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Article

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

by 1, 1,†, 1,† and 2,*
1
Mechanical Engineering Department, King Saud University, Riyadh 11451, Saudi Arabia
2
Chemical Engineering Department, King Saud University, Riyadh 11451, Saudi Arabia
*
Author to whom correspondence should be addressed.
KA.CARE Energy Research and Innovation Center at Riyadh, Riyadh 11451, Saudi Arabia.
Academic Editor: Xanel Vecino
Water 2021, 13(11), 1500; https://doi.org/10.3390/w13111500
Received: 21 April 2021 / Revised: 18 May 2021 / Accepted: 20 May 2021 / Published: 27 May 2021
(This article belongs to the Section Wastewater Treatment and Reuse)
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. View Full-Text
Keywords: multi-effect membrane distillation; performance indicators; specific electrical energy consumption; specific thermal energy consumption; exergetic efficiency; exergy destruction multi-effect membrane distillation; performance indicators; specific electrical energy consumption; specific thermal energy consumption; exergetic efficiency; exergy destruction
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MDPI and ACS Style

Najib, A.; Orfi, J.; Alansary, H.; Ali, E. Assessing the Impact of Operating Conditions on the Energy and Exergy Efficiency for Multi-Effect Vacuum Membrane Distillation Systems. Water 2021, 13, 1500. https://doi.org/10.3390/w13111500

AMA Style

Najib A, Orfi J, Alansary H, Ali E. Assessing the Impact of Operating Conditions on the Energy and Exergy Efficiency for Multi-Effect Vacuum Membrane Distillation Systems. Water. 2021; 13(11):1500. https://doi.org/10.3390/w13111500

Chicago/Turabian Style

Najib, A., J. Orfi, H. Alansary, and E. Ali 2021. "Assessing the Impact of Operating Conditions on the Energy and Exergy Efficiency for Multi-Effect Vacuum Membrane Distillation Systems" Water 13, no. 11: 1500. https://doi.org/10.3390/w13111500

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