[TRNSYS-users] time delay by means of type 93 (input value recall)

[David BRADLEY]

Stefan,
   Type93 simply holds onto a value for as many time steps as you ask it 
to, then "releases" the value. The control ought to work the same 
regardless of the system size. I am not sure what you mean by 
"continuous" controllers. If you mean that there are some controllers 
that continuously modify a flow rate in order to maintain an outlet 
temperature then a simple time delay might cause some problems. You 
might look at some of the controllers available in the TESS Controllers 
Library (for Trnsys17) as there are a number of devices in there with 
minimum run times and start-delays.
Best,
  David


On 4/8/2011 04:05, Stefan Wachter wrote:
> Hello everybody,
> I am new at trnsys-users.
> Currently I`m modeling an already existing solar heating system (for 
> hot water).
> In this system the loading pump is activated by a time delay of 4 
> minutes (after solar pump is launched).
> I tried to model this as follows:
> - simulation time step: 2 minutes
> - storage of the control signal of the solar pump over the last two 
> time steps by means of type 93 (input value recall)
> - if the control signal of the solar pump is "1" in the stored two 
> time steps, then the loading pump is launched.
> It works (tried by a simple example deck) but does it also works in 
> context with a quite big deck (120 m² apertur area, 2 continuous 
> controllers)?
> I`m concerned about that the small time step of 2 minutes could cause 
> problems (for example oscillations of the controllers).
> Could this work or have someone of you another idea how i can solve 
> this problem?
> Thanks a lot.
> Best regards.
> Stefan Wachter
>
>
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> TRNSYS-users at cae.wisc.edu
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-- 
***************************
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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