In the present study, an experiment was carried out to evaluate the fire suppression efficiency of NaCl and NaHCO3 powders for laminar premixed methane-air flame. Hybrid flame burner and shadowgraph technique were used to measure the burning velocity with powders over different concentrations at two equivalence ratios (0.9, 1.0), and an improved model was employed to explore the competitive process between the physical and chemical effects of the two powders. It was observed that both the two powders show their efficiency in reducing the burning velocity, and the suppression behavior of NaHCO3 can be more pronounced than NaCl. The agreement between the theoretical and experimental results for NaCladdition flames indicates that the powders absorbing heat, which is also known as the physical heat sink effect, is the major fire suppression mechanism for NaCl. However, there is a large discrepancy between the predicted and observed results for NaHCO3-addition flame, which suggests that the physical heat sink effect only behave as a part of the suppression process for NaHCO3 and, therefore, the apparent efficiency of NaHCO3 can be attributed to the powders decomposition and further chemical reactions. Furthermore, the chemical effect of NaHCO3 increases with the decrease in equivalence ratio, evidenced by the increase of experimental results and the similar value of the model-based results in lean- and stoichiometric-flames.

International Seminar on Fire and Explosion Hazards (9; 2019; Saint Petersburg, Russia). Proceedings of the Ninth International Seminar on Fire and Explosion Hazards [Электронный ресурс]: 21-26 April 2019, Saint Petersburg, Russia. Vol. 1 / Peter the Great St. Petersburg Polytechnic University, Autonomous Non-Profit Organization "Fire and Explosion Safety", Gefest Holding Ltd ; [edited by A. Snegirev [et al.]. — Электрон. текстовые дан. (1 файл : 118 Мб). — Saint Petersburg, 2019. — Загл. с титул. экрана. — Свободный доступ из сети Интернет (чтение, печать, копирование). — Adobe Acrobat Reader 7.0. — <URL:http://elib.spbstu.ru/dl/2/k19-45.pdf>. — <URL:http://doi.org/10.18720/SPBPU/2/k19-45>.