Fire Science and Technology

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Accumulated plastic waste is concerned to cause a spontaneous combustion. It is extremely difficult to notice the minor signs indicating the start of combustion inside the accumulated material. Spontaneous combustion of plastic waste was simulated using a temperature-controlled furnace, and the temperature of the sample and the intensity as well as quality of odorous gases emitted were measured during the process of self-ignition. Mixed plastic waste consisting of various plastics of food wrapping was subjected to heating furnace experiment as a single specimen. The odors generated from this specimen and each single individual plastic were measured. The ratio of the similarity indices aldehyde/ammonia was found to increase during the ignition process due to the accumulated heat in the central part of accumulated material. Specimens of individual plastic was burnt and thermally decomposed using TG-DTA under the normal atmospheric condition, the odor also showed a similar tendency with that obtained in the experiment for the mixed specimen.

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A series of experiments was carried out in order to investigate the visible flame height of a jet flame with a high initial discharging velocity where the fuel-release time and mass flow rate of fuel were varied. The values of non-dimensional heat release rate (Q^*) in present experiment were in the range of 10⁷ < Q^* < 10⁸. Even if the value of Q^* was larger than 10⁶, when the non-dimensional number (R_M) employed by Heskestad which implies the ratio of gas release momentum to the momentum made by a purely buoyant diffusion flame was less than 0.1, the flame height with a comparatively high initial discharging velocity increased with the heat release rate. In other words, whether flame height depends on the Q^*2/5 or not can be decided by the range of momentum ratio (R_M) regardless of the range of non-dimensional heat release rate (Q^*). This can be also decided by the fire Froude number employed by Delichatsios.

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