Search results for "MICI"

Electrodialysis with Bipolar Membranes for the Sustainable Production of Chemicals from Seawater Brines at Pilot Plant Scale

2023

Environmental concerns regarding the disposal of seawater reverse osmosis brines require the development of new valorization strategies. Electrodialysis with bipolar membrane (EDBM) technology enables the production of acid and base from a salty waste stream. In this study, an EDBM pilot plant with a membrane area of 19.2 m2 was tested. This total membrane area results much larger (i.e., more than 16 times larger) than those reported in the literature so far for the production of HCl and NaOH aqueous solutions, starting from NaCl brines. The pilot unit was tested both in continuous and discontinuous operation modes, at different current densities (200-500 A m-2). Particularly, three differe…

A methodology for assessing the impact of salinity gradient power generation in urban contexts

2018

Abstract The paper proposes a methodology to assess the potential impact of salinity gradient power technology in urban contexts. The idea to employ such energy source in urban contexts derives from the observation that, among the energy districts outputs, low-salinity treated wastewater can be used to produce electricity if a suitable source of high salinity feed (seawater of a salt-works) is also available. The methodology uses the HOMER software for assessing the district’s electric energy production, consumption and exchange with the main grid. Then, starting from the total gross surface and the number of inhabitants of the district, some possible realistic scenarios characterized by di…

Seawater Desalination for Freshwater Production

2009

In the last decades more and more countries have experienced water scarcity problems, thus pointing at alternative non-conventional sources of fresh water. Seawater desalination has proven to be a reliable and economically sustainable water resource since the second half of the 20th Century. A number of well proven technologies already exist, with advantages and disadvantages making each of them more suitable in specific sites. Moreover, quite recently, coupling the use of renewable energy to the production of fresh water from seawater results in novel technologies, able to minimise the environmental impact that desalination processes can create due to their intense energy consumptions.

Geometrical characterization of reverse electrodialysis stack via CFD simulations

2012

In the presente work, CFD simulations were carried out in order to assess the effects of different parameters on the global process efficiency, such as the choice of spacer material and morphology, and the optimisation of feed and blowdown distribution systems

A novel Reverse Electrodialysis application to generate power from low-grade heat

2015

A novel idea for the conversion of low-temperature heat into electricity is based on the generation of electricity from salinity gradients using a Reverse Electrodialysis (RED) device in a closed-loop system. In this concept a limited amount of artificial saline solutions can be used as the working fluids in a closed-loop. The solutions exiting from the RED unit are then regenerated, in order to restore the original salinity gradient, by means of a separation step, which uses low-temperature heat (40-100°C) as its energy source. A theoretical analysis of potentials of this technology is illustrated in the present work.

Maximum Net Power Density Conditions in Reverse Electrodialysis Stacks

2018

Reverse Electrodialysis (RED) harvests electrical energy from a salinity gradient. The maximum obtainable net power density (NPD) depends on many physical and geometric variables. Some have a monotonic (beneficial or detrimental) influence on NPD, and can be regarded as “scenario” variables chosen by criteria other than NPD maximization. Others, namely the thicknesses HCONC, HDIL and the velocities UCONC, UDIL in the concentrate and diluate channels, have contrasting effects, so that the NPD maximum is obtained for some intermediate values of these parameters. A 1-D model of a RED stack was coupled here with an optimization algorithm to determine the conditions of maximum NPD in the space o…

A multi-scale model for the reverse electrodialysis process with seawater and concentrated brines

2012

Long-run operation of a reverse electrodialysis system fed with wastewater solutions

2016

In the framework of Salinity Gradient Power technologies, Reverse ElectroDialysis (RED) is one of the most promising. In RED, two solutions of different salt concentration are fed into a series of alternate compartments, the one fed by the low salinity solution, the other by the high salinity solution. Compartments are separated by anion and cation exchange membranes alternatively piled to form a stack. Selective ion transport from the concentrate compartment to the dilute one across the membranes allows to generate an ionic current, which is eventually converted into electric current by means of suitable electrode compartments closing the stack. Several options for the feed solutions are p…

CFD modelling of profiled membranes channels for reverse electrodialysis

2014

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 were perform…

Fluid-structure interaction in electromembrane processes: modelling of membrane deformation, fluid dynamics and mass transfer

2018

In recent years, water and energy supply issues have boosted a noticeable interest in the scientific community on electromembrane processes such as electrodialysis and reverse electrodialysis. In order to gain an important place in the industrial market, technological challenges on various aspects are involved for the optimization of these processes. In this context, profiled membranes exhibit interesting performances and offer countless geometric alternatives. However, the mechanical behavior of the membranes and its interaction with fluid dynamics has been poorly investigated so far. In membrane-based processes, a trans-membrane pressure (Ptm) between the different solutions flowing throu…