Experimental investigation and modeling through using the solution-diffusion concept of pervaporation dehydration of ethanol and isopropanol by ceramic membranes HybSi

© 2016Results of experimental investigation of pervaporation dehydration of ethanol and isopropanol by HybSi membranes at concentrations of organic component in the feed in the range from ~50 to ~99 wt%, feed temperatures 60, 70 and 80 °C and permeate pressures 5 and 20 mm Hg are presented. The experimental data demonstrate a nonmonotonic dependence of separation factor on water concentration in the feed with maximum value of separation factor reached at water concentration in the feed of several percent for both ethanol dehydration and isopropanol dehydration. Values of both total permeate flux and separation factor for the isopropanol dehydration case are higher than for the ethanol dehydration case. Results of the experimental investigation are compared with similar results of other researchers obtained for pervaporation dehydration of ethanol and isopropanol by membranes coated with a selective layer made of silica-based and zeolite-based materials. Based on the “solution-diffusion” concept, a mathematical model is developed for the pervaporation process, which includes three parameters, two of which are permeability coefficients for pure components and the third parameter defines “active pores fraction”. Use of the model can lead to essential reduction of the number of pervaporation experiments needed for designing a pervaporation pilot plant as well as assist in determining optimum operating conditions of the pervaporation process. Results of calculations carried out with use of the proposed model are compared versus results of experimental investigation of pervaporation dehydration of ethanol and isopropanol by HybSi membranes, pervaporation dehydration of glycerin by HybSi membranes (of other researchers) and pervaporation dehydration of ethanol by NaA zeolite-based membranes (of other researchers). Results of calculations agree reasonably well with all considered experimental data. Additionally, the model allows determining the optimum thickness of the selective layer of HybSi membranes

Mathematical modeling of filtering process of two-phase suspensions in tubular filters under nonisothermal conditions

© 2016, Pleiades Publishing, Ltd.The hydrodynamic conditions in tubular filter cells operating under nonisothermal conditions are studied. The equations of mechanics of heterogeneous media are used to describe the separation process of two-phase suspensions, which are written and simplified in the cylindrical coordinate system taking into account characteristics of the flow. The challenge is solved semi-analytically. Using the methods of surfaces of equal consumptions and Slezkin, numerical calculations on the constructed mathematical model are presented for particular implementations of the separation process

Determination of local heat transfer coefficients at the entrance region of streamlined bodies

Prandtl’s two-layer model of the turbulent boundary layer is considered and the expression obtained through the use of the model is applied to calculate the heat transfer coefficient, calculations for which agree well with experimental data on mean values of the coefficients for various bodies. Determination of parameters of this expression is shown for the case of calculating local heat transfer coefficients in the entrance regions of the channels. The main parameters are  dynamic velocity, dimensionless thickness of  the  boundary layer  and dimensionless thickness of  the  viscous  sublayer.  Based  on  the  power-law  and  logarithmic velocity profiles, expressions are obtained for calculating the dimensionless parameters of the turbulent boundary layer. A satisfactory agreement of the results of calculations of loc al heat transfer coefficients for the flow over a flat plate and the pipe flow is shown. The presented approach represents a theoretical basis for modeling the local heat transfer for bodies of more complex shapes, if the friction coefficients are known

Experimental investigation and modeling through using the solution-diffusion concept of pervaporation dehydration of ethanol and isopropanol by ceramic membranes HybSi

© 2016Results of experimental investigation of pervaporation dehydration of ethanol and isopropanol by HybSi membranes at concentrations of organic component in the feed in the range from ~50 to ~99 wt%, feed temperatures 60, 70 and 80 °C and permeate pressures 5 and 20 mm Hg are presented. The experimental data demonstrate a nonmonotonic dependence of separation factor on water concentration in the feed with maximum value of separation factor reached at water concentration in the feed of several percent for both ethanol dehydration and isopropanol dehydration. Values of both total permeate flux and separation factor for the isopropanol dehydration case are higher than for the ethanol dehydration case. Results of the experimental investigation are compared with similar results of other researchers obtained for pervaporation dehydration of ethanol and isopropanol by membranes coated with a selective layer made of silica-based and zeolite-based materials. Based on the “solution-diffusion” concept, a mathematical model is developed for the pervaporation process, which includes three parameters, two of which are permeability coefficients for pure components and the third parameter defines “active pores fraction”. Use of the model can lead to essential reduction of the number of pervaporation experiments needed for designing a pervaporation pilot plant as well as assist in determining optimum operating conditions of the pervaporation process. Results of calculations carried out with use of the proposed model are compared versus results of experimental investigation of pervaporation dehydration of ethanol and isopropanol by HybSi membranes, pervaporation dehydration of glycerin by HybSi membranes (of other researchers) and pervaporation dehydration of ethanol by NaA zeolite-based membranes (of other researchers). Results of calculations agree reasonably well with all considered experimental data. Additionally, the model allows determining the optimum thickness of the selective layer of HybSi membranes

Experimental investigation and modeling through using the solution-diffusion concept of pervaporation dehydration of ethanol and isopropanol by ceramic membranes HybSi

© 2016Results of experimental investigation of pervaporation dehydration of ethanol and isopropanol by HybSi membranes at concentrations of organic component in the feed in the range from ~50 to ~99 wt%, feed temperatures 60, 70 and 80 °C and permeate pressures 5 and 20 mm Hg are presented. The experimental data demonstrate a nonmonotonic dependence of separation factor on water concentration in the feed with maximum value of separation factor reached at water concentration in the feed of several percent for both ethanol dehydration and isopropanol dehydration. Values of both total permeate flux and separation factor for the isopropanol dehydration case are higher than for the ethanol dehydration case. Results of the experimental investigation are compared with similar results of other researchers obtained for pervaporation dehydration of ethanol and isopropanol by membranes coated with a selective layer made of silica-based and zeolite-based materials. Based on the “solution-diffusion” concept, a mathematical model is developed for the pervaporation process, which includes three parameters, two of which are permeability coefficients for pure components and the third parameter defines “active pores fraction”. Use of the model can lead to essential reduction of the number of pervaporation experiments needed for designing a pervaporation pilot plant as well as assist in determining optimum operating conditions of the pervaporation process. Results of calculations carried out with use of the proposed model are compared versus results of experimental investigation of pervaporation dehydration of ethanol and isopropanol by HybSi membranes, pervaporation dehydration of glycerin by HybSi membranes (of other researchers) and pervaporation dehydration of ethanol by NaA zeolite-based membranes (of other researchers). Results of calculations agree reasonably well with all considered experimental data. Additionally, the model allows determining the optimum thickness of the selective layer of HybSi membranes

Mathematical modeling of filtering process of two-phase suspensions in tubular filters under nonisothermal conditions

© 2016, Pleiades Publishing, Ltd.The hydrodynamic conditions in tubular filter cells operating under nonisothermal conditions are studied. The equations of mechanics of heterogeneous media are used to describe the separation process of two-phase suspensions, which are written and simplified in the cylindrical coordinate system taking into account characteristics of the flow. The challenge is solved semi-analytically. Using the methods of surfaces of equal consumptions and Slezkin, numerical calculations on the constructed mathematical model are presented for particular implementations of the separation process

DETERMINATION OF HEAT TRANSFER COEFFICIENTS IN CHANNELS WITH INTENSIFIERS PROCESS

Reviewed equations for calculation of heat transfer coefficients from a smooth surface, obtained with the use of models of the turbulent boundary layer Prandtl and Deisler. It is shown that the inclusion of disturbances in the boundary layer (roughness of the walls, ledges, ring rolling) can be performed parametrically by adjusting the dynamic speed, the thickness of a viscous sublayer and boundary layer thickness. The results of calculations of the average values of heat transfer coefficients (in dimensionless form of Nusselt numbers and Stanton) and comparing with k nown experimental data

Mathematical modeling of filtering process of two-phase suspensions in tubular filters under nonisothermal conditions

© 2016, Pleiades Publishing, Ltd.The hydrodynamic conditions in tubular filter cells operating under nonisothermal conditions are studied. The equations of mechanics of heterogeneous media are used to describe the separation process of two-phase suspensions, which are written and simplified in the cylindrical coordinate system taking into account characteristics of the flow. The challenge is solved semi-analytically. Using the methods of surfaces of equal consumptions and Slezkin, numerical calculations on the constructed mathematical model are presented for particular implementations of the separation process

Mathematical modeling of filtering process of two-phase suspensions in tubular filters under nonisothermal conditions

© 2016, Pleiades Publishing, Ltd.The hydrodynamic conditions in tubular filter cells operating under nonisothermal conditions are studied. The equations of mechanics of heterogeneous media are used to describe the separation process of two-phase suspensions, which are written and simplified in the cylindrical coordinate system taking into account characteristics of the flow. The challenge is solved semi-analytically. Using the methods of surfaces of equal consumptions and Slezkin, numerical calculations on the constructed mathematical model are presented for particular implementations of the separation process

Experimental investigation and modeling through using the solution-diffusion concept of pervaporation dehydration of ethanol and isopropanol by ceramic membranes HybSi

© 2016Results of experimental investigation of pervaporation dehydration of ethanol and isopropanol by HybSi membranes at concentrations of organic component in the feed in the range from ~50 to ~99 wt%, feed temperatures 60, 70 and 80 °C and permeate pressures 5 and 20 mm Hg are presented. The experimental data demonstrate a nonmonotonic dependence of separation factor on water concentration in the feed with maximum value of separation factor reached at water concentration in the feed of several percent for both ethanol dehydration and isopropanol dehydration. Values of both total permeate flux and separation factor for the isopropanol dehydration case are higher than for the ethanol dehydration case. Results of the experimental investigation are compared with similar results of other researchers obtained for pervaporation dehydration of ethanol and isopropanol by membranes coated with a selective layer made of silica-based and zeolite-based materials. Based on the “solution-diffusion” concept, a mathematical model is developed for the pervaporation process, which includes three parameters, two of which are permeability coefficients for pure components and the third parameter defines “active pores fraction”. Use of the model can lead to essential reduction of the number of pervaporation experiments needed for designing a pervaporation pilot plant as well as assist in determining optimum operating conditions of the pervaporation process. Results of calculations carried out with use of the proposed model are compared versus results of experimental investigation of pervaporation dehydration of ethanol and isopropanol by HybSi membranes, pervaporation dehydration of glycerin by HybSi membranes (of other researchers) and pervaporation dehydration of ethanol by NaA zeolite-based membranes (of other researchers). Results of calculations agree reasonably well with all considered experimental data. Additionally, the model allows determining the optimum thickness of the selective layer of HybSi membranes