search

NREL / EnergyPlus

EnergyPlus™ is a whole building energy simulation program that engineers, architects, and researchers use to model both energy consumption and water use in buildings.
https://energyplus.net
Other
1.14k stars 392 forks source link

Controller fatal error in simulation with small flow rates #4413

Open BobHenninger opened 10 years ago

BobHenninger commented 10 years ago

Helpdesk Ticket 9469

Mike: When I run with the Edgewood.....idf and epw weather file for EastLasing,MI with v8.1 I get the same root controller severe error.

Bob: Use Edgewood_80pctBoiler 14-0612.idf attached to Jim's 12 June post as the test file. There's an epw file attached further down in the ticket, but I suspect this file will fail with Chicago as well. Mike

Posted on: 20 June 2014 06:11 PM Jim: The bypass setting doesn't matter, my file also fails as an annual simulation. I think it's because some of the component flow rates are rather small and are going below the SmallMassFlow tolerance which is hard-wired at 0.001 kg/s. Note that the error message indicates "Root candidate x=9.998980000000000E-005" which I'm fairly certain is a mass flow rate value in kg/s. So, just on a whim, I took the file and set all of the zone multipliers to 10, and the file runs to completion. So, that's one possible workaround. Results of course are all 10x. Bug report will be filed. Mike

Posted on: 12 June 2014 03:42 PM Can I change my mind and ask for another look? The attached file matches yours in all respects except two:

  1. I changed the simulation to run all year
  2. I changed the Hot water demand bypass branch to be a “control type” BYPASS, instead of “PASSIVE”

The sim runs through May and then fatals with a “FindRootSimpleController” error. It’s unusual in my experience to run part way and then have a fatal error. I looked over the file for other possible causes, and other than the BYPASS definition, didn’t see anything.

User files Edgewood_80pctBoiler 14-0612.idf USA_MI_EastLansing_589330_2009_amy.epw

Myoldmopar commented 9 years ago

Potential relation with #4187