Ciaci
Mechanical
- Jul 11, 2015
- 58
Hi all,
I am trying to demonstrate that a vacuum tube solar collector CPC have not caused the fire on the roof of wood structure. So I am trying evaluate the thermal condition of the plant, in particular the temperature of the absorber part of the collector. I found the dry bulb air temperature (it was 6°C) and the radiation on a tilt surface that is 120 W/m^2 (it was early morning).
Since the trasmission coefficient multiplicated for the absorption coefficient is 0,7, the absorbed radiation energy is 0,7*120=84 W/m^2.
Then I thought to use the Stefan-Boltzman low,
Eass = (5,67*10^-8)*(Tabsorber^4-Tair^4)
Where
Eass is absorbed radiation energy
Tabsorber is the temperature of the absorbe
Tair is the already measured themeperature of the air
So i found the Tabsorber since Eass and Tair were already known.
Do you think that this method could be right? I personally have some doubt since I have not considered the temperature of the glass collector face, and I have not considered the convection.
Do you have any advice? Have you ever heard of fire caused by thermal collectors?
Thank you so much
I am trying to demonstrate that a vacuum tube solar collector CPC have not caused the fire on the roof of wood structure. So I am trying evaluate the thermal condition of the plant, in particular the temperature of the absorber part of the collector. I found the dry bulb air temperature (it was 6°C) and the radiation on a tilt surface that is 120 W/m^2 (it was early morning).
Since the trasmission coefficient multiplicated for the absorption coefficient is 0,7, the absorbed radiation energy is 0,7*120=84 W/m^2.
Then I thought to use the Stefan-Boltzman low,
Eass = (5,67*10^-8)*(Tabsorber^4-Tair^4)
Where
Eass is absorbed radiation energy
Tabsorber is the temperature of the absorbe
Tair is the already measured themeperature of the air
So i found the Tabsorber since Eass and Tair were already known.
Do you think that this method could be right? I personally have some doubt since I have not considered the temperature of the glass collector face, and I have not considered the convection.
Do you have any advice? Have you ever heard of fire caused by thermal collectors?
Thank you so much