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A methodology for deriving material pyrolysis properties is proposed and validated by using three charring materials (pure cellulose, and two different particle boards designated as N and F). The methodology uses experimental data obtained in a pyrolysis apparatus together with an accurate integral thermal pyrolysis model for the charring pyrolysis process (see CST, 88, 309-328, 1993). The effects of various parameters on pyrolysis rates and surface temperatures are investigated by applying the integral pyrolysis model. This analysis shows that, in addition to the unpyrolyzed (virgin) material thermal properties, char conductivity (kc) and heat of pyrolysis (L) are adequate to describe the transient pyrolysis process for a charring material. The thermal capacity of char is shown to have negligible effects on the pyrolysis process because surface radiation loss from the hot char surface is the dominant mechanism causing the reduction of pyrolysis rates in charring materials. This result, which is ...

An experimental study of burning of natural gas puffs generated by a fully modulated jet, has been conducted. The present study concentrated on the effects of duty-cycle and puff volume, or equivalently the injection time, on the flame length. It is observed that when individual puffs are well-separated, considerably shorter flame lengths, by as much as a factor of four, are obtained compared to a steady jet flame. Furthermore, the flame length of individual puffs scales with the initial volume of puff, in agreement with the previous studies of buoyant puffs in aqueous media. For a given puff volume, as the duty-cycle is increased beyond a given value, the flame length tends to rise rapidly due to the interaction among neighboring puffs. A dimensionless parameter is found which indicates the transition of puff characteristics.