Solar energy conversion with thermal cycles - Solar Energy Sciences and Engineering Applications - page 444

Figure 14.3.20 Beam-Down solar concentration concept.

Table 14.3.3 Main operating conditions for solar tower receivers
for two different fluids.

Water steam Molten Salt Receiver

Outlet Temperature [ ◦ C] 250/525 566

Incident Flux [kW/m 2 ] 350 550

Peak flux [kW/m 2 ] 700 800

Maximum pressure [bar] 100-135 -

Thermal efficiency [%] 80-93 85-90

The application of central receiver technology to thermochemical processes
requires even higher temperature: zinc oxide thermal reduction (which is required
in water-splitting processes for hydrogen production) works at 1700 ◦ C (Schunk et al.,
2009), while coal gasification for syngas production works at 1100 ◦ C (Z'Graggen
et al., 2006).
It is difficult to provide figures for the thermal efficiency of central receivers
since there are several different design configurations of the receiver and working