Smoke control in case of fire in a large car park: Full-scale experiments

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, 50 N) 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.

► Analysis of more than 100 full-scale car park fire experiments with smoke and heat control (SHC).
► Parameter study: fire HRR; smoke extraction flow rate; flow patterns; effect of transversal beam.
► Analytical correlations confirmed for unidirectional flows.
► Recirculation regions must be avoided for smoke extraction.
► Much more than 10 air changes per hour required to keep smoke back-layering distance below 15 m.