A User's Manual for DELSOL3 - prod.sandia.gov - Sandia National ...
A User's Manual for DELSOL3 - prod.sandia.gov - Sandia National ...
A User's Manual for DELSOL3 - prod.sandia.gov - Sandia National ...
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c) PreciDitable Water<br />
The precipitable water overhead (in mm) on the Ith calculational day is given<br />
by DH20(I) (IWEATH=l) or H20 (IWEATH=O, 2). This quantity is used only<br />
in the Allen insolation model (INSOL=3).<br />
111.8-4. Sunshape-The image of the extraterrestrial sun is limb darkened; Le.,<br />
the insolation decreases toward the edge. The size and shape of the solar inten-<br />
sity is further modified by the very small angle scattering in the earth’s atmo-<br />
sphere. In general, the size of the solar image increases as the total insolation de-<br />
creases because of increased scattering. The shape of the solar image is important<br />
in its effects on the spillage and flux calculations. The sunshape models available<br />
in DELSOL are set by the choice of parameter NSUN (Namelist BASIC).<br />
a) NSUN = 0, Point Sun<br />
A point sun, while unrealistic, has been useful <strong>for</strong> debugging the field per<strong>for</strong>-<br />
mance calculation and <strong>for</strong> studying the effects of heliostat size and errors on the<br />
images projected on the receiver.<br />
b) U J N = 1, Limb Darkened Sun<br />
This is one of the simpler models <strong>for</strong> a limb darkened sun described by Refer-<br />
ence 3:<br />
So (1.0 - 0.5138(r/R)4) (rR)<br />
where r 1= angle subtended between the center of the sun to<br />
some point toward the edge (R)<br />
The user specifies the intensity vs. angle in a circularly symmetric sunshape.<br />
There are NSUNPT pairs of values of intensity, SUNI, vs. angle from the center<br />
of the sun, SUNR. The angles are in ascending order and the first angle must<br />
be zero (i.e., the center of the sun). mxSUNI(r)dr gives the power from the sun<br />
within a differential circular ring from r to r+dr.<br />
The default in the code is the limb darkened model (NSUN = 1).