[TRNSYS-users] Surprising phenomenon with Type 67

[Diego A. Arias]

Hi David,

I would like to add the following comments to Dave's answers.
> I've realised the following experience: I've used Type67 without 
> shadings (angular height equal to 0°) and Type34 without shadings 
> (overhang projection and wingwalls projection equal to 0).
> Direct and diffuse radiation should not change. Actually, diffuse 
> radiation vary. It's sometimes even greater after Type34 than before!
You got me very worried with this possible bug. I am attaching a very 
simple project. I used the types 15 and 67, in your project; I made two 
modifications: the slope in Type15 was set to zero in the file that you 
sent us; I set it to 90, and I got rid of the equation component.  I 
think that Type67 is working fine.
> Another phenomenon : I've tried the experience with a "detailed" 
> angular obstruction data file (24 surface angles) and a simplified one 
> (4 surface angles): it turns out that with the simplified obstruction 
> data file, diffuse radiation after Type34 varies with a greater 
> amplitude.
I agree with you on this topic.  Until we release a new version, I would 
recommend that your shading mask is more detailed than just a few angles.

> Finally, questions about basic use type 67 follow :
> 5 - I cannot use more than 20 orientations with type 67 eventhough the 
> max is 40 in the proforma. Can you help me?
In the attached example, I used 37 orientations.
> 6 - Besides, I did not manage to use 2 type 67 at the same time. I 
> made a few tests using 2 type 67 and it always generate an error of 
> reading of the external file, while both types 67 work alone. Is there 
> a bug somewhere?
>
Regards,

Diego

-- 
Diego A. Arias
TRNSYS Coordinator
Solar Energy Laboratory
University of Wisconsin - Madison
1500 Engineering Drive
Madison, WI 53706
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