Maybe some minor SAM bugs, please check

Hi Joe,
Here is the equation for the physical trough model's design point total loop conversion efficiency that appears on the Solar Field page:
Total Loop Conversion Efficiency = Loop Optical Efficiency * Loop HCE Heat Loss
The loop Optical Efficiency equation is in the Solar Field Help topic, and is calculated from the efficiency at design and optical derate values shown on the Collectors and Receivers page. We did not include the equation for the Loop HCE Heat Loss in the documentation because it is a little involved. I will try to describe it here.
HCE heat loss at design for a single collector assembly in the loop is:

Where:



The total loop heat loss is the sum of heat loss or each assembly divided by the total SCA length per loop.
Best regards,

Paul

Hi Paul,

thanks for your response.

The equation that you mentioned is slightly incorrect, which you can easily
see it by checking the units.

The unit of col_assy_hl is not W/m using this equation:

col_assy_hl = sca_len * (1 - ( hce_hl / ( ibn * sca_ap / sca_len ) ))

And as far as I understand, a dimensionless efficiency is needed
to calculate the "Total Loop Conversion Efficiency"

But slightly changing your equation, I finally got the right idea
on how to calculate the "Receiver Heat Loss Efficiency":

eta_loop_heat_loss = (1 - ( sca_len * hce_hl / ( ibn * sca_ap ) ))

Using this value, multiplied by the "Loop Optical Efficiency"
I get the same result that is displayed in the GUI
for the "Total Loop Conversion Efficiency".

Maybe there is some missunderstanding here, but the
equation for "heat loss at design for a collector assembly in W/m"
is mentioned for the Physical Trough Model in the
documentation at "Receivers (HCE)".
It is calculated by using the "fraction of field" and the manually entered
"Estimated heat losses".

Kind regards,
Joe