Quasi-steady characteristics of flowing propane/air mixture ignited by a heated surface. (March 2021)

• Record Type: Journal Article
• Authors: Imamura, Tomohiko; Uehara, Kosuke; Nakata, Keita; Maruyama, Shoya; Kuwana, Kazunori
• Is Part Of: Fire safety journal. Volume 120(2021)
• Publication Date: 2021-03
• Subjects: Ignition -- Flowing propane/air mixture -- Heated surface -- Experiment -- Theoretical analysis -- Ignition limit; Fire prevention -- Periodicals; Incendies -- Prévention -- Recherche -- Périodiques; Fire prevention -- Research; Periodicals; 628.92205
• DOI: 10.1016/j.firesaf.2020.103025
• Languages: English
• ISSNs: 0379-7112

Abstract

Abstract: Quasi-steady behavior of a flowing propane/air mixture ignited by a surface heated at a constant power was investigated as a first step in assessing the physical risk of alternative clean energy. A series of experiments was carried out in which flowing propane was exposed to a heated surface at various supplied voltages and flow velocities. From the experimental results, the following findings were obtained: (1) ignition initiated from the bottom of the heated surface, and a flame first propagated on the downstream side of the heated surface; (2) the existence of the critical heat flux to ignite the flowing mixture was found, which was a major difference between ignition by a constant-temperature, hot surface and that by a constant-heat-flux, heated surface; (3) the limit of ignition temperature was expressed as a function of flow velocity, and the size of heated surface, yielding a curve which converges to a critical value of ignition temperature. The experimentally-measured dependence of the critical heat flux and ignition temperature on the flow velocity was consistent with the prediction of theoretical analysis conducted in this study. Highlights: A series of experiments was conducted on ignition by a heated surface. Schlieren images of flame propagation in the early stage of ignition were taken. The limit of ignition temperature of the flowing flammable mixture was found. The experimental results were validated by theoretical analysis.