Energetic and exergetic performance analysis of different refrigerant fluids (coolants)in binary cycle geothermal power plant.

Worldwide, energy requirement increase gradually depending on population growth. It is known fact that limited fossil fuel sources run out, hence renewable sources gain great importance. Alternative energy sources and systems have been developed in order to meet energy requirement. Binary cycle which allow the production of electricity from geothermal energy sources is one of these systems. In this cycle, thermal energy obtained from geothermal sources is transfered to second working fluid. Therefore, selection of second working fluid plays a key role on the cycle performance.In this study, a sample geothermal binary power cycle has been modelled and 8 refrigerants have been selected as working fluid for this cycle. These refrigerants are HC and HFC types that have minimum enviromental impact. Selected refrigerants have been analyzed in the sample cycle under the same working conditions. Energy and exergy efficiencies of cycle have been calculated for 8 refrigerants. Dry types fluids of investigated refrigerants: R 600, R 236ea, R 600, R 600a and R 227ea showed higher energy and exergy efficiencies, respectively. On the other hand, R 143a, R 290,R 134a and R 152a that are wet fluids indicated lower energy and exergy efficiencies, respectively.