Prediction of carbon monoxide concentration and optimization of the smoke exhaust system in a busbar corridor

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Fire in underground structures can result in devastating consequences in terms of both economic damage and loss of life. Hydro-electric plants are typically underground windowless structures. In an underground hydropower station, the busbar corridor connects the busbar layer in the main power plant with the main transformer chamber. This structure forms the channel that is crucial for electrical power transmission. In this paper, a computational method, Fire Dynamics Simulator (FDS), was carried out on a model of a two-story busbar corridor structure based on actual fire test results as a validation case. Twenty-four prediction conditions were taken into account to evaluate the original design of the exhausting system and optimize the busbar corridor modeled smoke control scheme. In those predictions five factors were varied: the heat release rate (HRR), the story height, the air change rate (ACH), the exhaust outlet positions and the airflow inlet positions. Since toxic compounds, especially carbon monoxide, endanger evacuating people in fire scenarios, the carbon monoxide (CO) concentration was reported and used throughout this study as an indicator of the safety of occupants in the corridor. Of the five varied factors it was found that the story height and the airflow inlets with natural ventilation influenced the smoke suppression and control. For the story height of 6.0 m, the filling time is 52 s more than the story height of 4.5 m. The CO concentration of opening set upstairs only is twice as much of the design condition. Opening set downstairs only can exhaust smoke faster for occupied area.