Search results for "modeling"

Two-Dimensional Modeling of an Externally Irradiated Slurry Photoreactor

2013

Abstract A batch cylindrical photocatalytic reactor, externally irradiated by 1–6 UV fluorescent lamps and containing a stirred slurry of polycrystalline TiO2, was modeled by coupling a modified Langmuir–Hinshelwood kinetics together with a two-dimensional light intensity field. The radiation field has been determined on the main assumptions of diffuse radiation, isotropic scattering and negligible backward reflected photon flow. The model has been applied to the photocatalytic oxidation of organic substrates which do not undergo homogeneous photochemical degradation. The model is characterized by the following four parameters: the kinetic constants of substrate adsorption, desorption and d…

Once through multistage flash desalination: gPROMS dynamic and steady state modelling

2010

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.

CFD Investigation of Spacer-Filled Channels for Membrane Distillation

2019

The membrane distillation (MD) process for water desalination is affected by temperature polarization, which reduces the driving force and the efficiency of the process. To counteract this phenomenon, spacer-filled channels are used, which enhance mixing and heat transfer but also cause higher pressure drops. Therefore, in the design of MD modules, the choice of the spacer is crucial for process efficiency. In the present work, different overlapped spacers are investigated by computational fluid dynamics (CFD) and results are compared with experiments carried out with thermochromic liquid crystals (TLC). Results are reported for different flow attack angles and for Reynolds numbers (Re) ran…

Electrodialysis for water desalination: A critical assessment of recent developments on process fundamentals, models and applications

2018

Abstract The need for unconventional sources of fresh water is pushing a fast development of desalination technologies, which proved to be able to face and solve the problem of water scarcity in many dry areas of the planet. Membrane desalination technologies are nowadays leading the market and, among these, electrodialysis (ED) plays an important role, especially for brackish water desalination, thanks to its robustness, extreme flexibility and broad range of applications. In fact, many ED-related processes have been presented, based on the use of Ion Exchange Membranes (IEMs), which are significantly boosting the development of ED-related technologies. This paper presents the fundamentals…

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

2012

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 (DP) and uniform flow rates distribution within the channels is a topic of primary importance. Although literature studies on Computational Fluid Dynamics (CFD) a…

Lagrangian simulation of bubbling dynamics in a lab-scale 2D fluidized bed

2013

The present work focuses on the development of a novel computational code able to predict with a reasonable level of accuracy the bubble behavior in gas fluidized beds with minimum computational demands. The code simulates the bubble chaotic rise motion and coalescence along bed height via simple lagrangian tracking of bubbles. An original empirical model for the assessment of bubble-bubble interactions is developed. The code is used to simulate a lab-scale unit in bubbling and slugging mode. On this basis, fast simulations are performed to successfully predict bubble population and fluxes within the bed. The main aim of this code is to be embedded within CAPE codes for the process simulati…

CFD Predictions of Sufficient Suspension Conditions in Solid-Liquid Agitated Tanks

2012

Abstract Most research efforts on mechanically agitated solid-liquid contactors have been devoted to the assessment of the minimum impeller speed for complete off-bottom suspension, N js . Actually, many industrial vessels are operated at impeller speeds slightly lower than N js (Oldshue, 1983; Rieger et al., 1988). This suggests that the sufficient suspension condition, which is quantitatively specified in this paper by introducing a suitably defined quantity N ss , may represent a valid alternative to that of complete suspension. In the present work time-dependent RANS simulations were carried out with the aim of predicting the achievement of sufficient suspension conditions. The Eulerian…

Economic impact of Ice Thermal Energy Storage Systems in residential buildings in presence of double-tariffs contracts for electricity

2009

Thermal energy storage is one of the most important methods of demand-side load management, thanks to the capacity of reducing significantly the peak power demand for air conditioning in buildings. Thermal Energy Storage Systems (TESS) are indeed used for producing and storing cooling capacity during off-peak hours (in particular during night hours) to meet the following day's air conditioning requirements. The current paper presents a study on the effects of the installation of Ice TESS for cooling on the power daily profile of residential buildings, and examines the economic repercussions on the electricity billing. With reference to this second theme, the paper examines, in particular, t…

Modeling Alternatives Sustainable-Energy-Policy for the Supply Chain of Wind Power in Brazil.

2020

Renewable energy studies have received high attention in the last few years due the increasing deployment of alternatives such as wind, solar and biomass, as a result of the urgency in reducing fossil fuels consumption. This situation has involved an important challenge for long-term renewables policy and energy system planning. Brazil is the richest country in terms of renewable sources in Latin American. Brazil has energy generation portfolio not much different form the Colombia one, and the understanding of this very important country will contribute to inspire other countries in the region, particularly Colombia. Since 2004 the Brazilian energy policy promotes wind power development aim…