The burning of two species of pine needles: Pinus halepensis and Pinus pinaster, was studied to characterize the behavior of the forest floor in wildland fires. These fuels are representative of the Mediterranean ecosystem and have very different shapes and surface-to-volume ratios. Calorimetry was performed using the FM-global fire propagation apparatus (FPA). To better understand the effects of transport in the fuel beds, the standard sample holder was replaced by a holder that allowed for the porous properties of the fuel to be studied in a systematic manner. These holders were designed with holes on the surface to allow for different air flow rates to pass through the holder and into the fuel sample. These characteristics created different internal fuel bed conditions and were the first such tests that could be identified that examined transport on this level in these types of wildland fuels. Tests were conducted under natural convection and forced flow. The test series results were analyzed with respect to the direct values of the measured variables and calculated values of heat release rate. Discrete variables of time to ignition, duration of flaming combustion and peak heat release rate were compared using an analysis of variance method. As the experiments were conducted under well-ventilated conditions, the heat release rate calculated by calorimetry was compared to mass loss rate and heat of combustion. CO concentration in time proved to be a good indicator of the combustion dynamics in the fuel bed. Heat release rate, time to ignition and time to reach peak heat release rate indicated a strong dependence on flow conditions and on fuel specie. It was shown that the transport processes in the fuel beds had a significant effect on the burning characteristics.

The Dalmarnock Tests comprise a set of fire experiments conducted in a real high-rise building in July 2006. The two main tests took place in identical flats, Test One allowing the fire to develop freely to post-flashover conditions while Test Two incorporated sensorinformed ventilation management. The test compartments were furnished with regular living room/office items and fully instrumented with high sensor densities. The furniture and objects acting as fuel were arranged to provide conditions that favour repeatability. A full description of the set up of the tests, including fire monitoring sensors, is provided. Focus is on the larger Test One fire for which the major events are reported together with a thorough characterisation of the fire using sensor information. The main aim of the experiments was to collect a comprehensive set of data from a realistic fire scenario that had a resolution compatible with the output of field models. The characterisation of Test One provides a platform with potential for analytical and computational fire model validation.

a b s t r a c tThis work aims to characterize pine needles as a fuel for a better understanding of the behaviour of forest fuels in wildland fires. It does this in two ways: classify vegetation as a fuel for forest fires and understand the role of transport mechanisms in fuel beds. For this purpose, the physical and chemical characteristics of each fuel are taken into account. Three species of pine needles were studied: Pinus halepensis, Pinus pinaster and Pinus laricio. These were chosen because they are representative of the Mediterranean ecosystem and present different characteristics such as surface-to-volume ratio and chemical composition.The experiments were performed using the FM-Global Fire Propagation Apparatus with a Fourier transform infrared gas analyser to determine the pyrolysis gases released by the three species. The heat release rate (HRR) was estimated using oxygen consumption calorimetry. Specially constructed porous sample holders were used, with different percentages of basket openings, to allow different air flow rates to pass through the fuel samples. Forced flows of different magnitudes were also imposed through the sample in some cases.In this study, the focus has been made upon the influence of the two main experimental parameters, i.e. flow conditions through the fuel bed (varying with basket opening and forced flow conditions) and fuel species particularities, on the time dependent variable HRR. Discrete variables such as time to ignition, duration of flames and mean HRR during the flame were also analysed.Flow conditions appear to be an important parameter when analysing the combustion dynamics of a porous fuel. Fuel species also have an influence on the heat release rate. The role of these parameters and their interaction prove to be more complex than anticipated. Surface-to-volume ratio and fuel packing ratios are not the only parameters governing burning dynamics, even for closely related species such as pine needles. Chemical properties have also proved to have an influence when the oxygen supply in the combustion zone is high.

The Heat Release Rate (HRR) is a critical parameter to characterise a fire. Different methods have been developed to estimate it. The most widespread techniques are based on mass balance. If the heat of combustion of the fuel is known, the measure of the mass loss allows its evaluation. If the burning material can not be identified, calorimetric principles can be used. They rely on oxygen consumption (OC) or carbon dioxide and carbon monoxide generation (CDG) measurements. Their asset comes from the observation that the amount of energy release per unit mass of O 2 consumed or per unit mass of CO 2 produced is relatively constant for a large number of materials. Thus, an accurate HRR can be obtained without knowing the composition of the burning fuel. The aim of this work is to assess this last statement and define how essential the knowledge of the chemistry to calculate HRR for complex materials such as polymers including fire retardants and/or nanocomposites, energetic materials or pine needles is. This assessment ends in an OC and CDG calorimetry comparison of several materials in order to investigate the propensity to determine whether converging or diverging HRR results when average energy constants are used.

The cone calorimeter and the fire propagation apparatus (FPA) are often used to carry out flammability studies of materials. There are various differences in the set-up of these two devices that could lead to different fire behaviour for the same material. Among these, the impact of the different heat sources used is studied here. The cone calorimeter employs an electrical cone heater and the FPA uses tungsten lamps to radiate a given heat flux level to the sample. Experiments are conducted in the FPA set-up using a conical heater or tungsten lamps as the heat source with clear PMMA and wood samples. Mass loss and temperature measurements are taken during the tests, and the bubble layer depth is measured after the tests. Significant differences in pyrolysis behaviour of both samples between the cone calorimeter and the FPA are consistently observed at the same heat flux level. These different pyrolysis behaviours can be explained by the wavelength dependency of the radiative material properties (reflectance, absorptance and transmittance). This conclusion is in agreement with, and provides an experimental confirmation, to theoretical findings in previous studies.