[Wang, Feng] Chongqing Univ, Key Lab Low Grade Energy Utilizat Technol & Syst, Minist Educ, Chongqing 400030, Peoples R China.^[An, Zilong;Zhou, Jing] Chongqing Univ, Coll Power Engn, Chongqing 400030, Peoples R China.^[Qi, Bo] Univ South China, Mech Engn Dept, Hunan 421001, Peoples R China.