RE: how to use incident angle modifiers

["Timo Sengewald" <timo.sengewald@xxxxxxxxxxxxxxxxxx>]

Michaël,

thank you for your help.

I found b0 and b1 for my flat plate collector using the MS Excel
solver.

The K_diff I wrote about is the modifier for diffuse radiation. I
think
the types 1 and 71 are calculating it by themselves.

The detailed test protocol for the tube collector I want to use
contains
the IAMs for the transversal and longitudinal angles 30, 45, 50, 60
and 70
degrees. There are 10 values: 5 transversal, 5 longitudinal. But it
seems
that the subroutine DATA needs 5*5=25 values.

Could You (or any other) help me once more?

Best regards,

Timo Sengewald

------------------------------------------
Phönix Sonnenwärme AG
Am Treptower Park 28-30
D-12435 Berlin, Germany
e-mail: timo.sengewald@sonnenwaerme-ag.de
www.sonnenwaerme.ag
Tel.: +49-(0)30-53 00 07-237
Fax.: +49-(0)30-53 00 07-17
------------------------------------------
-----Ursprüngliche Nachricht-----
Von: owner-trnsys@relay.doit.wisc.edu
[mailto:owner-trnsys@relay.doit.wisc.edu]Im Auftrag von Michaël
Kummert
Gesendet: Dienstag, 7. Januar 2003 22:18
An: trnsys@relay.doit.wisc.edu
Betreff: RE: how to use incident angle modifiers


Dear Timo,

First, I must say that I am not sure how K_diff is assessed in
experimental tests according to EN 12975. I suspect it is the value of
KTauAlpha for an "equivalent angle" close to 60°. Hopefully someone
will
correct me if I am wrong!

For the flat-plate collector (Type 1), optical modes 2 and 3 allow you
to
take into account experimental data.

Mode 2 requires b0 and b1, the two parameters of an equation giving
KTauAlpha vs. Theta:
K = 1-bo*(1/cos(Theta)-1)-b1*(1/cos(Theta)-1)^2
b1 can often be neglected so you could fit a b0 value using only the
value
of K for 50°. If my assumption about K_Diff is right, you can use a
second
data point in your regression (K_diff for 60°).

Mode 3 allows you to enter data in a file. In this case, you would
have at
least 3 data points:
(Theta, KTauAlpha)
(0 , 1.0)
(50 , your value KTauAlpha50°)
(90 , 0.0)
(you could add (60 , K_diff) if my assumption on K_diff is correct).
Note
that the subroutine DATA will interpolate linearly between these
values.

I would suggest to use Mode 2 with a fitted b0 value but I don't think
you
would notice a big difference between the two options.
For the vacuum tube collector, you have to give data in a file (see
section 4.2.3 of the main manual). You can enter the 3 (or 4) data
points
I mentioned here above for each direction (longitudinal &
transversal). I
don't think it would be a good idea to fit a "b0" parameter for this
type
of collector. Be careful not to mix transversal and longitudinal
IAM's.

I hope this helps,

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 (NEW!)

SEL Web Site: http://sel.me.wisc.edu
TRNSYS Web Site: http://sel.me.wisc.edu/trnsys


> -----Original Message-----
> From: owner-trnsys@relay.doit.wisc.edu
> [mailto:owner-trnsys@relay.doit.wisc.edu] On Behalf Of Timo
Sengewald
> Sent: Monday, January 06, 2003 04:32
> To: TRNSYS group
> Subject: how to use incident angle modifiers
>
>
> Hello!
>
> I have got the test protocol (according to DIN EN 12975) of
> the german ISFH for two different solar collectors: a flate
> plate and a evacuated tube collector. Can I use the given
> incident angle modifiers with Type 1 and Type 71? For the
> flat plate collector the IAMs are called K_taualpha_dir(45°)
> and K_taualpha_dif. The IAMs for the tube collector are
> K_long(50°) and K_rad(50°). Which values do I have to provide
> by the IAM files?
>
> Thanks a lot,
>
> Timo Sengewald
>
>
>
> ------------------------------------------
> Phönix Sonnenwärme AG
> Am Treptower Park 28-30
> D-12435 Berlin, Germany
> e-mail: timo.sengewald@sonnenwaerme-ag.de
> www.sonnenwaerme.ag
> Tel.: +49-(0)30-53 00 07-237
> Fax.: +49-(0)30-53 00 07-17
> ------------------------------------------
>

Timo Sengewald
------------------------------------------
Phönix Sonnenwärme AG
Am Treptower Park 28-30
D-12435 Berlin, Germany
e-mail: timo.sengewald@sonnenwaerme-ag.de
www.sonnenwaerme.ag
Tel.: +49-(0)30-53 00 07-237
Fax.: +49-(0)30-53 00 07-17
------------------------------------------