Fire Protection Engineering
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Item DEVELOPMENT AND VALIDATION OF A PYROLYSIS MODEL FOR FLEXIBLE POLYURETHANE FOAM(2024) Kamma, Siriwipa; Stoliarov, Stanislav I; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Flexible polyurethane foam (FPUF) is a common material contained in household goods such as upholstered furniture and mattresses, which are known to significantly contribute to fire growth. An accurate prediction of fire development on FPUF containing items requires knowledge of FPUF pyrolysis and combustion properties. These properties include reaction kinetic parameters, thermodynamic parameters, and thermal transport properties. While many past studies focused on the thermal decomposing mechanism and thermodynamic properties of the reactions, the thermal transport properties have not been determined. In this study, a complete pyrolysis model of FPUF was developed by extending the thermal decomposition model from a previous study. The thermal transport properties were obtained using inverse modeling of the Controlled Atmosphere Pyrolysis Apparatus II experimental data. The complete model was validated against cone calorimetry data and found to perform in an adequate manner.Item Pyrolysis Model Development for a Multilayer Floor Covering(MDPI, 2015-09-14) McKinnon, Mark B.; Stoliarov, Stanislav I.Comprehensive pyrolysis models that are integral to computational fire codes have improved significantly over the past decade as the demand for improved predictive capabilities has increased. High fidelity pyrolysis models may improve the design of engineered materials for better fire response, the design of the built environment, and may be used in forensic investigations of fire events. A major limitation to widespread use of comprehensive pyrolysis models is the large number of parameters required to fully define a material and the lack of effective methodologies for measurement of these parameters, especially for complex materials. The work presented here details a methodology used to characterize the pyrolysis of a low-pile carpet tile, an engineered composite material that is common in commercial and institutional occupancies. The studied material includes three distinct layers of varying composition and physical structure. The methodology utilized a comprehensive pyrolysis model (ThermaKin) to conduct inverse analyses on data collected through several experimental techniques. Each layer of the composite was individually parameterized to identify its contribution to the overall response of the composite. The set of properties measured to define the carpet composite were validated against mass loss rate curves collected at conditions outside the range of calibration conditions to demonstrate the predictive capabilities of the model. The mean error between the predicted curve and the mean experimental mass loss rate curve was calculated as approximately 20% on average for heat fluxes ranging from 30 to 70 kW·m−2, which is within the mean experimental uncertainty.Item Development of a Semiglobal Reaction Mechanism for the Thermal Decomposition of a Polymer Containing Reactive Flame Retardants: Application to Glass-Fiber-Reinforced Polybutylene Terephthalate Blended with Aluminum Diethyl Phosphinate and Melamine Polyphosphate(MDPI, 2018-10-12) Ding, Yan; Stoliarov, Stanislav I.; Kraemer, Roland H.This work details a methodology for parameterization of the kinetics and thermodynamics of the thermal decomposition of polymers blended with reactive additives. This methodology employs Thermogravimetric Analysis, Differential Scanning Calorimetry, Microscale Combustion Calorimetry, and inverse numerical modeling of these experiments. Blends of glass-fiber-reinforced polybutylene terephthalate (PBT) with aluminum diethyl phosphinate and melamine polyphosphate were used to demonstrate this methodology. These additives represent a potent solution for imparting flame retardancy to PBT. The resulting lumped-species reaction model consisted of a set of first- and second-order (two-component) reactions that defined the rate of gaseous pyrolyzate production. The heats of reaction, heat capacities of the condensed-phase reactants and products, and heats of combustion of the gaseous products were also determined. The model was shown to reproduce all aforementioned experiments with a high degree of detail. The model also captured changes in the material behavior with changes in the additive concentrations. Second-order reactions between the material constituents were found to be necessary to reproduce these changes successfully. The development of such models is an essential milestone toward the intelligent design of flame retardant materials and solid fuels.Item Polyisocyanurate Foam Pyrolysis and Flame Spread Modeling(MDPI, 2021-04-13) Chaudhari, Dushyant M.; Stoliarov, Stanislav I.; Beach, Mark W.; Suryadevara, Kali A.Polyisocyanurate (PIR) foam is a robust thermal insulation material utilized widely in the modern construction. In this work, the flammability of one representative example of this material was studied systematically using experiments and modeling. The thermal decomposition of this material was analyzed through thermogravimetric analysis, differential scanning calorimetry, and microscale combustion calorimetry. The thermal transport properties of the pyrolyzing foam were evaluated using Controlled Atmosphere Pyrolysis Apparatus II experiments. Cone calorimetry tests were also carried out on the foam samples to quantify the contribution of the blowing agent (contained within the foam) to its flammability, which was found to be significant. A complete pyrolysis property set was developed and was shown to accurately predict the results of all aforementioned measurements. The foam was also subjected to full-scale flame spread tests, similar to the Single Burning Item test. A previously developed modeling approach based on a coupling between detailed pyrolysis simulations and a spatially-resolved relationship between the total heat release rate and heat feedback from the flame, derived from the experiments on a different material in the same experimental setup, was found to successfully predict the evolution of the heat release rate measured in the full-scale tests on the PIR foam.Item DEVELOPMENT OF A PYROLYSIS MODEL FOR ORIENTED STRAND BOARD(2021) Zhou, Hongen; Stoliarov, Stanislav I.; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Oriented Strand Board (OSB) is a widely used construction material responsible for a substantial portion of the fire load of many buildings. To accurately model the response of OSB to fire, Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC) and Microscale Combustion Calorimetry (MCC) tests were carried out to construct a thermal decomposition model using a numerical solver, ThermaKin2Ds, and a hill climbing (HC) optimization algorithm. The model was determined to consist of two distinct processes. The first process is a single step water vaporization. The second process is a chain of four consecutive reactions representing thermal decomposition of the organic constituents of OSB. The experiments and modeling revealed that the first two of the four reactions are endothermic, while the last two are exothermic, and that the net heat of decomposition is near zero. The heat capacities of condensed-phase species and heats of combustion of evolved gases were also determined from inverse modeling of the DSC and MCC tests, respectively. Controlled Atmosphere Pyrolysis Apparatus II (CAPA II) experiments were performed at 35 kW m-2 and 65 kW m-2 of the radiant heat flux. The sample bottom temperature data obtained at 65 kW m-2 were used to determine the thermal conductivities of condensed-phase species. The complete pyrolysis model of OSB was subsequently validated by comparing the experimental CAPA II mass loss rate profiles with the model predictions. The undecomposed OSB density was found to vary both along the sheet surface and through thickness. However, these density variations had only a minor impact on the key features of the mass loss rate profiles.Item Development of a Semiglobal Reaction Mechanism for the Thermal Decomposition of a Polymer Containing Reactive Flame Retardants: Application to Glass-Fiber-Reinforced Polybutylene Terephthalate Blended with Aluminum Diethyl Phosphinate and Melamine Polyphosphate(MDPI, 2018-09-17) Ding, Yan; Stoliarov, Stanislav I.; Kraemer, Roland H.This work details a methodology for parameterization of the kinetics and thermodynamics of the thermal decomposition of polymers blended with reactive additives. This methodology employs Thermogravimetric Analysis, Differential Scanning Calorimetry, Microscale Combustion Calorimetry, and inverse numerical modeling of these experiments. Blends of glass-fiber-reinforced polybutylene terephthalate (PBT) with aluminum diethyl phosphinate and melamine polyphosphate were used to demonstrate this methodology. These additives represent a potent solution for imparting flame retardancy to PBT. The resulting lumped-species reaction model consisted of a set of first- and second-order (two-component) reactions that defined the rate of gaseous pyrolyzate production. The heats of reaction, heat capacities of the condensed-phase reactants and products, and heats of combustion of the gaseous products were also determined. The model was shown to reproduce all aforementioned experiments with a high degree of detail. The model also captured changes in the material behavior with changes in the additive concentrations. Second-order reactions between the material constituents were found to be necessary to reproduce these changes successfully. The development of such models is an essential milestone toward the intelligent design of flame retardant materials and solid fuels.Item A Methodology for Determining the Fire Performance Equivalency Amongst Similar Materials During a Full-scale Fire Scenario Based on Bench-scale Testing(2015) Lannon, Chad Michael; Stoliarov, Stanislav I; Fire Protection Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)A methodology was developed for determining the equivalency amongst materials during a full-scale fire scenario. This procedure utilizes milligram-scale and or bench-scale tests to obtain the effective physical and chemical properties of individual materials through an optimization procedure. A flame heat feedback model was developed for corner-wall flame spread and implemented into a two-dimensional pyrolysis model, ThermaKin2D. ThermaKin2D was utilized to simulate upward flame spread during the room corner test. A criterion was created that determines the fire performance of similar materials during this full-scale fire scenario and compares how each material performed relative to one another. A fire investigator will be able to better select materials for their reconstructive fire test based on the modeled full-scale fire performance of candidate materials compared to the exemplar material found during the fire investigation. Overall, this procedure is expected to improve a fire investigator’s ability to perform accurate reconstructive fire tests.