[TRNSYS-users] Type 56 radiation with wall type "Boundary"

4 posts / 0 new
Last post

Hi all,
I am trying to model a small 0.5 m cubicle test cell with opaque walls,
placed inside a climate chamber with a step increase of the air
temperature.
I use Type 56 with all six walls with wall type "Boundary" and the
temperature step function as the boundary. However the air temperature
of the test cell increases at a slower rate than from the experiment,
and I wonder if longwave radiation from the external cubicle walls to
the walls of the climate chamber somehow can be included in the
simulations?

Best regards
Christian Krintel

=?UTF-8?Q?Christian_Herl=C3=B8v_Krintel?='s picture
Joined: 2016-04-05
Reputation: 0

Dear Christian,

longwave radiation of external walls is included in Type 56. Input 3 (T_sky) of Type 56 defines the temperature of the surrounding for longwave radiation exchange.

So use measured surface data from the climate chamber as Input for T_sky.
Notice: This approach is only valid for climate chamber walls with an emissivity close to 1.

Best regards
Jakob

_________________________________________________________________________________________________

Jakob Merk
TRNSYS Software Team

Transsolar Energietechnik GmbH
Curiestra?e 2
70563 Stuttgart
Fax: ?????? +49 711 67976-11
Email: ?? hotline at transsolar.com
Web:??? ??www.trnsys.de

-----Urspr?ngliche Nachricht-----
Von: TRNSYS-users [mailto:trnsys-users-bounces at lists.onebuilding.org] Im Auftrag von Christian Herl?v Krintel
Gesendet: Freitag, 11. M?rz 2016 09:12
An: trnsys-users at lists.onebuilding.org
Betreff: [TRNSYS-users] Type 56 radiation with wall type "Boundary"

Hi all,
I am trying to model a small 0.5 m cubicle test cell with opaque walls, placed inside a climate chamber with a step increase of the air temperature.
I use Type 56 with all six walls with wall type "Boundary" and the temperature step function as the boundary. However the air temperature of the test cell increases at a slower rate than from the experiment, and I wonder if longwave radiation from the external cubicle walls to the walls of the climate chamber somehow can be included in the simulations?

Best regards
Christian Krintel
_______________________________________________
TRNSYS-users mailing list
TRNSYS-users at lists.onebuilding.org
http://lists.onebuilding.org/listinfo.cgi/trnsys-users-onebuilding.org

hotline's picture
Offline
Joined: 2016-04-05
Reputation: 0

Dear Jacob,

Thank you for your reply. You describe that longwave radiation is
included in Type 56 for external walls, but how about boundary walls
where I prescribe an air temperature on the back side?

Best regards
Christian

hotline skrev den 2016-03-11 15:28:

=?UTF-8?Q?Christian_Herl=C3=B8v_Krintel?='s picture
Joined: 2016-04-05
Reputation: 0

Dear Christian,

Sorry, I missed that information regarding wall type "boundary".
For Boundary Walls, no radiative exchange on the back side is calculated.

Best
Jakob

_________________________________________________________________________________________________

Jakob Merk
TRNSYS Software Team

Transsolar Energietechnik GmbH
Curiestra?e 2
70563 Stuttgart
Fax: ?????? +49 711 67976-11
Email: ?? hotline at transsolar.com
Web:??? ??www.trnsys.de

-----Urspr?ngliche Nachricht-----
Von: TRNSYS-users [mailto:trnsys-users-bounces at lists.onebuilding.org] Im Auftrag von Christian Herl?v Krintel
Gesendet: Freitag, 11. M?rz 2016 15:51
An: TRNSYS users mailing list at OneBuilding.org
Betreff: Re: [TRNSYS-users] Type 56 radiation with wall type "Boundary"

Dear Jacob,

Thank you for your reply. You describe that longwave radiation is included in Type 56 for external walls, but how about boundary walls where I prescribe an air temperature on the back side?

Best regards
Christian

hotline skrev den 2016-03-11 15:28:
_______________________________________________
TRNSYS-users mailing list
TRNSYS-users at lists.onebuilding.org
http://lists.onebuilding.org/listinfo.cgi/trnsys-users-onebuilding.org

hotline's picture
Offline
Joined: 2016-04-05
Reputation: 0