• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.5
• /
• pp.1288-1300
• /
• 1994

Mathematical modeling and numerical calculation on the flow and thermal characteristics induced by fire in a partial enclosure are performed. The solution procedures include the Shvab-Zeldovich approximation for the physical transport equations, low Reynolds number k-.epsilon. model for the turbulent fluid flow and Discrete Ordinate method(DOM) to calculate the radiative heat transfer. PMMA(Polymethylmethacrylate) is adopted as a solid fuel. Two different cases are considered : combustions with and without gas radiation occuring in a open cavity for variable pyrolyzing location of PMMA. When the fire source is located at the left-wall, the flow region of flame gas is limited at the left-wall and ceiling and recirculation region of inlet gas is formulated at neat the floor. In case of neglecting the radiative heat transfer, more large flame size and higher temperature is predicted. It is essential to consider the radiative heat transfer for analysis of fire phenomenon.

• Transactions of the Korean hydrogen and new energy society
• /
• v.22 no.4
• /
• pp.520-526
• /
• 2011

In recent years, it is very important that hydrogen storage system is safe for user in any circumstances in case of crash and fire. Because the hydrogen vehicle usually carry high pressurized cylinders, it is necessary to do safety design for fire. The Global Technical Regulation (GTR) has been enacted for localized and engulfing fire test. High pressure hydrogen storage system of fuel cell electrical vehicles are equipped with Thermal Pressure Relief Device (TPRD) installed in pressured tank cylinder to prevent the explosion of the tank during a fire. TPRDs are safety devices that perceive a fire and release gas in the pressure tank cylinder before it is exploded. In this paper, we observed the localized and engulfing behavior of tank safety, regarding the difference of size and types of the tanks in accordance with GTR.

• Proceedings of the KSME Conference
• /
• 2001.06d
• /
• pp.708-714
• /
• 2001

Although LP gas has lots of advantages, there has been limitation in application for automotive engine due to the several disadvantages, such as power decrease, complex fuel supply unit, and back fire etc. However LP gas direct injection engine has possibility to solve the problems above mentioned. LEM(Light Extinction Method) was employed for analysis of spacial and temporal distribution of LP gas which is directly injected into combustion chamber under various pressure and temperature conditions. The results from CVC(Constant Volume Chamber) were compared to those of RICEM(Rapid Induction, Compression and Expansion Machine) which simulate early- and late injection of direct injection engine. LPG fuel spray is affected by temperature and pressure in evaporation characteristics but it is more benefit to direct injection engine in every way such as, fuel distribution, evaporating speed and well wetting reduction.

• Journal of the Korean Society of Combustion
• /
• v.18 no.4
• /
• pp.53-58
• /
• 2013

Lots of Coal power plants (about 30) using bituminous coals are being run in Korea. The use of high volatile low grade sub-bituminous coal is increasingly extended because of imbalance between the worldwide coal supply and demand. Mill-fire has been an important issue since the use of such sub-bituminous coal. In existing coal plants of Korea, shutdown of coal and air supplies could be only a way, and an alternative has not been found in suppressing the mill fire. The inside fowfield in the mills has a highly fuel-rich, low temperature, and high velocity and non-reactive such that it could be a nonreactive system essentially. Nevertheless, occasional fire-occurrence could be attributed to the existence of an ignition source. However it has not been so far investigated in detail. The current work has a focus on suppressing the mile fire via some parametric experimental study such as effects of temperature, residence time, ignition source, and inert gas mixing. The results show that an small amount of $CO_2$- or $N_2$-mixing with air is very effective in suppressing fire formation even at high temperatures or flying sparks. The results suggest that exhaust gas recirculation into the mill should be an alternative to suppress mill fire.

• Geosystem Engineering
• /
• v.21 no.5
• /
• pp.282-290
• /
• 2018

The onset of extreme fire behaviour in a mine drift with longitudinal ventilation was analysed. A fire in a mine drift with continuous fuel load, involving several separate fires may lead to flames tilted horizontally and filling up the entire cross section. This will lead to earlier ignition, higher fire growth rate, higher fire spread rate and a severe fire behaviour. The focus has been on what changes take place at the onset and signs of the impending phenomenon. It was found that the fire gas temperature at the ceiling level provided a poor indicator. At the downstream far-field region of the fire, the sudden temperature increase at the lowest levels of the cross section and the sudden increase in flow velocities would provide signs of extreme fire behaviour. The corresponding full-scale heat release rates of the experiments at the onset of extreme fire behaviour were found to be very high for mining applications but not necessarily for tunnel fires. The heat release rate threshold for a mine drift with smaller cross-sectional dimensions would decrease considerably, increasing the likelihood of occurrence. The distance between the fuel items will play an important role during the initiation of horizontal flames.

• Fire Science and Engineering
• /
• v.16 no.3
• /
• pp.77-83
• /
• 2002

We measured flame extinguishing concentration and flue gas composition in the n-heptane fuel cup-burner system using inert gas agents such as nitrogen, argon, carbon dioxide and their mixtures. The flame extinguishing concentration of binary gaseous mixture was well predicted by model which contains the flame extinguishing concentration and composition of pure components. The higher average specific gravity of the mixed inert gas agents, the more excellent flame extinguishing performance. And the structure of enclosed space also affects the fire extinguishing. The composition of carbon dioxide in the flue gas was decreased with increasing extinguishing agent used. Nitrogen monoxide production is not related with increasing nitrogen, but increased at rapid mass flow rate of air in the cup-burner.

• Journal of Korean Society of Forest Science
• /
• v.101 no.2
• /
• pp.286-290
• /
• 2012

Globally, the forest fires are a significant contributor of carbon dioxide and other greenhouse gases in the atmosphere. In this study, fuel load consumed by forest fire and emission of green house gases were analysed in the surface layer. For this, remaining fuel was collected and weighed with the species (Japanese red pine, deciduous) and the forest fire types (surface fire, crown fire) in the 51 forest fires. 8,361 kg/ha fuel load was consumed in deciduous forest damaged by surface fire, and 8,055 kg/ha, 12,333 kg/ha in Japanese red pine burned by surface fire and crown fire. The combustion ratios were 78, 59, and 90%, respectively. 15,856 kg/ha the green house gases such as $CO_2$, $CH_4$, $CH_4$ in deciduous forest burned by surface fire was emitted and 14,834 kg/ha, 22,709 kg/ha in Japanese red pine burned by surface fire and crown fire.

• Journal of the Korean Institute of Gas
• /
• v.25 no.5
• /
• pp.11-18
• /
• 2021

Since hydrogen has the lower minimum ignition energy than that of gasoline, hydrogen could be also appropriate for the IC engine systems. However, due to the low ignition energy, there might be a 'back-fire' and 'pre-ignition' problems with hydrogen SI(Spark-ignition) combustion. In this research, cooling effects of intake gas mixture on the improvement of the maximum power output were evaluated in a 2.4 L SI engine. There were two ways to cool intake gas mixtures. The first one was cooling intake fresh air by adjusting inter-cooler system after turbocharger. The other one was cooling hydrogen fuel before supplying by using heat ex-changer. Cooling hydrogen was performed under natural aspired condition. The result showed that cooling fresh air from 40 ℃ to 20~30 ℃ improved the maximum brake power up to 6.5~8.6 % and cooling hydrogen fuel as -6 ℃ enhanced the maximum brake power likewise.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.23 no.1
• /
• pp.47-60
• /
• 2021

Hydrogen is a next-generation energy source, and according to the roadmap for activating the hydrogen economy, it is expected that industries to stably produce, store, and transport of hydrogen as well as the supply of hydrogen fuel cell vehicles will be made rapidly. Accordingly, safety measures for accidents of hydrogen vehicles in confined spaces such as tunnels are required. In this study, as part of a study to ensure the safety of hydrogen fuel cell vehicles in road tunnels, a basic investigation and research on the risk of fire and explosion due to gas leakage and hydrogen tank rupture among various hazards caused by hydrogen fuel cell vehicle accidents in tunnels was conducted. The following results were obtained. In the event of hydrogen fuel cell vehicle accidents, the gas release rate depends on the orifice diameter of TPRD, and when the gas is ignited, the maximum heat release rate reaches 3.22~51.36 MW (orifice diameter: 1~4 mm) depending on the orifice diameter but the duration times are short. Therefore, it was analyzed that there was little increase in risk due to fire. As the overpressure of the gas explosion was calculated by the equivalent TNT method, in the case of yield of VCE of 0.2 is applied, the safety threshold distance is analyzed to be about 35 m, and number of the equivalent fatalities are conservatively predicted to reach tens of people.

• Journal of the Korean Society of Combustion
• /
• v.13 no.3
• /
• pp.1-8
• /
• 2008

A flame stability diagram in a partially premixed flame is typically expressed using the axis coordinates of heat input rate and equivalence ratio. These diagrams are inadequate for identifying changes in combustion conditions and flame stability when a reference fuel is substituted with other fuels under identical operating conditions. This study proposes a new type of diagram and validates it experimentally. In this new diagram, the axis coordinates are air flow rate and Wobbe fuel flow rate, defined as the fuel flow rate multiplied by the square root of the relative density. The diagram was validated in trials using various fuels, including $CH_4$, $C_{3}H_{8}$, and LFG-$C_{3}H_{8}$ mixed fuels, in a domestic gas-range and an gas interchangeability test burner. The results of these trials show that the new diagram can provide information useful for assessing gas interchangeability of combustion conditions and flame stability when one fuel is substituted with another under identical operating conditions.