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

[David BRADLEY <d.bradley@tess-inc.com>]

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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