Performance evaluation of a MED-MVC desalination plant driven by a concentrated photovoltaic thermal system and an organic Rankine cycle

Abstract

In this work, a novel integration of a multi-effect distillation (MED) desalination plant driven by mechanical vapor compression and powered by a concentrated photovoltaic thermal system and an organic Rankine cycle is presented. The combined system is designed to produce fresh water at a capacity of 2500 m3/day. Three desalination configurations are studied, forward, backward and parallel cross feed. Mass, energy and exergy balances for different component of the desalination plant are elaborated and validated. The results showed that the specific electricity consumption of MED increased by 69 %, 68 % and 40 % by increasing the steam temperature from 80 to 100 °C, for the forward, backward and parallel cross feed configurations, respectively. The performance ratio decreased by 40 %, 21 % and 28 % by increasing the seawater salinity from 32,000 ppm to 47,000 ppm, for the forward, backward and parallel cross feed configurations, respectively. The results also showed that the solution for optimizing the energy consumption of the compressor by using staged compression equipped with intermediate cooling has enabled a saving of approximately 12 % in terms of electricity consumption. The levelized cost of water desalinated for optimized MED configurations ranged from 0.4 to 1.965 US$/m3. The overall results showed that the parallel cross-feed is the best configuration for desalination driven by a concentrated photovoltaic thermal system and an organic Rankine cycle. The performance of the current desalination unit has been improved compared to that of other MED technologies integrated with renewable energy sources.