Thermodynamic analysis and optimization of Transcritical and Supercritical Organic Rankine and Brayton Cycles coupled to parabolic trough collectors

Abstract

The main objective of this work is to investigate the efficiency of three different power cycles coupled with parabolic through collectors in Athens/Greece. The power cycles analyzed where: subcritical ORC with n-Pentane and R245fa as working fluids, trans-critical ORC with R245fa as working fluid and super-critical Brayton cycle with CO 2 and R245fa as working fluid. Mathematical models were developed for both the solar farm and the power cycles in order to optimize the necessary parameters for the optimal operation of the plant. The inlet temperature and pressure of the turbine are the optimization parameters. The overall efficiency of the system (power to solar) for the sub-critical ORC with n-Pentane and R245fa is 14.12% and 10.31% respectively. For the trans-critical ORC with R245fa the efficiency is 15.14% and for the super-critical Brayton cycle for CO 2 and R245fa, 13.23% and 8.87% respectively.