Re: about the sky temperature

[Rauch-Muenster@xxxxxxxxxxx (Dr. Karl-Christian Rauch)]

cher monsieur,
 
in his master of science thesis (1976)
  Development of transfer function load models and their use in
  modeling the CSU solar house I
Michael James Pawelski refers to a formula
of Swinbank (source: Duffie,J.A., and Beckman,W.A., Solar Energy Thermal Processes)
where the sky temperature is represented to be
 
  Tsky = 0.0552 * Tamb ^ 1.5 (both temperatures in Kelvin)
 
This coincidences with the fact which had been said by Bengt Perers.
 
In the annex you will find "my" xls-sheets, where i had sorted your temperatures
according to the ambient temperature (rising temp.).
 
As you will see the total graph (all your values) is separated into two ranges
one until 16 degree celsius and another starting from 18 degree celsius.
 
If you look for the values between a small range say 10 until 11.95 degree celsius
you can observe a heavy oscillating from one value to the other. It seems to
be generated by a base value plus minus a small random value.
 
Please have a look to the source of that TRNSYS type.
 
Kind regards
Karl-Christian Rauch
 
 

----- Original Message ----- 
From: helmi ben rejeb 
To: trnsys@relay.doit.wisc.edu 
Sent: Wednesday, February 26, 2003 12:13 PM
Subject: about the sky temperature



Dear Trnsys users.
I’m working with the type 56, in the use of the type 69 for the 
calculation of the sky-temperature, I found strange values of this 
temperature. I have attached an excel file containing the sky-
temperature-values, calculated with the type 69 and the ambient 
temperatures.
First, the temperature change sharply at the early morning. Is it 
the influence of the solar radiation? Look at the values between the 
hours 79 and 80.
Second, the sky temperature should be very low in the summer at 
night, because the sky is very clear and there is no clouds and yet 
the sky-temperature is close to the ambient-temperature.
I will be grateful if some one can help me.
Thank you in advance.






Ing. Helmi Ben Rejeb
Ecole Nationale d'Ingénieurs 
de Tunis, BP 37, le 
bélvédère, 1002 Tunis, 
Tunisia.
Get your Free E-mail at http://gi2.zzn.com
___________________________________________________________
Get your own Web-based E-mail Service at http://www.zzn.com