First- and second-law analyses of thermal power plants in connection with irreversibility ratio

Sahin A. Z., Yilbas B. S.

INTERNATIONAL JOURNAL OF EXERGY, vol.18, no.3, pp.356-366, 2015 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 18 Issue: 3
  • Publication Date: 2015
  • Doi Number: 10.1504/ijex.2015.072896
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.356-366
  • Keywords: power plants, second-law efficiency, irreversibility ratio
  • Istanbul Technical University Affiliated: No


The rigorous assessment of thermal characteristics of power plants is important for the cost-effective operations. Thermodynamic analysis of the first- and the second-law efficiencies can be merged through the irreversibility ratio (IR = T-0(S) over dot(gen)/(Q) over dot(H)), which provides useful information on the thermal system characteristics and reduces the efforts for the thermal analysis. In this study, thermodynamic analysis of a power plant is carried out and the first- and the second-law efficiencies are formulated simultaneously incorporating the irreversibility ratio. The maximum output power and the maximum first- and second-law efficiencies are formulated. The effect of temperature ratio and irreversibility ratio on the output power as well as the first- and the second-law efficiencies is investigated. It is found that the influence of the irreversibility ratio is higher on the second-law efficiency than that of the first-law efficiency, which is more pronounced at low values of the temperature ratio (theta <= 0.6).