[TRNSYS-users] Error Message 441 - With Types 536 and 637a

[Jeff Thornton]

Jose, 

You are correct that the inlet flow rate to 637 and to 536 in the chosen
modes set their respective flow rates. But without any pipes or a tank
or something to provide some capacitance to the loop as you find in a
real system. I'm guessing that you are getting into convergence issues.
Try a small timestep and some thermal mass (pipe, tank, etc) to see if
it eliminates the problem. Also make sure you have the control mode set
correctly for the collector. Are you setting a fixed temperature for the
collector or one that is a function of the inlet temperature (ie a fixed
temperature rise). 

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 03/26/2019 10:39 am, José María Roca via TRNSYS-users wrote: 

> Hi community, hope everyone is well. 
> 
> I'm trying to model steam generation from solar parabolic trough, so to achieve this I have connected a type 536 outlet to the inlets of the counterflow HRSG type 637a. 
> 
> The T536, is set to vary the flowrate to try and reach specified outlet temperature, so the flowrate is set by this component and in turn the input flowrate isn't used. Right? 
> 
> The T637a calculates the maximum steam flowrate available from the inputs and restrains, so this component sets the steam flowrate, ans so the input of steam flowrate isn't used. Right? 
> 
> I have the resumed the main connections to: 
> 
> T536: Outlet flowrate --> T647a: Input hot side flowrate 
> T536: Out temp --> T647a: In hot temp 
> T637a: Out hot flow --> T536: in flow 
> T637a: Out hot temp --> T536: In temp 
> T637a: Out steam flow --> T637a: In steam flow (continuity?) 
> 
> This will produce a 441 message "_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…__" units are identified to the collector (T536) and HRSG (T637a)._ 
> _ _ 
> If I delete the 637a or the 536, the error 441 disappears, so this points that there is a problem with the connections or information exchanged between them. 
> 
> Where should I start checking? 
> 
> Best, 
> José María Roca 
> 
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