Numerical analysis of turbo-generator steam turbine energy efficiency and energy power losses change during the variation in developed power

  • 1 Faculty of Engineering, University of Rijeka, Croatia
  • 2 University of Zadar, Maritime Department, Croatia


Developed power variation of turbo-generator (TG) steam turbine allows insight into the change of turbine energy efficiency and energy power losses. Measurements were performed in five different TG steam turbine operating points and analysis is presented in three randomly selected operating points. Turbine developed power was varied from 500 kW until the maximum power of 3850 kW in steps of 100 kW. Turbine energy efficiency increases from 500 kW to 2700 kW and maximum energy efficiency was obtained at 70.13 % of maximum turbine power (at 2700 kW) in each operating point. From 2700 kW until the maximum of 3850 kW, TG turbine energy efficiency decreases. Change in TG turbine energy efficiency is caused by an uneven intensity of increase in turbine power and steam mass flow. For all observed operating points, energy efficiency during turbine exploitation is approximately 10 % or more lower than the maximum obtained one. A continuous increase in turbine energy power losses during the developed turbine power increase are the most influenced by the continuous increase in steam mass flow through the turbine.



  1. Schinas, O., Butler, M.: Feasibility and commercial considerations of LNG-fueled ships, Ocean Engineering 122, p. 84–96, 2016. (doi:10.1016/j.oceaneng.2016.04.031)
  2. Mrzljak, V.: Low power steam turbine energy efficiency and losses during the developed power variation, Technical Journal 12 (3), p. 174-180, 2018. (doi:10.31803/tg-20180201002943)
  3. Bloch, H. P., Singh, M. P.: Steam turbines-Design, Applications and Re-rating, 2 nd edition, The McGraw-Hill Companies, Inc., 2009.
  4. Baldi, F., Ahlgren, F., Melino, F., Gabrielii, C., Andersson, K.: Optimal load allocation of complex ship power plants, Energy Conversion and Management 124, p. 344–356, 2016. (doi:10.1016/j.enconman.2016.07.009)
  5. Orović, J., Mrzljak, V., Poljak, I.: Efficiency and Losses Analysis of Steam Air Heater from Marine Steam Propulsion Plant, Energies 2018, 11 (11), 3019; (doi:10.3390/en11113019)
  6. Hafdhi, F., Khir, T., Ben Yahyia, A., Ben Brahim, A.: Energetic and exergetic analysis of a steam turbine power plant in an existing phosphoric acid factory, Energy Conversion and Management 106, p. 1230-1241, 2015. (doi:10.1016/j.enconman.2015.10.044)
  7. Mrzljak, V., Prpić-Oršić, J., Senčić, T.: Change in Steam Generators Main and Auxiliary Energy Flow Streams During the Load Increase of LNG Carrier Steam Propulsion System, Scientific Journal of Maritime Research 32, p. 121-131, 2018. (doi:10.31217/p.32.1.15)
  8. Mrzljak, V., Poljak, I., Medica-Viola, V.: Dual fuel consumption and efficiency of marine steam generators for the propulsion of LNG carrier, Applied Thermal Engineering 119, p. 331–346, 2017. (doi:10.1016/j.applthermaleng.2017.03.078)
  9. Final drawing for generator turbine, Shinko Ind. Ltd., Hiroshima, Japan, 2006., internal ship documentation
  10. Mrzljak, V., Senčić, T., Žarković, B.: Turbogenerator Steam Turbine Variation in Developed Power: Analysis of Exergy Efficiency and Exergy Destruction Change, Modelling and Simulation in Engineering 2018. (doi:10.1155/2018/2945325)
  11. Lemmon, E.W., Huber, M.L., McLinden, M.O.: NIST reference fluid thermodynamic and transport propertiesREFPROP, version 8.0, User’s guide, Colorado, 2007.
  12. Mrzljak, V., Poljak, I., Mrakovčić, T.: 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, p. 307–323, 2017. (doi:10.1016/j.enconman.2017.03.007)
  13., (accessed 15.10.18.)
  14., (accessed 15.10.18.)
  15., (accessed 12.10.18.)

Article full text

Download PDF