Paratherm-NF aerosol combustion behavior simulation: Ignition delay time, temperature distribution of flame propagation, and heat kernel hypothesis of combustion process analysis

• Analysis of heat transfer fluid aerosol flame development in flow system.
• Determination of ignition delay time of aerosols.
• Factors characterization of aerosol ignition delay time and sustainable flame appearance.

Aerosol combustion, especially for high-flash point materials, is a very complicated phenomenon inclusive of droplet evaporation, temperature increase, flame formation, flame propagation, and flame quench. A better understanding of a flame development can make this process clear to analyze, with possible mitigation system design according to the explanation of how the aerosol system gets ignited and how long it takes to form a harmful flame, which can propagate, accelerate, and cause fire or explosions. The authors of this paper have conducted a series of simulation regarding physical formula in description of this combustion process, and will conclude with how temperature distribution influenced the appearance of luminous flames, which was the symbol of successful ignition of aerosol. The novelty on this research is on the cutting point of flame appearance by setting of different temperature probes within aerosol system and determining various locations of testing, while more common studies have been done usually by means of existing flame expansion. Aerosol system in this paper was according to an electrospray-generated droplet group from experiments (Huang, Li, & Mannan, 2013) and trying to improve the explanation on the complex behavior for mixture materials with high flash point, which has not been done by other studies yet. We obtained the result that most of the initial heating time (∼10–15 s after appearance of ignition source) is for turbulent heating on the closest, horizontal region of aerosol cloud; the next stage (∼up to 40 s), on the other hand, has the determining force on vertical movement of the “heated kernel” as the new ignition source on fresh aerosols feed. The sustainable flame occurred after the delay time regarding the above mechanism. The mitigation implementing timing and location can also be characterized with further understanding of this combustion process, which is the functionality of our results in this fundamental analysis. The potential application of the ignition delay will be beneficial to the mitigation timing and detector sensor setting of facilities to prevent aerosol cloud fires.