Fire Safety Evaluation of High-Pressure Ammonia Storage Systems

Ammonia combustion is a promising energy source as a carbon free fuel without greenhouse gas emissions. However, since the auto-ignition temperature is 651 degrees Celsius and the range of flammability limit is not wide compared to other fuels, fundamental studies on ammonia fires have rarely been conducted so far. Therefore, this study aims to numerically estimate fire spread characteristics when ammonia fuel in a high-pressure state leaks to the outside, especially focusing on the flammability limit according to oxygen concentration. Three kinds of reaction mechanism for numerical analysis were adopted to compare the flame structure, flammability limit, and combustion characteristics. Plank-mean absorption coefficients of nitrogen species were taken for the radiation model, in addition to the optically thin model. The effect of radiation heat loss could be identified from the maximum flame temperature trend at a low strain rate. It was confirmed that the pyrolysis of ammonia in the preheated zone results in hydrogen production, and the generated hydrogen contributes to heat release rate in the flame zone. It is found that the contribution of hydrogen would be an important role in the flammability limit of ammonia combustion. Finally, Karlovitz and Peclet numbers showed well the extinction behaviors of ammonia combustion as a result of LOC (Limit Oxygen Concentration) analysis as a function of global strain rate.

Fire Risk Analysis on Buildings Considering Fire Spread and Total Floor Area

Fire risk analysis models utilized for the fire risk assessment of domestic structures do not usually take into account flame spread and building size. Therefore, in this study, the effect of the building size on flame spread was investigated. Results showed that the frequency of occurrence of fires increased when the building has 11 or more floors. Additionally, the rate of occurrence of small-scale fires also increased when the total floor area was greater than or equal to 1,000 m2. From the risk analysis, the fire risk of health care, medical, and recreational facilities were calculated to be 25.7 × 10-3, 4.29 × 10-3, and 0.91 × 10-3 persons per year, respectively. As such, these were classified as high-risk facilities.

Fire Spread Risk Assessment Process for Radiant Heat Flux of Flame Ejected from Opening in Fire

When a flashover occurs from a fire in a building compartment, the fire intensifies explosively and changes from a fuel-controlled fire to a ventilation-controlled fire. As a result, flames and unburnt gas are ejected from openings. The ejected unburned gas reacts violently with external oxygen to form a large-scale ejected flame, which causes the fire to expand to the upper layer. Moreover, the radiation of extreme heat to neighboring buildings contributes to fire spreading between buildings. In this study, a quantitative evaluation process was established to evaluate the thermal effect of radiant heat generated from an open fire on the exterior materials of facilities, assuming a fully developed fire.

Prioritization of Interventions and Technologies to Prevent Fire Spread in Hospitals

Background: Fire is one of the potential dangers that threatens human activities more and more. Given that, this study sought to introduce the factors preventing the spread of fire in hospitals to policymakers through prioritization based on the techniques of applied mathematics (multi-attribute decision-making technique). Methods: This study consisted of two stages. In the first stage, through a comprehensive review of studies, factors preventing the spread of fire were identified, and then in the second stage, based on the experts’ opinions, the attributes affecting the prioritization and their weights were determined. Finally, based on the Simple Additive Weighting (SAW) model, the final prioritization was done for five types of hospital buildings. Results: Based on the literature review and experts’ opinions, seven factors and four attributes were identified. The most important factors were “the use of safety architecture and equipping with appropriate emergency exit accesses according to the standard” in highrise hospitals, “continuous firefighting training of the personnel” in wide hospitals, “use of fire extinguishing systems (automatic and manual)” in subsurface hospitals, “use of fire extinguishing systems (automatic and manual)” in combined hospitals, and “continuous firefighting training of the personnel” in portable hospitals. Conclusions: Fire safety is not limited to the installation of a manual fire extinguisher, but for fire safety, especially in hospitals, all aspects should be considered, including the architectural form of the building, how the materials and equipment in the building caught fire, fire behavior in terms of heat transfer, the firefighting training of the personnel, recognition, and application of modern and ready-made equipment for smoke ventilation systems and fire products, automatic and manual fire alarm systems, and extinguishing systems to prevent the spread of fire.