• Composites Research
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• v.28 no.2
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• pp.29-39
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• 2015

Natural fibers reinforced polymer composites are being used in several low strength applications. More research is going on to improve their mechanical and interface properties for structural applications. However, these composites have serious issues regarding flammability, which are not being focused broadly. A limited amount of literature has been published on the flame retardant techniques and flammability factor of natural fibers based polymer matrix composites. Therefore, it is needed to address the flammability properties of natural fibers based polymer composites to expand their application area. This paper summarizes some of the recent literature published on the subject of flammability and flame retardant methods applied to natural fibers reinforced polymer matrix composites. Different factors affecting the flammability, flame retardant solutions, mechanisms and characterization techniques have been discussed in detail.

• Nuclear Engineering and Technology
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• v.53 no.10
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• pp.3286-3297
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• 2021

The released hydrogen can be ignited even with weak ignition sources. This emphasizes the importance of the hydrogen flammability evaluation to prevent catastrophic failure in hydrogen related facilities including a nuclear power plant. Historically numerous attempts have been made to determine the flammability limit of hydrogen mixtures including several diluents. However, no analytical model has been developed to accurately predict the limit concentration for mixtures containing radiating gases. In this study, the effect of H₂O and CO₂ on flammability limit was investigated through a numerical simulation of lean limit hydrogen flames. The previous flammability limit model was improved based on the mechanistic investigation, with which the amount of indirect radiation heat loss could be estimated by the optically thin approximation. As a result, the sharp increase in limit concentration by H₂O could be explained by high thermal diffusivity and radiation rate. Despite the high radiation rate, however, CO₂ with the lower thermal diffusivity than the threshold cannot produce a noticeable increase in heat loss and ultimately limit concentration. We concluded that the proposed mechanistic analysis successfully explained the experimental results even including radiating gases. The accuracy of the improved model was verified through several flammability experiments for H₂-air-diluent.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.189-192
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• 2015

An experimental study was conducted to find the effect of DBD plasma on the flammability limits of inert-gas-diluted fuel. The results showed that the concentration of diluting nitrogen at flammability limit increased when nitrogen-diluted methane and propane were reformed by plasma, while it decreased when nitrogen-diluted ethylene was reformed by plasma. Gas chromatography results suggested that the fuel type dependence of flammability limits is due to the difference in the concentrations of hydrogen and hydrocarbon species in reformed fuel.

• Journal of the Korean Society of Safety
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• v.9 no.1
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• pp.83-88
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• 1994

The change of flammability limit of n-heptane by the addition of halogenated hydrocarbon was studied. Experimental results showed that halogenated hydrocarbon has a combustion suppression effect and the heat capacity was a Important factor on the flammability limit. The combustion suppression effect of halogenated hydrocarbon was lower than halon, but higher than nitrogen, and the order of effect was $C_3$C1$_3$F$_3$> $C_2$HC1$_2$F$_3$> $C_2$H$_2$F$_4$.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.323-324
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• 2012

Flammability limits of opposed flow diffusion flame in a narrow channel was investigated experimentally and theoretically. There were three different extinction modes corresponding to high strain rate (HSR), low strain rate (LSR) and dilution ratio (DR) limits. To investigate these limits, a theoretical study was followed by focusing on flow and heat transfer characteristics. Consequently, a dead space concept that has been used for premixed flames was important to reveal the heat loss mechanism in a narrow channel especially for LSR conditions even in the case of diffusion flames.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.319-321
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• 2012

The flammability limit and the flame instability of nitrogen-diluted LPG fuel was experimentally studied on a co-flow flame configuration. The combustion reaction of nitrogen-diluted hydrocarbon with air could be interpreted as the equivalent reaction of pure fuel with nitrogen-diluted air. Nitrogen-diluted LPG with nitrogen up to 90 % of nitrogen mole fraction in fuel, which is close to the flammability limit, could form a co-flow flame. Various parameters such as laminar or turbulent flame, the existence of diffusion flame with pure fuel, air temperature could affect the limit of flame formation.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.4
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• pp.47-55
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• 1998

A new ignition system concept was developed to improve ignition performance, accuracy of control and the reliability of the ignition system. The new ignition system has ho호 frequency discharge characteristics with 1.5-2.0 ms discharge duration, in place of the usual solitary longer duration event. We applied the system to a commercial engine to study its influence on the maximum combustion pressure attained during the cycle, when this peak pressure occurred, imep, variation rate of the engine speed and the flammability limit of a lean mixture. In this study, we clarified that the new ignition system had a beneficial effect of the lean mixture flammability limit. Also for a given mixture strength we found that the mew ignition system gave a higher peak cylinder pressure than in the case of the conventional ignition system.

• Journal of ILASS-Korea
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• v.28 no.3
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• pp.134-142
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• 2023

Electric field assisted combustion is a method that reduces instability in lean combustion. In this study investigated the effects of electrode position on propane-air flame characteristic using a ring electrode. Results showed that burning velocity was not affected by electrode position, but positive voltage expanded the flammability limit while negative voltage contracted it. The effect of voltage polarity on the flammability limit decreased as the electrode position increased. Expanding the flammability limit with a positive voltage can reduce NOx emissions.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.4
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• pp.305-316
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• 2022

Hydrogen energy is emerging as an alternative to the depletion of fossil fuels and environmental problems, and the use of hydrogen vehicles is increasing in the automobile industry as well. However, since hydrogen has a wide flammability limit of 4 to 75%, there is a high concern about safety in case of a hydrogen car accident. In particular, in semi-enclosed spaces such as tunnels and underground parking lots, a fire or explosion accompanied by hydrogen leakage is highly likely to cause a major accident. Therefore, it is necessary to review hydrogen safety through analysis of flammability areas caused by hydrogen leakage. Therefore, in this study, the effect of the air velocity in the tunnel on the flammability area was investigated by analyzing the hydrogen concentration according to the hydrogen leakage conditions of hydrogen vehicles and the air velocity in the tunnel in a road tunnel with standard section. Hydrogen leakage conditions were set as one tank leaking and three tanks leaking through the TPRD at the same time and a condition in which a large crack occurred and leaked. And the air velocity in the tunnel were considered 0, 1, 2.5, and 4.0 m/s. As a result of the analysis of the flammability area, it is shown that when the air velocity of 1 m/s or more exists, it is reduced by up to 25% compared to the case of air velocity of 0 m/s. But there is little effect of reducing the flammability area according to the increase of the wind speed. In particular, when a large crack occurs and completely leaks in about 2.5 seconds, the flammability area slightly increases as the air velocity increases. It was found that in the case of downward ejection, hydrogen gas remains under the vehicle for a considerably long time.

• Fire Science and Engineering
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• v.16 no.1
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• pp.51-59
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• 2002

Manifold physical properties of PASCON cable trough were evaluated, and its suitability of domestic test for flammability of plastic materials was examined. Particularly, suitability of PASCON material was investigated through study on the legal propriety of PASCON cable trough used for highspeed rail line and on a fire safety. As results, domestic test for flammability of PASCON cable trough material(KS M3015) was similar to UL 94 flammability testing and from the test outstanding capability of PASCON cable trough material was proved. Besides, possibility of fire enlargement would be very low in case of fire in PASCON cable trough installed around train express. Also, fire safety of PASCON cable trough was shown to be credible.