Effect of the Back Wall Draft on the Performance of Oscillating Water Column for Wave Energy Extraction

Document Type : Research Paper

Authors

1 Graduated Master of Water Structures, Department of Water Engineering, Faculty of Agricultural Engineering and Rural Development, Agricultural Sciences and Natural Resources University of Khuzestan, Iran

2 Assistant professor, Department of Water Engineering, Faculty of Agricultural Engineering and Rural Development, Agricultural Sciences and Natural Resources University of Khuzestan, Iran

3 Agricultural Sciences and Natural Resources University of Khuzestan, Iran

Abstract

There are different methods to extract energy and generating electricity from waves, which one of the simplest and most practical methods is oscillating water column (OWC). The OWC system consists of a chamber in which the wave motion inside the chamber produces a positive and negative dynamic pressure. This pressure causes turbine rotation placed at the end of the duct. In this study, three physical models; without back wall, 50 mm and 100 mm wall draft at different frequencies were used to investigate the effect of the back wall draft on the system performance. In addition, dimensional analysis has been performed to estimate the dynamic pressure based on the effective parameters. In order to evaluate the system efficiency and present the dynamic pressure formula based on dimensional analysis, the dynamic pressure at the end of chamber in both inhale and exhale modes were measured. The results of this research showed that the existence of back wall causes a significant increase in dynamic pressure and as the wall height increases, the system performance improves. In the inhale mode, the presence of the back wall causes an increase in the pressure ratio at some frequencies up to two times and for exhale mode up to four times. Based on the formula derived from dimensional analysis and sensitivity analysis, the wave height and the back wall draft have the most effectiveness on dynamic pressure. The results show in order to obtain the best system efficiency, the height of the back wall draft should be determined according to the wave height and frequency.

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Alamian, R., Shafaghat, R., Khazaee, A.M., & Yousefi, A. (2017). Experimental evaluation of a point absorber wave energy converter in a laboratory wave tank, Amirkabir Journal of Mechanical Engineering, 49(1), 93-100.  (In Farsi).
Antonio, F. d. O. (2010). Wave energy utilization: A review of the technologies. Renewable and sustainable energy reviews, 14(3), 899-918.
Ataie Ashtiani, B., & Najafi Jilani, A. (2016). Coastal Engineering (Coastal Hydrodynamics). Jahad University Press, Amir Kabir Industrial Unit. (In Farsi).
Delauré, Y., & Lewis, A. (2003). 3D hydrodynamic modelling of fixed oscillating water column wave power plant by a boundary element methods. Ocean engineering, 30(3), 309-330.
Dizadji, N. and Sajadian, S.E., 2011. Modeling and optimization of the chamber of OWC system. Energy, 36(5), pp.2360-2366.
Evans, D., & Porter, R. (1995). Hydrodynamic characteristics of an oscillating water column device. Applied Ocean Research, 17(3), 155-164.
Falcão, A.F.O., & Henriques, J.C.C.(2016) Oscillating-water-column wave energy converters and air turbines: A review. Renewable Energy, 85, 1391–1424.
Guo, L. (2010). Applicability and potential of wave power in China. MSc. dissertation, University in Gävle, Sweden.
Henriques, J.C.C., Gato, L.M.C., Lemos, J.M., Gomes, R.P.F. & Falcão, A.F.O. (2016). Peak-power control of a grid-integrated oscillating water column wave energy converter. Energy, 109, 378-390.
Lari, K., Abasian, G., & Mohseni, A. (2012). Investigating the energy conversion systems of sea waves in Anzali Port, Journal of Marine Science & Technology Research, 6(4), 55-68.  (In Farsi).
Mahmoudian Shooshtari, M. (2010). Principles of flow in open channels (Volume II). Shahid Chamran University Press, Ahvaz. (In Farsi).
Morris-Thomas, M. T., Irvin, R. J., & Thiagarajan, K. P. (2007). An investigation into the hydrodynamic efficiency of an oscillating water column. Journal of Offshore Mechanics and Arctic Engineering, 129(4), 273-278.
Morrison, I.G. and Greated, C.A. (1992). Oscillating water column modelling. Coastal Engineering Proceedings, 1(23).
Nazari Berenjkoob, B., & Ghasemi, H. (2011). Design of 10 kWatt convertor of energy-absorbing point of sea waves in the Asalouyeh port in Persian Gulf, Iranian Energy Journal, 14(3), 1-16.  (In Farsi).
Ning, D.-Z., Wang, R.-Q., Gou, Y., Zhao, M., & Teng, B. (2016). Numerical and experimental investigation of wave dynamics on a land-fixed OWC device. Energy, 115, 326-337.
Penalba, M. & Ringwood, J., 2016. A review of wave-to-wire models for wave energy converters. Energies, 9(7), 506.
Ram, K. R., Ahmed, M. R., Zullah, M. A., & Lee, Y.-H. (2016). Experimental studies on the flow characteristics in an inclined bend-free OWC device. Journal of Ocean Engineering and Science, 1(1), 77-83.
Sameti, M. & Farahi, E. (2014). Output power for an oscillating water column wave energy convertion device. Ocean and Environmental Fluid Research, 1(2), 27-34.
Sheng,W., Alcorn, R., & Lewis (2013), A. On thermodynamics in the primary power conversion of oscillating water column wave energy converters. Journal of Renewable and Sustainable Energy, 5, 023105.
Soltani Fard, A., & Kakandi, N. (2012). Energy extraction technologies from ocean waves. Khajeh Nasir Toosi University of Technology. (In Farsi).
Torresi, M., Camporeale, S., Strippoli, P., & Pascazio, G. (2008). Accurate numerical simulation of a high solidity Wells turbine. Renewable Energy, 33(4), 735-747.
Twidell, J., & Weir, T. (2012). Renewable energy resources ED2. Taylor & Francis, London Hearn G, Pace C (2006) Value-creating ecologies: understanding next generation business systems. Foresight, 8(1),55-65.
World Meteorological Organization. & World Meteorological Organization.  1998,  Guide to wave analysis and forecasting. Geneva, second edition, Switzerland
Zhang, Y., Zou, Q.-P., & Greaves, D. (2012). Air–water two-phase flow modelling of hydrodynamic performance of an oscillating water column device. Renewable Energy, 41, 159-170.