Simulations of Isothermal Oven Tests of Impregnated Activated Carbons in Cylindrical and Cubic Holders Based on Kinetics Derived from Isothermal DSC Measurements

摘要

Isothermal oven exposure tests using cylindrical and cubic sample holders werernconducted in air on a 14% (w/w) K_2CO_3 impregnated activated carbon at temperatures betweenrn115 and 200℃. Such oven tests are widely performed on potentially self-heating materials inrnagreement with the International Air Transport Association's regulations concerning therntransportation of dangerous goods. The thermal behavior of this impregnated carbon in bothrnholder geometries has been simulated successfully. The simulation algorithm is based on finiternelement mathematics and heat transfer and kinetic theories.rnFor the carbon studied here, the reaction takes place in 2 apparently independentrnprocesses. In the first process, the surface functional groups (SFG) decompose. In the secondrnprocess, the bulk carbon combusts. The impregnation process apparently imparts the reactivernSFG and the impregnate catalyzes carbon combustion. The reaction of the surface functionalrngroups in air obeys the following reaction rate in terms of the fractional degree of conversion,rndα_1/dt = γ1exp(-Ea_1/(k_BT))α_1~(0.5) (1-α_1)~(0.95). The reaction of the remaining carbon with air followsrnzero-order reaction kinetics. Moisture desorption was also introduced in the reaction model as arnfirst order process in accordance with experimental data. The kinetic triplets (activation energy,rnfrequency factor and kinetic model) were derived using DSC.