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Re: [TRNSYS-users] A lot of convergence warnings




Hello,

I have no experience with chilled ceilings, but as I understand the manual (chapter 6, page 47), the chilled ceiling layer has to be the first layer (inside surface) in a wall. Or, if you have an adjacent wall, it can also be the last one (inside surface of the adjacent zone).

I was hoping that someone else with more experience with chilled ceilings would see your posting and give a more helpful answer.


Best regards,
Knut Erik

 



From: Mavi Cambronero Vázquez <maviqnk@gmail.com>
To: knut.erik.enerstvedt@niva.no
Cc: trnsys-users@cae.wisc.edu
Date: 05/13/2010 05:38 PM
Subject: Re: [TRNSYS-users] A lot of convergence warnings





Thanks for your answers.....

I´ve noticed that the problem is the chilled ceiling used. It´s the first time that I try to use it and I supose I didn´t succeed. I know how to create a chilled ceiling layer, but I´m not sure what are the following steps. What I did was integrate the new layer as the last one in a new wall. TRNBuild said to me that a wall with chilled ceiling can´t be external, boundary or internal, so the only option is that it is adjacent.... adjacent to the roof???So I created a new zone called roof! I´m a bit confused.

 
If someone could help me I´d be very grateful!
 
Thanks

 

2010/4/29 <knut.erik.enerstvedt@niva.no>

In addition to reducing time step length, I would try the following:


- Check if there is sufficient thermal mass in your system (add pipes in fluid loops, for example).

- Use controllers (such as Type 2) instead of equations (LT, GT and similar) when variables that can change from one iteration to the next are involved.

- Place components in a "natural" calling order (controllers before controlled equipment, for example): Control cards->Component order: Click and drag the different components to order them.

- Use an online plotter to check if there are any unrealistic output values (very high temperatures, for example).


Best regards,

Knut Erik Enerstvedt





>You could change the simulation time step (in steps of 1/(2^n) so 1 hour, 0,5 hour, 0,25 hour etc). You can find this by assembly -> component >order.
 

>Good luck,

 

>Mariëlle Nuchelmans

 

 

>Hi,
 

>What can I do when there are lots of convergence problems??? The same project has different warnigs because of that if the simulation >starts at 3896 than if it starts at 0.... Does the option "Optimaze component order" work?? If I select that option other errors appear... :(


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