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Re: [TRNSYS-users] Long wave radiation in the energy balance (Type 56)

Dear Charles Luanay,
 
thanks for pointing this out!
 
I check the coding of this section, and the manual has a sign error and the drawing is wrong too:
 
Instead of

q_comb,s,o = q_c,s,o + q_r,s,o

 

it should be

q_comb,s,o = q_c,s,o - q_r,s,o

 

q_r,s,o is defined as a loss :

q_r,s,o = sigma * epsilon_s,o * (T_s,o^4 – T_fsky^4)

 
 
Cheers,
 
Marion
 
P.S.: What version of TRNSYS are you using? The section numbering of the Type 56 user’s manual looks somwhat strange to me.

   Von: LAUNAY Charles 226591 [mailto:charles.launay@cea.fr]
Gesendet: Donnerstag, 29. April 2010 10:25
An: trnsys-users@engr.wisc.edu
Betreff: [TRNSYS-users] Long wave radiation in the energy balance (Type 56)

Dear users,

 

I have a question concerning section 2.1.7. of the Type 56 user’s manual : “2. General Mathematical Description of the Thermal Model” > “2.1.7. The Long-wave radiation”.

My question is concerning the formulation of the net radiative heat transfer with surfaces in view of the outside surface, q_r,s,o. We can read :

q_r,s,o = sigma * epsilon_s,o * (T_s,o^4 – T_fsky^4)

that I understand as the net losses of the outside surface by long wave radiation.

 

However, q_r,s,o is counted as a gain in the energy balance (with a plus sign) :

q_s,o = q_comb,s,o + S_s,o

with q_comb,s,o = q_c,s,o + q_r,s,o

(see figure 3 “Surface heat flux and temperature”, section 2,1,5. for the nomenclature)

 

How does it happen? How is the heat transfer by long wave radiation really taken into account in Type 56?

 

Thanks for your help.

 

Kind regards,

 

Charles LAUNAY

 

CEA INES