Thermo-economic investigation of multi effect evaporation (MEE) and hybrid multi effect evaporation—multi stage flash (MEE-MSF) systems

In this work, a number of comparisons for Multi Effect Evaporation (MEE) and hybrid Multi Effect Evaporation—Multi Stage Flash (MEE-MSF) systems are performed using the exergy and thermoeconomic analysis. The comparison is performed based on the same platform and working under the same operating conditions. The numerical results reveal that the Forward Feed Multi Effect Evaporation (MEE-FF) performance ratio is 42% higher than that of the parallel/cross multi effect evaporation (MEE-P/C) system. The exergetic efficiency of the forward feed system is 17% higher than that of the parallel/cross feed system. As a result, the unit product cost of the MEE-FF configuration is 40% less than that of the MEE-P/C for eight effects. Thermoeconomic analysis of the hybrid (MEE-MSF) system showed that the running cost decreases with increasing the module number, however the capital cost increases. As a result, the minimum unit product cost is obtained at 8 modules and is settled by 1.65 $/m3. Comparison between MSF (20 stages), MEE-FF (10 effects), and the hybrid MEE-MSF (10 modules) showed that the unit product cost of the hybrid MEE-MSF system is obtained as 1.7 $/m3 which is 31% less than that of the MSF(2.63 $/m3) system and 9% less than that of the MEE-FF (1.87 $/m3) system. These results show that the hybrid MEE-MSF is more economical than either stand alone MSF or MEE system.