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Re: [TRNSYS-users] Sebha Weather Generation
Gassem,
I used Type 54a to generate meteorological year depending on average
meteorological data of weather records at Sebha city at the south of
Libya as shown below:
...
I got two questionable results:
1^st - *higher than normal daily ambient temperatures*, and my question
here is regarding, what average of daily monthly ambient temperatures I
should use in table 1 above, is it the average of Maximum daily monthly
ambient temperature or the average of Minimum daily monthly ambient
temperatures or the average of both such as:
Average daily monthly ambient Temp. = (Average Tmax + Average Tmin)/2 ……?
The values you need to provide are monthly averaged temperatures, so it
is none of the options you propose if I am right. The last option would
be the closest to what you need if you assume the average temperature
during a day is the same as (Tmin+Tmax)/2.
The concept of Monthly average daily "something" is only used for
radiation in Type 54 (because you average the daily sum of irradiation
levels).
2^nd – *the sum of Beam and Diffuse Irradiation give not the Global
Irradiation as it must be…? and* *The values of Beam (direct)
irradiation are higher than the values of Global irradiation during
summer months ( the Table 3 below contains the resulted monthly
integrated values of Solar Irradiation),* my question is where is the
mistake…..? since :
/G_h must equal (G_bh + G_dh ), where: G_h is the Global Horizontal
Irradiance, G_bh is the Beam Horizontal Irradiance and G_dh is the
Diffuse Horizontal Irradiance./
I am assuming you are using outputs 7-9 of Type 54. Output 7 is the
direct normal radiation (Gbn), not the direct (beam) horizontal
radiation (Gb). So it should not be equal to (global horizontal -
diffuse horizontal). If you want the beam horizontal radiation (Gb) you
have to substract output 9 (Gd, diffuse horizontal) from output 7 (G,
global horizontal). Or you can use Type 16, which you always need to do
if you want to use sub-hourly time steps or calculate the radiation on a
tilted surface.
Kind regards,
Michaël Kummert
--
_________________________________________________________
Michaël Kummert
Solar Energy Laboratory - University of Wisconsin-Madison
1303 Engr Res Bldg, 1500 Engineering Drive
Madison, WI 53706
Tel: +1 (608) 263-1589
Fax: +1 (608) 262-8464
E-mail: kummert@engr.wisc.edu
SEL Web Site: http://sel.me.wisc.edu
TRNSYS Web Site: http://sel.me.wisc.edu/trnsys