[TRNSYS-users] IAM (incidence angle modifier) using TESS Type538

[giulio betti]

dear all,
I'm using Type538 (TESS Solar Library, Evacueted tube collectors) at
university. I have a problem with IAM: I read the posts about it on this
mailing list and the chapter 5.11.14.4 of the Trnsys16 manual, so I think
I've understood how to use it. I made the external data file needed by
subroutine DYNAMICDATA as explained in the manual:

<Transversal angle 1> <Transversal angle 2> etc. Nt values [0;90]

<Longitudinal angle 1> <Longitudinal angle 1> etc. Nl values [0;90]

<IAM 1 1> IAM for transv. angle 1, long. angle 1

<IAM 1 2> IAM for transv. Angle 1, long. angle 2

...

<IAM 1 Nl> IAM for transv. angle 1, long. angle Nl

<IAM 2 1> IAM for transv. angle 2, long. angle 1

<IAM 2 2> IAM for transv. angle 2, long. angle 2

...

<IAM 2 Nl> IAM for transv. angle 2, long. angle Nl

<IAM 3 1> IAM for transv. angle 3, long. angle 1

...

<IAM Nt Nl> IAM for transv. angle Nt, long. angle Nl

Having 5 transversal angles [0°, 20°, 50°, 70°, 90°] and 3 longitudinal
angles [0°, 50°, 90°] my file .dat is something like this (I don't write all
15 values of the column):

0 20 50 70 90

0 50 90

1

0.95

0

.

.

.

0

In Type538 I set parameter 11 (Number of transverse angles) to 5 and
parameter 12 (Number of longitudinal angles) to 3. Now, I tried to run the
simulation: Trnsys didn't work: it said that there was an error without
specifing details:

Fatal Error at time   :      3245.010000
    Generated by Unit     :     3
    Generated by Type     :   538
    TRNSYS Message    109 : Error reading data stored in logical unit. NOTE:
the reported logical unit number may be automatically or internally
ASSIGNed, or you may have specified the incorrect number of independent
variables.
    Reported information  : Logical Unit number 33


So I tried to change parameter 11 and parameter 12: I set parameter 11 to 3
and parameter 12 to 5 (I simply reversed the number of transversal angles
with the number of longitudinal angles). In this way the simulation ran!

So the question is this: the file .dat has to be written as described in the
manual, and there is only an inversion in the definitions of "parameter 11"
and "parameter 12", so that the only change to do is the one described
above?

Or the definitions of "parameter 11" and "parameter 12" are right and there
is to change the file .dat putting in the first line the longitudinal angles
and in the second line the transversal angles? In this case, the column with
all the possible multiplications is to be left as it is described in the
manual, or I have to modify it in this way:

<IAM 1 1> IAM for long. angle 1, transv. angle 1

<IAM 1 2> IAM for long. Angle 1, transv. angle 2

...

<IAM 1 Nl> IAM for long. angle 1, transv. angle Nl

<IAM 2 1> IAM for long. angle 2, transv. angle 1

<IAM 2 2> IAM for long. angle 2, transv. angle 2

...

<IAM 2 Nl> IAM for long. angle 2, transv. angle Nl

<IAM 3 1> IAM for long. angle 3, transv. angle 1

...

<IAM Nt Nl> IAM for long. angle Nt, transv. angle Nl

?

I hope I've been clear enough, thank you all,

regards,

Giulio Betti
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