Thermal Boundaries in Cone Calorimetry Testing

Abstract

Bench-scale cone calorimetry is often used to evaluate the fire performance of intumescent-type coatings. During the tests, the coating geometry inflates. These thick, block-shaped specimens expose their perimeter side surfaces to both the heat source and the surroundings, unlike the typical thin, plate-shaped samples used in flammability tests. We assessed the thermal boundaries of block-shaped specimens using plain steel solids with several thicknesses. The heat transmitted through the exposed boundaries in convection and radiation modes was determined by four sub-defining functions: non-linear irradiance, convective loss, and radiant absorption into and radiant emission from solids. The individual functions were methodically derived and integrated into numerical calculations. The predictions were verified by physical measurements of the metals under different heating conditions. The results demonstrate that (1) considering absorptivity, being differentiated from emissivity, led to accurate predictions of time-temperature relationships for all stages from transient, through steady, and to cooling states; (2) the determined values for the geometric view factor and the fluid dynamic coefficient of convection can be generalized for engineering applications; (3) the proposed process provides a practical solution for the determination of optical radiative properties (absorptivity and emissivity) for use in engineering; and (4) the heat transmitted through the side surfaces of block specimens should be included in energy balance, particularly in the quantification of a heat loss mechanism. This paper outlines a comprehensive heat transfer model for cone calorimetry testing, providing insights into the mechanism of complex heat transmission generated on the test samples and quantifying their individual contributions.

Non-Isothermal Thermogravimetry of Selected Tropical Woods and Their Degradation under Fire Using Cone Calorimetry

“…Comparison of the combustibility of woods of different origin can be complicated due to differences in density, and therefore different initial masses of samples at uniform dimensions; this disparity may affect the time to ignition. There are also the different admixtures of both organic and inorganic nature with the result that unambiguous ordering of combustibility may be more complex [14][15][16][17][18]. This contribution, a continuation of previous research [19] is an attempt to characterize the thermal stability of 5 tropical woods, three of South American origin (Cumaru, Garapa, Ipe) and two of Southeast Asian origin (Kempas and Merbau), by non-isothermal thermogravimetry in air and oxygen.…”

“…Comparison of the combustibility of woods of different origin can be complicated due to differences in density, and therefore different initial masses of samples at uniform dimensions; this disparity may affect the time to ignition. There are also the different admixtures of both organic and inorganic nature with the result that unambiguous ordering of combustibility may be more complex [ 14 , 15 , 16 , 17 , 18 ].…”

Intumescent Coatings for Fire Resistance of Steel Structures: Current Approaches for Qualification and Design

“…For example, filler particles are incorporated into the formulation to act as nucleating sites or "bubble growth" locations and the resin binder theatres a large part in softening and charring [12]. This chemical transformation affects the thermal properties of ICs [13].…”

“…For example, filler particles are incorporated into the formulation to act as nucleating sites or "bubble growth" locations and the resin binder theatres a large part in softening and charring [12]. This chemical transformation affects the thermal properties of ICs [13]. Andersen [14] proposed the development of thermal resistance over time divided into four general phases, which were also confirmed and identified by de Silva et al in [15], investigating the thermal conductivity and swelling of ICs (Figure 3).…”

Toward an In‐Depth Fire Hazard and Resistance Diagnosis of Flame Retarded Liquid Electrolytes for Safer Lithium‐Ion Batteries

“…[39] However, the device has a limitation: its default sample holder is designed only to accommodate specimens in the solid-state such as solid polymers, woods, and other fabrics. [40,41] The solid samples are directly laid onto a fiber backing pad made of asbestos, [42,43] which poses a fundamental issue for the stability and the accurate analysis of liquid samples, as the fiber would absorb some of the liquid specimens or cause a spill and leakage of the sample, before the initiation of the test. Therefore, the design of a new sample holder that would enable the accurate and reliable measurement of liquid specimens' fire behavior and hazards is necessary.…”