Exergy analysis of solar radiation processes - Solar Energy Sciences and Engineering Applications - page 47

Table 2.4.1 Spectrum of the extraterrestrial solar radiation, (from Petela, 1962).

λ · 10 10 i 0 , λ · 10 − 10 ν · 10 − 11

i 0 , ν · 10 12

λ · 10 10 ν · 10 − 12

i 0 , ν · ν L 0 , ν · 10 13 L 0 , ν · ν

W
m 3 sr

1
s

J
m 2 sr

1
s

W
m 2 sr

J
m 2 ssr

W
m 2 Ksr

m m

1 2 3 4 5 6 7 8 9

2200
2300
2400
.
.
60000
70000

10
26
31
.
.

13627
13035
12492
.
.

15
47
59

100
100
100

62.0
56.7
52.1
.
.

960
2650
3090
.
.
1260
640

0.03
0.10
0.12
.
.
7.19
5.48

0.205
0.540
0.639
.
.
0.514
0.293

.
.
1765
1201

.
.
10000
10000

1
1

500
428

0.714
0.535

Total 10079300 2263.306

Figure 2.4.1 Spectrum of extraterrestrial solar radiation (from Petela, 1962).

The obtained result 1275.8 W/m 2 is the exergy of the extraterrestrial solar

radiation arriving in a 1 m 2 surface which is perpendicular to the direction of

the sun. The obtained ratio of radiosity (equal to emission) to exergy is ψ S =

1275 . 8 / 1367 . 9 = 0 . 9326.

2.4.1.2 Possibility of concentration of solar radiation exergy

Solar energy, although rich, is poorly concentrated and thus it requires a relatively
large surface to harvest the Sun's radiation. From this viewpoint solar radiation is
especially valuable for those countries which have lot of unused areas (e.g. deserts).