Coal and shale are both unconventional gas reservoirs. Comparison of pore characteristics in shale and coal would help understand organic pore structure in shale and investigate co-exploration of shale gas and coalbed...Coal and shale are both unconventional gas reservoirs. Comparison of pore characteristics in shale and coal would help understand organic pore structure in shale and investigate co-exploration of shale gas and coalbed methane in coal bearing strata. In this study, five shale samples and three coal samples of Taiyuan Formation were collected from Qinshui Basin, China. High pressure mercury injection, scanning electronic microscopy, and fractal theory have been used to compare pore characteristics in shale and coal. The results show that pore volumes in coal are much larger than that in shale, especially pores 3-100 nm. In coal, there are many semi-closed pores in micro pores (〈10 nm) and transition pores (10-100 nm). On the contrary, micro pores and transition pores are mainly with open pores in shale. The fractal curves show that pores larger than 65 nm in coal and shale reservoir both have obvious self-similarity and the fractal dimension values in shale and coal are similar. But the fractal characteristics of pores smaller than 65 nm in shale reservoir are quite different from that in coal.展开更多
Steam generator is optimized by applying entransy dissipation extremum principle and constructal theory and adopting analyti-cal method.The obtained results show that the optimal spacing between adjacent tubes,the mas...Steam generator is optimized by applying entransy dissipation extremum principle and constructal theory and adopting analyti-cal method.The obtained results show that the optimal spacing between adjacent tubes,the mass flow rate of gas and the maximum entransy dissipation rate all depend on the dimensionless diameter of one tube,the dimensionless pressure difference number and the dimensionless length of flow channel of gas.Besides the three dimensionless groups,the optimal numbers of riser tubes and downcomer tubes and their summation all depend on the dimensionless height of one tube.The maximum entransy dissipation rate increases as the pressure difference that drives the gas flowing increases,and as the diameter of one tube and the length of flow channel both decrease.The mean heat flux in the heat transfer process of hot gas grows greatly,and the performance of the system is improved.Compared with the optimal construct with heat transfer rate maximization,the optimal construct with entransy dissipation rate maximization can improved the heat transfer effect of the steam generator more.展开更多
The second Poincard kinematical group serves as one of new ones in addition to the known possible kinematics. The geometries with the second Poincard symmetry is presented and their properties are analyzed. On the geo...The second Poincard kinematical group serves as one of new ones in addition to the known possible kinematics. The geometries with the second Poincard symmetry is presented and their properties are analyzed. On the geometries, the new mechanics based on the principle of relativity with two universal constants (c, l) can be established.展开更多
基金The authors thank the National Science Foundation of China (41472135), the Research and Innovation Project for College Graduates of Jiangsu Province (KYLX15-1396), the Scientific Research Foundation of the Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process, Ministry of Education (China University of Mining and Technology) (No. 2015-04) for the support of the research.
文摘Coal and shale are both unconventional gas reservoirs. Comparison of pore characteristics in shale and coal would help understand organic pore structure in shale and investigate co-exploration of shale gas and coalbed methane in coal bearing strata. In this study, five shale samples and three coal samples of Taiyuan Formation were collected from Qinshui Basin, China. High pressure mercury injection, scanning electronic microscopy, and fractal theory have been used to compare pore characteristics in shale and coal. The results show that pore volumes in coal are much larger than that in shale, especially pores 3-100 nm. In coal, there are many semi-closed pores in micro pores (〈10 nm) and transition pores (10-100 nm). On the contrary, micro pores and transition pores are mainly with open pores in shale. The fractal curves show that pores larger than 65 nm in coal and shale reservoir both have obvious self-similarity and the fractal dimension values in shale and coal are similar. But the fractal characteristics of pores smaller than 65 nm in shale reservoir are quite different from that in coal.
基金supported by the National Natural Science Foundation of China (Grant No 10905093)the Program for New Century Excellent Talents in University of China (Grant No NCET-04-1006)the Foun-dation for the Author of National Excellent Doctoral Dissertation of China (Grant No 200136)
文摘Steam generator is optimized by applying entransy dissipation extremum principle and constructal theory and adopting analyti-cal method.The obtained results show that the optimal spacing between adjacent tubes,the mass flow rate of gas and the maximum entransy dissipation rate all depend on the dimensionless diameter of one tube,the dimensionless pressure difference number and the dimensionless length of flow channel of gas.Besides the three dimensionless groups,the optimal numbers of riser tubes and downcomer tubes and their summation all depend on the dimensionless height of one tube.The maximum entransy dissipation rate increases as the pressure difference that drives the gas flowing increases,and as the diameter of one tube and the length of flow channel both decrease.The mean heat flux in the heat transfer process of hot gas grows greatly,and the performance of the system is improved.Compared with the optimal construct with heat transfer rate maximization,the optimal construct with entransy dissipation rate maximization can improved the heat transfer effect of the steam generator more.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 10775140,10705048,10731080,10975141,11175245,11075206the President Fund of GUCASthe Fundamental Research Funds for the Central Universities under Grant No. 105116
文摘The second Poincard kinematical group serves as one of new ones in addition to the known possible kinematics. The geometries with the second Poincard symmetry is presented and their properties are analyzed. On the geometries, the new mechanics based on the principle of relativity with two universal constants (c, l) can be established.