Calculation of EOT in physical trough model

Hello Paul,

When i tried to calculate the EOT(equation of time) according to your technical manual of physical trough model, i found some difference between your formula and the formula from other papers, your formula is:
EOT_sam = 9.2*(0.000075+0.001868*COS(-0.032077*SIN(-0.014615*COS(2*-0.04089*SIN(2*)

while the other is :

EOT_else = 229.18*(0.000075+0.001868*COS(-0.032077*SIN(-0.014615*COS(2*-0.04089*SIN(2*)

and the B is the same formula, i want to know why? and which one is the correct one?

Thanks and best regards
Joey

Hi Joey,

You can see the actual equation in the physical trough model's source code, sam_mw_trough_Type250.f90, which you can find in your SAM installation folder (c:\SAM\2013.9.20\exelib\trnsys\source by default). The equation is on Line 809:

EOT = 229.2 * (0.000075 + 0.001868 * COS( - 0.032077 * SIN( - 0.014615 * COS(B*2.0) - 0.04089 * SIN(B*2.0))

That is different than Equation 2.27 in the reference manual. I suspect the error in the manual is a typo where the first two digits of 229.2 were omitted.

Best regards,
Paul.

Hi Paul,

Ok, i see, thank you.

Best regards
Joey

Hi Paul,

I can not found the physical trough model's source code, for example sam_mw_trough_Type250.f90, in SAM 2015.6.30. Are these codes containing in this version? If it is not contained, how can i found them? Thanks.

Best regards,
Jack.

Dear Jack,
Please see this post for an answer to your question.
Best regards,

Paul.

Dear Paul,

Thanks for the answer and help.

Best regards,
Jack.