Thermal, mechanical and hydrodynamic analysis to optimize the design of molten salt central receivers of solar tower power plants.

Abstract

One  of  the  main  problems  of  the  molten-salt  solar power  tower  plants is  the  reliability  and  lifetime  estimation  of central-receivers.   The   receiver   must   withstand   high   working temperatures,   molten   salt   corrosion   and   important   solar-flux transient  thermal  processes  that  lead  to  thermal  stresses  and fatigue. A thermal, mechanical and hydrodynamic analysis of the receiver  has  been  carried out  assuming  constant  temperature at each   cell   used   in   the   simulations,   but   assuming   axial   and circumferential  variation  temperature  in  the  whole  perimeter  of the  receiver.  The  optimal  design  of  this  kind  of  receivers  has been  found  varying  the  number  of  panels  and  the   external diameter  of  the  tubes.  It  has  been  obtained  that  the  maximum film temperature and thermal stress  follows a different evolution than  the  pressure  drop,  therefore  it  is  necessary  to  make a compromise  between  them.  The  optimal  receiver  design  must reduce  the  wall  and  film  temperatures  and  the  thermal  stresses, assure  the  correct  operation  and  prolong  the  lifetime  of  the receivers.  In  addition,  the  chosen  design  must have  the  highest thermal efficiency, reducing the number of heliostat and therefore the initial capital investment cost of the solar plant will be lower.