Early fire evolution and alarm characteristics of cable fires in long and narrow spaces

Abstract

In this study, experiments were conducted on a full-scale cable interlayer experimental platform to investigate the evolution of early fires (smoldering and initial fires) in cable interlayers. Additionally, the temperature field of the fire spread and CO gas propagation characteristics were studied. The effectiveness of point-type temperature detectors, point-type smoke detectors, cable-type temperature detectors, and suction-type smoke detectors with different response time thresholds were analyzed from experiments and numerical simulation. The results revealed that the temperature fields of early fires exponentially decay in long and narrow spaces. Further, although the average propagation velocity of CO in a smoldering fire remains almost constant with increasing distance from the fire source, it decreases gradually in an initial fire. The cable-type temperature detector that remains in direct contact with the cable exhibited the shortest response time, with the non-contact detectors, including the point-type smoke detector and the suction-type smoke detector, exhibiting relatively long response times. In particular, the point-type temperature detector failed to generate a response at all in this case. Finally, the response times of fire detectors with high alarm thresholds were observed to be 10–20% higher than those of fire detectors with low thresholds.