A study of the correlation between summer outdoor meteorological parameters and hydropower station ventilation schemes

For an underground hydropower stations, understanding the heat and mass transfer behaviour of outdoor air flowing through ventilation tunnel can help improve the design of ventilation systems and reduce energy consumption. The aim of this paper is to investigate the influences of summer outdoor meteorological parameters on the tandem ventilation process and the designed parameter requirements in the main plant. A series of field tests and numerical simulations were conducted to determine the variations in outdoor air parameters passing through the ventilation tunnel. Theoretical analyses were developed to clarify the variations in air parameters through the ventilation process in i-d diagram. Results show that the outdoor meteorological temperature has the largest influence on heat transfer between the ventilation tunnel and airflow. The relative humidity in the air at the tunnel outlet could reach 90% under most conditions. The reasonable air supply area and the critical air supply temperature of the mechanical ventilation were determined. Once the outdoor air passes through the ventilation tunnel and the i-d diagram falls in air supply area II, the outlet air can be directly supplied to the main plant. For conditions that did not satisfy the mechanical air supply scheme, the measure of setting dehumidifiers at 200—250 m arranging intervals in the tunnel were proposed to improve the air humidity. Based on the meteorological parameters of typical climate zones in China, a reasonable air supply scheme for the main plant was determined. The results could technically guide the ventilation design of underground hydropower stations, which can help to enchance energy-efficient and low-carbon ventilation schemes.