Hi Paul,

I am modelling a parabolic trough receiver of 100 m length using EES and SAM and my purpose is to compare the total useful heat output of both the models. The convection heat transfer between the HTF and inner surface of absorber wall will be total absorbed energy of the receiver (EES) which i am comparing with hourly data of Field thermal power absorbed MWt in SAM. My EES model produces an output of 249 W whereas SAM output is 1.16 MWt on June 22 12 pm.

my input is loop inlet temperature 300 C and outlet temperature of 350 C. The HTF average temperature is 325 C. SAM documentation says that temperature difference between the HTF and absorber inner surface is 2 C. I am assuming laminar flow. my HTF is Therminol VP 1 and conductivity at 325 C is 0.09 W/m.K. The diameter inner absorber is 0.066 m. Which gives convective heat transfer coefficient of 6 W/m2.K (Which is weird). My calculated mass flow rate is 0.05 kg/s. using this values convection heat transfer value is 249 W. I understand that this is not useful heat rather it is absorbed energy and after the losses it will give useful heat.

Am I messing up with some units or my approach is wrong.

I am also attaching my EES model and SAM Model with the meassage.