Conventional and advanced exergy and exergoeconomic analysis of a novel multi-fueled cogeneration system with desalination

Abstract

This work presents the economic, advanced thermodynamic, and exergoeconomic studies of a system for producing power and freshwater. The proposed system comprises a multi-effect desalination system, an organic Rankine cycle, a centrifuge, and process heaters by utilizing a mix of bagasse and municipal solid waste as primary fuels. The amounts of avoidable, unavoidable, endogenous, and exogenous shares of exergy destruction for the cycle’s components have been calculated by an advanced exergy method. For the integrated cycle, the electricity generation and freshwater productions are 36.6 MW and 7000 m3 per day, respectively. The costs of electricity production and water desalination are 2.6 US$/GJ and 4.6 US$/m3. To present an improved understanding of the system operation, an advanced exergy study is conducted on each involved component of the system at their operating conditions to identify the share of the avoidable irreversibilities. For the integrated system, 85% of the total exergy destruction is calculated to be unavoidable and just 15% of the estimated amount is avoidable. In this case, the opportunity to enhance the system’s operation is roughly limited. Additionally, 76% of the exergy destruction is endogenous, and the remaining belongs to exogenous exergy destruction.

Keywords

• Exergy analysis
• Cogeneration system
• Freshwater production
• Electricity generation