1. Key Laboratory of Efficient Utilization of Low and Medium Grade Energy, MOE, School of Mechanical Engineering, Tianjin University, 92 Weijin Road, Tianjin 300072, P. R. China
2. State Key Laboratory of Air-Conditioning Equipment and System Energy Conservation, Gree Electric Appliances Inc. of Zhuhai, Zhuhai, Guangdong 519070, P. R. China