[TRNSYS-users] Controllers Type 22 / 23 and Internal controls Type 536

Jeff Thornton thornton at tess-inc.com
Fri Nov 6 10:07:46 PST 2020


Jose,

The version of Type 536 for the v18 TESS Library release (scheduled for 
early next year), has an updated controller for Type 536 that shuts off 
the flow if the collector is losing energy.  If you can't wait that 
long, there are a few things you might be able to do. here are the steps

1) Use a 2nd version of Type 536 as your control collector.  Hook it up 
to the same inputs as your other Type 536.  Make sure it has NO thermal 
mass.
2) Change your existing Type 536 to not control the outlet temperature.
3) Use the outputs from the new model to make the final decision for 
your pump.  If it's gaining energy and everything is good, feed the pump 
with the control signal from this "control collector".  If it's not, 
turn the pump off.
4) You may have to delay the inlet temperature one timestep for the 
control collector to avoid convergence issues.  But with small timesteps 
and mass in your pipes and collector, this won't be a big deal.  You may 
get a few timesteps early and late in the day when the temperature falls 
away from the setpoint but I've used this approach with a lot of 
different models and it seems to behave nicely.

Jeff

---
Jeff Thornton
President - TESS LLC
3 N. Pinckney Street, Suite 202, Madison WI USA 53703
Office: (608) 274-2577  Fax: (608) 278-1475
www.tess-inc.com
E-Mail: thornton at tess-inc.com


On 11/06/2020 8:50 am, José María Roca via TRNSYS-users wrote:
> Hello community, hope you are all safe and sound.
> 
> I’m having some issues implementing controls over the pump flow on the
> parabolic concentrator to keep a stable output temperature.
> 
> If I use the Type 22 (iterative feedback controller) which I
> understand it’s a “perfect” controller (please correct me if i’m
> wrong) the output temperature and pump flow get crazy moves up and
> down.
> 
> On the other hand if i use the internal control of the Type 536, which
> sets the flow to keep the output temp, the flow and temp are very
> steady. However I can’t control what happens to the flow on low
> irradiance or when the system is loosing energy, so that’s why I want
> an external controller and what would better resemble a practical
> example to build such a system.
> 
> Any tips on what to look in those controllers to have a steady output?
> 
> Thanks!
> 
> Best,
> José María Roca
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