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

caused by the tilt of the heliostat, proportional to the cosine of the angle of incli-
nation of the normal of the heliostat surface to the sun’s rays.
Cost/Performance Ratio: A measure used in comparing system design
alternatives wherein both cost and system performance are taken into account.
CRTF: The Central Receiver Test Facility at Sandia National Laboratories in
Albuquerque, New Mexico.
Design Point: The time of day and day in a year for which the system or
component performance is specified.
Direct Normal Insolation: The solar energy incident on a surface that
comes from within the solid angle subtended by the solar disk; that sunshine
which can cast a sharply defined shadow.
Discount Rate: The annual rate used in present worth analyses that takes
into account inflation and the potential earning power of money while moving the
present worth forward or backward to a single point in time for comparison of
value.
Diurnal: Recurring every day.
DOE: The United States Department of Energy.
Downcomer: The pipe carrying the hot heat transport fluid down the re-
ceiver tower.
Emissivity: The ratio of the radiant energy given off by a surface to that
given off by a blackbody at the same temperature.
End Use: The final use of the thermal output of a solar central receiver
plant, e.g., in a turbine to generate electricity or in an industrial process.
External Receiver: A solar energy receiver in which the solar radiation is
absorbed on the external surfaces. External receiver configurations include bill-
board (flat plate) and cylindrical.
Fixed Charge Rate: The amount of revenue per dollar of capital expense
that must be collected annually to pay for the fixed charges associated with plant
ownership, e.g., return on equity, interest payment on debt, depreciation, income
taxes, property taxes, insurance and repayment of initial investment. It may also
include operations and maintenance expenses expressed as a fraction of the capi-
tal cost.
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Flux (Radiant): The time rate of flow of radiant energy.
Flux Density: The radiant flux incident per unit area.