Separation process undertaken in packed columns often displays anisotropic turbulent mass diffusion. The anisotropic turbulent mass diffusion can be characterized rigorously by using the Reynolds mass flux(RMF) model....Separation process undertaken in packed columns often displays anisotropic turbulent mass diffusion. The anisotropic turbulent mass diffusion can be characterized rigorously by using the Reynolds mass flux(RMF) model.With the RMF model, the concentration and temperature as well as the velocity distributions can be simulated numerically. The modeled Reynolds mass flux equation is adopted to close the turbulent mass transfer equation,while the modeled Reynolds heat flux and Reynolds stress equations are used to close the turbulent heat and momentum transfer equations, so that the Boussinesq postulate and the isotropic assumption are abandoned. To validate the presented RMF model, simulation is carried out for CO2 absorption into aqueous Na OH solutions in a packed column(0.1 m id, packed with 12.7 mm Berl saddles up to a height of 6.55 m). The simulated results are compared with the experimental data and satisfactory agreement is found both in concentration and temperature distributions. The sequel Part II extends the model application to the simulation of an unsteady state adsorption process in a packed column.展开更多
Different cell populations from bone marrow are used in various clinical trials for cardiac diseases during last decade. Four clinical studies are on going in our institution and enrol patients with cardiac diseases, ...Different cell populations from bone marrow are used in various clinical trials for cardiac diseases during last decade. Four clinical studies are on going in our institution and enrol patients with cardiac diseases, coronary disease and type 2 diabetes, patients with osteoarthritis. Density gradient is used to separate bone marrow mononuclear cells. Cell processing looses are significant. To find out critical control points we analysed processing process and differences in cell yields between operators performing cell extraction. Bone marrow mononuclear cells were isolated using Ficoll density gradient centrifugation. Cells were counted using flow cytometry for mononuclear cell total counts, CD34＋ population count and viability analysis. The patients who underwent bone marrow aspiration followed by cell isolation received cell suspension for transplantation. Two cells processing for separate patients were performed at once. Same standard operation procedures were applied. Processing looses between operators performing cell extraction were analysed. Bone marrow samples from eight patients were processed. Mononuclear cells were extracted. Operator performances were compared. Operator A average bone marrow mononuclear cell yield in starting material was 9,97 ± 9,98 %, CD34＋ population yield 75,46±79,67%. Operator B average bone marrow mononuclear cell yield in starting material was 24,68 ± 14,8 %, CD34＋ population yield 70,42 ±44.84%. Operator A average cell viability in starting material was 45,24 ± 9,55%, after cell processing 42,96 ± 23,66 %. Operator B average cell viability in starting material was 49,85 ± 5,48%, after cell processing 69,52 ± 6,65 %.展开更多
To study the pressure distribution of the volute casing, front casing and back casing in a prototype centrifugal pump, the pressure experiments and numerical simulations are carried out at six working conditions in th...To study the pressure distribution of the volute casing, front casing and back casing in a prototype centrifugal pump, the pressure experiments and numerical simulations are carried out at six working conditions in this paper. The experimental results shows that the asymmetry of static pressure distribution on volute casing and front cavity is caused by the tongue of the volute and it may result in high radial and axial resultant force which can cause vibration and noise in the centrifugal pump. With the increasing of flow rote, the asymmetry of static pressure distribution and the magnitude of static pressure values reduce. The numerical results indicate that the pressure fluctuation near the tongue is strongest and it becomes slighter at point away from the tongue. With the increasing of flow rote, the local high=pressure region in impeller passage reduces and the flow becomes smoother accordingly, whereas the fluid speed becomes much higher which may cause further flow losses. The results predicted by numcrical simulation are in coincident with the experimental ones. It shows that the turbulence model for simulating the flow field in centrifugal pumps is feasible.展开更多
基金Supported by the National Natural Science Foundation of China(21376163)
文摘Separation process undertaken in packed columns often displays anisotropic turbulent mass diffusion. The anisotropic turbulent mass diffusion can be characterized rigorously by using the Reynolds mass flux(RMF) model.With the RMF model, the concentration and temperature as well as the velocity distributions can be simulated numerically. The modeled Reynolds mass flux equation is adopted to close the turbulent mass transfer equation,while the modeled Reynolds heat flux and Reynolds stress equations are used to close the turbulent heat and momentum transfer equations, so that the Boussinesq postulate and the isotropic assumption are abandoned. To validate the presented RMF model, simulation is carried out for CO2 absorption into aqueous Na OH solutions in a packed column(0.1 m id, packed with 12.7 mm Berl saddles up to a height of 6.55 m). The simulated results are compared with the experimental data and satisfactory agreement is found both in concentration and temperature distributions. The sequel Part II extends the model application to the simulation of an unsteady state adsorption process in a packed column.
文摘Different cell populations from bone marrow are used in various clinical trials for cardiac diseases during last decade. Four clinical studies are on going in our institution and enrol patients with cardiac diseases, coronary disease and type 2 diabetes, patients with osteoarthritis. Density gradient is used to separate bone marrow mononuclear cells. Cell processing looses are significant. To find out critical control points we analysed processing process and differences in cell yields between operators performing cell extraction. Bone marrow mononuclear cells were isolated using Ficoll density gradient centrifugation. Cells were counted using flow cytometry for mononuclear cell total counts, CD34＋ population count and viability analysis. The patients who underwent bone marrow aspiration followed by cell isolation received cell suspension for transplantation. Two cells processing for separate patients were performed at once. Same standard operation procedures were applied. Processing looses between operators performing cell extraction were analysed. Bone marrow samples from eight patients were processed. Mononuclear cells were extracted. Operator performances were compared. Operator A average bone marrow mononuclear cell yield in starting material was 9,97 ± 9,98 %, CD34＋ population yield 75,46±79,67%. Operator B average bone marrow mononuclear cell yield in starting material was 24,68 ± 14,8 %, CD34＋ population yield 70,42 ±44.84%. Operator A average cell viability in starting material was 45,24 ± 9,55%, after cell processing 42,96 ± 23,66 %. Operator B average cell viability in starting material was 49,85 ± 5,48%, after cell processing 69,52 ± 6,65 %.
基金supported by the Joint Project from National Natural Science Foundation of China and Liaoning Province(U1608258)
文摘To study the pressure distribution of the volute casing, front casing and back casing in a prototype centrifugal pump, the pressure experiments and numerical simulations are carried out at six working conditions in this paper. The experimental results shows that the asymmetry of static pressure distribution on volute casing and front cavity is caused by the tongue of the volute and it may result in high radial and axial resultant force which can cause vibration and noise in the centrifugal pump. With the increasing of flow rote, the asymmetry of static pressure distribution and the magnitude of static pressure values reduce. The numerical results indicate that the pressure fluctuation near the tongue is strongest and it becomes slighter at point away from the tongue. With the increasing of flow rote, the local high=pressure region in impeller passage reduces and the flow becomes smoother accordingly, whereas the fluid speed becomes much higher which may cause further flow losses. The results predicted by numcrical simulation are in coincident with the experimental ones. It shows that the turbulence model for simulating the flow field in centrifugal pumps is feasible.
