The critical discontinuity of vertical temperature distribution along window opening height from intermediate-scale compartment fire

The fire plume spilled from a window is believed to be one of the main fire sources with respect to a building fa & ccedil;ade fire, which happened previously in China. To have a deep understanding of vertical temperature distribution at window opening is of significance. In the current contribution, a series of compartment fire tests under over-ventilation were conducted with a 1.35 m x 1.35 m x 1.35 m compartment to clarify the critical discontinuity position (H D ) by varying window opening sizes, opening aspect and heat release rate (HRR). Temperature history at the window openings were recorded by a thermocouple net. A theoretical calculation method of H D is detailed according to the compartment configuration. It is found that the critical discontinuity area is observed apparently along the window opening height, which has a big temperature difference. By the comparison of experimental and theoretical results, the constant comprehensive coefficient of 1.68, 1.92 and 3.85 of 300 kW, 600 kW and 900 kW are got for an engineered empirical prediction model are proposed, respectively. It provides an insight for the understanding of critical temperature discontinuity and reference for engineering calculations.