Modeling decomposition of unconfined rigid polyurethane foam

Hobbs, Michael L.; Erickson, Kenneth L.; Chu, T. Y.

doi:10.1016/s0141-3910(00)00040-9

Cited by 57 publications

(54 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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%

See 2 more Smart Citations

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

Hobbs¹

2004

View full text Add to dashboard Cite

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

show abstract

Section: Element Death Criterionmentioning

confidence: 99%

Section: Element Death Criterionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Hobbs¹

2004

View full text Add to dashboard Cite

show abstract

“…A) Centerline distance from heated surface for various time-step "zombie criterion," B) CPU-time as function of the zombie criterion, and C) percent of overall CPU attributed to radiation viewfactor calculations and chemistry calculations. [4].…”

Section: Example Calculation Of Inert Components Encapsulated In Rigimentioning

confidence: 99%

“…A better approach for confined systems would probably be a combination of the CPUF (chemical-structure based) and SPUF (general discretization bias correction) models with additional physics to account for off gas composition, mass transport, liquefaction, pressurization, and flow. Two foam response models have been developed previously for unconfined decomposition of polyurethane foam -PUF [3,4] and CPUF [5]. These models (PUF and CPUF) present a framework to determine gas composition necessary to predict dynamic pressurization in closed, confined systems.…”

Section: List Of Tablesmentioning

confidence: 99%

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

Hobbs¹,

Lemmon²

2003

View full text Add to dashboard Cite

A Simple PolyUrethane Foam (SPUF) mass loss and response model has been developed to predict the behavior of unconfined, rigid, closed-cell, polyurethane foam-filled systems exposed to fire-like heat fluxes. The model, developed for the B61 and W80-0/1 fireset foam, is based on a simple two-step mass loss mechanism using distributed reaction rates. The initial reaction step assumes that the foam degrades into a primary gas and a reactive solid. The reactive solid subsequently degrades into a secondary gas. The SPUF decomposition model was implemented into the finite element (FE) heat conduction codes COYOTE [1] and CALORE [2], which support chemical kinetics and dynamic enclosure radiation using "element death." A discretization bias correction model was parameterized using elements with characteristic lengths ranging from 1-mm to 1-cm. Bias corrected solutions using the SPUF response model with large elements gave essentially the same results as grid independent solutions using 100-µm elements. The SPUF discretization bias correction model can be used with 2D regular quadrilateral elements, 2D paved quadrilateral elements, 2D triangular elements, 3D regular hexahedral elements, 3D paved hexahedral elements, and 3D tetrahedron elements. Various effects to efficiently recalculate viewfactors were studied -the element aspect ratio, the element death criterion, and a "zombie" criterion. Most of the solutions using irregular, large elements were in agreement with the 100-µm grid-independent solutions. The discretization bias correction model did not perform as well when the element aspect ratio exceeded 5:1 and the heated surface was on the shorter side of the element. For validation, SPUF predictions using various sizes and types of elements were compared to component-scale experiments of foam cylinders that were heated with lamps. The SPUF predictions of the decomposition front locations were compared to the front locations determined from real-time X-rays. SPUF predictions of the 19 radiant heat experiments were also compared to a more complex chemistry model (CPUF) predictions made with 1-mm elements.The SPUF predictions of the front locations were closer to the measured front locations than the CPUF predictions, reflecting the more accurate SPUF prediction of mass loss. Furthermore, the computational time for the SPUF predictions was an order of magnitude less than for the CPUF predictions. 5 AcknowledgementsRobert Kerr provided considerable help in making many of the tetrahedral meshes using CUBIT.Steven W. Bova provided the program to convert HEX elements to TET elements using the same node points. The authors also gratefully acknowledge the technical assistance provided by Steven T. Sorensen and Weston Carter for help with optimization and image processing. Scot Waye

show abstract

Effects of composition and temperature of initial mixture on the formation and properties of polyurethane foam

Özdemir

Akar

2017

Adv Polym Technol

View full text Add to dashboard Cite

The purpose of the study is to optimize the initial conditions of the molding process of a multicomponent mixture into a refrigerator cabinet. Polyurethane foaming has been studied with different starting compositions and temperatures of the initial mixture. The kinetic mechanism has involved four reactions and species species. Using a standard recipe, the chemical kinetics and the numerical implementation have been first validated against the experimental values of the filling time and the density of the final foam. Thereafter, 11,763 different initial conditions are calculated. The results put in evidence that the filling time can be reduced without any significant change in the precursors of the rigidity of the foam. The final temperature of the foam has always remained lower than the limiting temperature so that thermal material deformations in the walls of the cabinet can be avoided. Increasing the physical blowing agent mass fraction beyond the standard recipe does not appear to be a useful option.

show abstract

Modeling decomposition of unconfined rigid polyurethane foam

Cited by 57 publications

References 8 publications

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

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

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

Effects of composition and temperature of initial mixture on the formation and properties of polyurethane foam

Contact Info

Product

Resources

About