A User's Manual for DELSOL3 - prod.sandia.gov - Sandia National ...

1II.C. Field Performance Calculation
DELSOL will compute field performance terms for specific times, sun an-
gles, or for a yearly sampling of times, depending on the choice of IPROB. For
IPROB=O or 4, for instance, DELSOL will compute daily and annual averages of
the total performance and the individual performance terms. These time averages
are weighted according to the following table:
Quantity Weighting
cosine
shadowing
blocking
attenuation
spillage
insolation '
insolation x cos
insolation x cos x shadowing
insolation x cos x shadowing x blocking
insolation x cos x shadowing x blocking x attenuation
For example, the average blocking from time tl to time t2 is:
< blocking >=
J$: block(t) shadow(t) cosine(t) insolation(t) dt
J: shadow(t) cosine(t) insolation(t) dt
c
The same type of weighting is used in averaging the performance for a user de-
fined field.
1II.D. Cosine Effect
In general, heliostats are not perpendicular to the incident direct insolation.
The total power reflected per unit area of heliostat is proportional to the cosine
6 - S = 6 - t^. The code uses the analytical formulas for the heliostat orientation and
the cosine derived in Reference 25. Therefore, the amount of energy reflected by a
heliostat, S,, is:
where
S, = S x (fi.6) x RMIRL
1
ii - B = -{ 1 + c0~6~cosdt + sin&sin6tcos(pt - ps)}1/2
fi
The angles are defined in Figure 11-2.
74
(1II.D - 1)
(1II.D - 2)