Experimental and theoretical studies on the heat extraction performance by natural ventilation with a board-coupled shaft during tunnel fires

Abstract

Abstract Experimental studies were conducted to investigate the effects of fire positions on the heat extraction performance in a 1:15 scale model tunnel with the board-coupled shaft (BCS). The general condition that the first shaft cannot exhaust all smoke was considered. Analytical models for predicting the dimensionless temperature difference inside and outside the BCS and the dimensionless heat extraction rate were derived. The results indicated that smoke temperature in the shaft becomes uniform as the height rise. And, the temperature difference and heat extraction capacity of the shaft gradually decrease, when the fire moves away from the shaft. Besides, it can also be observed that the heat extraction capacity of the BCS is superior to the traditional one, if the board is properly installed; and the optimal board location for the BCS to achieve the optimal heat extraction performance may change with fire locations. Beyond that, semi-empirical formulas were established based on the experiment results, which may contributes positive significance on the application of shaft in tunnel buildings.