Thermodynamic Analysis of Series and Parallel Two-stage Organic Rankine Cycle for Electricity Generation Enhancement

The electricity generation of ORC system produces low system performance because of the low heat source temperature. Modification of ORC is used to enhance the performance of ORC system. Series and parallel two-stage ORC (STORC and PTORC) are two from many ORC configuration that can be used to enhance electricity generation. This paper discusses the thermodynamic analysis of STORC and PTORC to determine the enhancement of electricity generation. Hot spring in Cimanggu, Jawa Barat, Indonesia with 78 degrees C and 70 l/minute of temperature and volume flow rate were used as initial data. R227ea was chosen as organic working fluid for each system. The first and second law of thermodynamics was used for the analysis. Analysis of the first law of thermodynamics is carried out to determine net power output and thermal efficiency of the system. The second law of thermodynamic analysis is carried out to determine exergy efficiency of the system. The result shows that net power output of STORC and PTORC is 5.94 kW and 5.01 kW respectively. Thermal and exergy efficiency of STORC are 6.21% and 6.50%, and 5.24% and 5.49% for PTORC.