[TRNSYS-users] Questions Regarding the B4_QTRANS , B6_QCOMI and heat transfer understanding in energy balance equations in balance output

[asmin aryal]

*Dear TRNSYS users,*

*I am using TRNSYS to model air conditioning system with DOAS and compare
it with radiant chilled ceiling (see fig1 in  attached file).*

 *In this process I have used BALANCE 4 - ENERGY BALANCE FOR ZONES (NTYPE
904)* for finding the energy gain in the zone.

B4_QBAL =- B4_DQAIRdt + B4_QHEAT - B4_QCOOL + B4_QINF

+ B4_QVENT + B4_QCOUP + B4_QTRANS

+ B4_QGINT + B4_QWGAIN + B4_QSOL

+ B4_QSOLAIR                    [kJ/hr]



>From this I have *generated B4_QTRANS which “is transmission into the
surface from inner surface node (might be stored in the wall, going to a
slab cooling or directly transmitted)”* as per TRNSYS manual. I printed
“B4_QTRANS”, which is the heat flux in the zone via the building envelope
as per my understanding.

And

 I also used *BALANCE 6 - ENERGY BALANCE FOR SURFACES (NTYPE 906) *for
finding heat flux in the room via the surface.

B6_BAL = - B6_DQWALLdt – B6_QCOMI + B6_QCOMO + B6_QRADGI

+ B6_QRADGO - B6_QALG           [kJ/hr]

 ;

*B6_QCOMI combined heat flux to inside (going into zone+; going into wall
-)*

I generated the heat flux inside the room from all the surface (6 surfaces)
and summed them up and let this be *Total_wall_in*.

Now, from this I have some questions.

My first question is

(1) “*what is the difference between **B4_QTRANS and the sum of – B6_QCOMI
from all the surfaces (Total _wall_in)?”* Shouldn’t they be same? (plot as
fig 2 in attached file)

I tried to see the difference between the heat flux from the zone balance
*B4_QTRANS* and *Total_wall_in*(sum of B6_comin from all the surfaces) and
got the following plot.





My second question is

2)   For the surface balance I plotted *B6_QCOMI* , *B6_QRADGI*, inside and
outside temperature of the surface. I calculated the heat flux via Q =
U(TD) and plotted it as well. The plot is shown in fig 3 of attached files.



* Should b6_comin_1 and Q_N be equal or not. What are the factors that make
them different?*
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