Structured packing is a good candidate for CO2 capture process because of its higher mass transfer efficiency and lower pressure drop. Now, the challenging problem of CO2 capture and storage demands more and more effi...Structured packing is a good candidate for CO2 capture process because of its higher mass transfer efficiency and lower pressure drop. Now, the challenging problem of CO2 capture and storage demands more and more efficiency equipment. The aim of the present study is to investigate the liquid film characteristics under counter current gas phase and throw some insight into the enhancing mechanism of mass transfer performance in structured packing. A high speed digital camera, non-intrusive measurement technique, was used. Water and air were working fluids. Experiments were carried out for different gas/liquid flow rates and different inclination angles. The time-average and instantaneous film widths for each set of flow parameters were calculated. It is shown that the effects of gas phase could be neglected for lower flow rate, and then, become more pronounced at higher flow rate. According to instantaneous film width, three different stages can be distinguished. One is the constant width of liquid film. The second is the slight decrease of film width and the smooth surface. This kind of character will lead to less interfacial area and deteriorate the packing mass transfer performance. For the third stage, the variation of film width shows clearly chaotic behavior. The prediction model was also developed in present work. The predicted and experimental results are in good agreement.展开更多
The empirical mode decomposition （EMD） is used to study the scale properties of turbulent transport and coherent structures based on velocity and temperature time series in stably stratified turbulence. The analysis...The empirical mode decomposition （EMD） is used to study the scale properties of turbulent transport and coherent structures based on velocity and temperature time series in stably stratified turbulence. The analysis is focused on the scale properties of intermittency and coherent structures in different modes and the contributions of energy-contained coherent structures to turbulent scalar counter-gradient transport （CGT）. It is inferred that the velocity intermittency is scattered to more modes with the development of the stratified flow, and the intermittency is enhanced by the vertical stratification, especially in small scales. The anisotropy of the field is presented due to different time scales of coherent structures of streamwise and vertical velocities. There is global counter-gradient heat transport close to the turbulence-generated grid, and there is local counter-gradient heat transport at certain modes in different positions. Coherent structures play a principal role in the turbulent vertical transport of temperature.展开更多
In this paper four families of orthogonal wavelets are applied to analyze the turbulent counter gradient transport phenomena in fully developed asymmetric channel flows. The results show that: (1) In the instance of c...In this paper four families of orthogonal wavelets are applied to analyze the turbulent counter gradient transport phenomena in fully developed asymmetric channel flows. The results show that: (1) In the instance of counter gradient transport, the principal scale of the coherent structure is responsible for the strong local counter gradient transport; (2) Counter gradient transport phenomena have a strong effect on the intermittency of turbulence; (3) Non-Gaussian part of the principal coherent structure is essential for counter gradient transport phenomena.展开更多
Turbulence structures and turbulent Counter-Gradient Transport（CGT） properties in the stratified flows with a sharp temperature interface are investigated by experimental measurements using LIF and PIV, by LES and b...Turbulence structures and turbulent Counter-Gradient Transport（CGT） properties in the stratified flows with a sharp temperature interface are investigated by experimental measurements using LIF and PIV, by LES and by correlation analysis.展开更多
为进一步探究局部对旋式通风机叶轮结构的可能优化路径,以FBD No8.0/2×55 k W型对旋通风机为研究对象,通过三维建模和有限元分析方法,对该通风机叶轮进行力学分析与模态分析,根据分析结果确定叶轮结构需要改进的方向,而后采用NACA4...为进一步探究局部对旋式通风机叶轮结构的可能优化路径,以FBD No8.0/2×55 k W型对旋通风机为研究对象,通过三维建模和有限元分析方法,对该通风机叶轮进行力学分析与模态分析,根据分析结果确定叶轮结构需要改进的方向,而后采用NACA4415翼型叶片对叶轮结构进行优化,结果显示,优化后的叶轮叶片应力和应变显著降低,且发生共振的风险大大降低,表明本次分析与优化工作具有一定的现实意义。展开更多
The electronic structure of protein chains L and M in photosynthetic reaction center (PRC) of Rhodobacter sphaeroides (Van Niel) Imhoff, Truper et Pfennig) was studied by using the Overlapping Dimer Approximation meth...The electronic structure of protein chains L and M in photosynthetic reaction center (PRC) of Rhodobacter sphaeroides (Van Niel) Imhoff, Truper et Pfennig) was studied by using the Overlapping Dimer Approximation method and the Extended Negative Factor Counter method at ab initio level. The result indicated that: (1) Amino acid residues, the molecular orbitals of which composed the main components of frontier orbitals of protein chain L (M), are located at the random coil areas of chain L (alpha helix areas of chain M). Since the random coil is flexible and more easy to change its conformation in the electron transfer process and to reduce the energy of the system, and the structure of the alpha helix is reletively stable, this difference might be one of the causes for the electron transfer in photosynthetic reaction center (PRC) only takes place along the L branch. (2) The His residues which axially coordinated to the 'special pair' P and accessory chlorophyll molecules (ABChls) are essentially important for the E-LUMO levels of P and ABChl. But, the corresponding molecular orbitals of these His residues do not appear in the composition of frontier orbitals of protein chains. It means that the interaction between pigment molecules and protein chains do not influence the contribution to the frontier orbitals of protein chains explicitly, but influences the corresponding E-LUMO levels significantly.展开更多
基金Supported by the National Natural Science Foundation of China （20070003154）, the National High Technology Research and Development Program of China （2006AA05Z316, 2006AA030202）, the Specialized Research Fund for Doctoral Program of Higher Education of China （20070003154）, and the Key Program for International Cooperation of Science and Technology, China （2001CB711203）.
文摘Structured packing is a good candidate for CO2 capture process because of its higher mass transfer efficiency and lower pressure drop. Now, the challenging problem of CO2 capture and storage demands more and more efficiency equipment. The aim of the present study is to investigate the liquid film characteristics under counter current gas phase and throw some insight into the enhancing mechanism of mass transfer performance in structured packing. A high speed digital camera, non-intrusive measurement technique, was used. Water and air were working fluids. Experiments were carried out for different gas/liquid flow rates and different inclination angles. The time-average and instantaneous film widths for each set of flow parameters were calculated. It is shown that the effects of gas phase could be neglected for lower flow rate, and then, become more pronounced at higher flow rate. According to instantaneous film width, three different stages can be distinguished. One is the constant width of liquid film. The second is the slight decrease of film width and the smooth surface. This kind of character will lead to less interfacial area and deteriorate the packing mass transfer performance. For the third stage, the variation of film width shows clearly chaotic behavior. The prediction model was also developed in present work. The predicted and experimental results are in good agreement.
基金supported by the National Natural Science Foundation of China(Nos.1110211411172179+2 种基金11332006and 11572203)the Innovation Program of Shanghai Municipal Education Commission(No.13YZ124)
文摘The empirical mode decomposition （EMD） is used to study the scale properties of turbulent transport and coherent structures based on velocity and temperature time series in stably stratified turbulence. The analysis is focused on the scale properties of intermittency and coherent structures in different modes and the contributions of energy-contained coherent structures to turbulent scalar counter-gradient transport （CGT）. It is inferred that the velocity intermittency is scattered to more modes with the development of the stratified flow, and the intermittency is enhanced by the vertical stratification, especially in small scales. The anisotropy of the field is presented due to different time scales of coherent structures of streamwise and vertical velocities. There is global counter-gradient heat transport close to the turbulence-generated grid, and there is local counter-gradient heat transport at certain modes in different positions. Coherent structures play a principal role in the turbulent vertical transport of temperature.
基金The project supported by the National Natural Science Foundation of China(10272071.10472063)
文摘In this paper four families of orthogonal wavelets are applied to analyze the turbulent counter gradient transport phenomena in fully developed asymmetric channel flows. The results show that: (1) In the instance of counter gradient transport, the principal scale of the coherent structure is responsible for the strong local counter gradient transport; (2) Counter gradient transport phenomena have a strong effect on the intermittency of turbulence; (3) Non-Gaussian part of the principal coherent structure is essential for counter gradient transport phenomena.
文摘Turbulence structures and turbulent Counter-Gradient Transport（CGT） properties in the stratified flows with a sharp temperature interface are investigated by experimental measurements using LIF and PIV, by LES and by correlation analysis.
文摘为进一步探究局部对旋式通风机叶轮结构的可能优化路径,以FBD No8.0/2×55 k W型对旋通风机为研究对象,通过三维建模和有限元分析方法,对该通风机叶轮进行力学分析与模态分析,根据分析结果确定叶轮结构需要改进的方向,而后采用NACA4415翼型叶片对叶轮结构进行优化,结果显示,优化后的叶轮叶片应力和应变显著降低,且发生共振的风险大大降低,表明本次分析与优化工作具有一定的现实意义。
文摘The electronic structure of protein chains L and M in photosynthetic reaction center (PRC) of Rhodobacter sphaeroides (Van Niel) Imhoff, Truper et Pfennig) was studied by using the Overlapping Dimer Approximation method and the Extended Negative Factor Counter method at ab initio level. The result indicated that: (1) Amino acid residues, the molecular orbitals of which composed the main components of frontier orbitals of protein chain L (M), are located at the random coil areas of chain L (alpha helix areas of chain M). Since the random coil is flexible and more easy to change its conformation in the electron transfer process and to reduce the energy of the system, and the structure of the alpha helix is reletively stable, this difference might be one of the causes for the electron transfer in photosynthetic reaction center (PRC) only takes place along the L branch. (2) The His residues which axially coordinated to the 'special pair' P and accessory chlorophyll molecules (ABChls) are essentially important for the E-LUMO levels of P and ABChl. But, the corresponding molecular orbitals of these His residues do not appear in the composition of frontier orbitals of protein chains. It means that the interaction between pigment molecules and protein chains do not influence the contribution to the frontier orbitals of protein chains explicitly, but influences the corresponding E-LUMO levels significantly.
