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

owing, blocking, atmospheric attenuation, spillage, and flux profiles. The code has
several special features. First, the running time for a single performance calcula-
tion is much less than for other codes, such as MIRVAL (Reference l), but with
the same accuracy for most problems. Second, because of the analytical form of
the spillage and flux, one annual performance calculation determines the perfor-
mance for any tower height or receiver size. Other codes must perform a new
calculation each time the system is varied. DELSOL, therefore, has a very sig-
nificant advantage in the execution time required for the large number of perfor-
mance calculations necessary in design tradeoff and optimization studies. Third,
DELSOL contains a detailed description of the types of errors that can degrade
the performance of heliostats. Finally, DELSOL is relatively easy to use. With
minimal input, DELSOL can analyze systems involving flat, focused, or canted
heliostats with round or rectangular shapes; external, multiple aperture cavity, or
multiple flat plate receivers; and variable aiming strategies.
As a system design tool, DELSOL determines the best combination of field
layout, heliostat density, tower height, receiver size and tower position (land con-
strained system) based on the performance, total plant capital cost, and system
energy cost. In this mode, the code can be used to define values of the key design
parameters on which a detailed design can be based. The need for manually do-
ing a succession of point designs in order to identify an optimum is eliminated.
The optimal design is evaluated by searching over a range of tower heights and
over two components of the receiver geometry (e. g., diameter and height of an
external receiver) at the design point power level(s) to find the system with the
minimum energy cost. The code is also capable of doing constrained optimiza-
tions in which the peak flux on the receiver is restricted below some maximum
value and/or land availability is limited.
The development of DELSOL followed that of Sandia’s other two central re-
ceiver performance codes, MIRVAL and HELIOS (References 1 and 2). The ear-
lier codes have been used to validate the theory and programming in DELSOL.
The agreement in performance predictions among the three codes is discussed in
Chapter VII. While any one of the codes can, in principle, do the same kinds of
problems, they were developed with different purposes in mind and thus do not
greatly overlap in use. HELIOS is specially adapted for analyzing experiments
at Sandia’s Central Receiver Test Facility. MIRVAL employs a Monte Carlo ray
trace technique, giving it the potential to analyze very complex systems that are
well defined. DELSOL has been developed with speed in mind; hence it typically
requires much less computer time for performance calculations, and it can also
readily handle the multiple performance calculations required for system design
and optimization.
DELSOL is based in part on the performance/design approaches developed
at the University of Houston (References 3 and 4), but with many important
additions. The mathematical basis is an analytical Hermite polynomial expan-
sion/convolution of moments method for predicting the images from heliostats
(Reference 3). The method has been extended at Sandia to allow a more general
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