THERMODYNAMIC ANALYSIS AND COMPARISON OF VARIOUS ORGANIC FLUIDS FOR ORC IN GAS TURBINE-ORGANIC RANKINE COMBINED CYCLE PLANT WITH SOLAR REHEATING AND REGENERATION OF ORC FLUID

Abstract

The integration of solar energy into natural gas combined cycles has been successfully demonstrated in several integrated solar combined cycles since the beginning of this decade in many countries. There are many motivations that drive investments on integrated solar combined cycles which are primarily the repowering of existing power plants, the compliance with more severe environmental laws on emissions and the mitigation of risks associated with large solar projects. Integrated solar combined cycles are usually developed as brown field facilities by retrofitting existing natural gas combined cycles and keeping the existing equipment to minimize costs. In this work energy and exergy analysis of Gas turbine-Organic Rankine combined cycle with solar reheating of organic fluid is done and results are compared with simple combined cycle, combined cycle with regeneration, combined cycle with solar reheating of organic fluid. The performance of the system is compared with different organic fluids such as R134a, R245fa, Acetone, and R1234yf at different organic Rankine cycle maximum pressure and maximum temperature. R1234yf shows maximum increase in efficiency by regeneration about 70%. Acetone shows maximum organic Rankine cycle efficiency of 25.96%. exergetic efficiency of combined cycle with regeneration and reheating 64%, 72%, 64%and 82% for R134a, R245fa, R1234yf and Acetone respectively. Acetone is recommended for practical applications due to its highest energy and exergetic efficiency among all selected organic fluids but some important problem related to flammability and explosion risk have to be considered while managing it. After Acetone, R245fa can be considered as better option in solar reheated combined cycle plant with regeneration.