[TRNSYS-users] Long wave radiation and internal convection

[Marion Hiller]

Dear Ivan Flores Abascal,

yes, in TRNSYS 17 you can use NTYPE 110 - Energy gain/loss by longwave 
radiation exchange with other surfaces

Best,

Marion

Dipl.-Ing. Marion Hiller 
TRANSSOLAR: KlimaEngineering - Technologien für energieeffizientes Bauen 
und Nutzerkomfort in Gebäude 
Munich - New York - Stuttgart + 49.711.67976.0 

Transsolar Energietechnik GmbH, Curiestrasse 2, 70563 Stuttgart 
Amtsgericht Stuttgart - HRB 23347, Steuernummer 99073/00911, USt-IdNr.: 
DE152272639
Geschäftsführer: Dipl.Ing. Matthias Schuler, Dipl.Ing. Thomas Auer, 
Dipl.Phys. Stefan Holst, Prof. Dipl.-Ing. Bleicher 

 

-----Ursprüngliche Nachricht-----
Von: Ivan Flores Abascal [mailto:ivan.flores at ehu.es] 
Gesendet: Montag, 27. Februar 2012 23:13
An: trnsys-users at cae.wisc.edu
Betreff: [TRNSYS-users] Long wave radiation and internal convection

Dear Sir / Madam:

I would appreciate if you could clarify some doubts about how does  
Type 56 treat the heat exchanged by convection and long wave  
radiation. In the Type 56 user' manual appears:
The long-wave radiation exchange between the surfaces within the zone  

and the convective heat flux from the inside surfaces to the zone air  
are approximated using the star network given by Seem...

The star temperature can be used to calculate a net radiative and  
convective heat flux from the inside wall surface:
Q_comb,s,i = Q_c,s,i + Q_r,s,i = (T_s,i  T_star) / (R_equiv,i  
A_s,i)"

I assume that Q_comb,s,i is equal to QCOMI (NTYPE 19). Is it correct?

If h_i is the internal convection coefficient, can I calculate the  
convective heat flux from surface i as:  Q_c,s,i = h_i  A_s,i   
(T_s,i  T_star) ?

I have solved the radiation exchange by the view factor method and I  
have compared the results with the value obtained as Q_r,s,i = QCOMI   

Q_c,s,i . The results are quite different so I think that difference  
is not for being an approximate method. Is there anything I  
misunderstood?

Is there any NTYPE to obtain the long wave radiation from a surface  
separately?

Thank you very much for your help

Ivan Flores






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