Solar multiple for physical PTC

Dear Sirs,

I am using SAM 2016 .3.14. I am trying to simulate a physical parabolic trough. For a gross power output within 100 MW with 100 bars as turbine pressure. By using a solar multiple above 2.5 the following message appears:

"No suitable pipe schedule found for this plant design. Looking for a schedule above 81.44 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 collector used is SkyFuel SkyTrough (with 80-mm OD receiver)
The receiver used is Schott PTR70 2008
The HTF is Therminol VP-1

One more thing... If i use a similar sitting (EuroTrough ET150 as a collector) with SAM 2014.1.14 the message is disappear! In fact i can reach 3.4 solar multiple.

Could you please explain why I am facing this error.

Attached SAM file.

Best regards.

Shaker

Dear Shaker,
Please see Section 2.5 of the Physical Trough Reference Manual for a description of the piping model in SAM's physical trough model. Table 9 shows the range of pipe sizes SAM uses in the model. The manual is available on the Performance Model Documentation page:
sam.nrel.gov/performance
SAM does its best to determine appropriate piping sizes for different parts of the solar field. The message about no suitable piping sizes suggests that there may be a problem with your system design given your design assumptions.
I ran your case using the TMY2 weather file for Phoenix, Arizona, and it did not generate the message about pipe schedule.
Best regards,

Paul.

Dear Pual

Thank you for your kind concern.
Which solar multiple have you used?
Could you please run the file again using solar multiple 3.4 or any value greater than 2.7.
Best regards
Shaker.

Dear Shaker,

When I use a solar multiple of 3.4, then I get the message you describe, indicating that the system with such a large solar field compared to the power cycle capacity requires piping with an inner diameter greater than the 70 inch maximum value allowed by SAM.

The message is indicating that for such a system, you need to make design changes, such as the ones suggested in the message.

Best regards,
Paul.

Dear Paul,

Thank you so much for your kind concern.


Shaker