Numerical model to quantify the influence of the cellulosic substrate on the ignition propensity tests

A numerical model based on the finite element method has been constructed to simulate the ignition propensity (IP) tests. The objective of this mathematical model was to quantify the influence of different characteristics of the cellulosic substrate on the results of the IP-tests. The creation and validation of the model included the following steps: (I) formulation of the model based on experimental thermodynamic characteristics of the cellulosic substrate; (ii) calibration of the model according to cone calorimeter tests; (iii) validation of the model through mass loss and temperature profiling during IP-testing. Once the model was validated, the influence of each isolated parameter of the cellulosic substrate was quantified via a parametric study. The results revealed that the substrate heat capacity, the cigarette temperature and the pyrolysis activation energy are the most influencing parameters on the thermodynamic response of the substrates, while other parameters like heat of the pyrolysis reaction, density and roughness of the substrate showed little influence. Also the results indicated that the thermodynamic mechanisms involved in the pyrolysis and combustion of the cellulosic substrate are complex and show low repeatability which might impair the reliability of the IP-tests.