Thermodynamic analysis of an Organic Rankine Cycle (ORC) based on industrial data

In this study, thermodynamic analysis of an Organic Rankine Cycle (ORC) is presented in a local power plant that is located southern of Turkey. The system that is analyzed includes an evaporator, a turbine, a condenser, a pump and a generator as components. System components are analyzed separately using actual plant data and performance cycle. The relationship between pinch point and exergy efficiency is observed. As the pinch point temperature decreases, the exergy efficiency increases due to low exergy destruction rate. The energy and exergy efficiencies of the ORC are calculated as 9.96% and 47.22%, respectively for saturated liquid form which is the real condition. In order to show the effect of the water phase of the evaporator inlet, exergy destruction and exergy efficiencies of components and overall system are calculated for different water phases. The exergy efficiency of the ORC is calculated as 41.04% for water mixture form which has quality 0.3. On the other hand, it is found as 40.29% for water mixture form which has quality 0.7. Lastly, it is calculated as 39.95% for saturated vapor form. Moreover, exergy destruction rates of the system are 520.01 kW for saturated liquid form, 598.39 kW for water mixture form which has quality 0.3, 609.5 kW for water mixture form which has quality 0.7 and 614.63 kW for saturated vapor form. The analyses show that evaporator has important effect on the system efficiency in terms of exergy rate. The evaporator is investigated particularly in order to improve the performance of the overall system. - Highlights: • Energy and exergy analysis of an Organic Rankine Cycle (ORC). • The main reasons of the irreversibility in the ORC. • Determination of exergy efficiency for the different water phases in the evaporator inlet. • Determination of the effect of the ambient temperature on ORC efficiency.