[TRNSYS-users] Type 19 Sol Air temperature

[Charron, Rémi]

Hello,

I read the mathematical model of Type 19 single zone and have a question related to the calculation of Sol Air Temperature (Tsa):  

The model uses the convective heat transfer coefficient calculated from the wind speed (hc,o=5.7+3.8*Vw) to calculate Tsa.  However, this convective heat transfer coefficient is not used in the model to determine the film coefficient.  When calculating heat transfer, and TF, the model uses a constant, combined convective and radiative heat transfer coefficient of 16.95 W/m2K. The question is, why would the model use hc,o calculated from wind velocity to determine Tsa when the model itself uses a constant ho of 16.95?  Won't this introduce error in the use of Tsa to represent the effective absorbed solar radiation?  The only way to make it consistent would be to use a constant Vw of 2.96m/s which would result in hc,o=ho.

Thanks,

Rémi