Learning Forum

[gopalakrishna.gangisetty]

I have a skylight for roof top modeled with two different materials

1.        regular window glass which is opaque for longwave radiation.

2.       ZnS glass is 75% (0.75) transparent to the longwave radiation.

 

I used Discrete Ordinates (DO) Model since it is the only model with 'semi-transparent' and 'non-gray' mode. 

I made four bands, 0 – 4, 4 – 8, 8-14, 14-50 µm in Model - Radiation - Number of Bands,

Let’s assume that :

Topside window glass and top side ZnS glass are exposed to ambient surroundings at 296 K

bottom side window glass and bottom side ZnS glass are located inside building space at 298 K

Now, I turned on solar calculator,

• Input the data such as Latitude, longitude, time, and data, (this is fine).

Direct solar irradiation as 660 W/m2

Diffuse solar irradiation as 125 W/m2

Then, I turned on solar BC options for both top side window glass (opaque for long wave radiation) and top side ZnS glass (75% transparent for long wave radiation), 

Question: for top side window glass, direct and diffuse irradiation values are already calculated by Ansys software?  But, to obtain direct and diffuse irradiation for top ZnS glass (tau = 0.75)?

Direct irradiation values for top ZnS multiply with 0.75 ? can you please clarify? 

I think, Diffuse fraction = Diffuse irradiation/(direct irradiation + diffuse irradiation).

Now, one more question is, based on top side window boundary conditions - 

For bottom side window glass, for bottom side ZnS glass, I want to set

Direct irradiation = ? Perhaps it is zero in all bands´(1 to 4)

Diffuse irradiations = band 1 to band 4 = (need help here).

Diffuse fraction= band 1 to band 4 = (need help here). 

Please find the attached screen shots for better idea.

Thank you in advance, evferyone ! 

[Rob]

Duplicate  https://innovationspace.ansys.com/forum/forums/topic/help-needed-solar-calculator-solar-bc-boundary-conditions/

[gopalakrishna.gangisetty]

Dear Sir,

I am sorry for duplicate the same question, my sincere apologies. 

But, I would request you or someone can help me to understand the boundary conditions please. 

Thank you 

[Rob]

It's in the system - any unanswered questions are flagged and will be answered.