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Implementation of a membrane gasexchange technique based on perfluorodecalin


Improved membrane gas sensor systems for online analysis of ethanol and other volatile organic compounds in fermentation media


Interventions: Extracorporeal CO2 removal was achieved through percutaneous cannulation of the femoral artery and vein, and a simple extracorporeal circuit using a commercially available membrane gas exchange device for carbon dioxide exchange.


Absorptionpervaporation separation of gas mixtures is studied and compared with membrane gas separation.


Thorough Cleaning of Argon and Germanium Tetrahydride To Remove Admixture of Water by Membrane Gas Separation

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 The success of asymmetric composite membrane system is a greatbreakthrough in membrane gas separation technology.The performanceof this kind of membrane permeator depends not only on its instinctpermeability,but also on membrane structure.Because the magnitude order of the size of pores in dense layer of the membrane can varyfrom 10~2 to 10~4 Angstroms,it is difficult to completely fill all thepores,small and larger with only one solution of coating material.On the basis of series/parallel... The success of asymmetric composite membrane system is a greatbreakthrough in membrane gas separation technology.The performanceof this kind of membrane permeator depends not only on its instinctpermeability,but also on membrane structure.Because the magnitude order of the size of pores in dense layer of the membrane can varyfrom 10~2 to 10~4 Angstroms,it is difficult to completely fill all thepores,small and larger with only one solution of coating material.On the basis of series/parallel resistance combination of gaspermeation through composite membrane,this paper presents a fluxexpression of onedimensional steadystate permeation with aconsideration of incomplete filling of the pores (defectfree coatingis only a particular case)J=K_1K_2/k_1l_2+K_2l_1+(K_0K_1)θ+K_1+l_1+l_2·ε (1)where l_1 and l_2 is the thickness of coating layer and dense layerrespectively,K_1 and K_2 is the instinct permeability of coatingmaterial and substrate respectively,ε is surface porosity of denselayer in substrate,θ is the fraction of unfilled pores and K_0 is theeffective permeability of an unfilled pore.If all the pores in dense layer are filled completely,θ=0,theneqn.(1)changs intoJ=K_1K_2/K_1l_2+K_2l_2+K_1ε/l_1+l_2 (2)Computation results show that eqn. (2) an RM model establishedby Henis and Tripodi are identical in predicting permeation fluxthough they are somewhat different in formula.With a reference to the membrane structure parameters and thecharacteristics of our Itype membrane separator,taking thepermeation of H_2 and N,through silicone rubber coated polysulfoneasymmetric composite membrane as an example,this paper has madecalculations and analyses of the effects of strucure parameters,such as l_1,l_2 and ε,and incomplete pore filling on J_(H2) and α_(H2/N2)·The effects of instinct permeability and selectivity of coatingmaterials on J_(H2) and α(H_2/N_2) of the composite membrane have alsobeen studied.Calculation results have shown that the thinner the coatinglayer,the more advantageous it will be to separation.The thickerthe dense layer of substrate,the larger the separation factor α,but the smaller the J,and the thickness of dense layer is much moreimportant than that of coatiog layer.Surface porosity of dense layerε has a critical value,ε_0=0.01(l_1+l_2)/l_1+l_2(K/K_2)_(?)where subscript s representsslow gas.If surface porosity ε is larger than ε.,performance of selective permeation will become worsen.Contrary if ε is smallerthan ε.,it is useless reducing the surface porosity to increaseseparation effectiveness.When the size of pores in dense layer isvery small,the performance of the membrane will not be affactednotably,even if there is a small amount of unfilled pores.But,if the unfilled pores are a bit larger,the performance will bereduced greatly.For a given asymmetric substrate,the instinctpermeability of a coating material is more important than its instinctselectivity,and the characteristics of a composite membrane arepredominantly determinded by its substrate.  根据气体渗透的阻力迭加概念,导得致密层中微孔未完全堵实(完全堵实仅是其特例)时一维稳态渗透速率表达式。以H_2和N_2通过表皮层涂复硅橡胶的聚矾非对称复合膜渗透为例,计算和分析了致密层中微孔完全堵实时膜结构参数1_1,1_2和ε对JH_2和αH_2/N_2的影响,及由于部分微孔未堵上产生的对JH_2和αH_2/N_2的影响。并考察了涂层材料的本征选择渗透性对了JH_2和αH_2/N_2的影响。  Gas concentration polarization can impair the performance of membrane gas separation activity.That phenomenon becomes more conspicuous in highflux,fi ning separation processes.Some discussions are made on the effect in the study.  气体的浓度差极化使气相分离效果变坏,在高通量、精分离中甚明显。本文对这种影响作些讨论。  A differential mathematical model for hollow fiber membrane gas separator including a gas pressure drop equation in hollow fibers was established and reduced to an algebraic one in order to simplify the calculations. The two models were tested experimentally and compared with the models in references. The models in this paper give better results than those in references when the pressure drop in hollow fiber can not be neglected. The models in this paper are very useful in design,calculation and... A differential mathematical model for hollow fiber membrane gas separator including a gas pressure drop equation in hollow fibers was established and reduced to an algebraic one in order to simplify the calculations. The two models were tested experimentally and compared with the models in references. The models in this paper give better results than those in references when the pressure drop in hollow fiber can not be neglected. The models in this paper are very useful in design,calculation and development of hollow fiber membrane gas separator. The influences of inside diameter and length of hollow fiber and operating pressure on the separation process were studied. The optimum pressure of permeated gas in hydrogen and nitrogen separation process was about 0.41.0MPa.  本文建立了中空纤维膜气体分离器的微分数学模型,对其数值解进行了实验验证,又将其简化的代数模型同文献上的模型进行了比较,指出了各种模型适宜的使用条件,并研究确定了气体膜分离过程中较适宜的丝内径、丝长度和操作压力的范围。   << 更多相关文摘 
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