Permeation temperature effects

Continuous Multicomponent Distillation Column 501 Gas Separation by Membrane Permeation 475 Transport of Heavy Metals in Water and Sediment 565 Residence Time Distribution Studies 381 Nitrification in a Fluidised Bed Reactor 547 Conversion of Nitrobenzene to Aniline 329 Non-Ideal Stirred-Tank Reactor 374 Oscillating Tank Reactor Behaviour 290 Oxidation Reaction in an Aerated Tank 250 Classic Streeter-Phelps Oxygen Sag Curves 569 Auto-Refrigerated Reactor 295 Batch Reactor of Luyben 253 Reversible Reaction with Temperature Effects 305 Reversible Reaction with Variable Heat Capacities 299 Reaction with Integrated Extraction of Inhibitory Product 280... 

To further investigate the pH and temperature effects on permeability, we analyzed the permeation of oxprenolol HCl under the four possible pH... 

Figure 2.64 Effect of permeation temperature on permeance and separation factor for a membrane fabricated at 40 mA cm-2 current density and 45 °C electrolysis temperature [94] (by courtesy of Springer-Verlag).

Analysis of the effect of permeation, temperature profile and sweep gas will be proposed hereafter considering a steady-state MR modeled by a 1D, first-order model. The model can be extracted from the mass and energy balance, Equations 13.14... 

Without permeation data for at least two temperatures, it is not possible to predict the magnitude of the temperature effect for any given chemical/ material pair. Tests must be performed at the maximum (worst case) temperature and/or over the temperature range of the anticipated application of the clothing. 

Figure 10. The effect of permeation temperature on permeance of membrane through CVD... 

Temperature effects are important, not only in high temperature applications, but also during accelerated aging of a material for laboratory study and subsequent evaluation of in-service life-time. Solubility of water In Neoprene Increases greatly with temperature as does permeation rate. The relative permeation rates of 3.5% saltwater and deionized water were shown to depend on elastomer composition. 

TEMPERATURE EFFECTS. The Arrhenius activation parameters viz., Ep and Ep for the processes of diffusion and permeation have been... 

Permeate flux increases on decreasing viscosity and therefore a higher permeability is achieved at higher temperatures. A common method to account for this change with temperature is to multiply the obtained flux with the viscosity ratio with respect to a reference temperamre. If temperature effects on flux are only influenced by changes in viscosity, then the product of flux and viscosity should be constant. 

For effective ultrafiltration, equipment must be optimized to promote the highest transmembrane flow and selectivity. A major problem which must be overcome is concentration polarization, the accumulation of a gradient of retained macrosolute above the membrane. The extent of polarization is determined by the macrosolute concentration and diffusivity, temperature effects on solution viscosity and system geometry. If left undisturbed, concentration polarization restricts solvent and solute transport through the membrane and can even alter membrane selectivity by forming a gel layer on the membrane surface—in effect, a secondary membrane — increasing rejection of normally permeating species. 

In permeation, the effect of wax in the formation of fouling can be minimized or canceled by the temperature of the feed. In experiments with the UF of miscella of crude sunflower and soybean oils, Pagliero et al. [65] reported that high temperatures (50°C) led to a complete dissolution of waxes present in crude sunflower oil, equaling the fouling obtained in this oil to the crude soybean oil and, consequently, leading to similar permeated flows in both sunflower and soybean oils. 

Many studies on systems in the current literature did not consider the Joule-Thompson effect caused by the expansion of permeate gas due to the pressure difference between the high retentate pressure and the low permeate pressure, also known as transmembrane pressure. This expansion leads to a decrease in the permeate temperature, which in turn decreases the membrane permeance. So, ignoring the Joule-Thomson effect may result in a wrong estimation of membrane separation performance and consequently of the reboiler/condenser duties and utility savings obtained from an HMD system. The membrane model employed in the present study takes into account the Joule-Thompson effect by including the following energy balance [Equation (10.2)] ... 

In this study, permeance values are considered as decision variables and will be varied over a range. So, considering permeance as a single average value across the membrane is easier. In other words, the temperature effect on permeance is neglected. However, the temperature drop due to the Joule-Thompson effect is limited to 10 °C to 20 °C, and the effect of this temperature drop is considered in heating the permeate stream, if required. 

Other aspects and phenomena which are often considered are concentration and temperature polarization, interactions between the permeating species, effect of fillers included in the membrane to induce positive modifications of the sorption and diffusion capabilities, interaction of the porous supporting layer, etc. 

In the treatment of biogas the Joule-Kelvin effect cannot be neglected. A biogas feed contains art equimolar mixture of methane to carbon dioxide. If a pressure of 50 bar is applied at the feed side at 30°C calculate then the recovery S at which the permeate temperature has been decreased below 0°C.(Assume that only carbon dioxide permeates through the membrane and that beat transfer is much faster than mass transfer). The Joule-Kelvin coefficient of carbon dioxide is, = 1.2 K/bar. 

Transport Measurements. The permeability test apparatus and membrane cell are similar to those used by Way et al. (27). Pure ethylene and ethane were mbced in a gas flow system to obtain the desired feed composition. Helium was used as the sweep gas and both the feed and sweep gases were saturated with water before entering the membrane cell. The gas flow configuration in the membrane cell was cross flow. The humidifiers and membrane cell were placed in a water bath for temperature control. The temperature was kept at 25 C, except for the temperature effect study. Permeate and retentate fi om the membrane cell were... 

Fig. 4.19 Effect of carbonization temperature on the permeance of COPNA based CMSMs (BDM/PCA= 1.25 permeation temperature, 100°C). (From [64])...

Fig. 4.3S Effect of oxidation at 300°C for 3 h on permeances of membranes carbonized at 700°C. Permeation temperature=65 C ( ) as formed, (o) oxidized in O Permeation temperature 100°C ( ) as formed, (A) oxidized in Oj-N, mixture (0 fraction = 0.1), ( ) oxidized in O. (From [99])...

Figure 4.4 shows the hydrogen permeation flux as a function of temperature for composite membranes with different effective porosities [15]. When the effective porosity is low, for example, eJL = 20 m", the hydrogen permeation flux decreases as the permeation temperature is increased. This implies that for this effective porosity the permeation... 

Fig. 13.13 Effect of PVDF ENMs thickness (S) on the water permeate flux at different feed temperatures The stirring rate of the feed and permeate liquid solutions is 500 rpm and the permeate temperature (T[,p) is 20° [99] (Reprinted with permission from Ref. [88]. Copyright 2013, Elsevier)...

Transport into or from the electrolyte by diffusion, electro-osmotic drag, hydraulic permeation, and temperature effects. 

Permeability coefficients of CO2 and water vapor and their temperature effect, activation energy for permeation, have been tabulated for most polymers. PS and PMMA (poly(methyl methacrylate)) are usually not used in packaging material, therefore experimental data for these two materials are scarce. However, the barrier properties of polymer nanoconposites have drawn interest recently. To the... 

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