Modeling thermodynamic analysis and simulation of organic rankine cycle using geothermal energy as heat source

Abstract

In this study, modeling and thermodynamic analysis of an Organic Rankine Cycle using geothermal heat source in Aydın, Turkey has been made and optimum operation conditions were determined by developing simulation software. The model has been validated using an existing study. In consequence, the differences between existing study data and the model seems reasonable close, so the model was verified. Simulation of model has been made by using EES software. In simulation the effect of minimum and maximum pressure and working fluid changes to the system performance has been investigated. ORC using working fluids R141b and R123 and Isopentane has been simulated for selected input values separately. Because of using Isopentane caused geothermal re-injection temperature decrease to inconvenient level, it has not been used as working fluid in simulation. For R141b and R123, maximum and minimum pressure values have been changed from 500 kPa to 3500 kPa and from 100 kPa to 300 kPa, respectively. 2331 kW of net work obtained at 3184 kPa maximum pressure and 2749 kW of net work obtained at 100 kPa minimum pressures for R141b. For R123, 1798 kW of net work obtained at 3184 kPa maximum pressure and 2119 kW of net work obtained at 100 kPa minimum pressures. It has been seen that reducing minimum pressure effects net work more than increasing maximum pressure and R141b has a better performance than R123, especially in the way of net work production.