Heat loss analysis of HCEs

Hi,

I have conducted a comparison of the heat loss of the different receiver models and conditions (New , H2 in annulus, Broken glass and Vacuum Lost) available in SAM´s database. To do that I used the formula for calculating the "HCE heat losses (W/m)" assuming:

- the solar field inlet and outlet temperatures are equal (Tsfout=Tsfin= T absorber )
- wind speed ref. =0.59 m/s
- DNI ref. = 800 W/m2
- Ambient temp. ref. =25 ºC

The results are uploaded.

What I could observe is that every model has more or less similar heat losses depending on its condition except for the 2008 Schott PTR70 in the "Vacuum loss" and "H2 in annulus" cases which seem out of the range. Furthermore, for this model the heat losses caused by H2 in annulus are less than the ones caused by vacuum loss, while for the rest of models is the other way around. In fact, the "2008 Schott PTR70 Vacuum loss" case fits better with the Hydrogen case of the other models and the "2008 Schott PTR70 Hydrogen" case fits better with the vacuum loss case of the other models. In this way, is there any chance that the heat loss coeffcients are swapped in the 2008 Schott PTR70 for these cases?

According to this document ( www.nrel.gov/docs/fy09osti/45633.pdf ), the database is correct...

Thank you in advance for your help.