Re: [TRNSYS-users] Type 1716: ROTARY DESICANT DEHUMIDIFIER - Maximum air flow rate?

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

Marcus,
  Make sure that you are using a short timestep (1-5 minutes) and that there is enough thermal capacitance in your flow loops. It may be that 10000 kg/h of air flowing through the device in the course of one time step is causing the system to be unstable. There was a recent post on this forum concerning a cooling tower connected to an absorption chiller that turned out to be exactly the same problem; far too much energy transferred in a system with far too little capacitance for the time step selected. The time step has to be shorter than the time constant of your system.
Kind regards,
 David

On 9/15/2013 08:36, Marcus wrote:

I am running type 1716. When I run with 1000 kg/hr flow, it simulates fine. When I increase to 10000, it causes psychometric SAT error  at -273K.

So far, I will use the wheel at 1/10 the flow, and then multiply after the wheel to get back to our design flow, just wondering if this is a known bug or I suppose the model isn't valid at such a flow rate?

Cheers,
Marcus

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