Membrane performance comparison

Evaluation of the membrane performances. Comparison between experimental and mathematical results. 

FIGURE 15.9. Performance comparison of RSn anode based direct ethanol fuel cells at 90°C. Anode catalysts Carbon supported PtSn with a R loading of 1.5 mg/cm, ethanol concentration 1.0 mol/L, flow rate 1.0 mL/min. Cathode (20 Pt wt.%, Johnson Matthey Inc.) with a R loading of 1.0 mg/cm, Pq2 = 2 bar. Electrolyte Naflon -115 membrane. 

In order to validate the reduced model (uncoupled population of Izhikevich neurons) we chose to perform comparisons with a direct simulation model. In this last model the internal state of each neuron is computed at each time step (with a forth-order Runge-Kutta method) using the equations of the Izhikevich model so we have complete access to individual information as opposed to the population density formalism where only the states distribution can be computed. The simulation parameters were 50 000 Izhikevich neurons in tonic spiking mode (a = 0.02, b = 0.2, c = —65, d = 6 as provided in [29]), a gaussian form of p(v, u, t) at t =0 and a constant input current of / =60 qA was applied to all neurons. The firing rate and the mean membrane potential (M M P) were computed at each time for the two methods during 15 ms. 

Baudot A and Marin M. Pervaporation of aroma compounds Comparison of membrane performances with vapor liquid equilibria and engineering aspects of process improvement. Trans. Inst. Chem. Eng. C. 1997 75 117-142. 

FIGURE 27.51 Performance comparison between fuel cells with Nafion 112 and Aciplex 1002 membranes according to Du et al. (Reproduced from Du, X.Z., Yu, J.R., Yi, B.L., Han, M., and Bi, K.W., Phys. Chem. Chem. Phys., 3, 3175, 2001. With permission from the PCCP Owner Societies.)... 

Table 9.5. Comparison of Membrane Performance Reported in the Literature... 

Membrane performance characteristics in the hydraulic and diffusion limits are compared to each other in Fig. 9. Figure 9(a) illustrates that in the diffusion model considerable deviations from the purely ohmic performance of the saturated membrane arise already at small jv/Jj, well below the critical current density. This is in line with the comparison of the water-content profiles calculated in the diffusion model, Fig. 9(b), with those from the hydraulic permeation model, in Fig. 7. Indeed, membrane dehydration is much stronger in the diffusion model, affecting larger membrane domains at given values of jp/./j. Moreover, the profiles exhibit different curvature from those in Fig. 7. 

The conclusion must be that reliable prospects of commercial applications can be made only for specific applications and specifications, and strongly depend on particular assumptions relating to membrane performance, process conditions and design and on particular future prospects which easily invalidate economic comparisons made today. 

An alternative approach to solving stability problems with ILMs is presented by Bhave and Sirkar (114). Aqueous solutions are immobilized in the pore structure of hydophoblc, polypropylene hollow fibers by a solvent exchange procedure. Gas permeation studies are reported at pressures up to 733 kPa with the high pressure feed both on the shell and lumen sides of the laboratory scale hollow fiber permeator. No deformation of the hollow fibers is observed. Immobilizing a 30 weight % KjCO, solution in the hollow fibers greatly improved the separation factor, a(C02/Na). from 35.78 with pure water to 150.9 by a facilitated transport mechanism. Performance comparisons with commercial COj separation membranes are made. 

An approximate analytical solution has been developed to calculate the exit concentration from a continuously recirculating facilitated transport liquid membrane system. The system is modeled as a series of SLM-CSTR pairs. The solution allows for two-dimensional transport (axial convective and radial diffusive) and laminar flow. The solution allows one to estimate the effect of a change in system variables on the operating performance. Comparison with experimental data was very good. 

Review. Comparison of membrane performance for aroma compounds with different functional groups. 

Van Dyk L, Miachon S, Lorenzen L, Torres M, Fiaty K, Dalmon JA (2003) Comparison of microporous MFl and dense Pd membrane performances in an extractor-type CMR. Catal Today 82 167-177... 

One-dimensional models have been extensively used in the literature to simulate membrane reactors and to compare the reactor performance with the conventional systems (without membranes). This comparison has been, so far, fair enough because thick membranes i.e. low flux membranes) were generally considered in those works. Even 40-100 pm thick self-supported membranes have been considered. At these conditions (unfortunately too far away to be... 

Nederlof MM, Kruithof JC, Taylor JS, van der Kooij D and Schippers JC (2000), Comparison of NF/RO membrane performance in integrated membrane systems , Desalination, 131,257-269. 

Switzer EE, Olson TS, Datye AK, Atanassov P, Hibbs MR, Fujimoto CY, Cornelius CJ (2010) Novel KOH-free anion-exchange membrane fuel cell performance comparison of alternative anion-exchange ionomers in catalyst ink. Electrochim Acta 55(9) 3404—3408... 

Han et al. investigated the gas separation behavior of the PBOs (Figure 5.57) prepared from thermal rearrangement of the fluorinated o-HPAs [80]. The thermal rearrangement occurred at a comparatively low temperature (350 °C) than the precursor poly-imides. The cavity sizes and distribution of FFV elements were tuned to obtain a higher combination of permeability (Phj = 206 Barrer) and selectivity by changing the precursor HPA structure and thermal treatment. The reduction of CO2 solubility for PBO in comparison to the precursor HPAs improved the H2/CO2 selectivity (a = 6.2 at 210 °C, in which Ph2 > 200 Barrer) and moved the membrane performance to polymeric upper bound (Robeson upper bound). 

Stassi A, Gatto I, Passalacqua E et al (2011) Performance comparison of long and short-side chain perfluorosulfonic membranes for high temperature polymer electrolyte membrane fuel cell operation. J Power Sources 196 8925-8930... 

Zhu Y, Zhu WH, Tatarchuk BJ (2014) Performance comparison between high temperature and traditional proton exchange membrane fuel cell stacks using electrochemical impedance spectroscopy. J Power Sources 256 250-257... 

Table 1.3 Performance comparison of thin-film nanoparticle membrane, QuantumFlwL, with conventional thin-fihn composite membranes.

Comparison of Membrane Performance with Commerciai Poiyimide Membrane... 

In their efforts to use various fluoropolymer films to develop PCMs, Scherer and co-workers [51] prepared PVDF-g-PSSA membranes in comparison with their counterparts based on ETFE films. PVDF films were activated from y-radiation (dose of 20 kGy at dose rate of 5.9 kGy h ) at room temperature in air and grafting of styrene with peroxidation method interestingly occurred at 60°C. The influence of the base polymer properties on the grafting behavior was addressed [52], Sulfonation of the grafted films conducted with chlorosulfonic acid/dichloromethane mixture at room temperature. The PEMFC performance of PVDF-based membranes was found to be inferior to their ETFE-based counterparts [52],... 

Scott et al. [56] tested the performance of radiation-grafted ElEE-g-PSSA membranes in comparison with Nafion in DMEC (90°C, 2M MeOH, and air). The ETFE-g-PSSA membranes showed comparable performance values with Nafion 117, especially with low current densities. 

Fig. 14.19 DMFC performance comparison of NafionllV and Nafion-PBI membranes at two methanol feed concentrations (1.0 and 5.0 M at a flow rate of 2 ml min O at 60°C and ambient pressure air. The Nafion-PBI membrane contained 5% PBI and was prepared from 40% proto-nated Nafion powder, with a wet thickness of 80 pm. Crossover is expressed as a relative fraction of the methanol flux observed for a Nafion 117 membrane at the fuel cell operation conditions with a 1.0 M methanol feed. (Reprinted from [31], with permission from Elsevier.)...

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