An Organic Rankine Cycle as Technology for Smaller Concentrated Solar Powered Systems

This paper analyses and simulates an organic Rankine cycle (ORC) specifically for smaller concentrated solar powered (CSP) systems to produce solar thermal electricity (STE) in the range from 500 kW to 5 MW. The plant efficiency is optimized with the evaporating and condensing temperatures as optimizing variables. A thorough process for selecting the working fluid is presented to help the designer with this monumental task. After considering various aspects n-Pentane is chosen as working fluid for the ORC. It is also the only organic working fluid that has been successfully used in conjunction with CSP on the scale from 500kW to 5MW. The power block is simulated by modelling each component and combining them to form a complete simulation model. The results of the simulation is document and a plant efficiency of about 14.2% is achieved across the power range. The output if the ORC simulation is then compared to a steam Rankine cycle under the same operating conditions and the ORC proved to be more efficient for a power output up to 3000kW