Některé aspekty detekce požáru z pohledu integrace požárně-bezpečnostního zařízení

Abstract

Interactions between a flame and gaseous extinguishing agents represent a very complex system of closely interconnected processes of fluid dynamics, heat transfer and combustion chemistry. The understanding of phenomena participating in these processes creates a necessary precondition for the selection of suitable parameters of a fire and for the design of an algorithm for their assessment, which would enable not only the detection of the fire, but also the monitoring of its suppression. The aim of the Ph.D. thesis was to verify a possibility of employing video flame detection methods to monitor the process of fire suppression using gaseous extinguishing agents. In the theoretical part of the thesis, the analysis of current knowledge of the flame is made and the present state in the area of video fire detection is assessed. In order to accomplish the aim of the Ph.D. thesis, a laboratory experiment method was used. In the framework of laboratory measurement, measurement of the intensity of radiation of the flame of a chosen gaseous and a liquid fuel with a designed and built experimental setup was carried out. The flame of both the fuel types was monitored in two different wavelength regions of the electromagnetic radiation spectrum at various concentrations of gaseous extinguishing agents below the value of minimum extinguishing concentration in the surrounding atmosphere of the flame. The mentioned measurement was supplemented by photographic imaging of the flame. Measurement results and also information acquired by flame imaging were theoretically interpreted and compared with partial findings from studies of other authors. In the conclusion of the thesis, findings of experimental measurement are confronted with the present state in the area of video flame detection methods. This Ph.D. thesis contributes to both the testing of present video fire detection methods and the validation of tools of mathematical modelling of combined models of chemical kinetics and fluid dynamics of combustion processes.