Exergy analysis of solar radiation processes - Solar Energy Sciences and Engineering Applications - page 63

Figure 2.4.12 Effect of varying temperature T a of absorbing surface, at constant T = 6000 K, T 0 = 300 K
and ε a = 0 . 8 (Petela, 2003).

Figure 2.4.13 The scheme of the SCPC, (from Petela, 2005).

surface 2 of the reflector has an area A 2 . The system is completed with the imagined
plane surface 1 of area A 1 .
The imagined surface 1, which represents the ambience and the irradiation supplied
to the considered system, is defined by transmissivity τ 1 = 1 (and thus reflectivity ρ 1 =

0), absorptivity α 1 0.

The effective emission of the imagined surface 1, can be determined as the
irradiation I calculated as follows:

= 0 and emissivity ε 1 =

10 − 5 A 1 ε S σT S I = 2 . 16 · (2.4.32)

10 − 5 accounts on the solid angle within which the Sun has been seen from
the Earth, ε S is the emissivity of the Sun surface, (assumed ε S =

where 2.16 ·

1), σ is the Boltzmann