Thermodynamic and exergoeconomic optimization of a novel cooling, desalination and power multigeneration system based on ocean thermal energy. (January 2023)

• Record Type: Journal Article
• Authors: Geng, Donghan; Gao, Xiangjie
• Is Part Of: Renewable energy. Volume 202(2023)
• Page Start: 17
• Page End: 39
• Publication Date: 2023-01
• Subjects: Ocean thermal energy conversion -- Dual-Kalina cycle -- Ejector refrigeration cycle -- Reverse osmosis desalination -- Multi-objective optimization; Renewable energy sources -- Periodicals; Power resources -- Periodicals; Énergies renouvelables -- Périodiques; Ressources énergétiques -- Périodiques; 333.794
• DOI: 10.1016/j.renene.2022.11.088
• Languages: English
• ISSNs: 0960-1481

Abstract

Abstract: For isolated islands and remote coastal and offshore areas, a multi-generation system based on ocean thermal energy conversion (OTEC) is one promising solution for electricity and water supply since it can exploit seawater resource and ocean thermal energy (OTE) simultaneously. In order to further improve the energy utilization efficiency, this paper proposes a novel combined cooling, desalination and power (CCDP) system consisting of open-OTEC cycle, dual-Kalina cycle, ejector refrigeration cycle (ERC) and reverse osmosis (RO) desalination. The integration of RO with OTEC can produce fresh water efficiently. A dual-pressure parallel Kalina cycle is introduced to utilize the ocean thermal energy in a stepwise manner. The adoption of an ejector can improve the power output. In addition, ERC is used to recover the exhausted heat from the turbine of the Kalina cycle. A detailed mathematical model is established, and a comparison with the stand-alone Kalina system under the same heat source conditions proves that the proposed CCDP system is more advantageous in terms of net power output, thermal efficiency and exergy efficiency. A parametric analysis is carried out with an emphasis on the effects of key parameters on the thermodynamic and exergoeconomic performance. Finally, a multi-objective optimization is executed based on non-dominated sorting genetic algorithm-II ( NSGA-II ). For the ammonia concentration of the basic solution, with the terminal temperature difference of vapor generator 2 and heat exchanger within the investigated range, there exist optimum values which can maximize the thermal and exergy efficiency and minimize SUCP simultaneously. Meanwhile, for the other five parameters, namely generation pressure 1 and 2, flash pressure1, the terminal temperature difference of vapor generator 1 and the evaporation temperature, there are trade-offs among the three performance indicators. The results suggest that the thermal efficiency (49.32%), exergy efficiency (50.08%) and SUCP (215.37 $/GJ) of the preferred optimal solution are improved by 7.43%, 9.87%, and 12.12%, respectively.