The maximum ceiling excess smoke temperature is a critical parameter for assessing fire safety in Z-shaped passages. These passages are long and narrow spaces formed by two horizontal segments connected by an inclined passage. Smoke movement in such passages significantly differs from traditional confined spaces due to the stack effect and the presence of corners where the horizontal and inclined segments meet. Previous empirical formulas for evaluating the maximum ceiling smoke temperature rise are not applicable to Z-shaped passages. Therefore, this study experimentally explored the impact of fire location, both longitudinally and vertically, on the flame shape and ceiling excess smoke temperature profile of the Z-shaped passage. The results revealed a strong correlation between the stack effect and smoke plume impinging position. By considering the smoke plume deflection angle and fire location, the position of the maximum ceiling smoke temperature rise was determined. Moreover, a new variable, the effective height (he) was introduced to replace the passage height. Various heat release rates (HRRs) and fire locations were taken into account in the development of a modified model to determine the maximum ceiling smoke temperatures rise in Z-shaped passages. Experimental data from this work and others were used to verify the model’s accuracy; the results showed greater accuracy in the absence of smoke backflow in the passage.

中文翻译：

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自然通风 Z 形通道火灾火源位置对最高天花板超烟温度影响的理论分析与实验


最高天花板超烟温度是评估 Z 形通道消防安全的关键参数。这些通道是由两个水平段形成的狭长空间，由倾斜的通道连接。由于烟囱效应以及水平和倾斜段相交处的拐角的存在，此类通道中的烟雾运动与传统的密闭空间明显不同。以前用于评估最大天花板烟温升的经验公式不适用于 Z 形通道。因此，本研究通过实验探讨了纵火位置对 Z 形通道火焰形状和天花板超烟温度剖面的影响。结果显示，烟囱效应与烟羽撞击位置之间存在很强的相关性。通过考虑烟羽偏转角度和火灾位置，确定了天花板烟温升最大的位置。此外，引入了一个新变量，即有效高度 （he） 来代替通道高度。在开发修改后的模型时，考虑了各种热释放率 （HRR） 和火灾位置，以确定 Z 形通道中天花板烟雾温度的最大上升。来自这项工作和其他工作的实验数据用于验证模型的准确性;结果表明，在通道中没有烟雾回流的情况下，准确性更高。