Assessment of Fire Engineering Design Correlations Used to Describe the Geometry and Thermal Characteristics of Externally Venting Flames

Externally venting flames (EVF) may emerge through openings in fullydeveloped under-ventilated compartment fires, significantly increasing the risk of firespreading to higher floors or adjacent buildings. Several fire engineering correlationshave been developed, aiming to describe the main characteristics of EVF that affectthe fire safety design aspects of a building, such as EVF geometry, EVF centrelinetemperature and EVF-induced heat flux to the fac ̧ ade elements. This work is moti-vated by recent literature reports suggesting that existing correlations, proposed infire safety design guidelines (e.g. Eurocodes), cannot describe with sufficient accuracythe characteristics of EVF under realistic fire conditions. In this context, a wide rangeof EVF correlations are comparatively assessed and evaluated. Quantification of theirpredictive capabilities is achieved by means of comparison with measurementsobtained in 30 different large-scale compartment-fac ̧ ade fire experiments, covering abroad range of heat release rates (2.8 MW to 10.3 MW), ventilation factor values(2.6 m5/2to 11.53 m5/2) and ventilation conditions (no forced draught, forceddraught). A detailed analysis of the obtained results and the respective errors corrob-orates the fact that many correlations significantly under-predict critical physicalparameters, thus resulting in reduced (non-conservative) fire safety levels. The effectof commonly used assumptions (e.g. EVF envelope shape or model parameters forconvective and radiative heat transfer calculations) on the accuracy of the predictedvalues is determined, aiming to highlight the potential to improve the fire engineeringdesign correlations currently availabl

Fire safety aspects of PCM-enhanced gypsum plasterboards: An experimental and numerical investigation

New trends in building energy efficiency include thermal storage in building elements that can be achieved via the incorporation of Phase Change Materials (PCM). Gypsum plasterboards enhanced with micro-encapsulated paraffin-based PCM have recently become commercially available. This work aims to shed light on the fire safety aspects of using such innovative building materials, by means of an extensive experimental and numerical simulation study. The main thermo-physical properties and the fire behaviour of PCM-enhanced plasterboards are investigated, using a variety of methods (i.e. thermo-gravimetric analysis, differential scanning calorimetry, cone calorimeter, scanning electron microscopy). It is demonstrated that in the high temperature environment developing during a fire, the PCM paraffins evaporate and escape through the failed encapsulation shells and the gypsum plasterboard's porous structure, emerging in the fire region, where they ignite increasing the effective fire load. The experimental data are used to develop a numerical model that accurately describes the fire behaviour of PCM-enhanced gypsum plasterboards. The model is implemented in a Computational Fluid Dynamics (CFD) code and is validated against cone calorimeter test results. CFD simulations are used to demonstrate that the use of paraffin-based PCM-enhanced construction materials may, in case the micro-encapsulation shells fail, adversely affect the fire safety characteristics of a building. © 2015 Elsevier Ltd. All rights reserved

Fire protection of light and massive timber elements using gypsum plasterboards and wood based panels: A large-scale compartment fire test

A full-scale compartment fire test was performed to assess gypsum plasterboards and wood based panels as cladding materials for the fire protection of light and massive timber elements. The test compartment was constructed using both the timber frame and the cross laminated timber techniques; a wood crib was used to achieve realistic fire conditions. Temperature measurements and optical inspection evidence suggested that gypsum plasterboards offered adequate fire protection since they did not fail and no charring was observed in the timber elements. A free standing wall inside the test compartment, protected by wood-based panels, partially collapsed. Measured values of characteristic failure times, such as time to failure of fire protection cladding and time to onset of charring, were compared to relevant Eurocode correlations, achieving good levels of agreement. The obtained set of measurements, describing the time evolution of a large variety of physical parameters, such as gas and wall layer temperatures, can be used for validation of relevant advanced fire simulation tools