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To determine the thermal kinetic triplets and elucidate the reaction mechanism of thin intumescent fire-retardant coatings (IFR) of steel structures, one efficient combined kinetic approach was implemented in this study. Thermogravimetric experiments were conducted in air atmosphere at four heating rates, and the whole IFR thermal degradation process was divided into two stages. The average activation energy values derived by model-free methods were 78.9 kJ/mol and 175.16 kJ/mol for Stage I (0<α < 0.2) and Stage II (0.2<α < 0.9), respectively. Furthermore, the linear Coats-Redfern (CR) and non-linear Masterplots models were applied to identify the possible reaction mechanism. It was found that the F3/2 mechanistic model was better suited to the main thermal degradation process. Then model reconstruction based on the F3/2 mechanism model was performed. The results showed that the reconstructed model had a strict linear relationship in the independence analysis and KCE analysis, along with a good agreement between the theoretical and experimental results. The current study provided new insights into the systematic thermal degradation mechanism of IFR, and the proposed kinetic model would be helpful for the thermal protection prediction for steel structure during fire. [ABSTRACT FROM AUTHOR]

Nano SiO2 particles (NPs) combined with organosilane surfactants present a promising avenue for the development of stable fluorine-free firefighting foams. In this study, hydrophilic nano SiO2 particles, non-ionic organosilane surfactant (SiCare2238), and amphoteric hydrocarbon surfactant (LAMC) were prepared as a mixed dispersion to investigate the interactions between nano particles and surfactants, foaming ability, and foam stability of the mixed dispersion. Results indicated that the surface activity, electrical conductivity, and foaming ability of the mixed dispersion decreased with increasing NPs concentration. The impact of NPs on foam stability depended on the filling and blocking mechanisms within the platform boundary of the formed liquid film. At NPs concentrations below 1.5%, strong electrostatic interactions among surfactant molecules resulted in the adsorption of surfactant molecules on the nano particle surface, preventing the formation of a network structure at the platform boundary, thereby reducing foam stability. At NPs concentrations above 1.5%, a significant number of NPs formed a network structure, filling and blocking the platform boundary, leading to delayed foam drainage, coarsening, and enhanced foam stability. This study provides theoretical guidance for the application of nano particles in fluorine-free. [ABSTRACT FROM AUTHOR]

This article investigates the suppression of transformer oil pool fires using compressed nitrogen aqueous film-forming foam extinguishing agents with varying nozzle pressures (0.1–0.4 MPa), and a comprehensive analysis of fire extinguishing behavior and resistance to re-ignition was conducted. The research findings indicate that at a nozzle pressure of 0.4 MPa, there is a significant enhancement in fire extinguishing efficiency, with a reduction in extinguishing time by 15.0%–29.2%, and an increase in resistance to re-ignition by 32.2%–48.2%, making it the optimal choice. In comparison to the 0.1 MPa condition, the maximum instantaneous emissions of CO and SO2 at 0.4 MPa are only 66.7%. The interaction of various effects, such as atomization, results in a significant enhancement of flame intensification and fire extinguishing effects when compressed nitrogen aqueous film-forming foam is sprayed at high nozzle pressures. The study provides valuable insights for firefighters in the practical use of foam extinguishing agents. [ABSTRACT FROM AUTHOR]

Flame detachment of jet fires are important in practical application such as elevated flares, where flame detachment is used to minimize damage on nozzle and the attendant fire safety problem. In this work, detachment behavior of a jet flame under crossflow was studied, especially focused on the difference in critical crossflow speeds for flame detachments at the windward and leeward sides of the nozzle exit, such problem has not been quantified previously. Experiments were conducted in a wind tunnel using propane as the fuel by adopting jet nozzles with inner diameters of 3, 5, 8, and 10 mm and an outer diameter of 15 mm; together with inner diameters of 13 and 15 mm and an outer diameter of 20 mm. The results showed that the critical crossflow speeds for flame detachments both at the windward and leeward sides decreased as the jet velocity increased. The critical crossflow speed for flame detachment at the windward side was weakly dependent on nozzle diameter, while that at the leeward side increased with the increase in nozzle diameter. A model was proposed to characterize this difference on the basis of a Damköhler number, which is defined as the ratio of the characteristic mixing time to chemical reaction time. A satisfactory correlation was achieved for the difference in critical crossflow speeds for flame detachments at the windward and leeward sides as a function of fuel jet velocity and nozzle dimensions of inner diameter and wall thickness. [ABSTRACT FROM AUTHOR]

The original article can be found online at https://doi.org/10.1007/s10694-022-01292-5.Correction: Fire Technology https://doi.org/10.1007/s10694-022-01292-5In this article, the last two Funds, which is not related with this work, are listed in Acknowledgement. The correct wordings should be "The present work was supported by the Science and Technology Project of State Grid Corporation of China (Grant No.5200-202123096A-0–0-00)."The original article has been corrected.By Jiaqing Zhang; Fengju Shang; Taiyun Zhu; Yi Guo; Xuan Liang and Qiang WangReported by Author; Author; Author; Author; Author; Author [Extracted from the article]