Influence of Particle Sizes and Environmental Conditions on High Temperature Pyrolysis of Cellulosic Material—I (Theoretical)

A solution via generalised intergral transform technique for the simultaneous transport processes during combustion of wood cylinders

“…The temperature of the gas surrounding the cylinder was considered to be T ∞ = 1200 • C. The time step used for updating the linearized properties and source terms in the LIF was taken as = ( k − k−1 ) = 1:32 × 10 −4 (0:5 s) during the pre-heating period and as = 2:6373 × 10 −2 (100 s) during the combustion period. For the sake of comparison, problems (11) and (15) were also solved by using the ÿnite volume method (FVM). Table II presents the results obtained for the temperature at the locationsÁ = 0:9; 0:95 and 1:0 for di erent times in the combustion period, by using the present GITT-LIF approach with di erent truncation orders for the series solution, as well as by using the ÿnite volume method.…”

“…The linearized coe cients and source terms of such a problem are updated at user-selected time steps as the solution of the original problem advances in time, so that the ÿlter can be e ective in the whole time domain. The application of the LIF approach to the solution of problems (11) and (15) is described next.…”

“…where F; k (Á; ) is the solution of the ÿlter problem obtained from the linearization of problem (11) in the time interval k−1 ¡ ¡ k . Such a ÿlter problem is given by…”

Pyrolysis of cellulose, an introduction to the literature

“…Thus, the rate of the pyrolysis can be ruled not only by chemical processes but also by physical factors, such as temperature gradients and migration of condensates. Maa and Bailie [156] have developed a mathematical model of the pyrolysis based on a shrinking, unreacted-core in which the pyrolysis is assumed to be determined in some regions by heat transfer control and in others by kinetic control.…”

Compensation Effects In The Non-isothermal Pyrolysis Of Wood

“…The heat of reaction showed that the secondary pyrolysis was absent in the shoulder regime even though the temperature of pyrolysis did not exceed 320˚C which was necessary for the physical fissuring in wood to occur in order to promote the escape of the pyrolysis products. The absence of the secondary reactions and autocatalytic effects could be explained on the ground of the fine powder form of samples used in both DSC and DTA; the 40 mesh or 0.40 mm in diameter has been shown to be reaction-controlled for pyrolysis of cellulosic materials occurred in samples sizes less than 0.2 cm [33]. Only as the particle size increased would the relative influence of the transfer phenomena and secondary reactions therefore increase.…”