On thermodynamics in the primary power conversion of oscillating water column wave energy converters

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Date
2013-03-06
Authors
Sheng, Wanan
Alcorn, Raymond
Lewis, Anthony
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American Institute of Physics
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Abstract
The paper presents an investigation to the thermodynamics of the air flow in the air chamber for the oscillating water column wave energy converters, in which the oscillating water surface in the water column pressurizes or de-pressurises the air in the chamber. To study the thermodynamics and the compressibility of the air in the chamber, a method is developed in this research: the power take-off is replaced with an accepted semi-empirical relationship between the air flow rate and the oscillating water column chamber pressure, and the thermodynamic process is simplified as an isentropic process. This facilitates the use of a direct expression for the work done on the power take-off by the flowing air and the generation of a single differential equation that defines the thermodynamic process occurring inside the air chamber. Solving the differential equation, the chamber pressure can be obtained if the interior water surface motion is known or the chamber volume (thus the interior water surface motion) if the chamber pressure is known. As a result, the effects of the air compressibility can be studied. Examples given in the paper have shown the compressibility, and its effects on the power losses for large oscillating water column devices.
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Keywords
Wave energy converter , Wave energy production , Oscillating water column , Isentropic process. , Air compressibility , Oscillating water column devices
Citation
Sheng, W., Alcorn, R. and Lewis, A. (2013) 'On thermodynamics in the primary power conversion of oscillating water column wave energy converters' Journal of Renewable and Sustainable Energy, 5, 023105. http://dx.doi.org/10.1063/1.4794750
Copyright
© 2013 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Sheng et al., Journal of Renewable and Sustainable Energy, 5, 023105 (2013) and may be found at http://dx.doi.org/10.1063/1.4794750