1. Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, P. R. China
2. Key Laboratory of Thermal Science and Power Engineering of Ministry of Education, Tsinghua University, Beijing 100084, P. R. China
3. Engineering Research Center for Ecological Restoration and Carbon Fixation of Saline-Alkaline and Desert Land, Tsinghua University, Beijing 100084, P. R. China