[TRNSYS-users] Sebha Weather Generation

[Gassem Azzain]

Dear TRNSYS users

 

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:

Table 1


1

 

 

 

 


Location Number & Place           Location Symbol         Latitude


1SEBHA

SE

27.02

.00

.00


Monthly Average of daily Global Radiation on Horizontal (kJ/m2)


14796

16812

18936

21816

25128

24552

24552

22464

21600

18360

15300

12600


Monthly Average of daily Humidity Ratio times 10,000 (kg water/kg air)


67

65

78

86

125

150

159

162

145

108

100

73


Monthly Average of daily Temperatures (°C) 


19.1

22.4

25.9

31.6

36.7

39.2

38.6

38

35.4

31

25

25


 

When I run the project with the following parameters:

Table 2


No.

Parameter

Value and Reason

1

Temperature model, 1 = Stochastic, 2 = Cosine

1= near realistic random profile

2

Hourly radiation correction, 1 = Yes, 2 = No

1= daily autocorrelation effect

3

Use default number of seeds, 1 = Yes

1= default values  

4

Average Wind Speed (AWS) in Jan. (m/s)

4.16

5 …15

AWS Feb…...Nov., (m/s)

5.19, 5.35, 6.79, 6.22, 5.96, 5.45, 5.19, 5.04, 5.24, 3.96 

16

AWS Dec. (m/s)

3.96

7

Altitude at Sebha city (m)

435 above sea level


 

I got two questionable results:

 

1st - 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    ……?

 

2nd – 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 :

Gh must equal (Gbh + Gdh), where: Gh is the Global Horizontal Irradiance, Gbh is the Beam Horizontal Irradiance and Gdh is the Diffuse Horizontal Irradiance.

 

Table 3 the resulted Monthly Integrated Solar Irradiation (MJ/m2)


 

Global      

Direct      

Diffuse     

Jan

459

292

249

Feb

472

325

232

Mar

589

438

257

Apr

654

585

225

May

784

884

174

Jun

742

873

160

Jul

766

878

175

Aug

695

655

216

Sep

647

557

231

Oct

571

433

250

Nov

460

307

240

Dec

389

221

236


 

Note; I got the almost similar results using Type 54b with the default number of seeds in the attached project !

 

 

Thanks in advance for your help 

 

G. Azzain

g_azzain at yahoo.com





		
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