Search results for " Gradient"

CFD analysis of concentration polarization phenomena in spacer-filled channels for Reverse Electro-Dialysis

2012

In this work, carried out within the EU-FP7 funded REAPower project, CFD simulations were carried out in order to study the fluid flow behaviour and mass transport phenomena within spacer-filled channels.

Energia da gradienti salini: dall’acqua l’energia del futuro

2017

Today, continuous research efforts are aimed at finding alternative renewable energy sources to conventional ones and efficient technologies able to exploit them. Saline gradient energy is an unconventional renewable energy source widely available and currently under-exploited. In the present document the most technologies are illustrated avant-garde for the conversion of this energy into electric current: Pressure Retarded Osmosis, PRO (Osmosis Delayed by Pressure) and the Reverse Electrodialysis, RED (Inverse Electrodialysis).

Ionic shortcut currents via manifolds in reverse electrodialysis stacks

2020

Abstract Reverse electrodialysis (RED) is a blue energy technology for clean and sustainable electricity harvesting from the mixing entropy of salinity gradients. Recently, many efforts have been devoted to improving the performance of RED units by developing new ion-exchange membranes and by reducing the detrimental phenomena affecting the process. Among these sources of “irreversibility”, the shortcut currents (or parasitic currents) flowing through alternative pathways may affect the process efficiency. Although such phenomena occur in several electrochemical processes (e.g. fuel cells, bipolar plate cells and vanadium redox flow batteries), they have received a poor attention in RED uni…

Potential applications of Salinity Gradient Power-Heat Engines for recovering low-temperature waste heat in cogeneration plants

2021

Abstract Salinity Gradient Power-Heat Engine is an innovative technology able to convert very low-temperature heat into electricity. Energy and economic benefits could be achieved by integrating this technology into cogeneration plants, where the exploitation of waste heat available during the operation could increase the revenues arising from “High-Efficiency” labels. For the first time, this paper proposes two potential applications in this field, and three illustrative case studies are purposely investigated. In the first case study, a salinity gradient-heat engine converts the waste heat available from a cogeneration plant serving an industrial process. In the second case study, a salin…

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…

Reverse Electrodialysis with seawater and concentrated brine: a comprehensive process modelling

2012

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…

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…

REVERSE ELECTRODIALYSIS HEAT ENGINE: Low-grade Waste Heat into Electricity

Our society is undergoing a progressive change about the life style and habits. The world population is continuously increasing with 7.6 billion of human beings in 2018, resulting in an increasingly demand of resources in terms of food, water and energy. The exploitation of the planet resources since the first Industrial Revolution, results today in an unsustainable condition, which requires fundamental changes. In particular, in the energy sector the adoption of fossil fuels as the main energy source for human beings’ activities resulted in a strong impact on our planet, leading to climate changes and environmental pollution. Nowadays these aspects have induced society to a substantial cha…