[TRNSYS-users] Type51

[Diego A. Arias]

Hi Amandine,

In order to solve the mass balance and energy balance that represent the 
process inside the cooling tower, Type51 uses correlations for the 
psychrometric properties.  Type51 has to perform internal iterations in 
order to solve those two equations.   It is possible that a combination 
of input conditions are resulting in a very difficult problem to find a 
solution for, and the iterations are going out of the limits considered 
appropriate  for the correlations.  Did you connect both the dry bulb 
temperature and the wet bulb temperature inputs of the model to the 
weather data reader?

My idea to debug this problem is that you use Type51b, and use the 
default parameters for the cooling tower. Find the time when the error 
is occurring, and look at the inlet conditions.  Use this values to 
calculate yourself the outlet conditions in the cooling tower:  you can 
use the mathematical reference (volume 5, section 5.4.17) to do the 
calculations.  Perhaps you may find an input that is causing the problem.

Please let me know if you have questions debugging this problem.
Best regards,

Diego

Amandine LE DENN wrote:
> Dear users,
>  
> About type51b (cooling tower - user supplied coefficient), what can be 
> the different origin of this message:
>  "the correlation for the saturation temperature used in the cooling 
> tower model was used with an enthalpy value outisde the allowable range".
>  
> I am using french meteo data and water temperature level 
> is basically [15°C - 28°C]. Mass transfert constant and exponant are 
> the default ones, sump volume is 200L.
>  
> Trnsys is generating too many of this error, my simulation stop 
> automatically after 800 hours.
>  
> Thank you for your help,
>  
> Amandine LE DENN
> INSA Toulouse
> Mel: amandine.le-denn at tecsol.fr <mailto:amandine.le-denn at tecsol.fr>
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-- 

Diego A. Arias
TRNSYS Coordinator
Solar Energy Laboratory
University of Wisconsin - Madison
1500 Engineering Drive
Madison, WI 53706