08/12/2024
By Susan D'Amore
Thursday, Aug. 15
3 - 5 p.m.
Southwick 240
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For more information please contact Susan_Damore@uml.edu
3 p.m.
Modeling Material Flammability
Stanislav I. Stoliarov
Department of Fire Protection Engineering | University of Maryland, College Park
To design fire safe buildings and means of transportation, engineers must have an ability to predict the dynamics of fire growth for a set of relevant scenarios. Despite substantial research efforts, a systematic and accurate prediction of fire development is yet to be demonstrated due to, to a large degree, our inability to fully resolve coupling between the gas-phase processes of flaming combustion and condensed-phase processes of pyrolysis, responsible for generation of gaseous fuels. Two key quantities that define this coupling are the rate of heat flow (or heat flux) into the condensed phase and the rate of mass flow (or mass flux) of decomposition products into the gas phase. Recognizing that an improvement in our ability to compute the latter quantity may hold the key to accurate fire growth predictions, a systematic effort has been made by the fire science community to develop progressively more sophisticated models of pyrolysis. State-of-the-art pyrolysis solvers can simulate complex, multi-reaction thermal decomposition mechanisms coupled with physically diverse heat and mass transfer processes taking place in the condensed phase. However, parameterization of these models remains a non-trivial exercise requiring many careful measurements and inverse modeling, which is necessary because some of the processes cannot be fully isolated through experimental design. This presentation will review the recent advancements in formulation, parametrization, and validation of pyrolysis models for combustible solids and identify remaining obstacles preventing us from intelligent design of fire safe materials and structures.
4 p.m.
Past, Present, & Future of Milligram-Scale Flame Calorimetry
Fernando Raffan-Montoya, Ph.D.
Department of Fire Protection Engineering | University of Maryland, College Park
R&D campaigns to develop novel flame retardant formulations can be costly, even if initial testing is performed at the bench scale. To address this issue, a novel apparatus was designed, built, and characterized at the University of Maryland: the Milligram-scale Flame Calorimeter (MFC). In the apparatus, a 30-50 mg sized sample is pyrolyzed and the volatiles are purged with inert gas. The flammable volatiles are ignited in a controlled atmosphere, establishing an axisymmetric, laminar diffusion flame. The apparatus can measure heat release rates via O2 consumption calorimetry, along with direct gravimetric measurements of solid product (soot) yields and solid residue (char) yields. Over the years, modifications to the apparatus have added measurement capabilities such as CO and CO2 yields, measurement of the radiative fraction of solid fuels, as well as an improved pyrolyzer design to better analyze intumescent samples. The history of the apparatus and its evolution will be presented along with key results from experimental campaigns dealing with sensitivity to gas-phase flame retardants, screening of synergistic additives, characterizing radiative output of solid-fueled flames, benchmarking the MFC against well-established test methods and, more recently, characterizing flammability of fabric samples. Future modifications to the apparatus to include toxicity measurements (time resolved soot, acid gases, PM2.5 precursors), as well as automation of the testing process will also be discussed, highlighting the potential for the MFC to become the first milligram-scale apparatus to be used as the core of a material flammability self-driving laboratory.