Parametric study and optimization of an ejector-expansion TRCC cycle integrated with a water purification system

A combined cogeneration cycle is proposed in which the waste heat from an ejector-expansion trans-critical CO2 refrigeration cycle is utilized for power production and water purification simultaneously. The waste heat utilization was performed by means of a CO2 supercritical power cycle and a desalination system for pure water production. In order to run the desalination system, an absorption heat transformer is employed to upgrade the lower temperature waste heat. Thermodynamic models are developed for both the ejector-expansion trans-critical CO2 cycle and the combined cogeneration cycle consisting of all the above mentioned cycles. A parametric study is conducted to investigate and optimize the performance of each cycle under various operating conditions. It is found that, at the optimum conditions, the energy efficiency ratio of combined cogeneration cycle is about 13-45% higher than the coefficient of performance of the ejector-expansion trans-critical CO2 cycle. It is also concluded that, as the gas cooler temperature increases, the pure water production rate in the combined cogeneration cycle is increased.