A triple-pressure organic Rankine cycle (TPORC) using geothermal energy for power generation has been investigated in this paper. The net power output of the TPORC was analyzed by varying the evaporation pressures, pinch temperature differences and degrees of superheat to find the optimum operation conditions of the system. The thermodynamic performance of the TPORC was compared with dual-pressure ORC (DPORC) and single-pressure ORC (SPORC) respectively for the heat source (geofluid) temperature between 135°C and 200°C. The results show that the net power output of the TPORC is higher than that of the DPORC and SPORC when the heat source temperature is low, especially when it is less than 150°C. Thus the TPORC could be a choice for power generation for utilizing medium-low geothermal resources (100°C-150°C) provided that it has a sound techno-economics.
Keywords Geothermal power generation systems, Single-pressure ORC, Dual-pressure ORC, Triple-pressure ORC.