Search results for "MICI"

CFD simulations of early- to fully-turbulent conditions in unbaffled and baffled vessels stirred by a Rushton turbine

2021

Abstract Laboratory scale unbaffled tanks provided with a top cover and a baffled tank both stirred by a Rushton turbine were simulated by carrying out RANS simulations. Three different turbulence models were adopted (k- ω SST, k- e and the SSG Reynolds stress model) to predict the flow field and the relevant performance parameters (power and pumping numbers) of the tank operated from early to fully turbulent conditions. CFD results were compared with literature experimental data and DNS simulation results to validate and properly compare the models. In the range of Reynolds numbers investigated, results showed that, for the unbaffled tank, the SSG model based on Reynolds stresses is a bett…

Electrochemical processes for the treatment of chlorinated ethanes in water solutions

In the present work, the electrochemical treatment of water solutions containing chloro ethanes was performed by cathodic reduction, anodic oxidation and coupled processes with the aim of evaluate the effectiveness of these methodologies.

Numerical simulation of electroconvection phenomena in electrodialysis

In water desalination by electrodialysis, the current density i cannot exceed specific constraints, notably the diffusion limit. Working at higher i (overlimiting current regime) would make higher desalination rates possible. The main phenomenon allowing overlimiting current densities is the electrokinetic instability that arises when a sufficiently intense electric potential gradient is imposed, and leads to electroconvective mixing in the near-wall layer. In this study, these phenomena were investigated by CFD. The governing equations were the Nernst-Planck transport equations for anions and cations, the Poisson equation for the electrical potential and the Navier-Stokes and continuity eq…

CFD study on the influence of water transpiration on flow and mass transfer in channels with bipolar membranes

2018

The future energetic supply based on the massive use of renewable sources poses issues linked to fluctuations of power produced and consumed, thus requiring the use of energy storage systems.

Mechanical-fluid dynamics coupled model for profiled Ion Exchange Membranes design

2018

In this work, we developed an advanced model useful for the design of profiled IEMs, based on the coupled simulation of local mechanical deformations and of fluid dynamics and associated mass transport phenomena within deformed channels

Integrated modelling of membrane deformation, fluid dynamics and mass transfer in electromembrane processes

In recent years, water and energy supply issues have drawn the attention of the scientific community to electromembrane processes. Electrodialysis (ED) and Reverse Electrodialysis (RED) are two of the most attractive electromembrane technologies for water desalination and electric energy production from salinity gradients, respectively. In order to gain an important place in the industrial market, technological challenges on various aspects are involved in the optimization of these processes. In this context, profiled membranes exhibit interesting performance. However, the mechanical behavior of the membranes and its interaction with fluid dynamics has been poorly investigated so far. In me…

Comparison of different hollow fibre haemodialysis module configurations by a CFD multiscale approach

2021

Objectives The study aims to predict 3-D flow and solute concentrations fields both for blood and dialysate and overall performance parameters (such as dialysate pressure drop and clearance) for different hollow-fibre haemodialysis modules. Methods A multiscale approach was used. At small (unit cell)-scale, dialysate flow and mass transfer around straight cylindrical fibres arranged in regular lattices were simulated. At module-scale, hydraulic permeabilities and mass transfer coefficients derived from small-scale simulations were used to define two different porous media representative of blood and dialysate, sharing the same volume and exchanging solute. Simulations involved different mod…

Modeling and Design of Membrane Process Recovery of HCl and Metals from Pickling Solutions

2018

Abstract Hydrochloric acid pickling is one of the key steps in the hot-dip galvanizing process. It is a process widely used as a chemical pre-treatment method for cleaning, where metal surfaces with oxides are immersed into an acid solution. During the pickling process, the acid concentration decreases with time while the metal is accumulated. Thus, the efficiency of the pickling solution decreases and fresh solution must be used. Continuous regeneration of pickling solutions enhances pickling rate and process performance, but also minimises industrial wastewater disposal and chemicals consumption. The recovery and recycling process of valuable substances (e.g. acid and metals) can be accom…

An integrated approach for HCl and metals recovery from waste pickling solutions: pilot plant design and operations

Continuous regeneration of industrial pickling solutions and recovery of valuable materials are implemented in a pilot-scale plant including diffusion dialysis, membrane distillation and reactive precipitation units. The main results of the preliminary assessment of on site operation are presented. Different hydrochloric acid concentration and metals composition were investigated and the performance of the system were analysed in terms of quality of recovered compounds, energy efficiency and environmental footprint.

Economic Benefits of Waste Pickling Solution Valorization

2022

An integrated hybrid membrane process, composed of a diffusion dialysis (DD), a membrane distillation (MD) and a reactive precipitation unit (CSTR), is proposed as a promising solution for the valorization and onsite recycling of pickling waste streams. An economic analysis was performed aiming to demonstrate the feasibility of the developed process with a NPV of about EUR 40,000 and a DPBP of 4 years. The investment and operating costs, as well as the avoided costs and the benefits for the company operating the plant, were analyzed with an extensive cost tracking exercise and through face-to-face contact with manufacturers and sector leaders. A mathematical model was implemented using the …