrace tunnel.Therefore,the tailrace tunnel is regarded as a huge natural air conditioner.It is a energy and cost saving cool source.And it has many advantages of energy saving, reproduce and environment protection and so on.An experimental study was work up to find out the cooling effect of TTV in hydropower stations.The variation law of that with the inlet air temperature,inlet air velocity,the roughness of the inwall tail water velocity,and tail water velocity would be got from measuring of air temperature in all stations.The result indicates that velocity of tail water,velocity of air,temperature of air, the roughness of inwall and the length of the tunnel all have effect to ventilation and heat exchanger of tailrace tunnel..The temperature of inlet air decreased 12.27～27.26℃after passing through the tailrace tunnel.The temperature of outlet air was basically close to that of the water in the tailrace tunnel with a temperature difference of 0.53～1.26℃.By calculating the convective heat transfer coefficient,it was found that the induced air velocity had a relatively significant effect on this process.In this experiment, the inlet air temperature of the smooth tunnel was set 35℃and the water flow velocity was set 0.1m/s.Results showed that the convective heat transfer coefficient was 41.87 W/m~2℃,55.73W/m~2℃,81.04 W/m~2℃respectively when the air flow velocity was 0.5m/s,1.0 m/s,1.5m/s respectively.The equations describing the relationship between Re,Pr and Nu in the induced-air heat transfer process in the tailrace tunnel were obtained based on a mass of data and the theory of dimension analysis.The formula and methods for calculating the convective heat transfer coefficient of the heat and moisture transfer process in the open air tailrace tunnel was proposed.