Process analysis of the novel Flash-ME desalination process driven by low-grade thermal energy

Low-grade thermal desalination can contribute to reduce the energy and carbon footprint of the water sector since it can be coupled to both waste heat and renewable energy sources. In this work we present a new process, named FlashME, that integrates MSF and MED architectures in an innovative and compact configuration able to obtain desalinated water from non-conventional sources with the highest energy and exergy efficiency. The paper presents the overall process scheme and the related simulation campaign carried in the Aspen Plus environment. The sensitive analysis is implemented to highlight the effect of main independent variables and operative parameters. The results point out the role of the first flashing temperature that should be reduced as much as possible (in relation to the allowable temperature differences between stages) to increase the thermodynamic performances. FlashME simulations are compared with the data available from recent work on low-temperature MED and different "boosted-MED" configurations showing better performances, in particular at very low top brine temperatures where it shows the highest II-law efficiencies among the available thermal processes. In comparison with MED-based and boosted-MED configurations, this system has the advantage to avoid additional flashing stages and vapor injections with the advantage of less complexity as well as improved performance along with reduced energy consumption. In the lowest temperature range (65-70 degrees C) the results show that the FlashME production rate is in-creased by 20-28% compared to FB-MED and up to 100% relative to conventional MED.(c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.