The internal heat transfer of different gases in microporous media was investigated experimentally and numerically.The experimental test section had a sintered bronze porous media with average particle diameters from ...The internal heat transfer of different gases in microporous media was investigated experimentally and numerically.The experimental test section had a sintered bronze porous media with average particle diameters from 11 μm to 225 μm.The Knudsen numbers at the average inlet and outlet pressures of each test section varied from 0.0006 to 0.13 with porosities from 0.16 to 0.38.The particle-to-fluid heat transfer coefficients of air,CO 2 and helium in the microporous media were determined experimentally.The results show that the Nusselt numbers for the internal heat transfer in the microporous media decrease with decreasing the particle diameter,d p,and increasing Knudsen number for the same Reynolds number.For Kn>0.01,the rarefaction affects the internal heat transfer in the microporous media.A Nusselt number correlation was developed that includes the influence of rarefaction.The computational fluid dynamics(CFD) numerical simulation was carried out to do the pore scale simulation of internal heat transfer in the microporous media considering the rarefaction effect.Pore scale three-dimensional numerical simulations were also used to predict the particle-to-fluid heat transfer coefficients.The numerical results without slip-flow and temperature jump effects for Kn<0.01 corresponded well with the experimental data.The numerical results with slip-flow and temperature jump effects for 0.01<Kn<0.13 are lower than the numerical results without rarefaction effects,but closer to the experimental data.The numerical results with rarefaction effects can accurately simulate the unsteady heat transfer in the microporous media.展开更多
The aim of this study is to conduct the validity analysis of the test paper of the academic English reading and writing course referring to the freshmen of non-English majors in a university of Technology in Shanghai....The aim of this study is to conduct the validity analysis of the test paper of the academic English reading and writing course referring to the freshmen of non-English majors in a university of Technology in Shanghai.The validity is mainly analyzed from these three aspects:the content and construct validity,the reaction process,and the internal structure of the test paper.And the principles of language assessment in the design of the test paper are given in this study.The validity study was also conducted in a class with 42 freshmen,and the scores of them were analyzed through the internal correlation coefficient from Statistic Package for Social Science(SPSS)25.0.Finally,the validity of the test paper is concluded.展开更多
基金supported by the Key Project Fund from the National Natural Science Foundation of China (Grant No. 50736003)the Major Project of Beijing Natural Science Foundation (Grant No. 3110001)+1 种基金the Industrial Technology Development Program (Grant No. B1420110113)the National High Technology R&D Program of China (GrantNo.2012AA052803)
文摘The internal heat transfer of different gases in microporous media was investigated experimentally and numerically.The experimental test section had a sintered bronze porous media with average particle diameters from 11 μm to 225 μm.The Knudsen numbers at the average inlet and outlet pressures of each test section varied from 0.0006 to 0.13 with porosities from 0.16 to 0.38.The particle-to-fluid heat transfer coefficients of air,CO 2 and helium in the microporous media were determined experimentally.The results show that the Nusselt numbers for the internal heat transfer in the microporous media decrease with decreasing the particle diameter,d p,and increasing Knudsen number for the same Reynolds number.For Kn>0.01,the rarefaction affects the internal heat transfer in the microporous media.A Nusselt number correlation was developed that includes the influence of rarefaction.The computational fluid dynamics(CFD) numerical simulation was carried out to do the pore scale simulation of internal heat transfer in the microporous media considering the rarefaction effect.Pore scale three-dimensional numerical simulations were also used to predict the particle-to-fluid heat transfer coefficients.The numerical results without slip-flow and temperature jump effects for Kn<0.01 corresponded well with the experimental data.The numerical results with slip-flow and temperature jump effects for 0.01<Kn<0.13 are lower than the numerical results without rarefaction effects,but closer to the experimental data.The numerical results with rarefaction effects can accurately simulate the unsteady heat transfer in the microporous media.
文摘The aim of this study is to conduct the validity analysis of the test paper of the academic English reading and writing course referring to the freshmen of non-English majors in a university of Technology in Shanghai.The validity is mainly analyzed from these three aspects:the content and construct validity,the reaction process,and the internal structure of the test paper.And the principles of language assessment in the design of the test paper are given in this study.The validity study was also conducted in a class with 42 freshmen,and the scores of them were analyzed through the internal correlation coefficient from Statistic Package for Social Science(SPSS)25.0.Finally,the validity of the test paper is concluded.
