Field Thermal efficiency - Linear Fresnel MS - CSP

Dear Paul,

Could you please guide me on the physical meaning of the variable "Field thermal efficiency" in the Linear Fresnel Molten Salt model?
Shouldn't the value of this variable be between 0 and 1? Since it is an efficiency, right?

Please find attached a picture of the hourly results in the simulation. Thank you very much!

Miguel

Hi Miguel,

Those results seem to indicate something wrong with the inputs. The field thermal power absorbed should be positive, and as you note, the field thermal efficiency should be between zero and one.

Would you mind attaching the .sam file that generated these results?

Best regards,
Paul.

Hi Paul,

Thanks for your answer. Please find attached the sam input file. I'm using one specific weather file "Andasol.csv" (you will find it attached too)

You can find values of thermal eff. outside [0,1] also in the default case. The following results were obtained using the deafult model Linear Fresnel with MS - in Dagget (I have also attached the file).

Hi Miguel,

I think the problem is with the data in the Andasol.csv file. If you change the weather file in the Andasol_Fresnel case to daggett, the results look more reasonable.

The Andasol.csv weather file has a column for Dew Point Temperature, but the values are all zeros. The table in SAM's Help topic "Weather Data Elements" (under "Weather Data" in the table of contents) shows what weather data is required for the CSP models, including linear Fresnel.

Best regards,
Paul.

Hi Paul,

Thanks for the answer, I corrected the weather data.  Could you please post the definition of "Field thermal efficiency"? Which is the eq used to calculate this variable? 
Do you know where I can find the definition of the hourly data output variables?  I tried looking in the help and the manual but I cannnot find them. Thanks very much and merry Christmas!  Miguel

Hi Miguel,

Unfortunately, we do not have a complete list of definitions for all of the CSP hourly outputs in SAM.

You can find publications describing the models here:

sam.nrel.gov/concentrating-solar-power/csp-publications.html

For the linear Fresnel molten salt model, the field thermal efficiency is very close to field thermal power produced / field thermal power absorbed.

I will ask the CSP team for a more precise definition of the field thermal efficiency.

Best regards,
Paul.