Thermodynamic analysis of a nuclear desalination cogeneration plant to be built on the Mediterranean coast

While population growth, intensification of agricultural and industrial activities in the World increase the demand for fresh water, pollution and limited or unequal distribution of water resources reduce the per capita water supply. Since 97.5% of water on Earth is not directly usable and the water scarcity risk is gradually increasing, access to clean and safe water has become important, and desalination plants have been one of the effective methods that can be used to meet the need for fresh water in regions suffering from water scarcity. Desalination systems, which can operate with an energy source, can provide this energy requirement in various ways such as fossil fuels or renewable energy sources, as well as by the use of nuclear energy in recent years. The fission energy obtained from a nuclear reactor is converted into thermal energy in nuclear desalination cogeneration plants, which was found to be technically feasible as a result of studies carried out by the International Atomic Energy Agency. Some or all of this thermal energy is used for seawater desalination in a desalination system integrated to a nuclear power plant. In this study, thermodynamic analysis of a nuclear desalination cogeneration plant to be built on the Mediterranean coast is carried out. In the nuclear desalination cogeneration plant studied, the energy source is a Pressurized Water Reactor, while desalination process is Multi Stage Flash Distillation. The mass and energy conservation and exergy balance equations are applied to all components of the nuclear desalination cogeneration plant, and the thermodynamic modeling of the plant is built using the MATHEMATICA 11 software. The thermal efficiency, exergy efficiency, thermal utilization factor, ecological performance coefficient, exergy destruction factor and waste exergy ratio of the facility are considered as the objective functions. The impacts of design parameters such as thermal energy of nuclear reactor, reheater mass flow rate fraction, live steam temperature, steam extraction nodes for desalination, dead state temperature, salinity of seawater, throttling valve mass flow rate fraction, product water mass flow rate, feed seawater mass flow rate and temperature on these objective functions are investigated. As a result of the analysis, with an increase of 18 K in the live steam temperature, thermal efficiency, exergy efficiency, thermal utilization factor and ecological performance coefficient of the plant increase by approximately 1.6%, 3.2%, 1.6% and 0.23, respectively, while exergy destruction factor and waste exergy ratio decrease by approximately 3.1% and 3.2%, respectively. With an increase of 0.02 in the reheater mass flow rate fraction, thermal efficiency, exergy efficiency, thermal utilization factor and ecological performance coefficient increase by about 2%, 2%, 3.9% and 0.28, respectively, while exergy destruction factor and waste exergy ratio decrease by about 3.9%. A 10 K increase in the dead state temperature increases the exergy efficiency by about 1.4%, while the increase in the feed seawater mass flow rate negatively affects the efficiency.