Thermodynamic modelling of a power generation plant using solar concentrators assisted by organic Rankine cycle for João Pessoa city, Brazil

The potential for generating electricity through solar energy makes Brazil a very promising country in this segment, with several possibilities for the use of solar energy, whether in the thermal or photovoltaic part, due to the high incidence of solar radiation throughout much of the country, especially in the Northeast region. In this study, an analysis of the perfor-mance of the organic Rankine cycle (ORC) that produces electricity using solar concentrators was performed. The fluids used in the system were classified as dry type  toluene, isobutane, isopentane, R227ea, R113, R114, R245fa and R600. During the study, the energy and exergy analysis of the system was conducted for different evaporator pressures (500−2500 kPa), and two types of solar collectors were tested (parabolic trough collector and parabolic compound collec-tor). In addition, a system case study was simulated for radiation and temperature conditions in the city of João Pessoa, Brazil. Based on this analysis, the performance of the cycle components was examined, and the first and second law effi-ciencies of the system were compared for different configurations. The solar collector (parabolic trough collector) proved to be the most suitable for the studied cycle. With the adequate selection of the refrigerant, collector and evaporation pressure, the first and second law efficiencies of the cycle improve up to 41% and 44%, respectively. For the city of João Pessoa, the highest exergy efficiency occurs in the month of January, the hottest month of the year when the sun shines brightly, and the lowest exergy efficiency occurs in the month of June.