Low-temperature organic Rankine cycle engine with isothermal expansion for use in desalination


Groundwater salinity is a widespread problem that contributes to the freshwater deficit of humanity. Consequently, where conventional energy supply is also lacking, organic Rankine cycle (ORC) engines are being considered as a feasible option to harness readily available low-grade heat (<180°C) to drive the desalination of the saline water via reverse osmosis (RO). However, this application is still not very well developed, and has significantly high specific energy consumption (SEC). Hence, this study explores the isothermal expansion of the ORC working fluid to achieve improved efficiency for driving a batch-RO desalination process, "DesaLink". Here, the working fluid is directly vaporized in the expansion cylinder which is heated externally by heat transfer fluid, thus obviating the need for a separate external boiler and high-pressure piping. Experimental investigations with R245fa have shown cycle efficiency of 8.8%. And it is predicted that the engine could drive DesaLink to produce 256 L of freshwater per 8 h per day, from 4000 ppm saline water, with a thermal and mechanical SEC of 2.5 and 0.36 kWh/m3, respectively, representing a significant improvement on previously reported or predicted SEC values.

Publication DOI: https://doi.org/10.1080/19443994.2014.940657
Divisions: College of Engineering & Physical Sciences > School of Engineering and Technology > Mechanical, Biomedical & Design
College of Engineering & Physical Sciences > Sustainable environment research group
Additional Information: This is an Accepted Manuscript of an article published by Taylor & Francis in Desalination and Water Treatment on 23/7/14, available online: http://www.tandfonline.com/doi/abs/10.1080/19443994.2014.940657
Uncontrolled Keywords: desalination,energy and water,isothermal expansion,low-grade heat,organic Rankine cycle,Ocean Engineering,Water Science and Technology,Pollution
Publication ISSN: 1944-3986
Last Modified: 05 Jan 2024 08:07
Date Deposited: 13 May 2015 11:05
Full Text Link: http://www.tand ... 994.2014.940657
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2015
Published Online Date: 2014-07-23
Authors: Igobo, Opubo N.
Davies, Philip A. (ORCID Profile 0000-0003-4783-1234)



Version: Accepted Version

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