Physicochemical properties of aerosol released in the case of a fire involving materials used in the nuclear industry

Quantification and prediction of water uptake by soot deposited on ventilation filters during fire events

Soot samples from different fuels were produced in small and pilot combustion test benches at various O₂ concentrations, and were then characterized in terms of primary particle diameter, specific surface area and oxygen content/speciation. Water sorption measurements were then carried out for soot compacted into pellet form and in powder form, using both a gravimetric microbalance and a manometric analyser. Water adsorption isotherms are all found to be Type V, and reveal the central role of the specific surface area and the oxygen content of soot. A single parametrization of the second Dubinin-Serpinsky model gives a proper fit for all isotherms. To the best of our knowledge, this is the first study to provide physico-chemical parameters and water sorption results for fire soot. This enables a better description of the soot cake formed on filters during a fire, in particular in industrial confined facilities as simulated in this study. Humidity can be then explicitly considered in the same way as other parameters influencing the aeraulic resistance of soot cakes. These results can be used to improve predictions of the consequences of fires on the containment of toxic materials within industrial facilities.

Taylor series expansion scheme applied for solving population balance equation

Population balance equations (PBE) are widely applied to describe many physicochemical processes such as nanoparticle synthesis, chemical processes for particulates, colloid gel, aerosol dynamics, and disease progression. The numerical study for solving the PBE, i.e. population balance modeling, is undergoing rapid development. In this review, the application of the Taylor series expansion scheme in solving the PBE was discussed. The theories, implement criteria, and applications are presented here in a universal form for ease of use. The aforementioned method is mathematically economical and applicable to the combination of fine-particle physicochemical processes and can be used to numerically and pseudo-analytically describe the time evolution of statistical parameters governed by the PBE. This article summarizes the principal details of the method and discusses its application to engineering problems. Four key issues relevant to this method, namely, the optimization of type of moment sequence, selection of Taylor series expansion point, optimization of an order of Taylor series expansion, and selection of terms for Taylor series expansion, are emphasized. The possible direction for the development of this method and its advantages and shortcomings are also discussed.