Ultra-high freshwater production in multistage solar membrane distillation via waste heat injection to condenser

Poredoš, Primož (author), Gao, Jintong (author), Shan, He (author), Yu, Jie (author), Shao, Zhao (author), Xu, Zhenyuan (author), Wang, Ruzhu (author)

Passive solar membrane distillation (MD) is an emerging technology to alleviate water scarcity. Recently, its performance has been enhanced by multistage design, though the gains are marginal due to constrained temperature and vapor pressure gradients across the device. This makes condenser cooling enhancement a questionable choice. We argue that condenser heating could suppress the marginal effect of multistage solar MD by unlocking the moisture transport limit in all distillation stages. Here, we propose a stage temperature boosting (STB) concept that directs low-temperature heat to the condensers in the last stages, enhancing moisture transport across all stages. Through STB in the last two stages with a heat flux of 250 W m−2, a stage-averaged distillation flux of 1.13 L m−2 h−1 S−1 was demonstrated using an 8-stage MD device under one-sun illumination. This represents an 88% enhancement over the state-of-the-art 10-stage solar MD devices. More notably, our analysis indicates that 16-stage STB-MD devices driven by solar energy and waste heat can effectively compete with existing photovoltaic reverse osmosis (PV-RO) systems, potentially elevating freshwater production with low-temperature heat sources.

• Language: English
• Keywords: membrane distillation, solar energy, photothermal properties of membrane, multistage design, waste heat, exergy, distillate enhancement
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2024
• Number of pages: 19 str.
• Numbering: Vol. 15, art. 7890
• PID: 20.500.12556/RUL-163052
• UDC: 536:621.311.243
• ISSN on article: 2041-1723
• DOI: 10.1038/s41467-024-51880-y
• COBISS.SI-ID: 209731587
• Publication date in RUL: 01.10.2024

Record is a part of a journal

• Title: Nature communications
• Shortened title: Nat. Commun.
• Publisher: Nature Publishing Group
• ISSN: 2041-1723
• COBISS.SI-ID: 2315876

Licences

• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.

Secondary language

• Language: Slovenian
• Keywords: membranska destilacija, solarna energija, fototermalne lastnosti membrane, večstopenjski dizajn, odpadna toplota, eksergija, povečanje destilata