Search results for "Distillation"

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…

Experimental and computational investigation of heat transfer in channels filled by woven spacers

2017

Abstract Models of woven-type spacer-filled channels were investigated by Computational Fluid Dynamics (CFD) and parallel experiments in order to characterize the performance of Membrane Distillation (MD) modules. The case of overlapped spacers was analysed in a companion paper. Experiments were based on a non-intrusive technique using Thermochromic Liquid Crystals (TLC) and digital image processing, and provided the distribution of the local convective heat transfer coefficient on a thermally active wall. CFD simulations ranged from steady-state conditions to unsteady and early turbulent flow, covering a Reynolds number interval of great practical interest in real MD applications. A specif…

Investigation of heat transfer in spacer-filled channels by experiments and direct numerical simulations

2016

Abstract The analysis of flow fields and heat or mass transfer phenomena is of great importance in the optimum design of spacer-filled channel geometries for a variety of membrane-based processes. In the present work, models of spacer-filled channels often adopted in Membrane Distillation are simultaneously investigated by experiments and Computational Fluid Dynamics (CFD). Experiments rely on a non-intrusive technique, based on the use of Thermochromic Liquid Crystals (TLC) and digital image processing, and provide the local distribution of the convective heat transfer coefficient on a thermally active wall. CFD relies on steady-state (laminar flow) simulations in the lower end of the Reyn…

Performance comparison between overlapped and woven spacers for membrane distillation

2017

The sustainable production of freshwater from seawater desalination is receiving increasing attention. Recently, some desalination technologies are taking advantage from the coupling with renewable resources; among them, membrane distillation (MD) is one of the most promising since it can be easily powered by low-grade thermal energy. MD being an emerging technology, efforts are required to optimize geometry and operating conditions of real units in order to reduce the unitary freshwater production cost. In particular, temperature polarization is a well-known detrimental effect for the process driving force; spacers are traditionally used to enhance mixing and make temperature boundary laye…

Application of computational fluid dynamics technique in membrane distillation processes

2022

This Chapter illustrates the application of CFD to spacer-filled channels for membrane distillation. The topics discussed cover finite volume grids and grid independence, the unit-cell treatment of spatially periodic net spacers, and the dependence of flow and thermal fields and overall performance parameters (pressure drop and mean heat transfer coefficients) upon geometry and operating conditions (Reynolds number, flow attack angle, pitch-to-height ratio, spacer thermal conductivity, thermal boundary conditions, and one-side vs. two-side heat transfer).

Effect of spacer geometry on the process performance of pervaporation membrane modules

2009

Membrane distillation: solar and waste heat driven demonstration plants for desalination

2011

Design of a novel membrane-integrated waste acid recovery process from pickling solution

2019

Abstract Hydrochloric acid pickling is a common practice in steel manufacturing industry. During the process, acid is consumed to dissolve surface oxides and metals ions are accumulated in the solution, which becomes less effective with time. In addition, the costly and risky waste acid disposal is another issue affecting the hot-dip galvanizing industry. In this work, a novel sustainable waste acid recovery process from pickling solutions based on circular approach is proposed to tackle these issues. The innovative system allows (i) the continuous regeneration of pickling solutions to enhance process rate and performance and (ii) minimise the highly expensive and environmentally risky wast…

Sustainable water and energy: the EU-FP7 MEDIRAS and REAPOWER research projects

2014

CHP retrofit for a large Med-Tvc Desalination Plant: High efficiency assessment for different design options under the current legislative EU framewo…

2015

Integrated power plants in "dual purpose" configuration may represent a viable option for energy cost abatement of desalted water produced by MED-TVC (Multiple Effect Distillation along with Thermal Vapour Compression). In this paper an existing large MED-TVC plant with a 36,000 m(3)/day capacity is studied: a plant retrofit is designed, based on a steam power plant with condensation and steam extraction used to drive the steam ejector. As the plant operates in CHP (Combined Heat and Power) mode, the possibility to assess the integrated "CHP + MED-TVC" as high efficiency cogeneration according to Directive 2004/8/EC is discussed. Based on a model developed in Engineering Equation Solver, a …