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:
col_assy_hl = sca_len * (1 - ( hce_hl / ( ibn * sca_ap / sca_len ) ))
Where:
col_assy_hl_hl = heat loss at design for a collector assembly in W/m<br />
sca_len = length of SCA in m<br />
hce_hl = HCE heat loss at design in W/m<br />
ibn = reference DNI (irradiance at design from the Solar Field page) in W/m2<br />
sca_ap = SCA aperture area in m2<br />
sca_len = SCA length in m</p>
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
