Thermodynamic analysis of a transcritical power cycle using CO2

In our world where energy demand is increasing day by day, efforts to develop technology to meet these needs continue, too. As a result of these technological developments, ultra-supercritical steam turbines, which are one of the important elements of power generating plants, are commercially produced up to certain parameters. By thermodynamic principles, increase in inlet temperature and pressure of turbine means higher power production efficiency. Higher efficiency also provides lower emissions in thermal power plants. When high temperatures and pressures are reached to increase turbine efficiency, due to the sudden reduction in the endurance of the steel materials used in vapor turbine and winglets leakage and deformation occurs. When it is demanded that turbine materials are replaced by durable materials, turbine sizes and costs increase. Therefore, there is a need for a cycle fluid with higher density when compared to the water vapor in the same turbine inlet conditions. When all factors are compared, the most reasonable solution is to prefer CO2 as the cycle fluid. So that the turbine sizes will not only be reduced, but also the cost will decrease and the efficiency will increase. In this study, thermodynamic analysis of an ultrasupercritical Rankine power cycle with CO2 fluid is performed. The analysis of the cycle was calculated in the computer program environment called Engineering Equation Solver (EES). The efficiency of the cycle for different cycle parameters was determined with the help of parametric analysis. The energy efficiency of the cycle at maximum turbine inlet pressure and temperature was calculated as 45.63%, exergy efficiency 45.64% and turbine power 26424 kW. The benefits of using CO2 turbines in power cycles are evaluated. The future of CO2 turbines and the gains that can be obtained in thermal power plants are discussed.