Suppression effectiveness of water sprays on accelerated wood-crib fires

Solid-fire extinguishment by water sprays has received remarkable attention over the decades. Though several approaches have been taken to understand the important physical phenomena, empirical correlations remain very common in discussions of these fires. Historically, wood-cribs have offered an important means by which to study the extinguishment of combustible solids, as their simple and well-defined structure lends a degree of repeatability to experimental investigations. Therefore, several classical experiments in this area focus on wood-crib fuel packages [1-3]. The primary objective of this mainly experimental study is to determine the relationship between the water flux applied to a burning wood crib and the total damage sustained by the crib, as assessed by the crib’s mass loss. A thermodynamic discussion of the potential cooling mechanisms also provides physical insight into the suppression results. As an additional feature of the present work, an experimental characterization of the water mist spray was performed in terms of flux and drop-size distribution, following previous spray studies [4]. Moreover, additional parameters were investigated to better understand the wood-crib fire dynamics (e.g., air entrainment at the lateral surface and heat release rate)

Suppression effectiveness of water-mist sprays on accelerated wood-crib fires

An experimental analysis was conducted to quantify the water-mist discharge characteristics required to suppress wood-crib fires. The overall aim of this research was to investigate the effectiveness of these innovative systems in a canonical fire scenario. To this end, an experimental suppression facility was constructed including commercially available water mist nozzles, thermocouples for measuring the thermal transient in and around the wood cribs and a load cell for measuring the mass loss rate and the final wood crib damage. 510\uc3\u97510\uc3\u97380 mm wood cribs were used as the fuel source in all the experiments. The injection pressure and orifice diameter of the water-mist nozzles were varied in the experiments to modify the applied water flux and the initial spray momentum. These quantities were identified to be the governing parameters for suppression performance. They were characterized for all experiments along with the drop-size and velocity distributions. Critical values were determined for these quantities from first order kinematic and thermal analysis based on spray and fire source characteristics. The experimental results demonstrated critical suppression behavior consistent with this first order analysis