Design And Analysis Of Supercritical Carbon Dioxide Brayton Cycle

The Supercritical Carbon Dioxide?SCO₂?Brayton Cycle has the advantage of the special properties of supercritical carbon dioxide?31.1?,7.39 MPa?.The efficiency of this cycle is higher than that of the large-scale steam-powered cycle.This cycle can be widely applied to the areas of power generation,but there is still a lot of research work need to be done on parameters of component and the selection of layout under different operating conditions.The high turbine inlet temperature can greatly improve the thermal efficiency of the cycle.In the published literature,there is a lack of SCO₂ Brayton cycle when the inlet temperature of turbine is higher than 700?,especially in the area of choosing the parameters of components and the optimization of layout.In this paper,the author consider the industrial level and material constraints.It is modeled the key components such as compressors,turbines,heat exchangers and others by Fortran language.A flexible and controllable cycle model is established,which can be used to maximize cycle efficiency by the control variable.Based on the first law of thermodynamics,effects of the cycle parameters including the compressor pressure ratio,the layout of the turbine and the heat exchanger performance are compared and analyzed based on the method of controlling local variables.The results show that using two-stage compressors with an intermediate condenser and two-stage turbines with a reheater has beneficial effects on the efficiency of the cycle.The compressor,turbine,heat exchanger and other components are analyzed from the views of energy and exergy.It is found that the exergy efficiency of all components except the combustor is high.Moreover,the simple cycle,recompression cycle,pre-compress cycle and part-cooling cycle are simulated and analyzed.The defect of the system is examined by analyzing distributions of the energy and the loss of the exergy.This can help to find the possible way to improve the thermal efficiency in future.Finally,the author sums up experience and propose a new cycle.These results also provide a valuable reference for optimizing the layout of SCO₂ Brayton cycles and the similar power generation cycles.