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

the receiver or tower dimensions or field configuration were changed, the costs
and thus energy costs would no longer be correct for the modified system. (How-
ever, storage costs may be modified due to storage optimization which was re-
quested during the optimization process but which is actually accomplished dur-
ing a final performance run. See Section 1V.C-5.) It is strongly suggested that
only the input relating to flux calculations be varied during a final performance
calculation of a previously optimized system using DELSOL.
111. J. Performance of Small Systems
DELSOL can be used to design systems having small power levels, if certain
precautions are observed. The accuracy of Hermite polynomials, used to predict
flux and spillages, becomes less when the slant range decreases with respect to
heliostat and receiver sizes, or when receiver dimensions decrease for a constant
heliostat size. Thus, for the most accurate results for small systems the use of a
smaller heliostat might be required. Use of a smaller heliostat will also reduce the
actual amount of spillage, especially when the image size is greater than the re-
ceiver size. One further advantage of using small heliostats is seen for DELSOL
calculations on very small systems. DELSOL calculates heliostat images for each
zone. However, if less than one heliostat is in each zone, then the DELSOL cal-
culated image may be smaller than in actuality. By using more and smaller he-
liostats, the zonal approximation that DELSOL makes will not become invalid.
If different sized heliostats are used, it is necessary for the user to also vary
the cost of heliostats (dollars/m2), since it is commonly accepted that smaller
heliostats cost more per unit area. Also, turbine efficiencies and parasitic losses
should be adjusted properly to account for the lower power levels and perhaps
less efficient components that would be required.
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