Temperature measurements are presented as obtained in a full-scale experimental campaign on large closed car park fires. Since the main objective of the study is the investigation of the impact of a smoke and heat control (SHC) system with forced mechanical horizontal ventilation on the smoke pattern in case of a car park fire, the desired fire heat release rate (HRR) is imposed by means of well-controlled liquid pool fires. Different parameters are varied: the fire HRR; the smoke extraction flow rate; the flow patterns (through modification of inlet air opening); and the presence (or not) of a transversal beam. Not surprisingly, less smoke back-layering is observed for lower fire HRR and higher smoke extraction rate, the effect of the latter being more important. The exact position of the extraction fans is not essential, when they are not close to the fire source. The impact of the flow pattern is substantial: when smoke is trapped inside a recirculation region, the smoke and heat are not removed effectively. A transversal beam can block the smoke, even for high HRR. The primary effect of jet fans (induction type, 50N) in the study at hand is a local cooling effect, not a significant impact on the global flow pattern. For the cooling effect to be observed, the jet fans must not be in a smoke filled region.
SUMMARYIn various medium to large scale fire test equipment, such as the ISO room corner (RC) test and more recently the single burning item (SBI) test, the mass flow measurement of the combustion gases plays a key role in the determination of the heat release rate and smoke production rate. To date a bi-directional lowvelocity pressure probe has been used to calculate this flow based on a differential pressure measurement on the axis of the exhaust duct. The objectives of this paper were to evaluate this bi-directional probe}and the modified SBI version}when used for measuring flows in exhaust ducts.Recommendations are given on the future use of pressure probes measuring exhaust gas mass flows.
SUMMARYIn various medium-to-large-scale fire test equipments like the ISO room corner test (RC), and more recently, the single burning item test (SBI) the mass flow rate measurement of the combustion gases plays a key role in the determination of the heat-release rate and smoke-production rate.With the knowledge of the velocity profile and the temperature of the flow, the mass flow rate is obtained by measuring the velocity on the axis of the duct. This is done by means of a bi-directional probe based on the pitot principle.However, due to the variation of the mean temperature and the temperature gradient in any cross section of the duct, introduced by ever changing combustion gas temperatures, the velocity nor the density profile are constant in time. This paper examines the resulting uncertainty on the mass flow rate.
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