Analysis and optimization of air distribution and ventilation performance in a generator hall using an innovative attached air supply mode

The continuous development of hydropower necessitates the extensive design and construction of hydropower stations. As an underground large space building, it is difficult for the air in the hydropower station to directly exchange with the external environment. Scientifically reasonable air supply modes are indispensable for ensuring a uniform air distribution with low energy consumption. In this study, numerical simulations were carried out to analyse the air distributions and thermal environments under three air supply modes: roof air supply (RAS), sidewall air supply (SAS), and attached air supply (AAS). A set of evaluation indices, namely, the air velocity, air temperature, nonuniformity coefficient, and energy efficiency coefficient, were adopted to assess the ventilation performance of these three modes. Moreover, an orthogonal experiment was conducted to optimize the ventilation performance with four factors (air outlet height, air outlet width, air supply velocity, and heat source intensity) in the AAS mode. The average temperatures among the RAS, SAS, and AAS were 26.1 °C, 26.4 °C, and 26.0 °C, respectively. The results indicated that the attached air supply (AAS) mode is recommended for generator hall applications due to its lower nonuniformity coefficient and higher energy efficiency coefficient. Based on the range analysis and variance analysis, the air outlet height exhibited significant effects on the air distribution and ventilation performance. This research provides design references for the innovative design of air supply systems in large space buildings. •An innovative attached air supply mode was conducted in hydropower stations.•The dimensionless velocity and the temperature distribution of attached air supply mode were acquired.•Air-outlet height had a significant effect on the attached ventilation performance.