Exergy Analysis of A Hermatic Turbine 500 kW Organic Rankine Cycle Geothermal Binary Power Plant

Up to 2025, Indonesia will approximately utilize 150 MWe promising small scale of waste heat geothermal sources for electricity power plants. As the characteristic of the brine water is has a low grade of heat and low grade of enthalpy. Therefore, the Organic Rankine Cycle geothermal binary power plant system is well suited to maximize these potentials to construct low-capacity power plants to maximize the utility of geothermal power plant. The aim of this research is to examine a case study on the performance of the turbine of the 500 kW ORC power plant. The turbine is rotated by the working fluid. The working fluid used for this research is npentane. An exergy analysis is performed to reduce losses or energy wasted, especially on the turbine component. Results of analysis with random data collected in April to July 2018 from the turbine system. The result shows that the minimum efficiency of 56.24% is when inlet heat source temperature of 117oC and ambient temperature of 22oC. While the maximum efficiency of 69.92% at an inlet heat source temperature of 133oC and ambient temperature of 33oC. The largest exergy losses is recorded at 175.83 kW, while the smallest exergy losses is recorded at 130.78 kW and average exergy losses is at 154.86 kW. Keywords: Organic Rankine Cycle, Turbine, Exergy, Efficiency, Losses