[TRNSYS-users] Fwd: Problem connecting EES to TRNSYS

Javier Vega via TRNSYS-users trnsys-users at lists.onebuilding.org
Tue Dec 6 11:00:34 PST 2016


Hello TRNSYS community!

I have a problem trying to connect an EES heat pump model to TRNSYS. The
model has calculations on every component of the heat pump plus the
thermodynamic state of the exhaust humid air in the evaporator (it's an air
to water heat pump).

Trying to keep it simple, for now the only inputs in the model are the Dry
Bulb Temperature and the Relative Humidity percentage. based on fixed
parameters as, for example, the water inlet or outlet temperature and
flows, between others, the model calculates the energy flows and COP. Using
that, the model runs well simulating the whole year on EES using a Lookup
and Parametric Tables with the dry bulb temperature and Relative Humidity
Data.

The problem comes when I try to do the same simulation calling EES from
trnsys. In a simple project file with just a Type 15-6, a type 66,printers
and plotters, with EXACTLY the same input data, the EES fails to converge
on several timesteps. I'm trying to start with 1 hour simulation timestep
before shortening it.

I've tried several things and it seems that the problem is that EES doesn't
update the Guess Values when calling it from TRNSYS. So, the model has
trouble to converge without a previous clue of the solution of the system
of equations.

Is it a way to automatically update Guess Values from TRNSYS? I've tried
using Type 66a and Type 66d.

Thanks in advance,
Javier Vega Benavente
Mechanical Engineering student, Universidad de Concepcion
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