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Re: [TRNSYS-users] Error in Trnsys Model

Roberto,

  The two things to check in this situation are the timestep and the amount of thermal capacitance in the system. A 0.1h timestep is still fairly long in my experience. I typically use a 1 minute timestep. As far as thermal capacitance is concerned, watch out for loops that contain all quasi steady state models. For instance your cooling tower loop and cooling coil loops do not have any pipes in them. I would add sufficient volume (either piping or a buffer tank) to each loop so that the volume of liquid transferred by the pump in a single time step is less than the volume modeled in the loop.

kind regards,

 David


On 11/28/2021 22:51, Roberto Pippia via TRNSYS-users wrote:
Hi,
I have constructed a cooling system for a multi-zone building, incorporating an absorption chiller, cooling tower, and other components as shown in the attached image. When I run the model in TRNSYS an error message eventually appears due to the model reaching the maximum number of warnings that are set in the settings for the model. The warnings stilled in the error manager are all the same as shown below.

TRNSYS Message 441: The inputs to the listed units have not converged at this timestep. The values at the last iteration will be used and the simulation will proceed
(Reported information : UNITS: 42 44 45 47 48

I have tried adjusting the timestep in the settings but that has not worked as the warning appears for each timestep whether is it set at 0.1, 0.5, or 1 hr. I have tried increasing the number of warnings in the settings to see if the model would complete a one-year cycle before the error message appears, but this has not worked either. Does anyone know how to fix this issue and get my inputs to converge at each timestep?

Regards,
Roberto

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David BRADLEY
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Thermal Energy Systems Specialists, LLC
3 North Pinckney Street - suite 202
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