Analysis and modelling of organic rankine cycle with geothermal energy resource

At the beginning of this thesis, the potential and utilization fields of geothermal energy are given in detail and the status of geothermal energy in the world and particularly in Turkey are presented on graphs. For low temperature heat sources, Organic Rankine Cycle (ORC) that has organic fluid instead of water is used. This thesis presents analysis of Organic Rankine Cycle by the help of a geothermal energy source for electricity generation. The considered heat resource for ORC is in the form of geothermal water (140 °C) at mass flow rate of 0.675 kg/s. In this thesis, cycle components, working conditions and thermodynamic properties are taken into consideration to identify the most suitable organic fluid, which was selected as R245fa for steady state ORC system. All components of cycle were modelled and energy-mass balance is realized step by step with the help of modelling program Flownex version SE 8.2.1.2028. For each component, steady state results were calculated. To make an analysis, the Organic Rankine cycle demo with 250 kW turbine output power is designed using all these inputs. In this thesis, steady state and dynamic simulation were made based on prepared model. Organic Rankine cycle was examined thermodynamically and the studies were done to improve cycle efficiency. The design criteria of these components have been explained. Flownex program was also used for dynamic analysis by removing boundary conditions. The scenario was created by the help of dynamic analysis such as condenser cooling water temperature to increase the cycle efficiency. 2.5°C temperature decrease in condenser cooling water temperature increased the cycle efficiency from 14% to 14.26%.