A Critical Analysis on Performance of ORC through a Modified Thermodynamic Model Based on Fluid Property

In accordance with evolution of irreversible process where Organic Rankine cycle (ORC) approaches to Carnot cycle, the paper takes a critical analysis on performance indicators of ORC abiding by thermodynamic laws and considering relations between fluid property, operation condition as well as cycle structure and cycle performance. Previous deviation analysis revealed that modified thermodynamic model can replace approximatively traditional complex numerical calculation with high accuracy and wide range especially for engineering decision. In other words, as for the same working fluid, when Jacob increases, its corresponding energy efficiency of ORC increases accordingly, both exergy efficiency and net work increase firstly and decrease secondly. However, for different working fluids at the same Carnot efficiency, energy efficiency and exergy efficiency of ORC decrease as Jacob increases, but net work increases. Simultaneously, modified thermodynamic model represented interaction between ORC and its approximate cycles such as Carnot cycle and Triangular cycle, which also provided a thermodynamic approach for application of working fluids with different molecular complexity and development of evaluation indexes in different aspects of ORC.