[TRNSYS-users] Radiation processor / printer

David BRADLEY d.bradley at tess-inc.com
Fri Nov 19 07:52:09 PST 2010


Jérôme,
   There isn't much that you can do about the second error (radiation 
exceeding extraterrestrial). It happens quite often and has to do with 
the sub-hourly interpolation used. If it happens a lot during your 
simulation (5 percent of the timesteps?) then it might be worth having 
your distributor look at it.

   For the issue about having the printer rounding. Trnsys takes the 
timestep that you indicate (in decimal hours) and tries to fit it to a 
ratio of two integers. If you enter a 10 minute timestep as 
0.16666666666666666666667 (in other words lots of decimal places) then 
chances are good that Trnsys will find 10/60 for the best 
representation. If you put in 0.1667, however, it can find a crazy 
representation of the time step and what ends up happening is that the 
printer is trying to print at the end of the hour and there is no time 
step at the end of the hour (0.1667 does not divide evenly into 1). The 
safest approach is as follows:

in your control cards, set the simulation time step to a "string" and 
enter "DELT" in the field.

in the small window at the bottom of the control cards, enter the following:

EQUATIONS 1
DELT = 10/60

in this way you are giving TRNSYS the exact ratio of integers that you 
want it to use and your printer and timestep will line up with each other.
Best,
  David


On 11/19/2010 08:32,  wrote:
> Hi everybody,
> i have 2 warning messages in TRNSYS16 that i dont succeed in fixing them.
>
> The first one refers to output printers Type25a :
> the printer has rounded the reset time to an even number of 
> steps.-Please check to make sure that it doesnt adversly affect your 
> simulation results.
>
> I think it is because i have put my steptime (in control cards) to 
> 10min that is to say 0.1667h. I havent this message when i put back 1h 
> as a timestep.
> I think the cause in printer is the 1st parameter set to STEP with 
> unit=hr. Could you tell me what STEP represents? I was thinking this 
> value to be the steptime in control cards.
>
> The second message refers to irradiation :
> "the direct beam is greater than the maximum allowed for this 
> timestep. The extraterrestrial radiation has been used for this time 
> step."
>
> this message refers to unit 60 which is type16c (radiation processors).
> i read my total horizontal radiation from datareader (type 9c). the 
> maximum value in my file for radiation is 975W/m² (3510kJ/hr.m²).  I 
> use a multiplication factor in data reader for radiation (3.6) in 
> order to switch to kJ/hr.m² and i send the output to radiation 
> processor which solar constant parameter is seto to 4920kJ/hr.m².
>
> Maybe the problem is about units of the input from data reader. I have 
> tried to send the output of datareader to unit conversion routine 
> (type57). I put parameter 1=17 parameter 2 and 3=1.
>
> Thank you for reading. I hope i have put enough details in order you 
> can understand and help me.
>
>
>
>
> _______________________________________________
> TRNSYS-users mailing list
> TRNSYS-users at cae.wisc.edu
> https://www-old.cae.wisc.edu/mailman/listinfo/trnsys-users

-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA

P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com

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