Based on a three-step kinetic mechanism, a one-dimensional, time dependent, numerical model is presented for the smoldering propagation in a horizontally packed bed of cellulosic material. The kinetic processes includ...Based on a three-step kinetic mechanism, a one-dimensional, time dependent, numerical model is presented for the smoldering propagation in a horizontally packed bed of cellulosic material. The kinetic processes include pyrolysis and oxidation degradation of fuel and oxidation of char. Heat transfer between solid and gas is taken into account, and the diffusion coefficient varies with the temperature. Radiative heat transfer is included by using the diffusion approximation. The effects of airflow velocity and oxygen concentration are simulated on the smoldering velocity and the averaged maximum temperature of smoldering fuel. The results indicate that the spread rate varies linearly with increasing airflow velocity, and the inlet air velocity has little effect on the maximum temperature. The evolutions of gas species and solid compositions are predicted. The effects of frequency factors （A1, A2 and A3） are analyzed. Simulations show that the smoldering spread rate increases with increasing A2 （fuel oxidation）, but decreases with A1 （fuel pyrolysis） and A3 （char oxidation）.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No.50476073)
文摘Based on a three-step kinetic mechanism, a one-dimensional, time dependent, numerical model is presented for the smoldering propagation in a horizontally packed bed of cellulosic material. The kinetic processes include pyrolysis and oxidation degradation of fuel and oxidation of char. Heat transfer between solid and gas is taken into account, and the diffusion coefficient varies with the temperature. Radiative heat transfer is included by using the diffusion approximation. The effects of airflow velocity and oxygen concentration are simulated on the smoldering velocity and the averaged maximum temperature of smoldering fuel. The results indicate that the spread rate varies linearly with increasing airflow velocity, and the inlet air velocity has little effect on the maximum temperature. The evolutions of gas species and solid compositions are predicted. The effects of frequency factors （A1, A2 and A3） are analyzed. Simulations show that the smoldering spread rate increases with increasing A2 （fuel oxidation）, but decreases with A1 （fuel pyrolysis） and A3 （char oxidation）.
