Thermodynamic, Exergy, and Thermoeconomic analysis of Multiple Effect Distillation Processes

Multiple effect distillation (MED) is nowadays the preferred technology for the construction of new plants based on thermal processes in the growing desalination market. MED technology, in fact, presents a number of advantages with respect to the more traditional multistage flash technology, among all the lower energy consumption achievable in MED plants. However, a large potential for improvement in terms of lowering production costs still exists, which stimulates further efforts on process optimization from companies and researchers involved in the field. Thermodynamic and exergy analysis provides useful insights regarding the identification of main inefficiencies and the margins for performance improvements. A number of works have focused their attention on these aspects, presenting innovative investigation tools eventually applied to theoretical or real case studies. In the present chapter, the fundamentals of thermodynamic and exergy analysis for MED process optimization are presented. “Exergy costing” is also discussed and proposed as an innovative method capable of reflecting how thermal inefficiencies contribute to a gradual increase in the economic value (to be intended as a cost of generation) of material streams along the process. In order to achieve a more comprehensive view, the aforementioned analyses are carried out for a reference MED plant assumed as the case study.