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International Conference on Innovative Applied Energy    

E-Proceedings ISBN: 978-1-912532-05-6

14-15 March 2019, Oxford, United Kingdom



Thermo-economic modelling and optimization of a zeotropic organic Rankine cycle with composition adjustment during operation



Xianglong Luo, Chaonan Chen, Jianyong Chen, Zhi Yang and Ying Chen

School of Material and Energy, Guangdong University of Technology, Guangzhou Higher Education Mega Center, China


Talk Abstract

Low-grade energies such as solar energy, geothermal energy, and waste heat are abundant across the world. Effective utilizing these low-grade energies is significant in alleviating the problems of energy shortage and environment deterioration. Heat-to-power is a popular route for these low-grade energy utilizations. Organic Rankine cycle (ORC) is regarded one of the most promising low-grade heat-to-power technologies and is recently receiving increasing attention in both academia and engineering. As the heat source or environment temperature vary with time and season, the ORC operates mostly under off-design conditions. Compared to the conventional fossil energy-to-power technologies, ORC is more sensitive to the variation of heat source/sink parameters. The investigation on the off-design performance and operation strategy is essential in improving the energy conversion efficiency and reducing the power generation cost for the life-span of ORC. Conventional ORC is usually designed under a given condition known as rated condition. When working conditions deviate from the rated condition, the ORC is passively operated with lower performance than the rated condition, resulting in low annual average performance. In this study, a novel composition adjustable zeotropic ORC (CAZORC) is proposed. In the CAZORC, a liquid-separation condenser-based composition adjustment system is conceptually designed for zeotropic mixture composition adjustment in response to the environment temperature variation. A thermodynamic analysis model is formulated to demonstrate the superiority of the CAZORC over the traditional ORC. A thermo-economic optimization model and a solution strategy are developed to achieve the best life-span performance of ORC by optimizing the component size and operation parameters under off-design conditions. The thermodynamic analysis results show that the CAZORC can significantly improve the annual average efficiency or the total net power output. For a 100 oC industrial waste heat source driven ORC in Beijing, the net power output of CAZORC is 9.15% higher than that of the traditional fixed-composition ORC. A three-tank and a five-tank composition system are simulated to meet the composition adjustment requirement.  For different zeotropic mixtures, the annual net power output can be improved by 2.95- 15 % compare to the conventional ORC. The thermo-economic optimization results show that the proposed optimization model and solution algorithm are effective in achieving the optimal component size and off-design operation scheme. Up to 8.0% of power generation cost reduction of the CAZORC can be achieved when coupling the functions of compositon adjustment and heat transfer enhancement of liquid-separation condenser. 

Paper Keywords
Zeotropic; ORC; Off-design; Composition adjustment; Optimization
Corresponding author Biography

 Dr. Xianglong Luo is a professor of Guangdong Provincial Key Laboratory of Functional Soft Matter at School of Material and Energy, Guangdong University of Technology. He received PhD degree in Chemical Engineering in June 2007 at South China University of (SCUT). He joined Guangdong University of Technology (GDUT) since 2007 and was promoted to Professor in 2014. He was awarded Guangzhou Pearl River Science and Technology New Star in 2013. During Aug 2015 to Aug 2016, he worked as an academic visitor at Prof. El-Halwagi’s lab in Texas A&M University. He is engaged in the field of advanced energy system, focusing on the heat transfer intensification and heat exchanger optimization, heat integration, thermo-economic-environmental modelling and optimization of thermal energy system. He has authored/co-authored more than 50 peer-reviewed journal papers and 10 patents.

The International Conference on Innovative Applied Energy (IAPE’18)