[esp-r] Fwd: Re: Re: instable with global solar

[Georgios Kokogiannakis]

Hi Holger,

Not sure about the rest of your warnings but those that you list here are
triggered when high direct normal is calculated (which means that it uses
your Global horizontal and calculates the direct normal).
To be more precise, I see in the code that the warning pops up when the
calculated direct normal exceeds 1353.0 W/m^2.
The calculation that I see indicates that this is possible only when solar
altitude is less than 12 degrees (e.g. late hours of the day).

The values 211 and 41 that I see in this line of your file:
>  0,211,41,2,57,78

indicate that at any point below 7-7.5 degrees of solar altitude, you will
exceed the limit for the warning. The calculation in the code looks simple.
It is this line in solar.F
      QD=(QDF-QFF)/SIN(SALT*R)
where (unfortunately the variables have confusing names so that they make new
students to suffer when trying to understand them):
QD is the direct normal, QDF is your global horizontal, SALT is the solar
altitude (I guess) and R is a trick to account for degrees in the code as
PI/180.

Regards,
Georgios

On Friday 31 October 2008 09:17, you wrote:
> Hi,
>
> I took the CSV-file as userdefined-database
> and tried to switch the CSV-file...
> First choosing make new database with zeros
> and then importing the CSV into it works fine.
>
> But it still is very instable,
> even with the model without mineralwool
> and a time-step of one Minute.
> I found some new messages, for example:
>
>  Default invoked; diffuse h.= global h.; direct n.=0.
>  Day No. = 183 (i.e.  2nd of July),  Time 19:15 Hours
>  MZSINT: increment 293416 direct n.1478.1 > solar constant
>  Default invoked; diffuse h.= global h.; direct n.=0.
>  Day No. = 183 (i.e.  2nd of July),  Time 19:16 Hours
>  MZSINT: increment 293417 direct n.1632.1 > solar constant
>
> The climate-file for this day is:
>
> * day  2 month  7
>  0,169,0,3,338,97
>  0,166,0,3,339,99
>  0,163,0,2,339,100
>  1,161,1,2,339,100
>  0,160,34,2,340,100
>  1,168,134,2,343,100
>  58,184,305,2,341,93
>  125,201,485,2,349,87
>  164,216,635,1,12,86
>  177,231,739,2,64,77
>  177,241,841,2,78,75
>  173,247,878,3,78,74
>  177,248,839,3,71,68
>  178,248,759,3,67,67
>  167,248,658,4,69,66
>  96,242,402,4,73,67
>  55,235,297,3,68,71
>  12,226,177,3,63,76
>  0,211,41,2,57,78
>  0,196,0,2,57,86
>  0,187,0,2,70,87
>  0,180,0,2,61,90
>  0,173,0,2,39,93
>  0,166,0,2,41,95
>
> Does anybody know what to do?
>
> Thanks in advance
> and best regards,
> Holger
>
>
>
> Am Donnerstag, den 30.10.2008, 19:44 +0000 schrieb Georgios
>
> Kokogiannakis:
> > Hi Holger,
> >
> > The switch from Direct normal to Global Horizontal works fine as far as I
> > am aware. It also exorts ascii files correctly (just tested it).
> > If you manage to open the ascii file you will see a line similar tp this
> > one: 1967,52.00,0.00,123   # year, latitude, long diff, global horiz rad
> > flag
> >
> > the last number (i.e. "123") means that it is using Global horizontal. If
> > it is 0 then it uses direct normal.
> >
> > Regarding the MZELWE Longwave Flux Messages I think you should check your
> > relative humidity values. Do not leave to 0% - change them to something
> > like 50%.
> >
> > Hope this helps.
> > Georgios
> >
> > On Thursday 30 October 2008 19:27, Holger Bertling wrote:
> > > Dear All,
> > >
> > > I solved my stable-problems within normal simulations.
> > > (see: MZELWE Longwave Flux Messages)
> > >
> > > Now I want to simulate the model with different climate-files.
> > > There are only global solar horizontal available.
> > >
> > > I switched the climate-files with clm to global solar.
> > > Now the simulation is really getting instable.
> > > MZELWE-Messages without ending.
> > >
> > > What surprised me:
> > > I could read the files with an editor,
> > > but after I switched them to global solar
> > > they cannot be opend with an editor anymore,
> > > even if I write the data out to ASCII-files again.
> > >
> > > Now I think that maybe the switch is not enough
> > > and the model gets the full global as direkt power...
> > >
> > > Am I missing something?
> > >
> > > Best regards,
> > > Holger
> > >
> > >
> > > _______________________________________________
> > > esp-r mailing list
> > > esp-r at lists.strath.ac.uk
> > > http://lists.strath.ac.uk/mailman/listinfo/esp-r

--
Energy Systems Research Unit (ESRU)
Department of Mechanical Engineering
University of Strathclyde

-------------------------------------------------------

-- 
Energy Systems Research Unit (ESRU)
Department of Mechanical Engineering
University of Strathclyde