1. School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beinong Rd 2, Beijing 102206, China
2. Institut für Energietechnik, Technische Universität Berlin, Marchstraße 18, Berlin 10587, Germany
3. School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beinong Rd 2, Beijing 102206, China e-mail:
4. Institut für Energietechnik, Technische Universität Berlin, Marchstraße 18, Berlin 10587, Germany e-mail: