Title: A seawater RO desalination process driven by dynamic pressure of high-speed seawater droplets

Authors: Yi Xiang; Hui Lu; Qingfen Ma; Mengnan Hao

Addresses: College of Mechanical and Electrical Engineering, Hainan University, Haikou, Hainan 570228, China ' Institute of Environment and Plant Protection, Chinese Academy of Tropical Agriculture Sciences, Haikou, Hainan 571101, China ' College of Mechanical and Electrical Engineering, Hainan University, Haikou, Hainan 570228, China ' Faculty of Mechanical Engineering Materials and Energy, Dalian University of Technology, Dalian, Liaoning 116024, China

Abstract: Seawater reverse osmosis (RO) desalination requires driving pressure of 5~8 MPa which is usually offered by the high-pressure pump, the standard device employed in the commercial application, accompanied by a series of problems. To replace the high-pressure pump, a seawater RO desalination technique driven by the dynamic pressure of high-speed seawater droplets is proposed. By theoretical calculation and computational fluid dynamic (CFD) simulation, the required operating conditions for the acquisition of effective impacting seawater droplets were investigated. The results showed that the velocity of the seawater droplets should exceed 70 m/s to achieve the driving pressure of 5 MPa, and simultaneously the air flow velocity should exceed 70 m/s to act as the accelerating medium. The proper size of the accelerated droplets at different air flow velocity within the range of 70~100 m/s was determined not only considering the final velocity of the droplets but also their gravitational settling limitation. In addition, five structures of the RO membrane module were designed and tested, in which the ring-shaped and semicircle-shaped structure exhibited good performance with droplet trap rate greater than 90%. Furthermore, the energy balance of the whole system was analysed, and some constructive suggestions are provided to reduce the energy consumption.

Keywords: seawater desalination; RO technique; dynamic pressure; micro droplets.

DOI: 10.1504/IJSPM.2020.10034722

International Journal of Simulation and Process Modelling, 2020 Vol.15 No.6, pp.562 - 570

Received: 23 Aug 2018
Accepted: 19 Sep 2019

Published online: 19 Jan 2021 *

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