SPUF - a simple polyurethane foam mass loss and response model.

Hobbs, Michael L.; Lemmon, Gordon

doi:10.2172/917167

Cited by 6 publications

(11 citation statements)

References 3 publications

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“…The framework used to develop the SREF model is based on three previously developed polyurethane foam decomposition models--referred to as the PUF, CPUF, and SPUF models [6][7][8]. The PUF [6] and CPUF [7] models were based on the chemical-structure of the polyurethane foam with 9 and 16 reaction steps, respectively.…”

Section: Nomenclaturementioning

confidence: 99%

SREF - a Simple Removable Epoxy Foam decomposition chemistry model.

Hobbs¹

2003

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A Simple Removable Epoxy Foam (SREF) decomposition chemistry model has been developed to predict the decomposition behavior of an epoxy foam encapsulant exposed to high temperatures. The foam is composed of an epoxy polymer, blowing agent, and surfactant. The model is based on a simple four-step mass loss model using distributed Arrhenius reaction rates. A single reaction was used to describe desorption of the blowing agent and surfactant (BAS). Three of the reactions were used to describe degradation I would like to thank Art Ratzel, Gene Hertel, Mike Prairie, and Martin Pilch for management support and funding. Ken Erickson provided data obtained from the low-pressure unconfined/partially-confined TGA apparatus as well as enthalpy data from a differential scanning calorimeter. Ted Borek provided adsorption tube analysis. Tom Fletcher and Dan Clayton (Brigham Young University) provided elemental analysis, chemical structure, and low/high pressure unconfined TGA data. Anita Renlund provided dynamic pressurization data from her hot cell experiment. Walt Gill and Terry Aselage provided the heat capacity data. Amy Sun helped articulate the VLE model. Shawna Liff (coop student from Northeastern University, Boston) helped calculate the RMS errors and to plot the results. Scot Waye (student intern from the University of Utah) also helped plot some of the results.

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Section: Nomenclaturementioning

confidence: 99%

SREF - a Simple Removable Epoxy Foam decomposition chemistry model.

Hobbs¹

2003

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“…Removal of elements from the computational domain is referred to as "element death." A solid fraction death criterion, In previous studies [5][6][7], the element death criterion was selected based on the measured onset of burnout. Burnout is defined as the solid mass fraction where most of the organic material has decomposed and the residue primarily consists of nonvolatile matter.…”

Section: Element Death Criterionmentioning

confidence: 99%

“…The temperature of the onset of burnout was determined for various experiments. In previous studies [5][6][7], the mean of the temperature corresponding to the onset of burnout was used with the mass loss model to define the death criterion.…”

Section: Element Death Criterionmentioning

confidence: 99%

“…The SREF response model discussed in the current report is based on concepts from several polyurethane foam response models developed previously [5][6][7], which use "element death" to describe the regressing surface of the foam exposed to high heat fluxes. "Element death" is used to describe removal of elements from the computational domain when the solid mass fractions within elements approach zero.…”

Section: Introductionmentioning

confidence: 99%

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Response of removable epoxy foam exposed to fire using an element death model.

Hobbs¹

2004

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Response of removable epoxy foam (REF) to high heat fluxes is described using a decomposition chemistry model [1] in conjunction with a finite element heat conduction code [2] that supports chemical kinetics and dynamic radiation enclosures. The chemistry model [1] describes the temporal transformation of virgin foam into carbonaceous residue by considering breakdown of the foam polymer structure, desorption of gases not associated with the foam polymer, mass transport of decomposition products from the reaction site to the bulk gas, and phase equilibrium. The finite element foam response model considers the spatial behavior of the foam by using measured and predicted thermophysical properties in combination with the decomposition chemistry model. Foam elements are removed from the computational domain when the condensed mass fractions of the foam elements are close to zero. Element removal, referred to as element death, creates a space within the metal confinement causing radiation to be the dominant mode of heat transfer between the surface of the remaining foam elements and the interior walls of the confining metal skin. Predictions were compared to front locations extrapolated from radiographs of foam cylinders enclosed in metal containers that were heated with quartz lamps [3,4]. The effects of the maximum temperature of the metal container, density of the foam, the foam orientation, venting of the decomposition products, pressurization of the metal container, and the presence or absence of embedded components are discussed. 4Intentionally left blank 5

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“…A subgrid model for the CPUF foam response model was developed to correct the solution so that 1-mm elements can be used for large-scale calculations to give the same solution as a solution with a 100-µm sized grid. The methodology for bias correction could have been generalized for any size element, including mixed-element type such as hexahedral and tetrahedral elements [33].…”

Section: Three-dimensional Simulation Of Experiments 750-2mentioning

confidence: 99%

CPUF - a chemical-structure-based polyurethane foam decomposition and foam response model.

Fletcher

Thompson²,

Erickson³

et al. 2003

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A Chemical-structure-based PolyUrethane Foam (CPUF) decomposition model has been developed to predict the fire-induced response of rigid, closed-cell polyurethane foam-filled systems.The model, developed for the B-61 and W-80 fireset foam, is based on a cascade of bondbreaking reactions that produce CO 2 . Percolation theory is used to dynamically quantify polymer fragment populations of the thermally degrading foam. The partition between condensed-phase polymer fragments and gas-phase polymer fragments (i.e. vapor-liquid split) was determined using a vapor-liquid equilibrium model. The CPUF decomposition model was implemented into the finite element (FE) heat conduction codes COYOTE and CALORE, which support chemical kinetics and enclosure radiation. Elements were removed from the computational domain when the calculated solid mass fractions within the individual finite element decrease below a set criterion.Element removal, referred to as "element death," creates a radiation enclosure (assumed to be non-participating) as well as a decomposition front, which separates the condensed-phase encapsulant from the gas-filled enclosure. All of the chemistry parameters as well as thermophysical properties for the CPUF model were obtained from small-scale laboratory experiments. The CPUF model was evaluated by comparing predictions to measurements. The validation experiments included several thermogravimetric experiments at pressures ranging from ambient pressure to 30 bars. Larger, component-scale experiments were also used to validate the foam response model. The effects of heat flux, bulk density, orientation, embedded components, confinement and pressure were measured and compared to model predictions. Uncertainties in the model results were evaluated using a mean value approach. The measured mass loss in the TGA experiments and the measured location of the decomposition front were within the 95% prediction limit determined using the CPUF model for all of the experiments where the decomposition 4 gases were vented sufficiently. The CPUF model results were not as good for the partially confined radiant heat experiments where the vent area was regulated to maintain pressure. Liquefaction and flow effects, which are not considered in the CPUF model, become important when the decomposition gases are confined.5

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SPUF - a simple polyurethane foam mass loss and response model.

Cited by 6 publications

References 3 publications

SREF - a Simple Removable Epoxy Foam decomposition chemistry model.

SREF - a Simple Removable Epoxy Foam decomposition chemistry model.

Response of removable epoxy foam exposed to fire using an element death model.

CPUF - a chemical-structure-based polyurethane foam decomposition and foam response model.

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