[TRNSYS-users] I: TYPE 56 - chilled ceiling

[hotline]

Bettina,
a.) the Type 56 building model so far is not a geometric model thus geometric distribution of radiation exchange between walls is by surface area weightening only.
b.) you cannot define the emissivity
 
c./d.) thank you for finding this bug in the TRNBuild Interface, we will correct this for the next update.
In the "Properties" table the correct expressions must be:
 
constant chilled ceiling, if   (Tsurfceiling-Tairceiling)  <  0         3.888
exponent chilled ceiling, if   (Tsurfceiling-Tairceiling)  <  0        0.31
 
and
 
constant heated ceiling, if   (Tsurfceiling-Tairceiling)  > 0         7.2
exponent heated ceiling, if   (Tsurfceiling-Tairceiling)  > 0        0.31
 
The unit of the resulting alfa_conv is kJ/(h*m^2*K). So of course the constant has to have another unit which however includes K to the power of the exponent. What we wanted to make clear is that the constant has to be a value which includes the capacity given in TRNSYS units (kJ/h)  We will have t think of how to explain this better in TRNBuild.
 
e.) yes
 
f.) the sign of Qcomo and Qcomi is giving the direction of the heat flow:
QCOMI combined heat flux to inside (going into zone+; going into wall -)

QCOMO combined heat flux to outside (going to outside-; going into wall +)

 
I hope this can help.
 
Monika
 
 
 

	-----Urspr¨¹ngliche Nachricht-----
	Von: Bettina Nocke [mailto:bettina at dream.unipa.it]   
	Gesendet: Donnerstag, 14. Juni 2007 10:41
	An: trnsys-users at engr.wisc.edu
	Betreff: [TRNSYS-users] I: TYPE 56 - chilled ceiling
	
	

	 

	 

	
  _____  


	Da: Bettina Nocke [mailto:bettina at dream.unipa.it] 
	Inviato: mercoled¨¬ 13 giugno 2007 20.08
	A: 'trnsys-users at engr.wisc.edu'
	Oggetto: TYPE 56 - chilled ceiling

	 

	Dear TRNSYS User¡¯s,

	 

	 

	using the Integrated Model for Chilled Ceiling Panels I¡¯m not able to resolve some problems. My questions are:

	 

	a) if I define only internal walls (test room for cooling panels), how let I know the model the geometrics of the room (perpendicular walls etc.)? 

	 

	b) can I define the emissivity of the internal surfaces? (prEN 14240 stipulates an emission rate at least 0.9)

	 

	c) the coefficients const and exp (Properties) are done for the condition Tsurfceiling ¨C Tairceiling < 0. but so I have to apply the exponent for a negative value. It means only the amount, without sign? ¨C 

	 

	d) For calculate ¦Áconv with equation 6.3.2-157, the constant is done in KJ/m^2K, but multiplying with delta T, remains KJ/m^2. I¡¯m not sure if I understand rightly the units, so I have a problem to change the default values (for achieve in the simulatione the same results as the test of radiant panels). 

	 

	e) is the same model suited to be used for a heating ceiling? The results of my simulation seems a little bit strange¡­

	 

	I want to add another question at the mail of yesterday:

	In the energy balance output, in the cooling case, gains (SQCSURF) AND energy flows to other surfaces (QCOMO, QCOMI) have a negative value. This is a little bit confusing for me, for understand the convective and the radiative part of energy changes (setting identical all boundary temperatures).

	 

	 

	Can anybody help me? Thanks very much.

	 

	Bettina

	 

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