Performance of steam ejector with nonequilibrium condensation for multi-effect distillation with thermal vapour compression (MED-TVC) seawater desalination system

Abstract

The single-phase and two-phase flow models are developed and compared for the performance evaluation of a steam ejector for the multi-effect distillation with thermal vapour compression (MED-TVC) seawater desalination system. The results show that a single-phase flow model with ignoring the phase change predicts an unphysical temperature of the steam in the supersonic flow with the minimum value of approximately 122 K, which raises the query of the formation of the ice. The two-phase wet steam model corrects the distribution of the flow parameter by predicting the heat and mass transfer during the phase change. The steam achieves the first nonequilibrium condensation process inside the primary nozzle and another four alternating condensation and re-evaporation processes. The single-phase flow model underpredicts the entropy loss coefficient by approximately 15% than the two-phase wet steam model. The performance comparison is achieved against the single-phase model

Commercial Thermal Technologies for Desalination of Water from Renewable Energies: A State of the Art Review

“…It is worth mentioning the growing interest in the development of hybrid systems that TVC uses to optimize MED systems, due to the high quality of the fresh water produced [138] and the high system performance, if adequate control of operational parameters is carried out [139,140]. In this sense, use and improvements in the design of steam ejectors have shown increases in the performance of MED-TVC systems [141][142][143]. Selfadjusting ejectors can achieve higher drag ratios [144], and two-stage ejectors can achieve Among the advantages that vapor compression distillation (VC) systems have are the high efficiency of converting heat into work, the reduced volume compared to other distillation systems, they do not require large-scale heat sources and that the compressor works with electricity or with diesel engines, so they are suitable for implementation on ships, islands, and maritime bases, i.e., on a reduced scale.…”

“…It is worth mentioning the growing interest in the development of hybrid systems that TVC uses to optimize MED systems, due to the high quality of the fresh water produced [138] and the high system performance, if adequate control of operational parameters is carried out [139,140]. In this sense, use and improvements in the design of steam ejectors have shown increases in the performance of MED-TVC systems [141][142][143]. Self-adjusting ejectors can achieve higher drag ratios [144], and two-stage ejectors can achieve vacuums of approximately 5.3 kPa [145].…”

A Novel Dehumidification Strategy to Reduce Liquid Fraction and Condensation Loss in Steam Turbines

“…In the present study, the two-dimensional (2D) simulation is carried out based on the wet steam two-phase flow model [ 28 , 29 ]. The phase change is determined by the nonequilibrium condensation behaviour due to the high expansion process of the steam in the transonic flows [ 30 , 31 ].…”

Commercial Thermal Technologies for Desalination of Water from Renewable Energies: A State of the Art Review

“…The developed model showed that disequilibrium condensations play a crucial role in the performance analysis of steam ejectors for MED-TVC. Xue et al, 2020 [124] Design and research of a two-stage vacuum ejector to improve performance of the MED + TVC desalination system [123,124,128,129,132,138], mathematical modeling of MVC coupled with MED [127,137,141], and hybridization systems of MVC [144,145] and TVC [131,139] with other desalination technologies.…”