Thermodynamic analysis of organic rankine cycle (ORC) systems based on turbine performance prediction

Energy shortage and environmental deterioration are two crucial issues that the developing world must face. As a promising solution, the conversion of low grade energies is attracting more and more attention. Among all of the existing technologies, Organic Rankine Cycle (ORC) has been proven to be an effective method to utilize the low grade energies. Thermodynamic analysis is important for working fluid selection and system parameter determination in the ORC system. In conventional studies, the efficiency of the organic turbine is fixed at a constant value. However, the turbine efficiency is evidently related to the working fluid property and system operating condition. Thus, the constant turbine efficiency is unreasonable and may lead to sub-optimal thermal results. To enhance the reliability and accuracy of ORC system analysis, the one-dimensional analysis model is used to predict the turbine performance in this paper. The calculated onedimensional turbine efficiency replaces the constant efficiency in the system analysis. The influence of the working fluid property and system operating condition on the turbine performance is evaluated. Thermal performances of the ORC systems with the one-dimensional turbine efficiency and the constant turbine efficiency are simulated and compared. The results reveal that the turbine efficiency plays a significant role in working fluid selection and system parameter determination for the ORC system.