Search results for "0204 chemical engineering"
showing 10 items of 273 documents
CFD modelling of profiled-membrane channels for reverse electrodialysis
2014
Abstract: Reverse electrodialysis (RE) is a promising technology for electric power generation from controlled mixing of two differently concentrated salt solutions, where ion-exchange membranes are adopted for the generation of ionic currents within the system. Channel geometry strongly influences fluid flow and thus crucial phenomena such as pressure drop and concentration polarization. Profiled membranes are an alternative to the more commonly adopted net spacers and offer a number of advantages: avoiding the use of non-conductive and relatively expensive materials, reducing hydraulic losses and increasing the active membrane area. In this work, Computational Fluid Dynamic simulations we…
REAPOWER – USE OF DESALINATION BRINE FOR POWER PRODUCTION THROUGH REVERSE ELECTRODIALYSIS
2015
Salinity gradient power (SGP) represents a viable renewable energy source associated with the mixing of two solutions of different salinities. Reverse electrodialysis (SGP-RE or RED) is a promising technology to exploit this energy source and directly generate electricity. However, although the principle of this technology is well known since several years, further R&D efforts are still necessary in order to explore the real potential of the SGP-RE process. With this regard, the aim of the REAPower project ( [GRAPHICS] ) is the development of an innovative system for power production by SGP-RE process, using sea (or brackish) water as a diluted solution and brine as a concentrate. The use o…
Flow and mass transfer in spacer-filled channels for reverse electrodialysis: a CFD parametrical study
2016
Abstract In reverse electrodialysis (RED) concentration polarization phenomena and pressure drop affect strongly the power output obtainable; therefore the channel geometry has a crucial impact on the system optimization. Both overlapped and woven spacers are commonly commercialised and adopted for RED experiments; the latter exhibit some potential advantages, such as better mixing and lower shadow effect, but they have been poorly investigated in the literature so far. In this work, computational fluid dynamics was used to predict fluid flow and mass transfer in spacer-filled channels for RED applications. A parametric analysis for different spacer geometries was carried out: woven (w) and…
Diffusion dialysis for the treatment of H2SO4-CuSO4 solutions from electroplating plants: Ions membrane transport characterization and modelling
2021
Diffusion dialysis (DD) is proposed to separate and recover mineral acids and transition metals from electroplating industry process waters promoting a circular approach of resources recovery. In this work, a DD module with two anionic membranes (Fumasep FAD and Neosepta AFN) are used for the separation of H2SO4 from Cu2+ containing solutions. The membrane performances with sole H2SO4 solutions (0.2–2 M) and sole CuSO4 solutions (0.8–1.1 M Cu2+) and with mixtures of H2SO4 (0.6 M) and CuSO4 (0.2–1.1 M Cu2+) as feed are studied. H2SO4 recovery efficiency decreases as the concentration of acid increases. For H2SO4 solutions, the water drag flux from the retentate to the diffusate prevails agai…
Water desalination by capacitive electrodialysis: Experiments and modelling
2020
Abstract Electrodialysis-related technologies keep spreading in multiple fields, among which water desalination still plays a major role. A new technology that has not yet been thoroughly investigated is capacitive electrodialysis (CED), which couples the standard ED with capacitive electrodes. CED has a number of advantages such as removal of toxic products and system simplification. Little mention is made of this technology in the literature and, to the best of our knowledge, no modelling works have ever been presented. In this work, the CED process has been studied through experiments and modelling. A CED model is presented for the first time. With a simple calibration based on macroscop…
A Novel Ionic Exchange Membrane Crystallizer to Recover Magnesium Hydroxide from Seawater and Industrial Brines
2020
A novel technology, the ion exchange membrane crystallizer (CrIEM), that combines reactive and membrane crystallization, was investigated in order to recover high purity magnesium hydroxide from multi-component artificial and natural solutions. In particular, in a CrIEM reactor, the presence of an anion exchange membrane (AEM), which separates two-compartment containing a saline solution and an alkaline solution, allows the passage of hydroxyl ions from the alkaline to the saline solution compartment, where crystallization of magnesium hydroxide occurs, yet avoiding a direct mixing between the solutions feeding the reactor. This enables the use of low-cost reactants (e.g., Ca(OH)2) without …
CFD simulations of early- to fully-turbulent conditions in unbaffled and baffled vessels stirred by a Rushton turbine
2021
Abstract Laboratory scale unbaffled tanks provided with a top cover and a baffled tank both stirred by a Rushton turbine were simulated by carrying out RANS simulations. Three different turbulence models were adopted (k- ω SST, k- e and the SSG Reynolds stress model) to predict the flow field and the relevant performance parameters (power and pumping numbers) of the tank operated from early to fully turbulent conditions. CFD results were compared with literature experimental data and DNS simulation results to validate and properly compare the models. In the range of Reynolds numbers investigated, results showed that, for the unbaffled tank, the SSG model based on Reynolds stresses is a bett…
Empirical estimates of the radiative impact of an unusually extreme dust and wildfire episode on the performance of a photovoltaic plant in Western M…
2019
Abstract We have estimated the radiative impact produced by an unusually extreme dust and wildfire episode on the performance of a photovoltaic (PV) plant. The dust and wildfire events were mostly active on 26–28 and 29–30 June 2012, respectively. We took advantage of the consecutiveness of both events to separate and derive empirically the radiative effect of dust and smoke aerosols. With this purpose, we employed measurements of aerosol load, radiation and PV power output from a collocated atmospheric station and PV plant located at Burjassot (Valencia, Spain). The empirical estimates were obtained by direct comparison with a summer background day, happened right before the two consecutiv…
An experimental study for the characterization of fluid dynamics and heat transport within the spacer-filled channels of membrane distillation modules
2018
Abstract The thermo-fluid dynamic behavior of spacer-filled channels for membrane distillation was investigated experimentally. Several different geometry were investigated thanks to customized reference spacers manufactured using a 3D printer. In particular, two sets of experiments were conducted: in the first set, cylindrical filaments were orthogonally arranged and the flow attack angle was made to vary from 0o to 90o; in the second set, the flow attack angle was kept symmetrical and the filament angle was made to vary from 30° to 150°. Each spacer was tested for Reynolds numbers between 200 and 900 in the hot channel, while maintaining a constant temperature difference of 13 °C between …
Integral relations, a simplified method to find interfacial resistivities for heat and mass transfer.
2007
International audience; Integral relations were used to predict interface film transfer coefficients for evaporation and condensation. According to these, all coefficients can be calculated for one-component systems, using the thermal resistivity and the enthalpy profile through the interface. The expressions were verified in earlier work using non-equilibrium molecular dynamics simulations for argon-like particles, which interacted with a short-range Lennard-Jones (LJ) spline potential, which becomes zero at about 1.7 times the LJ-diameter. In this paper we verify the validity of these relations for a long-range LJ spline potential which becomes zero at 2.5 times the diameter. In an earlie…