[TRNSYS-users] QUA and Qheat in a cube
Joana Margarida Vieira Batista
joana.batista at tecnico.ulisboa.pt
Tue Jun 24 07:40:11 PDT 2014
Dear Trnsys users,
I have a cubic building with 64 m^3. The cube doesn't have any incident
radiation, and its walls are only made of concrete (without windows and
doors). The temperature outside the cube was set to 10 ºC. The cube
doesn't have occupation, ventilation or infiltration. The only thing
inside the cube is a radiator with constant value 3000 kJ/hr with no
I tried to use the internal calculation for the convective heat
transfer coefficient, calculated with the constants given in
"properties" of trnbuild. I defined as output Qheat (that gives me 2999
kJ/hr), QUA=UAdT (static UA transmission loss of the zone, that gives me
5600 kJ/hr) and also Qcsurf (total convection to air from all surfaces
within zone, that gives me 2600 kJ/hr).
Shouldn't the values be similar?
Is there anything else I should take into consideration?
If I look to the parameters for internal calculation of heat transfer
coefficients I have a constant in kJ/(m^2K) and an exponential. The heat
transfer coefficient is given by "constant*(∆T)exp", so how does trnsys
get units in (W/m^2K) with this expression?
Thanks in advance,
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