Mathematical Simulation of Heat and Mass Transfer During Forest Fuel Pyrolysis Caused by High Temperature from Crown Forest Fire

Abstract

Pyrolysis (thermal decomposition) is the main stage of a forest fire before forest fuel ignition. The aim of this study is to study the mathematical modeling of heat and mass transfer in a typical forest fuel (birch leaf), taking into account the pyrolysis process caused by crown forest fire. The originality of the research is explained by simulation of heat and mass transfer in birch leaf caused by crown forest fire. The majority of known and published researches have been focused on thermal conditions corresponding to surface forest fires. The implementation of the calculations has been carried out in the RAD Studio software. Differential equations have been solved using the finite difference method. The partial derivatives of the equation are replaced by their finite-difference analogues. As a result, an open system of equations is obtained. For its closure, a difference representation of the boundary conditions is used. The closed system of the linear algebraic equations obtained after these operations is numerically solved by marching method. In order to solve the non-linear effect caused by pyrolysis, the simple iteration method has been used. The key findings of this research are: 1) physical and mathematical models developed to simulate leaf forest fuel pyrolysis caused by crown forest fire; 2) computer program coded using high level programming language; 3) temperature distributions obtained across the leave thickness; 4) dry organic matter fraction obtained depending on different parameters (time and spatial coordinate); 5) induction period calculated for typical conditions of crown forest fire. The obtained results can be used for forest fire danger prediction and assessment.