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

["Matt Duffy" <duffy@tess-inc.com>]

Hello Stefan,

As long as you implement the timestep as a fraction in an EQUATIONS in the control cards, you should be ok. For example,

EQUATIONS 1
TIMESTEP=2/60 !Timestep of 2 mins

Please see the attached for reference.


Best regards, 

Matt Duffy

----- Original Message -----
From: "Stefan Wachter" <wachter@mail.hs-ulm.de>
Sent: Fri, April 8, 2011 4:05
Subject: [TRNSYS-users] time delay by means of type 93 (input value recall)

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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