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Nonlinear coupling mathematical models on percolation‐patterned underground coal gasification

Percolation‐patterned underground coal gasification is an important gasification method to improve gas production conditions and stability. According to the theories of momentum, mass and energy as well as the features of the underground gasification, the nonlinear coupling mathematical models on the process of percolation‐patterned underground coal gasification are established. The determination methods of major parameters are introduced. Additionally, the control volume method is adopted to solve the numerical models. On the basis of the model experiment, the results of the experiment are analysed. The calculation value of temperature field is a little higher than the experiment one, with the relative error of almost every measuring point within 13%. By prolonging gasification time, the heating value of gas will heighten gradually. The effect of temperature field on the heating value of gas is obvious. The simulated results of the pressure field in the gasification panel indicate that the relative error of the pressure field is 8.54–17.15% and 4.90–13.64%, respectively, 25 and 70 h after the ignition. The drop rate for the fluid pressure is 8.93 and 12.75%. Research shows that the simulated values conform with the experimental values comparatively well, which demonstrates that the numerical simulation on the temperature field, concentration field and pressure field of the percolation‐patterned underground coal gasification is correct. Thereby, the study provides necessary theoretical basis for further quantitative research and the prediction of the patterns of variation in the process of the underground coal gasification. Copyright © 2005 John Wiley & Sons, Ltd.