THERMODYNAMIC OPTIMIZATION OF THE TWO-STAGE RANKINE CYCLE WITH ORGANIC FLUID FOR THE NEEDS OF A GEOTHERMAL POWER PLANT

U ovom radu je odrađeno termodinamičko optimiranje Rankinevog ciklusa s organskim fluidom (ORC) za potrebe geotermalne elektrane. Definiran je matematički model postrojenja na osnovu prvog i drugog glavnog stavka termodinamike. Kao osnovni alat u završnom radu je korišten programski paket Engineering Equation Solver (EES). Za odabrane radne fluide je provedeno termodinamičko optimiranje navedene konfiguracije geotermalne elektrane pri temperaturama 120 °C, 140 °C, 160 °C i 180 °C. Naposljetku je odrađena konvencionalna eksergetska analiza za najbolje predstavnike kod odgovarajućih temperatura geotermalnog izvora pri čemu je zaključeno da je potrebno, obzirom na temperaturu geotermalne vode, upotrijebiti najprikladnije fluide za traženo postrojenje iz kojeg je cilj proizvesti što veću snagu sa najboljim vrijednostima energetske i eksergetske učinkovitosti.This paper presents thermodynamic optimization of the Rankine cycle with organic fluid (ORC) for the needs of a geothermal power plant. The mathematical model of the plant is based on the first and second main terms of thermodinamics, using an Engineering Equation Solver (EES) as a main tool. Thermodynamic optimization, of the mentioned configuration of the geothermal power plant, was carried out for the selected working fluids at different temperatures (120 °C, 140 °C, 160 °C and 180 °C). Ultimatelly, the conventional exergetic analysis is performed to determine the optimal temperature of geothermal source. In conclusion, it is necessary to use the most suitable fluids for the requested improvement, considering the temperature of the geothermal water, to produce more power with the best values of energetic and exergetic efficiency