مدلسازي فرآيند تراوش گاز در غشاهاي مركب

چكيده انگليسي :

Abstract Prior models for prediction of permeability in MMMs such as Maxwell Bruggman Higuchi Pal and other models are based on the consideration of only two distinct phases of polymer and non organic particles in its structure Thereby models based on consideration of three phases such as modified Maxwell Felske and modified Pal models were developed These models besides of the mentioned two phases consider a third phase as an intermediate phase within the MMM structure Due to existing similarity between gas permeation and heat transfer in nano fluids some presented models for prediction of nano fluids effective thermal conductivity coefficient are used for prediction of MMM permeability In this thesis a new model based on applying different structural models for predicting effective permeability in complex particles and MMMs is proposed It is based on their physical and structural differences In the new established model the effective permeability of complex particles has been calculated by co continuous structural model that was recently proposed for prediction of effective conductivity coefficient in composite materials In the next step by substituting the calculated effective permeabilities of complex particles and polymer matrix into the Maxwell Garnett model the final model for permeability of MMM was derived By applying Bruggman differential procedure inaccuracy of Maxwell Garnett model for large concentration of fillers was treated The new model considers the effects of particle shape and interfacial shell layer formed between polymer and filler particles The prior three phase s models are unable to calculate the interfaciale shell layer properties such as volume fraction of this phase in complex particles and its permeability The prior models uses a curve fitting procedure for estimation the shell layer properties while the new model make a more accurate estimation based on some assumptions for estimation of the volume fraction and defining an experimental parameter for estimation of the permeability of various gases through interfacial shell layer without using of curve fitting procedure The new model uses primary data including permeability of polymer and fillers and volume fraction of fillers in MMM For evaluation of model accuracy and its ability to predict the MMMs performance several experimental data from literatures were used Results show that the maximum averaged relative error between model prediction and experimental data is 10 65 for permeation of N2 through a Ultem and Zeolite 4A MMM while the minimum averaged relative error is 2 8 for permeation of N2 through a matrimid and carbon molecular sieve MMM Furthermore in this thesis another model for prediction of effective permeability in MMMs with cylindrical shape fillers such as carbon nano tubes is proposed For derivation of this model in the first step a model according to self consistent concept for predicting the effective permeability in the complex particles was derived In the next step by substituting the complex particles and polymer permeabilities into Maxwell Garnett model a new model for prediction of effective permeability of MMMs was developed The proposed model was applied for prediction of intrinsic permeability of gases through the carbon nano tubes For this purpose in the first step by using several published experimental data permeability of carbon nano tubes was estimated based on the proposed model and the interfacial shell layer properties according to the first proposed model Then the estimated permeabilities were used for prediction of effective permeability Comparisons of the predicted data with another set of experimental data show that relative errors are less than 7 3

احمدي سبزواري، صادق

مدلسازي فرآيند تراوش گاز در غشاهاي مركب

غشاهاي جداسازي گاز , تراوايي غشاهاي مركب پليمري , نانو سيالات