Thermodynamic analysis of a cogeneration gas turbine and desalination plant

This work deals with a thermodynamic analysis of the performance of a cogeneration gas turbine and thermal desalination plant. A heat recovery steam generator links the two units together. The analysis is based on the application of mass, energy and exergy balances on the whole cogeneration plant as well as on each of its components. The analysis is also based on an accurate evaluation of the seawater properties, which leads to correct calculations of the flow exergy and exergy efficiency of any component of the desalination plant. The main results of the study concern the influence of the pressure ratio of the compressor and the turbine inlet temperature on the exergy efficiency of the gas turbine and the whole combined system. It was found in particular that as the performance ratio of the desalination plant increases the specific exergy destruction rate decreases.