Applicability of FLASH-CAT Model to Cable Tray Fire Modeling in Zone Model BRI2002

Abstract

Abstract To clarify the heat and smoke propagation in multi-compartments under the spread of cable fire, a large-scale multi-compartment fire test (hereinafter the CFS-2 test) was performed by the Institut de Radioprotection et de Sûreté Nucléaire (IRSN) in France within the framework promoted by the Nuclear Energy Agency (NEA) in Organization for Economic Co-operation and Development (OECD) program PRISME2 (OECD/NEA, 2017). In the CFS-2 test, two rooms of a large-scale facility were adopted and these rooms have an identical volume (120 m3) enclosed with fire walls and were connected by a doorway (0.8 m in width and 2.17 m in height). As a fire source, five-layer cable trays (tray length of 2.4m, tray width of 0.45m and separation distance between trays of 0.3 m) with a fire-retardant PVC cable (77 kg) were used and ignited by a propane gas burner. The power level of the propane gas burner was set to around 80 kW. Moreover, all rooms were mechanically ventilated, and the renewal rate was 15 times per hour (3600 m3/h). During the fire test, the mass loss rate of fuel, gas and soot mass concentration, gas temperature, and etc. were measured. The measured peak values of the HRR, the mass loss rate and gas temperature were about 800 kW, 58 g/s and greater than 600 °C, respectively (Zavaleta, 2017). As a fire model predicting fire characteristics in a compartment, a two-zone model, which divides the fire room into the hot smoke upper layer and lower layer consisting of cool fresh air, is widely used due to the advantages of the brevity of the calculation routine and the reliability of the calculation results. Among them, the BRI2 series, developed in Japan, is now reaching the current BRI2002 software (Wakamatsu, 2004) after several upgrades to improve the calculation precision. The Central Research Institute of Electric Power Industry (CRIEPI) introduced the cable tray fire source model based on the FLASH-CAT (Flame Spread over Horizontal Cable Trays) developed by National Institute of Standards and Technology (NIST) (McGrattan, 2012) into the zone code BRI2002. By comparing the numerical results with the experimental values measured during the CFS-2 test, the methodology for ignition time delay of each tray and horizontal flame propagation speed for each tray were discussed.