User-defined HTF Error (Physical Parabolic Trough)

Dear Sirs,

I got below error message when I press "Simulate button" as I already define new HTF (Fill 7 different temperatures '50 - 350 with 50 C step' lines with required values; specific heat, density, dynamic viscosity ... etc)
I also checked "Header design min/max flow velocities" to be in the range of "min/max field flow velocities"
I don't clearly got what below error message mean! Could you please help me with that error. I'll be very thankful.

Best Regards,
Ahmed Abbas



"...
...
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No suitable pipe schedule found for this plant design. Looking for a schedule above 1.#R in ID. Maximum schedule is 70.00 in ID. Using the exact pipe diameter instead.Consider increasing the header design velocity range or the number of field subsections.
time 3600.00 { Physical Trough Solar Field 2 }:
No suitable pipe schedule found for this plant design. Looking for a schedule above 1.#R in ID. Maximum schedule is 70.00 in ID. Using the exact pipe diameter instead.Consider increasing the header design velocity range or the number of field subsections.
time 3600.00 { Physical Trough Solar Field 2 }:
No suitable pipe schedule found for this plant design. Looking for a schedule above 1.#R in ID. Maximum schedule is 70.00 in ID. Using the exact pipe diameter instead.Consider increasing the header design velocity range or the number of field subsections.
time 3600.00 { Physical Trough Solar Field 2 }:
The solution encountered an unresolvable NaN error in the heat loss calculations. Continuing calculations...
time 3600.00 { Physical Trough Solar Field 2 }:
The solution encountered an unresolvable NaN error in the heat loss calculations. Continuing calculations...
time 7200.00 { Physical Trough Solar Field 2 }:
The solution encountered an unresolvable NaN error in the heat loss calculations. Continuing calculations...
time 10800.00 { Physical Trough Solar Field 2 }:
The solution encountered an unresolvable NaN error in the heat loss calculations. Continuing calculations...
time 14400.00 { Physical Trough Solar Field 2 }:
The solution encountered an unresolvable NaN error in the heat loss calculations. Continuing calculations...
...
...
..."

Dear Ahmed

I am replying to your post to report receiving the same error messages, not to provide a solution. Sorry.

If I open a CSP physical trough (physical) project with PPA single owner (utility) and run the simulation with default inputs, then the simulation completes without any errors. If I change the solar field HTF to a user defined HTF, then the simulation reports many errors.

The user defined HTF data is for DowthermA and was obtained from a data sheet PDF. I did check that the correct units were used for the input to SAM. The PDF is available [checked 27 Feb 2015] at the following link: msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_0030/0901b803800303cd.pdf?filepath=/heattrans/pdfs/noreg/176-01337.pdf&fromPage=GetDoc

Regards
Edward

Hi all,

Unfortunately, in SAM 2015.1.30, the user-defined HTF option does not work properly (for both the field HTF and storage fluid). We are working to fix it and will consider sending a custom version to those of you who need it.

Best regards,
Paul.

Hello Paul,

The software version is still SAM 2015.1.30, but I have been using the Physical Parabolic Trough Model with a user-defined HTF with 68 data points at 6*C intervals, and have not been running into errors.

I happened to see this conversation while looking for discussions on HTF field flow rate/ inlet+outlet temperature problems with the Parabolic Trough Empirical Model. Getting infinite flow rate ("1.#INF") and severe temperature discontinuities (not the expected hourly discontinuities, but step-function between hours with/ without solar resource ie. 50*C jump to 256*C in morning, constant 256*C during day, and then back to 50*C at night). It is strange that is not throwing any errors either, so have I just somehow turned off error reporting by mistake? (I'm a coop student; please bear with me)

Regards,

Ming Xu

Dear Ming Xu,

Thank you for the message. We fixed the custom HTF issue in the March 2015 patch to SAM 2015.1.30. If you downloaded SAM after the update, or applied the update patch to the original version, then the model should work fine with custom fluids.

Best regards,
Paul.