[TRNSYS-users] Type 695 (variable speed pump) : mass balance check failed

[Damien Casetta]

Hi,

Please check the appended screenshot to see how my TRNSYS project looks
like (note that this screenshot is zoomed in the loop I am having problems
with).
In my project, a variable speed pump flow rate is set with a control
function. A tempering valve controls the pump entering temperature
according to a set temperature (read from an external file). It is a very
common system.

However, the problem is the following : mass balance check fails across the
pump (warning messages + I have checked the results and indeed, it occurs
during most of the timesteps). The difference between input and output flow
rates can be as large as 100%. On the other hand, mass balance is checked
when control signal is 0 or 1 (rated flow rate). Connections are set as it
follows :

-  Tee piece outlet temperature / flowrate --> pump inlet temperature /
flowrate
- Pump outlet flowrate --> valve inlet flowrate
- Valve inlet temperature from external file
- Valve set temperature from external file
- Pump control signal from external file

Please feel free to ask for more information about the project.

Thanks in advance for your help,

Have a good day,


Regards,

-- 
*Damien CASETTA*
*INSA Lyon / Génie Energétique et Environnement*
*ENERTECH / Cabinet SIDLER*
*26160 Félines sur Rimandoule*
*Tél & Fax : 04 75 90 18 54*
*Courriel : **damien.casetta at gmail.com* <damien.casetta at gmail.com>
*Site : **www.enertech.fr*
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