Exergy analysis of a solar-powered vacuum membrane distillation unit using two models

Miladi, Rihab; Frikha, Nader; Gabsi, Slimane

doi:10.1016/j.energy.2016.11.133

Cited by 38 publications

(16 citation statements)

References 40 publications

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“…The results for Case-A are shown in Table 6. The obtained exergetic efficiency is considered extremely high compared to the results of Miladi et al [28], as they reported exergy efficiency values of 2.3~3.25%. Our enhanced exergy efficiency could stem from a variety of parameters including the assumptions used in the mathematical models, the relatively better thermal separation process in the V-MEMD system, the fact that the dissipations of heat transfer throughout layers and effects were not significant, and the small heat supply by the hot water stream.…”

Section: Exergetic Analysiscontrasting

confidence: 51%

Assessing the Impact of Operating Conditions on the Energy and Exergy Efficiency for Multi-Effect Vacuum Membrane Distillation Systems

Najib

Orfi

Al-Ansary

et al. 2021

Water

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A comprehensive study was conducted to elucidate the effect of operating conditions on the performance of a multi-effect vacuum membrane distillation pilot plant. A theoretical assessment of the energy and exergy efficiency of the process was achieved using a mathematical model based on heat and mass transfer, which was calibrated using experimental data obtained from the pilot plant. The pilot plant was a solar vacuum multi-effect membrane distillation (V-MEMD) module comprising five stages. It was found that a maximal permeate mass flux of 17.2 kg/m2·h, a recovery ratio of 47.6%, and a performance ratio of 5.38% may be achieved. The resulting gain output ratio (GOR) under these conditions was 5.05, which is comparable to previously reported values. Furthermore, the present work systematically evaluated not only the specific thermal energy consumption (STEC), but also the specific electrical energy consumption (SEEC), which has been generally neglected in previous studies. We show that STEC and SEEC may reach 166 kWh/m3 and 4.5 kWh/m3, respectively. We also observed that increasing the feed flow rate has a positive impact on the process performance, particularly when the feed temperature is higher than 65 °C. Under ideal operational conditions, the exergetic efficiency reached 21.1%, and the maximum fraction of exergy destruction was localized in the condenser compartment. Variation of the inlet hot and cold temperatures at a constant differential showed an interesting and variable impact on the performance indicators of the V-MEMD unit. The difference with the lowest inlet temperatures exhibited the most negative impact on the system performance.

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Section: Exergetic Analysiscontrasting

confidence: 51%

Assessing the Impact of Operating Conditions on the Energy and Exergy Efficiency for Multi-Effect Vacuum Membrane Distillation Systems

Najib

Orfi

Al-Ansary

et al. 2021

Water

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“…Note that this number is far from the consumption of conventional processes as RO, around 2-4 kWh/m 3 [11]. However, as was pointed out before, what is interesting of MD technology is that these energy requirements (around 95 %) can be provided by solar energy [12]. Consequently, there are also numerous works proposing effective combinations [13] and new designs of integrated solar membrane-based desalination systems [14], showing that the overall efficiency can be improved up to 15 %.…”

Section: Introductionmentioning

confidence: 88%

A general optimal operating strategy for commercial membrane distillation facilities

et al. 2020

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“…Miladi et al [49] compared two models, the ideal solutions model (Cerci et al [24]'s model) and the thermodynamic properties of seawater model (Sharqawy et al [23]'s model), by applying them to a solar-powered VMD system. Two different approaches for exergy efficiency were used, the overall exergy efficiency related to the input-output method and the utilitarian exergy efficiency, which is the ratio of the useful outputs to the required inputs.…”

Section: Membrane Distillationmentioning

confidence: 99%

“…Operating data (temperature, pressure, flow, etc.) from previous works by Okati et al [54] and Miladi et al [49] were used in the present study. The process is designed to treat seawater with a salinity of 35,000 ppm and produces 21.6 kg/h of product water.…”

Section: Membrane Distillation Plant Powered By Solar Thermal Systemmentioning

confidence: 99%

Definition of Exergetic Efficiency in the Main and Emerging Thermal Desalination Technologies: A Proposal

Arakcheeva El Kori,

Blanco-Marigorta,

Melián Martel

2024

Water

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Increasing attention is being given to reduce the specific energy consumption in desalination processes, which translates into greater use of exergy analysis. An exergetic analysis provides relevant information related to the influence of the efficiency of a single component in the global plant performance and in the exergy cost of the product. Therefore, an exergy analysis identifies the main improvement potentials in a productive thermodynamic process. Related to desalination technologies, many previous papers deal with the calculation of the parameters involved in the exergy analysis, the exergetic efficiency of different processes, plants, and technologies among them. However, different approaches for formulating the exergetic efficiency have been suggested in the literature, often without sufficient understanding and consistency. In this work, these formulations, applied to the main desalination components and processes, are compared and critically reviewed. Two definitions of exergy efficiency are applied to the desalination components of the three main thermal desalination processes (multieffect distillation–thermal vapour compression, multistage flash distillation, and direct-contact membrane distillation). The results obtained for the exergy efficiency of the MED-TVC, MSF, and DCMD processes for the input–output approach are 21.35%, 17.08%, and 1.28%, respectively, compared to the consumed–produced approach that presented 3.1%, 1.58%, and 0.37%, respectively. The consumed–produced approach seems to better fit the thermodynamic behaviour of thermal desalination systems.

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Exergy analysis of a solar-powered vacuum membrane distillation unit using two models

Cited by 38 publications

References 40 publications

Assessing the Impact of Operating Conditions on the Energy and Exergy Efficiency for Multi-Effect Vacuum Membrane Distillation Systems

Assessing the Impact of Operating Conditions on the Energy and Exergy Efficiency for Multi-Effect Vacuum Membrane Distillation Systems

A general optimal operating strategy for commercial membrane distillation facilities

Definition of Exergetic Efficiency in the Main and Emerging Thermal Desalination Technologies: A Proposal

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