THERMODYNAMIC BEHAVIOUR OF REGENERATIVE CYCLES AND ITS CONTRIBUTION TO PARABOLIC TROUGH POWER PLANTS PERFORMANCE

André Felippe Vieira da Cunha¹; Naum Fraidenraich¹

¹ Federal University of Pernambuco

doi:10.20906/CPS/COB-2015-0090

Resumo

Heliothermal systems for power generation are being built in many countries all around the world, with the leadership of Spain and the United States. In those systems, water circulates and is heated in the absorber of the cylindrical-parabolic collectors' field and transform in superheating vapor. A thermodynamic Rankine cycle completes the process by converting the thermal energy of the steam into electricity. It is, therefore, a direct heat generating system. One possibility to increase the efficiency of the solar-electric plant is to improve the Rankine cycle performance. The regenerative cycle with multiple extractions in the turbine increases the efficiency making fully or partially adiabatic the preheating phase of the cycle. This paper provides an overview of how the thermodynamic variables of the regenerative system behave. It can be seen that the turbine extraction pressures tend to follow a polynomial function, as well as the enthalpy difference between two consecutive extraction exchangers is not constant, as predicted by simplified treatments reported in the literature. The efficiency of the conventional Rankine cycle, heat to electricity increases from 39% to 43%. Further gains can be obtained by introducing other improvements in the cycle.

Palavras-chave: Regenerative Cicle; thermodynamic cicle