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This study investigates numerically the burning behaviour of a liquid pool fire in a medium-scale corridor-like enclosure in order to identify the key factors influencing External Venting Flames (EVF) characteristics as well as heat impact of the EVF on façades. Simulations were performed for four door-like openings with the fire located either at the front or back of the enclosure and the predicted gas temperatures and heat fluxes are analysed and compared with experimental data. Results show that FDS generally predicts accurately the gas temperature inside the corridor and captures well the detachment and propagation of the flame when the burner is positioned at the back of the corridor. The heat fluxes on the floor of the corridor are reasonably predicted in terms of both trends and maximum values for the cases where the fire is located at the back of corridor but generally under-predicted for the test cases where the burner is located at the front. Though similar trends, the predicted heat fluxes on the façade are considerably lower than the measurements highlighting the importance of accurate prediction of the burning characteristics of the EVF on the heat impact on the facade.

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.

In a compartmentfire, Externally Venting Flames (EVF) may significantly increase the risk offire spreading toadjacentfloors or buildings, especially when combustible insulation materials are installed on the buildingfaçade. An increasing number of recent reports suggest that existingfire engineering design methodologiescannot describe with sufficient accuracy the characteristics of EVF under realisticfire load conditions. In thiscontext, a series offire safety engineering design correlations used to describe the main EVF thermalcharacteristics, namely EVF centreline temperature and EVF-induced heatflux on the exposed façade surface,are comparatively assessed. Towards this end, measurements obtained in a medium- and a large-scalecompartment-façadefire test are employed; aiming to broaden the scope of the validation study, predictionsof the investigated correlations are further compared to measurements obtained in 6 large-scalefire tests foundin the literature. It is found that the correlation proposed in EN1991-1–2 (Eurocode 1) for the estimation of theEVF centreline temperature is under-predicting the measured values in large-scalefire tests. In addition, it isconcluded that estimation of the localflame emissivity should take into account the specific fuel type used ineach case.

In a fully developed under-ventilated compartment fire, flames may spill out of external openings (e.g. windows); Externally Venting Flames (EVF) pose a significant risk of fire spreading to adjacent floors or buildings. The main aim of this work is to comparatively assess a range of fire engineering design correlations used to describe the external dimensions of the EVF envelope. The predictive accuracy of each correlation is evaluated through comparison with experimental data obtained in a medium-scale compartment-façade fire facility, using typical fire loads suggested in the Eurocode. A series of fire tests is performed, employing a ¼ scale model of the ISO 9705 room, equipped with an additional extended façade. An “expendable” fuel source (n-hexane) is utilized to effectively simulate realistic building fire conditions. An extensive sensor network is used to monitor the dynamic behaviour of a broad range of important EVF physical parameters and a dedicated image processing tool is developed to allow estimation of the EVF envelope main dimensions (e.g. height, width, projection). Digital camera imaging is used to determine the main geometrical characteristics of the EVF envelope. Comparison of fire engineering design correlation predictions with experimental data reveals that correlations for the estimation of EVF height err on the safe side in under-ventilated fire conditions; decreasing the fire load results in under-prediction of EVF height and projection. It is shown that EVF projection and width strongly depend on both excess heat release rate and height. In addition, the necessity to derive appropriate criteria for the identification of the EVF projection is demonstrated. The obtained extensive set of experimental data, covering three different fire load levels, can be also used to validate numerical simulation tools or evaluate the accuracy of other available fire design correlations.

In a compartment fire, externally venting flames (EVF) may significantly increase the risk of fire spreading to adjacent floors or buildings; EVF-induced risks are constantly growing due to the ever-increasing trend of using combustible materials in building facades. The main aim of this work is to investigate the fundamental physical phenomena associated with EVF and the factors influencing their dynamic development. In this context, a series of fire tests is conducted in a medium-scale compartment-façade configuration; an n-hexane liquid pool fire is employed, aiming to realistically simulate an “expendable” fire source. A parametric study is performed by varying the fire load density (127.75, 255.5 and 511 MJ/m2) and ventilation factor (0.071 and 0.033 m3/2). Emphasis is given to characterization of the thermal field developing adjacent to the façade wall. Experimental results suggest that the three characteristic EVF phases, namely “internal flaming”, “intermittent flame ejection” and “consistent external flaming”, are mainly affected by the opening dimensions, whereas the fuel load has a notable impact on the fuel consumption rate and heat flux to the façade. Fuel consumption rates were found to increase with increasing fire load and opening area, whereas the global equivalence ratio increases with decreasing opening factor. The obtained extensive set of experimental data can be used to validate CFD fire models as well as to evaluate the accuracy of available fire design correlations.

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 available

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.

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.

Carbon monoxide (CO), a highly toxic gas, is produced during the incomplete combustion of carbon-based fuels. In indoor environments, high CO concentrations constitute a serious occupational health hazard; this is especially true in the case of automotive repair shop (ARS) employees who are exposed on a daily basis to vehicle exhaust streams. The present study focuses on the experimental investigation and numerical simulation of CO production and dispersion inside an ARS facility. Detailed measurements of CO concentration, vehicle traffic and ventilation system velocities are performed; the obtained data are appropriately formulated to provide quantitative information for modelling purposes. A detailed Computational Fluid Dynamics simulation of the developing transient flow-field is performed. The numerical results are validated using the experimental data; an overall good qualitative and quantitative agreement is achieved. Aiming to improve the energy efficiency of the mechanical ventilation system, three alternative scenarios are investigated; it is shown that the utilization of a dynamic ventilation system may result in significant energy consumption benefits, while, at the same time, CO concentrations remain below the values suggested by current occupational health legislation. The obtained results may be utilized to assist the design of mechanical ventilation systems for ARS facilities.

The ability of currently available Computational Fluid Dynamics (CFD) tools to adequatelydescribe Externally Venting Flames (EVF) is assessed, aiming to demonstrate compliance withperformance-based fire safety regulations. The Fire Dynamics Simulator (FDS) CFD tool is used tosimulate the EVF characteristics in a corridor-compartment-façade configuration exposed to natural fireconditions. Numerical results of the temporal evolution of gas velocity, gas temperatures and flame shapeare obtained for both the interior and the exterior of the compartment. Predictions are compared to respectiveexperimental data, as well as to correlations suggested by the Eurocode methodology. The effects ofventilation conditions are investigated by simulating both Forced Draught (FD) and No Forced Draught(NoFD) test cases. The obtained results suggest that currently available CFD tools are capable of achievinggood qualitative agreement with experimental data and, in certain cases (e.g. FD conditions), adequatequantitative agreement, that generally outperforms the Eurocode prescriptive methodology.