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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system variables, an optimal field is built up. At each design point power level at-<br />
tained in the field build-up, the levelized energy cost is tested to see if it is a new<br />
minimum. If it is a new minimum, the system design, per<strong>for</strong>mance, and costs are<br />
saved. When the iterations are complete, the lowest energy cost system from the<br />
allowed system variations is known at each power level.<br />
Even if the user asks DELSOL to examine every system in the range of vari-<br />
ables (IALL=l), not every system will be examined. DELSOL contains tests to<br />
avoid searching over systems that cannot meet the minimum power of interest. If<br />
a given tower height is too small to meet the minimum design power level <strong>for</strong> any<br />
receiver, DELSOL automatically skips to the next tower height without search-<br />
ing (in vain) <strong>for</strong> the optimum receiver size. Also, DELSOL checks to make sure<br />
that cavity receiver geometries are consistent. Requests to allow aperture widths<br />
which are wider than twice the depth of the cavity are ignored. This is due to the<br />
DELSOL assumption that cavity receivers are configured internally as right circu-<br />
lar cylinders centered on the aperture., so that the interior of the cavity will never<br />
be greater than twice the depth of the cavity.<br />
Other than <strong>for</strong> the above exceptions, DELSOL will examine every system re-<br />
quested in the range of variables when IALL=l. However, considering every pos-<br />
sible combination of system variables is an inefficient way to find the optimum<br />
system(s). DELSOL, there<strong>for</strong>e, has an option to do a “smart” search over the<br />
receiver variables. This option (IALL=O) is the default option. Smart search-<br />
ing tries to consider the minimum set of system variables necessary to find the<br />
optimum system(s). The search algorithm attempts to start iterating a receiver<br />
variable at a value greater than its minimum allowed value and to stop iterating a<br />
variable be<strong>for</strong>e it reaches its maximum allowed value. The search strategy makes<br />
the following assumptions: (1) there is a single, well defined minima in each vari-<br />
able, which is not significantly dependent on the choice of the other receiver vari-<br />
able or the tower variables; and (2) the optimum tower height and receiver size<br />
increase when the power level increases.<br />
The first assumption of smart optimization, that a single well defined min-<br />
ima in each receiver variable exists, allows DELSOL to find that minima <strong>for</strong> the<br />
second receiver variable using the first choice of the first receiver variable which<br />
results in the requested design point power level, and then to continue searching<br />
<strong>for</strong> the minima in the first receiver variable <strong>for</strong> values of the second receiver vari-<br />
able close to its minima. If increasing a receiver variable increases the energy cost<br />
of each system whose power level can be reached by changing that variable, DEL-<br />
SOL will stop the iteration and assume that a minima has been found <strong>for</strong> that<br />
variable. However, in actuality the minima values will move slightly as other re-<br />
ceiver and tower dimensions are changed. There<strong>for</strong>e, after DELSOL has found a<br />
minima <strong>for</strong> an inner variable and increases an outer variable to the next value,<br />
it starts the iteration on the inner variable at the discrete value which is one less<br />
than the minima found previously. For example, suppose the user has allowed re-<br />
ceiver sizes of 10, 11, 12 ... 20. At THT = 150 the minimum receiver size that is<br />
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