1. Key Laboratory of Low-Grade Energy Utilization Technologies and Systems, Ministry of Education of PRC, Chongqing University, 174 Shazheng Street, Shapingba, Chongqing 400044, China
2. Centre for Energy (M473), The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
3. State Environmental Protection Key Laboratory of Efficient Utilization Technology of Coal Waste Resources, Shanxi University, Wucheng Road, Taiyuan 030006, PR China