Modeling fluid transport, including
strongly temperature dependent one way reactions and high temperature variations,
suffers from long calculation times because of the very short time steps required.
To overcome this problem, element distinction algorithms for reactive transport
modeling are developed. The relaxation time of the fastest reaction component
is taken as the criterion to distinguish between transport and reaction-kinetically-dominated
numerical elements. These algorithms are implemented into the ROCKFLOW (FE)
and NTRANS (FD) program codes. Underground coal fire calculations are used as
application examples. Fire propagation is controlled by transport and the reaction
kinetics of the component with the fastest consumption rate, namely oxygen.
Coal consumption and heat production are determined by this fast process. The
calculations solve the balance equations for gas hydraulics, including buoyancy,
oxygen, coal, ash, exhaust gas and thermal energy. Simulation results of the
Sino German Coal Fire Project are presented. Test site is the Wuda Coal Mining
Area (Inner Mongolia, PR China). Element distinction calculations in combination
with the well-known operator splitting and the new developed sharp front method
(SF-method) are discussed. Calculations document the possible advantage in planning
fire fighting operations by using predictive modeling.