论文部分内容阅读
为了研究N_2和CO_2气体灭火剂在抑制煤明火燃烧特性方面的不同,通过搭建受限空间煤明火燃烧试验,分别开展了11.97%、16.81%、20.76%的N_2和10.79%、14.89%、20.32%的CO_2作用下煤明火燃烧抑制试验。鉴于火焰表面积变化与热释放速率变化呈正相关,基于火焰图像分析法开展试验研究。试验过程中,首先,通过数码摄像仪记录不同体积分数惰性气体作用下煤燃烧火焰面积的变化,然后利用Matlab软件进行火焰图像特征提取和“对比度增强”预处理,消除图像记录过程中存在的噪声,以便于有效进行火焰目标识别;其次,基于“阈值法”原理,利用Image-Pro Plus软件对预处理过的火焰目标进行识别和计算,进而实时获得试验过程中火焰表面积;最后,使用小波变换理论对火焰表面积变化曲线进行消噪处理,以获得火焰表面积变化趋势及主要波动信息。结果表明,CO_2比N_2具有更好的熄灭煤明火燃烧的能力,CO_2作用下煤火火焰表面积呈现指数下降,而N_2作用下呈现直线下降,且CO_2的灭火时间比N_2缩短了25%以上。该试验结果明确了N_2和CO_2在熄灭煤明火特性上的不同,弥补了CO_2仅比N_2具有更好的抑爆特性的认识。
In order to study the difference of the combustion characteristics of N 2 and CO 2 gas fire suppressants in open flame test, 11.97%, 16.81% and 20.76% N 2 and 10.79%, 14.89% and 20.32% Combustion Control Test of Open Flame of Coal under CO_2. In view of the positive correlation between the change of flame surface area and the rate of heat release, a pilot study was carried out based on flame image analysis. During the experiment, firstly, the change of flame area of coal combustion under inert gas with different volume fraction was recorded by digital camera, and then the flame image feature extraction and contrast enhancement were preprocessed by Matlab to eliminate the existence of image burning Of the noise in order to facilitate the effective identification of the flame target; secondly, based on “threshold method ” principle, using the Image-Pro Plus software to identify and calculate the pre-treated flame target, and then real-time access to the flame surface area during the test; , The wavelet transform theory is used to denoise the curve of the change of the surface area of the flame to obtain the change trend of the surface area of the flame and the main fluctuation information. The results show that CO_2 has better ability to extinguish the open flame of coal than that of N_2. The surface area of coal flame decreases exponentially under the action of CO_2, while decreases linearly with N_2. The CO_2 extinguishing time is shortened by 25%. The test result clearly shows that the difference between N 2 and CO 2 in the open flame properties of the coal, makes up for the fact that CO 2 has better explosion suppression characteristics than N 2.