Exergy analysis of a two-cylinder steam turbine from combined cycle power plant at three operating regimes

  • 1 Faculty of Engineering, University of Rijeka, Croatia


This paper presents an exergy analysis of a two-cylinder low power steam turbine from combined cycle power plant at three operating regimes. The highest mechanical power produced in the whole turbine is 6807.24 kW in Operating regime 1. Cylinders of the observed turbine did not have the same operation dynamics in relation to produced mechanical power in all operating regimes. In each operating regime High Pressure Cylinder (HPC) has lower exergy destruction and higher exergy efficiency in comparison to Low Pressure Cylinder (LPC) due to the influence of wet steam which expands through the last LPC stages (water droplets in wet steam increases LPC exergy destruction and decreases LPC exergy efficiency). Whole turbine exergy efficiency is between 51.62% (in Operating regime 2) and 64.98% (in Operating regime 1). This range of exergy efficiencies can be expected for a low power steam turbine. An increase in the ambient temperature decreases exergy efficiency of the whole turbine and both turbine cylinders, regardless of the observed operating regime. The exergy efficiency of the LPC is low in all operating regimes, so any improvements should be based on this cylinder first.



  1. Khanmohammadi, S., Azimian, A. R., & Khanmohammadi, S. (2013). Exergy and exergo–economic evaluation of Isfahan steam power plant. International Journal of Exergy, 12(2), 249-272. (doi:10.1504/IJEX.2013.053386)
  2. Ebrahimgol, H., Aghaie, M., Zolfaghari, A., & Naserbegi, A. (2020). A novel approach in exergy optimization of a WWER1000 nuclear power plant using whale optimization algorithm. Annals of Nuclear Energy, 145, 107540. (doi:10.1016/j.anucene.2020.107540)
  3. Talebi, S., & Norouzi, N. (2020). Entropy and exergy analysis and optimization of the VVER nuclear power plant with a capacity of 1000 MW using the firefly optimization algorithm. Nuclear Engineering and Technology, 52(12), 2928-2938. (doi:10.1016/
  4. Abbaspour, H., Ehyaei, M. A., Ahmadi, A., Panahi, M., Abdalisousan, A., & Mirzohosseini, A. (2021). Energy, exergy, economic, exergoenvironmental and environmental (5E) analyses of the cogeneration plant to produce electrical power and urea. Energy Conversion and Management, 235, 113951. (doi:10.1016/j.enconman.2021.113951)
  5. Mrzljak, V., Poljak, I., & Medica-Viola, V. (2017). Dual fuel consumption and efficiency of marine steam generators for the propulsion of LNG carrier. Applied Thermal Engineering, 119, 331- 346. (doi:10.1016/j.applthermaleng.2017.03.078)
  6. Baressi Šegota, S., Mrzljak, V., Anđelić, N., Poljak, I., & Car, Z. (2023). Use of Synthetic Data in Maritime Applications for the Problem of Steam Turbine Exergy Analysis. Journal of Marine Science and Engineering, 11(8), 1595. (doi:10.3390/jmse11081595)
  7. Najjar, Y. S., & Manaserh, Y. M. A. (2019). Aligning combined cycle power plant performance with field measurements. Arabian Journal for Science and Engineering, 44, 1657-1669. (doi:10.1007/s13369-018-3615-2)
  8. Lorencin, I., Anđelić, N., Mrzljak, V., & Car, Z. (2019). Genetic algorithm approach to design of multi-layer perceptron for combined cycle power plant electrical power output estimation. Energies, 12(22), 4352. (doi:10.3390/en12224352)
  9. Mohammed, M. K., Awad, O. I., Rahman, M. M., Najafi, G., Basrawi, F., Abd Alla, A. N., & Mamat, R. (2017). The optimum performance of the combined cycle power plant: A comprehensive review. Renewable and Sustainable Energy Reviews, 79, 459-474. (doi:10.1016/j.rser.2017.05.060)
  10. Leyzerovich, A. S. (2021). Steam turbines for modern fossil-fuel power plants. River Publishers.
  11. Elhelw, M., Al Dahma, K. S., & el Hamid Attia, A. (2019). Utilizing exergy analysis in studying the performance of steam power plant at two different operation mode. Applied Thermal Engineering, 150, 285-293. (doi:10.1016/j.applthermaleng.2019.01.003)
  12. Behrendt, C., & Stoyanov, R. (2018). Operational characteristic of selected marine turbounits powered by steam from auxiliary oil-fired boilers. New Trends in Production Engineering, 1(1), 495-501. (doi:10.2478/ntpe-2018-0061)
  13. Mrzljak, V., Prpić-Oršić, J., & Poljak, I. (2018). Energy power losses and efficiency of low power steam turbine for the main feed water pump drive in the marine steam propulsion system. Pomorski zbornik, 54(1), 37-51. (doi:10.18048/2018.54.03)
  14. Drbal, L., Westra, K., & Boston, P. (Eds.). (2012). Power plant engineering. Springer Science & Business Media.
  15. Vedran, M., Ivan, L., Nikola, A., & Zlatan, C. (2020). Dual-flow dissymmetrical low pressure steam turbine energy analysis– comparison of both turbine cylinders. Machines. Technologies. Materials., 14(8), 336-339.
  16. Tanuma, T. (Ed.). (2017). Advances in steam turbines for modern power plants. Woodhead Publishing.
  17. Poljak, I., Mrzljak, V., Gospić, I., & Glavan, I. (2021). The Change in Low Power Steam Turbine Operating Parameters During Extractions Opening/Closing. Pomorski zbornik, 61(1), 57-78. (doi:10.18048/2021.61.05)
  18. Elčić, Z. (1995). Steam turbines. ABB, Karlovac, National and University Library Zagreb.
  19. Stradioto, D. A., Seelig, M. F., & Schneider, P. S. (2015). Reprint of: Performance analysis of a CCGT power plant integrated to a LNG regasification process. Journal of Natural Gas Science and Engineering, 27, 18-22. (doi:10.1016/j.jngse.2015.06.009)
  20. Mrzljak, V., Šegota, S. B., Kocijel, L., & Prpić-Oršić, J. (2020). Energy (isentropic) analysis of three-cylinder steam turbine with re-heating. Innovations, 8(1), 37-40.
  21. Poljak, I., & Mrzljak, V. (2023). Thermodynamic Analysis and Comparison of Two Marine Steam Propulsion Turbines. NAŠE MORE: znanstveni časopis za more i pomorstvo, 70(2), 0-0. (doi:10.17818/NM/2023/2.2)
  22. Szargut, J. (2005). Exergy method: technical and ecological applications (Vol. 18). WIT press.
  23. Kopac, M., & Hilalci, A. (2007). Effect of ambient temperature on the efficiency of the regenerative and reheat Çatalağzı power plant in Turkey. Applied Thermal Engineering, 27(8-9), 1377-1385. (doi:10.1016/j.applthermaleng.2006.10.029)
  24. Kanoğlu, M., Çengel, Y. A., & Dinçer, İ. (2012). Efficiency evaluation of energy systems. Springer Science & Business Media.
  25. Mrzljak, V., Poljak, I., Prpić-Oršić, J., & Jelić, M. (2020). Exergy analysis of marine waste heat recovery CO2 closed-cycle gas turbine system. Pomorstvo, 34(2), 309-322. (doi:10.31217/p.34.2.12)
  26. Tan, H., Shan, S., Nie, Y., & Zhao, Q. (2018). A new boil-off gas re-liquefaction system for LNG carriers based on dual mixed refrigerant cycle. Cryogenics, 92, 84-92. (doi:10.1016/j.cryogenics.2018.04.009)
  27. Erdem, H. H., Akkaya, A. V., Cetin, B., Dagdas, A., Sevilgen, S. H., Sahin, B., ... & Atas, S. (2009). Comparative energetic and exergetic performance analyses for coal-fired thermal power plants in Turkey. International Journal of Thermal Sciences, 48(11), 2179- 2186. (doi:10.1016/j.ijthermalsci.2009.03.007)
  28. Koroglu, T., & Sogut, O. S. (2018). Conventional and advanced exergy analyses of a marine steam power plant. Energy, 163, 392-403. (doi:10.1016/
  29. Lemmon, E. W., Huber, M. L., & McLinden, M. O. (2010). NIST Standard Reference Database 23, Reference Fluid Thermodynamic and Transport Properties (REFPROP), version 9.0, National Institute of Standards and Technology. R1234yf. fld file dated December, 22, 2010.
  30. Mrzljak, V., Poljak, I., & Mrakovčić, T. (2017). Energy and exergy analysis of the turbo-generators and steam turbine for the main feed water pump drive on LNG carrier. Energy conversion and management, 140, 307-323. (doi:10.1016/j.enconman.2017.03.007)
  31. Mrzljak, V., & Poljak, I. (2019). Energy analysis of main propulsion steam turbine from conventional LNG carrier at three different loads. NAŠE MORE: znanstveni časopis za more i pomorstvo, 66(1), 10-18. (doi:10.17818/NM/2019/1.2)
  32. Mrzljak, V., Jelić, M., Poljak, I., & Prpić-Oršić, J. (2023). Analysis and Comparison of Main Steam Turbines from Four Different Thermal Power Plants. Pomorstvo, 37(1), 58-74. (doi:10.31217/p.37.1.6)
  33. Mrzljak, V., Poljak, I., Jelić, M., & Prpić-Oršić, J. (2023). Thermodynamic Analysis and Improvement Potential of Helium Closed Cycle Gas Turbine Power Plant at Four Loads. Energies, 16(15), 5589. (doi:10.3390/en16155589)
  34. Baressi Šegota, S., Lorencin, I., Anđelić, N., Mrzljak, V., & Car, Z. (2020). Improvement of marine steam turbine conventional exergy analysis by neural network application. Journal of Marine Science and Engineering, 8(11), 884. (doi:10.3390/jmse8110884)
  35. Wilding, P. R., Murray, N. R., & Memmott, M. J. (2020). The use of multi-objective optimization to improve the design process of nuclear power plant systems. Annals of Nuclear Energy, 137, 107079. (doi:10.1016/j.anucene.2019.107079)

Article full text

Download PDF