[TRNSYS-users] time calculation

[David Bradley]

Matthieu,
   Your explanation of what you are trying to do is very clear - thanks. I 
think that in order to speed up your simulation, you are going to have to 
write an iterative solution method in which you guess a solution and then 
check to see if it is a good one. If not, then you guess a different 
solution and try that one. Essentially the idea is the same as you have 
done in Excel but there are a lot of well known methods for writing such 
iteration methods. You might look for a book that is called "Numerical 
Recipes" (http://www.nr.com/) to get started. There are also some iterative 
methods implemented in certain TRNSYS Types; Types 543 and 544 in the TESS 
Solar Library contain one method for getting an iterative solution 
(implemented in Fortran).
Cheers,
  David

At 10:58 9/6/2006, Matthieu Cosnier wrote:
>Hello to all TRNSYS users,
>
>I ve created a model of a "kind" of  counterflow heat exchanger. It is 
>composed of several subunits that represents small successive parts of 
>italong the flow. This subunits are linked  each others by the fact that 
>the temperature of the outlet of one
>is the inlet temperature of the following one etc..
>I know the temperature at the inlet of on side (hot fluid)and the 
>temperature at the inlet of the other side (cold fluid).
>Each subunit is defined by a matrix system that calculate the outlet 
>temperatures (on the cold side and on the hot side), knowing the inlet 
>temperature of each.
>My problem is that i can't solve it easily because the only temperature i 
>know are opposite (Tinlet hot and Tinlet cold)
>So i created an excel file that calculate all this equations with the 
>option "solveur". The procedure is a step by step one, and consist of 
>impose arbitrary values of each temperatures, to solve each system, to 
>compare the calculated values to the imposed ones, and to start again if not.
>It works very good but it's quite slow (about 5 seconds).
>The problem is that i have linked this program with Trnsys
>(type 62), but as you can imagine it's very long to complete my simulation 
>because each timestep is about 5 second long.
>My questions are : have i some solutions to do my simulation faster? may i 
>use a fortran program (or another one)? and if yes, how to write it? ( 
>i've never use fortran)
>
>Apologize for this bad english long text
>Best regards
>Matthieu.
>
>°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°
>COSNIER Matthieu
>Doctorant
>LOCIE
>ESIGEC-Université de Savoie, Campus Scientifique,
>Savoie Technolac, 73376
>Le Bourget-Du-Lac cedex
>Tel :   06 77 75 09 31
>Fax :  04 79 75 81 44
>E-mail : matthieu.cosnier at etu.univ-savoie.fr
>°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°°
>
>
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