Pool fires in open atmosphere and in air-tight compartments: experimental measurements and mathematical predictions of the heat release rate

The energy consumption in Europe is for the 40% accountable to households and the building sector. In the European Directive 2010/31/EU the main topic is the construction of highly efficient dwellings exploiting renewable sources of energy and engineered methodologies to heat up and insulate their premises. Passive houses are one example of these highly efficient constructions. Inside these new hazards can be outlined when a fire is triggered. The main parameter that has to be focused is pressure, which is the most important value when an occupant has to open a door to escape from a fire. The maximum force that a person can exert to open a door is 133 N. In the literature high values of overpressure have been reported, which means that this value of force is undoubtedly overcome, preventing the inhabitant to open the door to escape. Simulations with the use of the software FDS (Fire Dynamics Simulator) were carried out to show whether it is able to predict the heat release rate of a heptane pool fire. Firstly, heptane pool fires were simulated outdoor. Then, comparisons were drawn with experimental tests to explain the positive aspects and the drawbacks faced in the study. Secondly, the heptane pool fires were put inside a building, representing the passive house. The first step about the prediction of the heat release rate did not give consistent outcomes, involving a high heat flux on the pool surface, resulting in an important overestimation of the heat release rate. Instead, fixing the heat release for fires inside the enclosure shows good agreement, however mistakes in the temperature field of the gas phase showed up. In conclusion, the software FDS can be considered a reliable software to predict the heat release rate for heptane pool fires in open atmosphere. Nonetheless, inside a building, important drawbacks have been displayed which are not present, at least not at a such high level, for a fire in which the heat release rate results fixed as an input data.