Questions about SAM

Dear Sir or Madam,

As a new SAM user, I am facing some difficulties and raising questions that you will certainly be able to answer easily. Please find below these questions. Thanks in advance for your help on these topics.
Best regards,

Receiver thermal power
My understanding is that receiver thermal power is determined by targeted steam turbine output * efficiency * solar multiple.
What if a max receiver flux (in Receiver Thermodynamics Characteristics) below the calculated one is entered? How this value is taken into account?

Design HTF inlet temperature
Can you please confirm that this temperature is relative to molten salts and not to steam?

Cooling system
An ITD is entered when air-cooled condenser is chosen. But oddly, we noticed that power generation was increasing with increased ITD. Coudl you please explain us how ITD is taken into account compared to rated cycle cinvesrion efficiency?

Parasitics
Could you explain how factor and coefficients taken into account for BOP and auxiliary heater parasitics are used in the calculation?

Degradation
It seems that the year-to-year decline in output does not affect the annual energy produced. Could you please explain us why and how this factor is taken into account?

First of all, you did not mention what model you are using in SAM, but I see that you mention "Receiver Thermodynamic
Characteristics," so I will assume that your questions are about the molten salt power tower model.
And, before I answer your questions, I should mention that simulating a power tower system in SAM involves two steps: 1.
Running the
optimization wizard to
calculate the tower height and field layout, and 2.
running a simulation to calculate
the system's hourly output.

Receiver Thermal Power

The description of the "Max Receiver Flux" input variable in Help (
SAM Help - Tower and
Receiver) says "The upper limit of solar radiation incident on the receiver allowed to be reflected from the heliostat
field. SAM ensures that the optimal receiver size and heliostat positions do not result in a receiver flux that exceeds this
value." So, if you enter a maximum value that is lower than the flux value, the optimization wizard will choose a tower
size and heliostat layout that prevents the flux under design conditions to exceed that value.

Design HTF inlet temperature

Yes. That is the temperature of the molten salt heat transfer fluid at the power block inlet. (Again, that is explained
in Help in the input variable descriptions for the Power Cycle page).

Cooling system

Please see the Help system on this one too. There is a note for the ITD input variable description that says: " When
you adjust the ITD, you are telling the model the conditions under which the system will achieve the thermal efficiency that
you've specified. If you increase the ITD, you should also modify the thermal efficiency (and/or the design ambient
temperature) to accurately describe the design-point behavior of the system. The off-design penalty in the modified system will
follow once the parameters are corrected."

Parasitics

SAM uses the
design parasitics value shown for sizing calculations before simulations. The hourly simulation includes a separate
set of calculations to determine the actual parasitic losses during simulation. Here's how the design values you see on the
Parasitics page are calculated



PAR_bop = PAR " F " (C_0 + C_1 + C_2) " P_pb



PAR_bop = Total design balance-of-plant parasitics (shown as "BOP")

PAR = Balance of plant parasitic (MWe/MWcap)

F = Factor

C0, C1, C2 = Coeff 0, Coeff 1, and Coeff 2

P_pb = Design Turbine Gross Output (MWe) from the Power Cycle page

Degradation

The degradation and other factors on the peformance adjustment page apply to the output of the performance model, and are
technically part of the financial model. The 8,760 hourly output profile calculated by the performance mocel is for Year 1, so
the degradation factor does not apply to those values. You can see the effect of the degradation factor in the energy value of
the cash flow: The degradation factor applies to the annual Energy value in Years 2 and later.