Exergy analysis of reverse electrodialysis

Giacalone, Francesco; Catrini, Pietro; Tamburini, Alessandro; Cipollina, Andrea; Piacentino, Antonio; Micale, G.

doi:10.1016/j.enconman.2018.03.014

Cited by 74 publications

(46 citation statements)

References 52 publications

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“…When a solution at high concentration is mixed with a solution at low concentration, the resulting effect is a variation of the Gibbs free energy of the system, i.e. the Gibbs free energy of mixing, which may ideally be converted in electricity when no dissipative phenomena are involved in the recovery process [28].…”

Section: The Gibbs Free Energy Of Mixingmentioning

confidence: 99%

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Novel solutions for closed-loop reverse electrodialysis: Thermodynamic characterisation and perspective analysis

Giacalone

Olkis

Santori

et al. 2019

Energy

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Closed-loop Reverse Electrodialysis is a novel technology to directly convert low-grade heat into electricity. It consists of a reverse electrodialysis (RED) unit where electricity is produced exploiting the salinity gradient between two saltwater solutions, coupled with a regeneration unit where waste-heat is used to treat the solutions exiting from the RED unit and restore their initial composition. One of the most important advantages of closed-loop systems compared to the open systems is the possibility to select ad-hoc salt solutions to achieve high efficiencies. Therefore, the properties of the salt solutions are essential to assess the performance of the energy generation and solution regeneration processes. The aim of this study is to analyse the influence of thermodynamic properties of non-conventional salt solutions (i.e. other than NaCl-aqueous solutions) and their influence on the operation of the closed-loop RED. New data for caesium and potassium acetate salts, i.e. osmotic and activity coefficients in aqueous solutions, at temperature between 20 and 90°C are reported as a function of molality. The data are correlated using Pitzer's model, which is then used to assess the theoretical performance of the whole closed-loop RED system considering both single and multi-stage regeneration units. Results indicate that KAc, CsAc and LiCl are the most promising salts among those screened.

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Section: The Gibbs Free Energy Of Mixingmentioning

confidence: 99%

“…It is worth noting that the maximum achievable energy of mixing has been assumed to compute the power output (as in [33]), though in practical applications such conditions might be not realizable [28].…”

Section: Thermal and Exergy Efficiency Of The Ideal Red Enginementioning

confidence: 99%

Novel solutions for closed-loop reverse electrodialysis: Thermodynamic characterisation and perspective analysis

Giacalone

Olkis

Santori

et al. 2019

Energy

Self Cite

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“…For the sake of brevity, all relevant details are reported in the Section S2 of the Supplementary Information file. The RED model, already validated against experimental data [45], is extensively described in [38,41].…”

Section: Reverse Electrodialysis Processmentioning

confidence: 99%

“…The other two membrane properties, i.e., the water permeability, L p , and the salt diffusivity, D s , were taken equal to zero for the ideal case, since in this way the diffusive flux of the salt from the concentrate to the dilute compartment and the osmotic flux resulted equal to zero. These last two terms are detrimental for the RED performances as they cause uncontrolled mixing, which leads to a reduction of the driving force and the destruction of part of the exergy contained in the inlet streams [45]. Table 2.…”

Section: Red-med Coupled Systemmentioning

confidence: 99%

“…Table 2. Membrane properties adopted in the two scenarios current and ideal membranes [45]. For each set of conditions, concentration and flow rate of the solution entering the MED unit were computed from the mass balance Equations (5) and (6) taking into account the outlet conditions (flow-rates and concentrations) from the RED unit.…”

Section: Red-med Coupled Systemmentioning

confidence: 99%

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Performance Analysis of a RED-MED Salinity Gradient Heat Engine

et al. 2018

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A performance analysis of a salinity gradient heat engine (SGP-HE) is presented for the conversion of low temperature heat into power via a closed-loop Reverse Electrodialysis (RED) coupled with Multi-Effect Distillation (MED). Mathematical models for the RED and MED systems have been purposely developed in order to investigate the performance of both processes and have been then coupled to analyze the efficiency of the overall integrated system. The influence of the main operating conditions (i.e., solutions concentration and velocity) has been quantified, looking at the power density and conversion efficiency of the RED unit, MED Specific Thermal Consumption (STC) and at the overall system exergy efficiency. Results show how the membrane properties (i.e., electrical resistance, permselectivity, water and salt permeability) dramatically affect the performance of the RED process. In particular, the power density achievable using membranes with optimized features (ideal membranes) can be more than three times higher than that obtained with current reference ion exchange membranes. On the other hand, MED STC is strongly influenced by the available waste heat temperature, feed salinity and recovery ratio to be achieved. Lowest values of STC below 25 kWh/m3 can be reached at 100 °C and 27 effects. Increasing the feed salinity also increases the STC, while an increase in the recovery ratio is beneficial for the thermal efficiency of the system. For the integrated system, a more complex influence of operating parameters has been found, leading to the identification of some favorable operating conditions in which exergy efficiency close to 7% (1.4% thermal) can be achieved for the case of current membranes, and up to almost 31% (6.6% thermal) assuming ideal membrane properties.

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An Opportunity for Synergizing Desalination by Membrane Distillation Assisted Reverse‐Electrodialysis for Water/Energy Recovery

Mujahid,

Umar Farooq,

Wang

et al. 2024

The Chemical Record

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Industry, agriculture, and a growing population all have a major impact on the scarcity of clean‐water. Desalinating or purifying contaminated water for human use is crucial. The combination of thermal membrane systems can outperform conventional desalination with the help of synergistic management of the water‐energy nexus. High energy requirement for desalination is a key challenge for desalination cost and its commercial feasibility. The solution to these problems requires the intermarriage of multidisciplinary approaches such as electrochemistry, chemical, environmental, polymer, and materials science and engineering. The most feasible method for producing high‐quality freshwater with a reduced carbon footprint is demanding incorporation of industrial low‐grade heat with membrane distillation (MD). More precisely, by using a reverse electrodialysis (RED) setup that is integrated with MD, salinity gradient energy (SGE) may be extracted from highly salinized MD retentate. Integrating MD‐RED can significantly increase energy productivity without raising costs. This review provides a comprehensive summary of the prospects, unresolved issues, and developments in this cutting‐edge field. In addition, we summarize the distinct physicochemical characteristics of the membranes employed in MD and RED, together with the approaches for integrating them to facilitate effective water recovery and energy conversion from salt gradients and freshwater.

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Exergy analysis of reverse electrodialysis

Cited by 74 publications

References 52 publications

Novel solutions for closed-loop reverse electrodialysis: Thermodynamic characterisation and perspective analysis

Novel solutions for closed-loop reverse electrodialysis: Thermodynamic characterisation and perspective analysis

Performance Analysis of a RED-MED Salinity Gradient Heat Engine

An Opportunity for Synergizing Desalination by Membrane Distillation Assisted Reverse‐Electrodialysis for Water/Energy Recovery

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