Thermal and Exergy Efficiency Analysis of a Solar-driven Closed Brayton Power Plant with Helium and s-CO2 as Working Fluids

Abstract

 Solar  Thermal  Energy  power  plants  operating with traditional steam Rankine cycles have a low thermal and  exergy  efficiency.  An  attractive  pathway  to  increase the  competitiveness  of  this  technology  is  to  investigate Closed Brayton cycles working with different fluids with desirable  properties  that  show  potential  for  improving their efficiency  In  this  work  a  solar  driven  regenerative  Brayton  cycle  is studied  employing  two  different  working  fluids:  Helium and    supercritical    CO2.    The    cycle    efficiencies    are determined  for  different  turbine  inlet  temperatures  and for  the  optimal  compressor  pressure  ratios.  Additionally, an  exergy  analysis  breakdown  of  the  different  plant components is shown  for each case,  while the  solar field sizes  and  working  fluid  flows  are  calculated  for  a  fixed gas turbine output.