Hi TRNSYS users,
I was just checking the codes of Type 553 and Type 1290 (Unglazed Solar Collector models) and something grabbed my attention. When both models do the Net Long Wave Radiation Balance, they do the following:
!Account for the long wave losses from the collector surface
T_ambient_K = T_ambient+273.15
T_sky_K = T_sky+273.15
Sigma = 3.6*5.67d-08 !Stefan Boltmann constant
Net_Longwave = Sigma*(T_ambient_K**4.-T_sky_K**4.)*Emissivity/Absorptance
That is a copy/paste of Type 553.
Why the Net Long Wave is defined with the Ambient Temperature and not with the Collector Average Temperature? It doesn't make sense to me. Is there something I'm uderstanding wrong?
Bests of wishes,
Javier Vega Benavente
Universidad de Concepción, Chile.