Investigations of Supercritical CO2 Rankine Cycles for Geothermal Power Plants

by Adrian S. Sabau, Hebi Yin, Lou A. Qualls, & Joanna McFarlane
Oak Ridge National Laboratory

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Supercritical CO2 Rankine cycles are investigated for geothermal power plants. The system of equations that describe the thermodynamic cycle s solved using a Newton-Raphson method. This approach allows a high computational efficiency when thermophysical properties of the working fluid depend strongly on the temperature and pressure. Numerical simulation results are presented for different cycle configurations in order to assess the influences of heat source temperature, waste heat rejection temperatures and internal heat exchanger design on cycle thermal efficiency. The results show that thermodynamic cycle efficiencies above 10% can be attained with the supercritical brayton cycle while lower efficiencies can be attained with the transcritical CO2 Rankine cycle.

Notice: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes.