Experiment and cycle analysis on a partially admitted axial-type turbine used in the organic Rankine cycle

The ORC (organic Rankine cycle) has been used to generate electrical or mechanical power from low-grade thermal energy. However, even though many kinds of such energy are available, this thermal energy is typically not available continuously at a constant level. In order to utilize fluctuating thermal energy optimally, an axial-type turbine was applied to the expander, and two nozzles were used to control the mass flow rate. The tip diameter of the rotor was 80 mm and the nozzle was designed as a supersonic nozzle to increase the turbine output power. Experiments were conducted at various TIT (turbine inlet temperatures) with the partial admission rate of 16.7%. The experimental results were compared with the predicted results of the cycle analysis. In the cycle analysis, the output power of the ORC was predicted considering the load dissipating the output power produced by the ORC, as well as the turbine efficiency. The predicted results showed the same trend as the experimental results, and the experimental results showed that the system efficiency of 2% was obtained at the TIT of 100 degrees C. Hence, this type of turbine can be applied to produce a wide range of power continuously where the available thermal energy varies. (C) 2015 Elsevier Ltd. All rights reserved.