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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power and annual energy. Section 111.1 discusses the effect this approximation<br />
might have on calculating design point receiver thermal power during system op-<br />
timization. Essentially, the approximation is good if design point spillage is close<br />
to annual average spillage. However, the shape of the image at design point may<br />
well be different from the annual average, so flux levels at a specific point may be<br />
up to 10% different than calculated during a final per<strong>for</strong>mance run.<br />
The cosine, shadowing and blocking, and atmospheric attenuation losses used<br />
in system optirnization are calculated using minor assumptions of the effect of<br />
scaling with tower height and receiver size, as discussed below. Unlike spillage<br />
and flux calculations, these losses are calculated separately <strong>for</strong> design point and<br />
<strong>for</strong> annual averages used during the optimization.<br />
DELSOL designs a field <strong>for</strong> each system during optimization by using the in-<br />
solation value REFSOL and the design point efficiencies as discussed below, and<br />
by adding zones or fractions of zones based on best cost/per<strong>for</strong>mance until the<br />
requested design power is reached. Note that total yearly insolation, which is<br />
used <strong>for</strong> calculating annual energy, is calculated during the initial per<strong>for</strong>mance<br />
run dependent on the insolation model chds'en, and the design point insolation as<br />
predicted by that model may be different from REFSOL. For an actual plant, in-<br />
solation at design point will vary due to weather conditions, but if design point<br />
insolatioil is reached (REFSOL) then design point per<strong>for</strong>mance predictions will be<br />
valid.<br />
1V.A-I. Cosine-The field points remain at the same relative position in units<br />
of tower height as the tower height is varied. The angles between the sun, helio-<br />
stat, and receiver (Section 1I.A) remain the same, and there<strong>for</strong>e the cosine is not<br />
a function of the tower height. The very small change in the cosine as the receiver<br />
width from the tower centerline is varied is ignored. Thus, only one design point<br />
and one annual average loss calculation is needed <strong>for</strong> examining a set of systems<br />
during optimization.<br />
1V.A-2. Shadowing and Blocking-The actual shadow cast by a heliostat in<br />
the same relative field position is independent of the tower height. However, the<br />
displacement of heliostats relative to each other in radial layouts depends on the<br />
ratio of the heliostat dimension to the tower height. Hence, the shadowing and<br />
blocking has a small dependence on the tower height. The code, however, neglects<br />
this effect. For large systems, i.e., heliostat dimension/tower height