Performance improvement of a flash-binary geothermal power system using zeotropic working fluid; A comprehensive exergoeconomic analysis and optimization
In this paper, a geothermal system is combined with an organic Rankine cycle to generate power. The zeotropic mixture is utilized to improve the organic Rankine cycle performance. The mass, energy, exergy, and exergoeconomic analysis is applied to evaluate the proposed system performance, in which the system led generated 3841 kW net power with 61.09% exergetic efficiency and 3.55 years of payback period. Then, a parametric study is performed to obtain the effect of vapor generator temperature and zeotropic mixture’s mass fraction on the proposed system’s main performance criteria. Based on the parametric study results, the mass fraction variation influences the net power generation, energy and exergetic efficiencies, and the payback period is higher than the evaporation temperature in the vapor generator unit while, the exergy
destruction is influenced by the evaporation temperature higher than the zeotropic mixture mass fraction. Also, the net present value is estimated for three different geofluid and electricity sale prices. Increasing the electricity price about 22% with the same geofluid price decreases the payback period by about 23% and improves the system profit by about 54.7%. Finally, applying a multi-objective optimization refers to obtaining the payback and exergetic efficiency by about 3.26 years and 62.15%, respectively.