A method for calculating the moisture load in the tailrace surge tank of underground hydropower station based on field tests

As an important part of a hydropower station, the tailrace surge tank is usually buried deep underground. The indoor air is in contact with a large area of water, resulting in excessive air humidity, especially in the summertime when the hot and humid environment is harsh. Therefore, the moisture exchange process in the tailrace surge tank is first analyzed in this research. Based on this analysis, a method for calculating the moisture load is proposed. After that, the hot and humid environment in the tailrace surge tank at the Xiluodu hydropower station is tested for a year. The test results show that the relative humidity of the air at the tailrace surge tank's entrance is negatively correlated with the amount of moisture dissipation. Meanwhile, the rate of moisture dissipation exhibits a law of low in the summer and high in the winter, with summer lows of −103.2 kg/h and winter highs of 1404.7 kg/h. In addition, the fitting formula for moisture load in the tailrace surge tank is obtained in this paper by combining test data with mass transfer theory, and the relative error between the calculation results and the test results is less than 9.32%. The study's findings can be utilized as a reference when creating a ventilation and mechanical dehumidification plan for the tailrace surge tank's hot and humid environment.