Abstract
As the fossil fuel consumption is increasing, the energy shortage has gradually become a big problem nowadays. However, the industrial energy utilization is less than 50%, which means almost half of the precious energy is discharged into the air as waste heat or other forms that cannot be further used. The environment is deteriorating, so people are more concerned about the waste heat recovery and the uses of renewable energies (such as geothermal energy). Our laboratory has focused on researches about waste heat recovery system for plants for many years. From subcritical cycle systems (Organic Rankine Cycle, ORC) to supercritical cycle systems (Supercritical CO2 Brayton Cycle), the latter is our main research at present. The reasons for choosing CO2 as working fluid are because of its stability, low critical point conditions, wide range of applications and greenhouse gas reduction. The Turbine-Alternator-Compressor (TAC) component is a very important part in supercritical Brayton cycle system, especially the designs of rotors in compressor and expander, which are extremely difficult. The radial type of rotor is used both in compressor and turbine, and to reduce difficulties, I used the rotor of P-15 jet engine as basic model, but its blade shape still need to be modified corresponding to design points. Then CFD simulation is applied to improve rotor efficiency by repeatedly correct errors. At last, semi-closed system is used to reduce the difficulties of initial test and also for the safety issues.