Journal of Applied Science and Engineering

Published by Tamkang University Press


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Haoyu Wu This email address is being protected from spambots. You need JavaScript enabled to view it.1, Jingping Peng1, Yunzheng Ge1, Lei Liu1, Fengyun Chen1 and Weimin Liu1,2

1The First Institute of Oceanography, Ministry of Natural Resources, Qingdao 266061, Shandong, PR China
2Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, Shandong, PR China


Received: December 10, 2019
Accepted: May 1, 2020
Publication Date: September 1, 2020

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Ocean thermal energy provides an eco-friendly and sustainable clean energy source; however, low system efficiency impedes the commercial application of ocean thermal energy conversion (OTEC). The present research proposes an OTEC cycle, which uses an ammonia-water mixture as a working fluid, and improves the thermal efficiency and net output of the OTEC system by recovering and using surplus heat based on regeneration and a vapor extraction mode. To evaluate the performance of the proposed cycle, the thermal model of the cycle was established based on the energy conservation and the laws of thermodynamics and by analyzing the cycle process. In addition, a performance comparison between the proposed cycle and the basic OTEC—Rankine cycle was performed. The results show that the mass fraction of working fluid, turbine inlet pressure, and cold and heat source temperatures affect the thermal cycle performance. With an increase in turbine inlet pressure, both the thermal cycle efficiency and net output increase initially and later drastically decrease under the same cold and heat source temperature. As a result, the highest efficiency and maximum net output are achieved under the corresponding optimal pressure. The thermal efficiency and net power output of the proposed cycle (5.5% and 8.19 kW) are both evidently higher than the Rankine cycle (4.6% and 6.47 kW) under uniform conditions.

Keywords: OTEC; Rankine cycle, ammonia–water mixture, thermal cycle efficiency, net output



  1. [1]  Zhang, W., Li, Y., Wu, X, and Guo, S., “Review of the applied mechanical problems in ocean thermal energy conversion,” Renewable, Sustainable. Energy. Rev, Vol. 93, pp. 231–244 (2018). doi:10.1016/j.rser.2018.05.048 
  2. [2]  Wang, S., Yuan, P., Li, D., and Jiao, Y., “An overview of ocean renewable energy in China,” Renewable, Sustainable. Energy. Rev, Vol. 15, pp. 91–111 (2011). doi:10.1016/j.rser.2010.09.040
  3. [3]  Ng, K.C., and Shahzad, M.W., “Sustainable desalination using ocean thermocline energy,” Renewable. Sustainable. Energy. Rev, Vol. 82, pp. 240–246 (2018). doi:10.1016/j.rser.2017.08.087
  4. [4]  Khan, N., Kalair, A., Abas, N., and Haider, A., “Review of ocean tidal, wave and thermal energy technologies,” Renewable. Sustainable. Energy. Rev, Vol. 72, pp. 590–604 (2017). doi:10.1016/j.rser.2017.01.079
  5. [5]  Goto, S., Motoshima, Y., Sugi, T., Yasunaga, T., Ikegami, Y., and Nakamura, M., “Construction of simulation model for OTEC plant using Uehara cycle,” Electrical. Engineering. In. Japan, Vol. 176, pp. 1–13 (2011). doi:10.1002/eej.21138
  6. [6]  Fujita, R., Markham, A.C., Diaz Diaz, J.E., Rosa Martinez Garcia, J., Scarborough, C., Greenfield, P., Black, P., and Aguilera, S.E., “Revisiting ocean thermal energy conversion,” Marine. Policy, Vol. 36, pp. 463–465 (2012). doi:10.1016/j.marpol.2011.05.008
  7. [7]  Liu, W., Ma, C., Chen, F., Liu, L., Ge, Y., Peng, J., Wu, H., and Wang, Q., “Exploitation and technical progress of marine renewable energy,” Adv. Mar. Sci, Vol. 36, pp. 1–18 (2018). doi:3969/j.issn.1671-6647.2018.01.001
  8. [8]  Su, J., Zeng, H., Xiao, G., Wang, J., and Jiang, J., “Research status and prospect of ocean thermal energy conversion technology,” China. Offshore. Oil. Gas, Vol. 24, pp. 84–98 (2012). doi:10.3969/j.issn.1673-1506.2012.04.018
  9. [9]  Kobayashi, H., Jitsuhara, S., and Uehara, H., “The present status and features of OTEC and recent aspects of thermal energy conversion technologies,” in 24th Meeting of the UJNR Marine Facilities Panel, Honolulu, HI, USA, (2004).
  10. [10] Heydt, G.T., “An assessment of ocean thermal energy conversion as an advanced electric generation methodology,” Proc. IEEE 1993, Vol. 81, No. 3, pp. 409–418 (1993). doi: 10.1109/5.241487
  11. [11] Vega, L.A., “Ocean thermal energy conversion primer,” Mar. Technol. Soc. J, Vol. 36, pp. 25–35 (2002). doi:10.4031/002533202787908626
  12. [12] Bharathan, D., Kreith, F., Schlepp, D., et al. “Heat and Mass Transfer in Open-Cycle OTEC Systems,” Heat Transfer Engineering, Vol. 5, No. 1-2, pp. 17-30 (1984). doi: 10.1080/01457638408962766
  13. [13] Zangrando, F., Bharathan, D., Link, H., and Panchal, C. B., “Seawater test results of open-cycle ocean thermal energy conversion (OC-OTEC) components.” Heat Transfer Engineering, Vol. 11, No. 4, pp. 44-53 (1994). doi: 10.1080/01457639008939740
  14.  [14] Kim, A. S., Kim, H. J., Lee, H. S., et al. “Dual-use open cycle ocean thermal energy conversion (OC-OTEC) using multiple condensers for adjustable power generation and seawater desalination.” Renewable Energy, Vol. 85, pp. 344-358 (2016). doi: 10.1016/j.renene.2015.06.014
  15. [15] Amano, M., Tanaka, T., “Open-cycle OTEC systems with freshwater product: Effects of noncondensable gases on performance of condenser.” Electrical Engineering in Japan, Vol. 154, No. 1, pp. 29-35 (2006). doi: 10.1002/eej.20179
  16. [16] Park, S. S., Kim, N. J., “Study on OTEC for the Production of Electric Power and Desalinated Water.” Journal of the Korean Solar Energy Society, Vol. 30, No. 3, pp. 124-130 (2010).
  17. [17] Rabas, T., Panchal, C., Genens. L., “Conceptual Design Analysis for Hybrid-Cycle OTEC Plants for Co-Production of Electric Power and Desalinated Water.” American Society of Civil Engineers, International Conference on Ocean Energy Recovery, Honolulu, HI, 28-30 Nov. (1989).
  18. [18] Uehara, H., Miyara, A., Ikegami, Y., Nakaoka, T., “Performance analysis of an OTEC plant and a desalination plant using an integrated hybrid cycle.” J. Sol. Energy Eng., Vol. 118, No. 2, pp. 115–22 (1996). doi: 10.1115/1.2847976
  19.  [19] Panchal, C., Bell, K., “Simultaneous production of desalinated water and power using a hybrid-cycle OTEC plant.” J. Sol. Energy Eng., Vol. 109, No. 2, pp. 156–60 (1987). doi: 10.1115/1.3268193
  20.  [20] Yuan, H., Zhou, P.L., Mei, N., “Performance analysis of a solar-assisted OTEC cycle for power generation and fishery cold storage refrigeration.” Appl. Therm. Eng.,Vol. 90, pp. 809–19 (2015). doi: 10.1016/j.applthermaleng.2015.07.072
  21. [21] Sun, F., Zhou, W., Nakagami, K., and Su, X., “Energy-economic analysis and configuration design of the kalina solar-otec system,” Int. J. Comput. Electr. Eng, Vol. 5, pp. 187-191 (2013). doi:10.7763/IJCEE.2013.V5.692.
  22. [22] Sun, F., Zhou, W., Ikegami, Y., Nakagami, K., and Su, X., “Energy–exergy analysis and optimization of the solar-boosted Kalina cycle system 11 (KCS-11),” Renewable Energy, Vol. 66, pp. 268–279 (2014). doi:10.1016/j.renene.2013.12.015
  23. [23] Yamada, N., Hoshi, A., and Ikegami, Y., “Performance simulation of solar-boosted ocean thermal energy conversion plant,” Renewable Energy, Vol. 34, pp. 1752–1758 (2009). doi:10.1016/j.renene.2008.12.028
  24. [24] Yang, M. H., Yeh, R. H., “Analysis of optimization in an OTEC plant using organic Rankine cycle.” Renewable Energy, Vol. 68, pp. 25-34 (2014). doi: 10.1016/j.renene.2014.01.029
  25. [25] Liu, W. M., Xu, X. J., Chen, F. Y., Liu, Y. J., Li, S. Z., Liu, L., Chen, Y., “A review of research on the closed thermodynamic cycles of ocean thermal energy conversion.” Renewable and Sustainable Energy Reviews, Vol. 119, pp. 1-11 (2020). doi: 10.1016/j.rser.2019.109581
  26. [26] Faizal, M., and Ahmed, M.R., “Experimental studies on a closed cycle demonstration OTEC plant working on small temperature difference,” Renewable Energy, Vol. 51, pp. 234–240 (2013). doi:10.1016/j.renene.2012.09.041
  27. [27] Kusuda, E., Morisaki, T., and Ikegami, Y., “Performance test of double-stage Rankine cycle experimental plant for OTEC,” Procedia Eng, Vol. 105, pp. 713–718 (2015). doi:10.1016/j.proeng.2015.05.061
  28. [28] Yang, M. H., and Yeh, R. H., “Analysis of optimization in an OTEC plant using organic Rankine cycle,” Renewable Energy, Vol. 68, pp. 25–34 (2014). doi:10.1016/j.renene.2014.01.029
  29. [29] Uehara, H., Ikegami, Y., and Nishida, T., “Performance analysis of OTEC using new cycle with absorption and extraction process,” Proc. of Oceanology Int.’ 94, 6, (1994).
  30. [30] Uehara, H., Ikegami, Y., and Nishida, T., “Performance analysis of OTEC system using a cycle with absorption and extraction processes,” Trans. Jpn. Soc. Mech. Eng., B, Vol. 64, pp. 2750–2755 (1998). doi:10.1299/kikaib.64.2750
  31. [31] Uehara, H., “The experimental research on ocean thermal energy conversion using the Uehara cycle,” Proc. of Int. OTEC/DOWA Conference, Japan, (1999).
  32. [32] Kalina, A.I., “Combined-cycle system with novel bottoming cycle,” J. Eng. Gas Turbines Power, Vol. 106, pp. 737-742 (1984). doi:10.1115/1.3239632
  33. [33] Kim, N.J., Ng, K.C., and Chun, W., “Using the condenser effluent from a nuclear power plant for ocean thermal energy conversion(OTEC),” Int. Commun. Heat Mass Transfer, Vol. 36, pp. 1008–1013 (2009). doi:10.1016/j.icheatmasstransfer.2009.08.001
  34. [34] Yuan, H., Mei, N., Hu, S., Wang, L., and Yang, S., “Experimental investigation on an ammonia-water based ocean thermal energy conversion system,” Appl. Therm. Eng, Vol. 61, pp. 327–333 (2013). doi:10.1016/j.applthermaleng.2013.07.050
  35. [35] Yoon, J.-I., Son, C.-H., Baek, S.-M., Ye, B.H., Kim, H.-J., and Lee, H.-S, “Performance characteristics of a high-efficiency R717 OTEC power cycle,” Appl. Therm. Eng, Vol. 72, pp. 304–308 (2014). doi:10.1016/j.applthermaleng.2014.05.103
  36. [36] Yoon, J.-I., Son, C.-H., Seol, S., Kim, H.-U., Ha, S.-J., Jung, S.-H., Kim, H.-J., and Lee, H.-S., “Performance analysis of OTEC power cycle with a liquid–vapor ejector using R32/R152a,” Heat. Mass. Transfer, Vol. 51, pp. 1597–1605 (2015). doi:10.1007/s00231-015-1526-2
  37. [37] Upshaw, C.R., Webber, M. E., “Integrated Thermal-Fluids System Modeling of an Ocean Thermal Energy Conversion Power Plant for Analysis and Optimization.” ASME 2011 5th International Conference on Energy Sustainability, Parts A, B, and C, Aug. 7-10, 2011, Washington, DC, USA. doi: 10.1115/es2011-54595
  38. [38] Yilmaz, F., Ozturk, M., and Selbas, R., “Thermodynamic performance assessment of ocean thermal energy conversion based hydrogen production and liquefaction process.” International journal of hydrogen energy, Vol. 43, No. 23, pp. 10626-10636 (2018). doi: 10.1016/j.ijhydene.2018.02.021
  39. [39] Mohd Idrus, N.H., Musa, M.N., Yahya, W.J., Ithnin, A.M., “Geo-Ocean Thermal Energy Conversion (GeOTEC) power cycle/plant.” Renewable Energy, Vol. 111, pp. 372-380 (2017). doi: 10.1016/j.renene.2017.03.086
  40. [40] Arcuri, N., Bruno, R., Bevilacqua, P., “LNG as cold heat source in OTEC systems.” Ocean Engineering, Vol. 104, pp. 349-358 (2015). doi: 10.1016/j.oceaneng.2015.05.030
  41. [41] Park, S. S., Kim, W. J., Kim, Y. H., Kim, J. D., and Kim, N. J., “Regenerative otec systems using condenser effluents discharged from three nuclear power plants in south korea.” International Journal of Energy Research, Vol. 39, No. 3, pp. 397-405 (2014). doi: 10.1002/er.3251
  42. [42] Azhar, M. S., Rizvi, G., and Dincer, I., “Integration of renewable energy based multigeneration system with desalination.” Desalination, Vol. 404, pp. 72-78 (2017). doi: 10.1016/j.desal.2016.09.034
  43. [43] Chen, F., Liu, L., Peng, J., Ge, Y., Wu, H., and Liu, W., “Theoretical and experimental research on the thermal performance of ocean thermal energy conversion system using the rankine cycle mode,” Energy, Vol. 183, pp. 497–503 (2019). doi:10.1016/
  44. [44] NIST, NIST Reference Fluid Thermodynamic and Transport Properties–REFPROP, Version 9.0, NIST, 2009.
  45. [45] Incropera, F., Dewit, D., Fundamentals  of  heat  and  mass transfer. New York: John Wiley and Sons, 2002.
  46. [46] Gungor, K., Winterton, R., “Simplified general correlation for saturated flow boiling and comparisons of correlation with data.” Chemical Engineering Research and Design, Vol. 65, No. 2, pp. 148-156 (1987).
  47. [47] Feng, Y., Zhang, Y., Li, B., Yang, J., and Shi, Y., “Sensitivity analysis and thermoeconomic comparison of ORCs (organic Rankine cycles) for low temperature waste heat recovery.” Energy, Vol. 82, pp. 664-677 (2015). doi: 10.1016/
  48. [48] Agustín M. Delgado-Torres, Lourdes, García-Rodríguez., “Analysis and optimization of the low-temperature solar organic rankine cycle (orc).” Energy Conversion & Management, Vol. 51, No. 12, pp. 2846-2856 (2010). doi: 10.1016/j.enconman.2010.06.022