An Ocean Thermal Energy Conversion power plant: Advanced exergy analysis and experimental validation

Abstract

An ocean thermal energy conversion power plant was simulated from the point of view of the first, the second law of thermodynamics, and advanced exergy analysis with the aim of increasing the efficiency of the cycle, quantifying and knowing the nature of the exergy destruction. First, the net power output and efficiency of the cycle were successfully calculated as a function of the surface temperature and a certain depth of the ocean, given a pinch temperature differential and the mass flow of seawater in the evaporator and condenser. The numerical simulation are compared with experimental evidence, obtaining better results than thermodynamic models previously reported. Then, the second law of thermodynamics analysis was made using appropriate correlations for the estimation of thermo-physical properties of seawater, revealing the imprecision of assuming properties of pure water in the calculation of the total exergy destruction of the system. Finally, advanced exergy analysis is developed, it provides the nature of the exergy destruction and the best strategy to increase the efficiency of the cycle. The evaporator and turbine are presented as the most promising pieces of equipment to be developed in new future research due to their avoidable endogenous nature of exergy destruction.