Experimental evaluation of organic Rankine cycle using zeotropic mixture under different operation conditions. (1st February 2023)

• Record Type: Journal Article
• Authors: Wang, Zhiqi; Zhao, Yabin; Xia, Xiaoxia; Pan, Huihui; Zhang, Sifeng; Liu, Zhipeng
• Is Part Of: Energy. Volume 264(2023)
• Publication Date: 2023-02-01
• Subjects: Organic Rankine cycle -- Zeotropic mixture -- Scroll expander -- Cooling conditions; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2022.126188
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: The zeotropic mixture is a feasible way to improve the thermodynamics performance of organic Rankine cycle (ORC). A small-scale ORC experimental apparatus with a scroll expander was established. Then, the system performance using different zeotropic mixtures (including 0.75R245fa/0.25R141b, 0.5R245fa/0.5R141b and 0.25R245fa/0.75R141b) was tested and compared with the pure fluid of R245fa and R141b to determine whether the mixture fluid can improve the system performance. The experimental results show that the thermal efficiency and exergy efficiency of ORC system gradually increase with the increase of cooling water flow rate and the decrease of expander rotational speed. Under different working conditions, mixture fluids can produce more shaft power and have lower condenser exergy destruction than pure fluids. The zeotropic mixture is not always better than the pure fluid, while it can improve the thermal efficiency and exergy efficiency of the ORC system with an appropriate mass fraction. In the experiment, the best mass fraction of R245fa/R141b is 0.25/0.75, and its thermodynamic performance is significantly higher than that of R141b and R245fa. The maximum thermal efficiency and exergy efficiency of 0.25R245fa/0.75R141b are 5.58% and 23.2% respectively. Highlights: ORC system performance using R245fa/R141b was tested and compared with its pure component. Effects of coolant flow rate and expander rotational speed on system performance is studied. Mixture fluid with a suitable mass fraction can improve ORC system performance. 0.25R245fa/0.75R141b is the best fluid with a maximum exergy efficiency of 23.2%.