Luigi Gurreri

CFD analysis of the fluid flow behavior in a reverse electrodialysis stack

Abstract Salinity Gradient Power by Reverse Electrodialysis (SGP-RE) technology allows the production of electricity from the different chemical potentials of two differently concentrated salty solutions flowing in alternate channels suitably separated by selective ion exchange membranes. In SGP-RE, as well as in conventional ElectroDialysis (ED) technology, the process performance dramatically depends on the stack geometry and the internal fluid dynamics conditions: optimizing the system geometry in order to guarantee lower pressure drops (ΔP) and uniform flow rates distribution within the channels is a topic of primary importance. Although literature studies on Computational Fluid Dynamics (CFD) analysis and optimization of spacer-filled channels have been recently increasing in number and range of applications, only a few efforts have been focused on the analysis of the overall performance of the process. In particular, the proper attention should be devoted to verify whether the spacer geometry optimi...

CFD modelling of profiled-membrane channels for reverse electrodialysis

AbstractReverse 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 performed to predict the fluid flow and mass transfer behaviour in channels with profiled membranes for RE applications. In particular, channels equipped with pillars were simulated. The influence of channel geometry on fluid flow and concentration polarization was assessed by means of a parametric analysis for differe...

Assessment of temperature polarization in membrane distillation channels by liquid crystal thermography

AbstractThe measurement of local temperature distributions within a membrane distillation (MD) channel is a crucial step for the optimization of the channel and spacer geometry. This information allows the estimation of temperature polarization phenomena, which can dramatically influence the thermal efficiency of the process and the optimal choice of the geometric configuration (net spacer features, channel size, etc.). In the present work, a recently presented experimental technique, based on the use of thermochromic liquid crystals and digital image analysis, has been employed in order to assess the temperature polarization phenomena. The local heat transfer coefficient distribution on the membrane surface in a MD spacer-filled channel was thus assessed. The membrane has been modelled by a heat transfer polycarbonate layer. Different diamond spacer geometries were investigated, in order to highlight how the geometrical features affect both pressure drop and heat transfer in spacer-filled channels.

Reverse electrodialysis: Applications

Abstract Reverse electrodialysis (RED) technology has grown significantly in the last decade, gaining a fast increase in its technology readiness level and presenting some interesting examples of RED pilot systems operating under very different real environments. In this chapter, an overview of technological developments and piloting examples are reported. In particular, a short introduction is given on the historical trend of RED technology growth, followed by a careful analysis of which feed solutions can be adopted and how these can affect the process performance, potentials, and applications. Most prominent fluid dynamics aspects for the RED process are presented, highlighting how these can influence the design and operation of RED systems, being able to affect the overall performance of a RED plant. For the first time, two practical experiences of RED technology piloting are analysed: the Afsluitdijk pilot plant in The Netherlands ( Blue Energy project), operating with seawater and river water, and the Marsala pilot plant in Italy ( REAPower project), operating with concentrated brines and saline waters. The main achievements, progresses, growth directions and world key actors in the technology development will be underlined. Finally, the envisaged R&D routes and perspectives for the future of RED technology development will be outlined.