[TRNSYS-users] Control strategy heating circuit

[Simon Janse]

Hey together,

 

I need some advice on a control strategy I want to implement in TrnSys17.

 

Following problem:
My heating circuit( A large single building, for simplicity I neglect losses
here) delivers a on a monthly basis changing mass flow with a return
temperature of 40°C and need a supply temperature of 50°C.

I want to heat this mass flow in a heat exchanger to maximum of 60°C and
regulate the supply temperature with a tempering valve (In praxis this would
be a mixing loop). The heat on the source side of the heat exchanger is
supplied from the top of a thermal storage (This one is supplied with heat
by a solar thermal system and a seasonal thermal storage) which will be
stratified between 20°C and 97°C. I now want to determine the mass flow for
the source side of the heat exchanger in dependence of the temperature of
the outgoing flow from the thermal storage and the maximum temperature on
the load side of 60°C. I want to use a variable speed pump and need to
control its control signal. It shouldn’t be too hard I guess and a quite
normal control strategy which is comparing the thermal energy of the load
and the source side of the heat exchanger. As the mass flow on the load side
and temperature on the load side differs over the year (load mass flow as
mentioned above on a monthly basis, but constant over the month, source
temperature on a time step basis due to the dynamic structure of the solar
thermal and seasonal storage systems).

 

I think a PID control would be the right concept to put into place (and it
is existing in TrnSys as well), but as I’m really not familiar with TrnSys I
don’t know how to implement this kind of control strategy.

 

So could anybody give me some advice what to do here and which control is to
be used? It would be much appreciated.

 

Thank you very much for your help.

 

Best regards

Simon

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