[TRNSYS-users] Type 34 - Wrong calculation of beam fraction?

[Marko Brandes]

Thank you, I will stay tuned...
Best regards,
Marko Brandes.

-----Ursprüngliche Nachricht-----
Von: Matt Duffy [mailto:duffy at tess-inc.com] 
Gesendet: Samstag, 31. Oktober 2009 13:02
An: Marko Brandes
Cc: Timo Sengewald
Betreff: Re: AW: [TRNSYS-users] Type 34 - Wrong calculation of beam fraction ?


Dear Marko Brandes,

I apologize for the delay. Thank you for bring this to our attention. I
tried running the simulaiton with the Potsdam TMY2 file and saw the
strange results with that output, Direct Beam Fraction. Please note that I
also decreased the timestep to 0.03125 hr to increase the resolution. This
phenomenon occurs when there is no incident beam radiation, yet there is
diffuse radiation. This makes me think that perhaps somewhere in the
source code there is a division by zero (beam radiation) that is setting
this value to zero to avoid the 'Not a Number'. I will walk through the
source code with the editor of this component and get back to you with any
significant results.

Best regards,

Matt Duffy


----- Original Message -----
From: "Marko Brandes" <marko.brandes at bls-energieplan.de>
Sent: Tue, October 20, 2009 8:04
Subject:AW: [TRNSYS-users] Type 34 - Wrong calculation of beam fraction ?


Dear Matt,
thanks für digging into it... Attached to this mail you will find three
files
(weather, tpf and results). You can find the results in question at hour
2118 to
2133.
I checked again and again but it stays that way.

Greetings

BLS Energieplan GmbH
i. A. Marko Brandes

Elsenstraße 106
D-12435 Berlin
Tel.: +49 30 53 32 81-0
Fax.: +49 30 53 32 81-40
_________________________________________________________________
BLS Energieplan GmbH
Sitz der Gesellschaft: Berlin
Geschäftsführer: Christoph Lange, Wolfgang Sturm
Registergericht: Amtsgericht Berlin-Charlottenburg, HRB-Nr. 32021

-----Ursprüngliche Nachricht-----
Von: Matt Duffy [mailto:duffy at tess-inc.com]
Gesendet: Montag, 19. Oktober 2009 20:34
An: Marko Brandes; trnsys-users at engr.wisc.edu
Betreff: Re: [TRNSYS-users] Type 34 - Wrong calculation of beam fraction ?

Dear Marko,

I just ran a simulation with Type34 - very similar to your description -
and got very reasonable results.  Perhaps if you could share location and
time information, I could try and recreate the simulation, or simply the
*.tpf.
Thanks,

Matt


----- Original Message -----
From: "Marko Brandes" <marko.brandes at bls-energieplan.de>
Sent: Fri, October 16, 2009 7:25
Subject:[TRNSYS-users] Type 34 - Wrong calculation of beam fraction ?

Hello TRNSYS users,
using Type 34 (overhang and wingwall shading) with long extensions I ran into
strange results.

>>> The scenario: <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
- Receiver: H = 1m / W = 1m / receiver azimuth = 0 (south)
- Overhang: depth s = 1m / gap d = 0 / extension left e1 = 2m / extension
right e2 = 2m
- Wingwalls: none

>>> Expected results for beam fraction: <<<<<<<<<<<<<<<<<<<
The output beam fraction should be only dependent on receiver an overhang
geometry,
so the results should look like:
- sunrise: starting close to 1, continuously falling
- noon: lowest beam fraction (max. beam shading)
- sunset: continuously rising, ending close to 1

>>> Results from Type 34 for some test data <<<<<<<<<<<<<<<<
|row        |hour        |zenith        |azimuth        |beam fraction
1        6        87,5                -93,5                0,000
2        7        85,2                -88,3                0,791
3        8        76,2                -76,2                0,366
4        9        67,6                -63,2                0,086
5        10        60,0                -48,8                0,124
6        11        54,1                -32,4                0,142
7        12        50,5                -13,9                0,149
8        13        49,8                5,6                0,151
9        14        52,2                24,7                0,146
10        15        57,2                42,0                0,134
11        16        64,2                57,2                0,106
12        17        72,4                70,7                0,164
13        18        81,3                83,1                0,615
14        19        87,5                91,1                0,000

>>> Conclusion: <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
Have a look at row 4 and row 5: Type 34 calculates a rising (!) beam
fraction even
though the turning points for zenith and azimuth are not reached yet.
Furthermore the beam fraction rises aftwerwards (less shading) until 1
p.m. This is
even more disturbing as shading should increase with falling zenith angles.

Can someone confirm this or knows what is wrong here?

Greetings from Berlin

BLS Energieplan GmbH
i. A. Marko Brandes

Elsenstraße 106
D-12435 Berlin
Tel.: +49 30 53 32 81-0
Fax: +49 30 53 32 81-40
____________________________________________________
BLS Energieplan GmbH
Sitz der Gesellschaft: Berlin
Geschäftsführer: Christoph Lange, Wolfgang Sturm
Registergericht: Amtsgericht Berlin-Charlottenburg, HRB-Nr. 32021


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