A dynamic organic Rankine cycle using a zeotropic mixture as the working fluid with composition tuning to match changing ambient conditions

Collings, P., Yu, Z. and Wang, E. (2016) A dynamic organic Rankine cycle using a zeotropic mixture as the working fluid with composition tuning to match changing ambient conditions. Applied Energy, 171, pp. 581-591. (doi: 10.1016/j.apenergy.2016.03.014)

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Air-cooled condensers are widely used for Organic Rankine Cycle (ORC) power plants where cooling water is unavailable or too costly, but they are then vulnerable to changing ambient air temperatures especially in continental climates, where the air temperature difference between winter and summer can be over 40 °C. A conventional ORC system using a single component working fluid has to be designed according to the maximum air temperature in summer and thus operates far from optimal design conditions for most of the year, leading to low annual average efficiencies. This research proposes a novel dynamic ORC that uses a binary zeotropic mixture as the working fluid, with mechanisms in place to adjust the mixture composition dynamically during operation in response to changing heat sink conditions, significantly improving the overall efficiency of the plant. The working principle of the dynamic ORC concept is analysed. The case study results show that the annual average thermal efficiency can be improved by up to 23% over a conventional ORC when the heat source is 100 °C, while the evaluated increase of the capital cost is less than 7%. The dynamic ORC power plants are particularly attractive for low temperature applications, delivering shorter payback periods compared to conventional ORC systems.

Item Type:Articles
Additional Information:This research is funded by Royal Society (RG130051) and EPSRC (EP/N005228/1) in the United Kingdom.
Glasgow Author(s) Enlighten ID:Wang, Dr Enhua and Collings, Mr Peter and Yu, Professor Zhibin
Authors: Collings, P., Yu, Z., and Wang, E.
College/School:College of Science and Engineering > School of Engineering > Systems Power and Energy
Journal Name:Applied Energy
ISSN (Online):1872-9118
Copyright Holders:Copyright © 2016 The Authors
First Published:First published in Applied Energy
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
684301Dynamic Organic Rankine Cycle for Recovering Industrial Waste HeatZhibin YuEngineering & Physical Sciences Research Council (EPSRC)EP/N005228/1ENG - ENGINEERING SYSTEMS POWER & ENERGY
642241Investigating zeotropic mixtures as working fluids for high efficiency Organic Rankine Cycle (ORC) power plantsZhibin YuRoyal Society (ROYSOC)RG130051ENG - ENGINEERING SYSTEMS POWER & ENERGY