Chung-Hwei Su

Computational analysis on the performance of smoke exhaust systems in small vestibules of high-rise buildings

The vestibules in high-rise buildings are specified zones for fire safety. In Taiwan, the designs of the structures and smoke exhaust systems of the vestibules are supervised by different government agencies. The design principles of these smoke exhaust systems take into consideration the flow rates and the impact of the flow momentum. Unfortunately, the current regulations in Taiwan only consider the former. Some small vestibules legally exist in high-rise buildings as they are in compliance with building regulations. This study uses the Fire Dynamics Simulator to analyse 20 modes of smoke exhaust systems under 1.0 MW of the fire load in small vestibules (2 m2 in area). The results indicate that the performance of different smoke exhaust systems significantly varies with different airflow momentums. Some improvement measures are discussed for the worst cases.

Experimental and Numerical Analysis of the Cooling Performance of Water Spraying Systems during a Fire

The water spray systems are effective protection systems in the confined or unconfined spaces to avoid the damage to building structures since the high temperature when fires occur. NFPA 15 and 502 have suggested respectively that the factories or vehicle tunnels install water spray systems to protect the machinery and structures. This study discussed the cooling effect of water spray systems in experimental and numerical analyses. The actual combustion of woods were compared with the numerical simulations. The results showed that although the flame continued, the cooling effects by water spraying process within 120 seconds were obvious. The results also indicated that the simulation results of the fifth version Fire Dynamics Simulator (FDS) overestimated the space temperature before water spraying in the case of the same water spray system.

Application of Schlieren Photography to Study Neutral Plane in a Compartment Fire With Scale Models

In this paper, the neutral plane in a compartment fire was measured by Optical Schlieren Photography. This is a highly sensitive, optical, nonintrusive and remote technique to visualize fluid flow, utilizing refraction when light passes through air of different densities. The positions and variations of hot air flowing out of an opening can be determined clearly. A 1/14 scale model room burning candles inside was used. Hot air induced by the candle flame flowing out a 15 cm opening was observed. Thermocouples were also placed at the opening to compare with the neutral plane determined by the Schlieren Photography method. Simulations with Computational Fluid Dynamics were performed to justify the observed locations of the neutral planes.Copyright

Isothermal and non-isothermal kinetic and safety parameter evaluation of tert-butyl(2-ethylhexyl)monoperoxy carbonate by differential scanning calorimetry

Tert-butyl(2-ethylhexyl)monoperoxy carbonate (TBEHC) 95 mass% is intrinsically a very unstable substance that can induce self-decomposition even under normal atmospheric condition. During storage, TBEHC 95mass% can release an enormous amount of heat if the temperature is higher than the recommended storage temperature, due to the self-accelerating reaction having been ignited. In this study, TBEHC 95mass% was tested by differential scanning calorimetry (DSC) under five heating rates (1, 2, 4, 6, and 8 °C/min) and four isothermal conditions (120, 125, 130, and 135 °C) to evaluate the basic kinetic and safety parameters of time to maximum rate (TMR), self-accelerating decomposition temperature (SADT), and temperature of no return (TNR). Under runaway reaction TBEHC 95 mass% releases a great quantity of heat. This study establishes an important guiding principle for related manufacturing processes worldwide.

Effect of Fire Detection Function on Fire Suppression in Home Stay Facilities in Taiwan

Home stay facility has been one of the main options of lodging in Taiwan. Besides the lodging supplies, the decorative articles inside the buildings are indeed inflammable. The home stay facilities are mostly located in remote scenic areas, where the firefighters cannot reach immediately in case of a fire. How to detect and extinguish the fire immediately at the initial stage of fire is an important topic for the home stay facility. Many studies have discussed the firefighting in large hotels, but seldom on firefighting in home stay facilities. Different detector types have varied detection lengths, thus affecting the timeliness of fire suppression. Referring to the “Regulations for the Management of Home Stay Facilities” enacted in 2001, this study analyzed the fire suppression timeliness of fire detectors. The Fire Dynamics Simulator was used to discuss the extent of harm of a fire on the persons attempting to suppressing fire. The changes of parameters, including temperature, visibility, and fire behavior parameters, due to dense smoke and fire over time were obtained. The activation time of two detectors, namely, smoke detector and rate of rise detector, in a case of fire was quantitatively analyzed. The results showed the scenarios the persons may be confronted with when suppressing a fire.

The Evaluation of Fire Rescue Capability from Post-Earthquake Fires in Taipei, Taiwan

This paper assesses the Taipeis fire rescue capability against post-earthquake fires (PEFs) from a hypothetical earthquake. Taiwans Shanchiao Fault was used as the trigger fault for establishing earthquake modeling assumptions. Monte Carlo simulation was used with hypocenter coordinates, the Richter magnitude scale, and earthquake focal depths as the uncertainty analysis variables for performing stochastic simulations of 100 sets of seismic event parameters. These parameters were entered into the Simple Earthquake Seismic System (SESS) and the Taiwan Earthquake Loss Estimation System (TELES) to conduct uncertainty analysis regarding PEFs. PEFs were simulated and the disaster readiness of all firefighting squads (strongholds) in Taipei was investigated to analyze the uncertainty in PEF rescues. The SESS analysis results indicate that the original risk probability was 25.26%, increasing to 45.88% with the activation of a regional mutual aid system. The original risk calculated by the TELES was 52.97%, which increased to 96.22% of the overall disaster response capacity requirements after the regional mutual aid system was launched. Although the SESS results remained below the 60% risk threshold following the launch of the regional mutual aid system, the rescue capacity was substantially increased. The TELES analysis results indicate that the regional mutual aid system can substantially increase local disaster rescue capacity, nearly satisfying all disaster resource scheduling requirements. The location, scale, and pattern of earthquakes and the resulting casualties are always uncertain. However, the results of this study verify that the 2 independently developed earthquake damage estimation systems can provide an effective reference for post-earthquake rescue scheduling assessments.