Improving the accuracy and precision of coal bed methane(CBM) estimates requires correction of older data from older coal exploration surveys to newer standards.Three methods,the depth gradient method,the contour aeri...Improving the accuracy and precision of coal bed methane(CBM) estimates requires correction of older data from older coal exploration surveys to newer standards.Three methods,the depth gradient method,the contour aerial weight method,and the well-point aerial weight method,were used to estimate the correction coefficient required to predict CBM gas content from coal exploration data.The data from the Nos.3 and 15 coal seams provided the coal exploration data while the CBM exploration stages within the X1 well block located in the southern part of the Qinshui Basin provided the data obtained using newer standards.The results show the correction coefficients obtained from the two aerial weight methods are similar in value but lower than the one obtained from the depth gradient method.The three methods provide similar results for the Nos.3 and 15 seams in that the correction factor is lower for the former seam.The results from the depth gradient method taken together with the coal seam burial depth and the coal rank suggest that variations in the correction factor increase linearly along with coal seam burial depth and coal rank.The correlation obtained can be applied to exploration and the evaluation of coal bed gas resources located in coalfields.展开更多
With an understanding of the processes of methane production, oxidation and emission, a semi-empirical model, focused on the contributions of rice plants to the processes and also the influence of environmental factor...With an understanding of the processes of methane production, oxidation and emission, a semi-empirical model, focused on the contributions of rice plants to the processes and also the influence of environmental factors, was developed to predict methane emission from rice paddy soils. In the present model, the amount of methane transported from the soil to the atmosphere was determined by the rates of CH4 production and an emitted fraction. The rates of CH4 production in irrigated rice soils were computed from the availability of methanogenic substrates that are primarily derived from rice plaaes and added organic matter and the influence of soil texture, soil redox potential and temperature. The fraction of methane emitted was assumed to be modulated by the rice plants and declines with rice growth and development. TO make it applicable to a wider area with limited data sets, a simplified version of the model was also derived to predict methane emission in a more practical manner.展开更多
The large eddy simulation (LES) using the steady laminar flamelet model is applied to a simple turbulent jet flame with 33.2% H2,22.1% CH4 and 44.7% N2 at the Reynolds number of 15,200 in order to validate the numeric...The large eddy simulation (LES) using the steady laminar flamelet model is applied to a simple turbulent jet flame with 33.2% H2,22.1% CH4 and 44.7% N2 at the Reynolds number of 15,200 in order to validate the numerical methods and to investigate the flame structure.For the validation,the detailed experimental data of DLR-A flame is used.The numerical results are in reasonable agreement with experimental results except mass fractions of minor species.In the flow field,the break-down of the potential core,the vortex structure and the mixing intensity are well captured.In the combustion field,mass fractions of major species (H2O,CO2,CO) are well predicted quantitatively.Minor species are well predicted qualitatively.In the present study,the simulations conducted on the Cartesian and cylindrical grids with approximately 6.6× 10 5 nodes are compared.展开更多
基金supported by the National Basic Research Program of China (No. 2009CB219605)the National Natural Science Foundation of China (Nos. 40730422 and 40872104)
文摘Improving the accuracy and precision of coal bed methane(CBM) estimates requires correction of older data from older coal exploration surveys to newer standards.Three methods,the depth gradient method,the contour aerial weight method,and the well-point aerial weight method,were used to estimate the correction coefficient required to predict CBM gas content from coal exploration data.The data from the Nos.3 and 15 coal seams provided the coal exploration data while the CBM exploration stages within the X1 well block located in the southern part of the Qinshui Basin provided the data obtained using newer standards.The results show the correction coefficients obtained from the two aerial weight methods are similar in value but lower than the one obtained from the depth gradient method.The three methods provide similar results for the Nos.3 and 15 seams in that the correction factor is lower for the former seam.The results from the depth gradient method taken together with the coal seam burial depth and the coal rank suggest that variations in the correction factor increase linearly along with coal seam burial depth and coal rank.The correlation obtained can be applied to exploration and the evaluation of coal bed gas resources located in coalfields.
文摘With an understanding of the processes of methane production, oxidation and emission, a semi-empirical model, focused on the contributions of rice plants to the processes and also the influence of environmental factors, was developed to predict methane emission from rice paddy soils. In the present model, the amount of methane transported from the soil to the atmosphere was determined by the rates of CH4 production and an emitted fraction. The rates of CH4 production in irrigated rice soils were computed from the availability of methanogenic substrates that are primarily derived from rice plaaes and added organic matter and the influence of soil texture, soil redox potential and temperature. The fraction of methane emitted was assumed to be modulated by the rice plants and declines with rice growth and development. TO make it applicable to a wider area with limited data sets, a simplified version of the model was also derived to predict methane emission in a more practical manner.
文摘The large eddy simulation (LES) using the steady laminar flamelet model is applied to a simple turbulent jet flame with 33.2% H2,22.1% CH4 and 44.7% N2 at the Reynolds number of 15,200 in order to validate the numerical methods and to investigate the flame structure.For the validation,the detailed experimental data of DLR-A flame is used.The numerical results are in reasonable agreement with experimental results except mass fractions of minor species.In the flow field,the break-down of the potential core,the vortex structure and the mixing intensity are well captured.In the combustion field,mass fractions of major species (H2O,CO2,CO) are well predicted quantitatively.Minor species are well predicted qualitatively.In the present study,the simulations conducted on the Cartesian and cylindrical grids with approximately 6.6× 10 5 nodes are compared.
