Search results for " Reverse"
showing 10 items of 243 documents
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…
Reverse electrodialysis with NH4HCO3-water systems for heat-to-power conversion
2017
Abstract A Reverse ElectroDialysis Heat Engine (REDHE) system operating with “thermolytic” ammonium hydrogen-carbonate (NH4HCO3) aqueous solutions as working fluids is studied. The engine is constituted by (i) a RED unit to produce electric power by mixing the solutions at different salinity and (ii) a thermally-driven regeneration unit including a stripping and an absorption column to restore the initial salinity gradient thus closing the cycle. In the present work only the RED unit and the stripping column are taken into account. In particular, a simplified integrated process model for the whole cycle was developed: it consists of (i) a lumped parameter model for the RED unit validated wi…
Bipolar membrane reverse electrodialysis for the sustainable recovery of energy from pH gradients of industrial wastewater: Performance prediction by…
2021
Abstract The theoretical energy density extractable from acidic and alkaline solutions is higher than 20 kWh m−3 of single solution when mixing 1 M concentrated streams. Therefore, acidic and alkaline industrial wastewater have a huge potential for the recovery of energy. To this purpose, bipolar membrane reverse electrodialysis (BMRED) is an interesting, yet poorly studied technology for the conversion of the mixing entropy of solutions at different pH into electricity. Although it shows promising performance, only few works have been presented in the literature so far, and no comprehensive models have been developed yet. This work presents a mathematical multi-scale model based on a semi-…
Pressure drop in woven-spacer-filled channels for reverse electrodialysis: CFD prediction and experimental validation
2015
Reverse electrodialysis (RED) is a promising technology for electric power generation by the chemical potential difference of two salt solutions within a stack equipped by selective ionexchange membranes (salinity gradient energy). Mechanical energy is required for pumping the feed solutions, which can reduce dramatically the net power output. In this work Computational Fluid Dynamics (CFD) simulations of spacer-filled channels for RED were carried out in parallel with an experimental campaign focused on the collection of data for model validation.
CFD prediction of scalar transport in thin channels for reverse electrodialysis
2014
Reverse ElectroDialysis (RED) is a very promising technology allowing the electrochemical potential difference of a salinity gradient to be directly converted into electric energy. The fluid dynamics optimization of the thin channels used in RED is still an open problem. The present preliminary work focuses on the Computational Fluid Dynamics (CFD) simulation of the flow and concentration fields in these channels. In particular three different configurations were investigated: a channel unprovided with a spacer (empty channel) and two channels filled with spacers, one made of overlapped filaments the other of woven filaments. The transport of two passive scalars, representative of the ions …
Reverse Electrodialysis: Applications to Different Case Studies
2018
Salinity gradient is a non-conventional renewable energy form which is widely available worldwide. Reverse Electrodialysis is a promising and innovative technology able to convert directly this chemical renewable energy into electricity. This paper presents a number of different scenarios where salinity gradients are naturally available or they result from industrial/urban activities. A sophisticated model accounting for all the main phenomena (including all the detrimental ones) occurring within a Reverse Electrodialysis unit has been purposely developed. The model is used to calculate how much electric energy can be harvested from the above-mentioned salinity gradients.
ELECTRICAL ENERGY STORAGE DEVICES BASED ON pH AND SALINITY GRADIENTS: MODELLING, EXPERIMENTS AND PILOTING
2021
Electrodialysis Applications in Wastewater Treatment for Environmental Protection and Resources Recovery: A Systematic Review on Progress and Perspec…
2020
This paper presents a comprehensive review of studies on electrodialysis (ED) applications in wastewater treatment, outlining the current status and the future prospect. ED is a membrane process of separation under the action of an electric field, where ions are selectively transported across ion-exchange membranes. ED of both conventional or unconventional fashion has been tested to treat several waste or spent aqueous solutions, including effluents from various industrial processes, municipal wastewater or salt water treatment plants, and animal farms. Properties such as selectivity, high separation efficiency, and chemical-free treatment make ED methods adequate for desalination and othe…
"A KNOWLEDGE-BASED EXPERT SYSTEM IN BIOINFORMATICS: AN APPLICATION TO REVERSE ENGINEERING GENE REGULATORY NETWORK"
2011
The huge amount of biological data has spread the development of plenty of bionformatics tools, databases and web services. In order to face a computational biology problem, there not exist only a way, but different methodologies and strategies, with their own pros and cons, can be applied. In this PhD thesis I present a knowledge-based expert system that aims at helping a bionformatics researcher in the choice of the proper strategy and heuristic in order to resolve a bioinformatics issue. The Knowledge Base of the system is structured by means of an ontology and codes the expertise about the application domain. KB is organized into decision-making modules that introduce a set of metareaso…
Lipid and apoprotein composition of HDL in partial or complete CETP deficiency
2012
Hyperalphalipoproteinemia, as observed in patients who are either homozygous or heterozygous for cholesteryl ester transfer protein (CETP) deficiency, has been shown to be associated with striking changes in apolipoprotein size distribution, namely, of high-density lipoprotein (HDL) and HDL-like particles. We compared the effect of varying degrees of CETP activity on the HDL apolipoprotein profile in Caucasian CETP-deficient subjects and following pharmacological decrease in CETP activity, using Size Exclusion Chromatography followed by Reverse Phase Protein Array (SEC RPA). The main HDL-associated apolipoproteins (Apo), i.e. ApoA-I, ApoA-II, ApoC-I, and ApoC-III, co-eluted with the HDL pea…