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Re: [EnergyPlus_Support] Severe Geometry & Fatal Airflow Network Iterations Errors
Kristin:
I got your input file and tested it. Here is what I found:
An exhaust fan is used as a part of Controlled Zone Equip Configuration and
in the AirflowNetwork model. The AirflowNetwork model only allows a constant
volume fan as a component of a primary air loop. The zone exhaust fan is not
allowed in the AirflowNetwork model for air distribution simulations. You
have two choices to work around:
1 Perform multizone simulations only
Change the field choice of AirflowNetwork Control in the AirflowNetwork
Simulation object from "Multizone with Distribution" to "Multizone without
Distribution". In this way, air distribution system will not be simulated. A
zone exhaust fan can be used in conjuction with multizone air flow
simulation.
2 Perform multizone with distribution simulations wihtout exhaust fans
Since zone exhaust fans are not allowed in air distribution system
simulations using the AirflowNetwork model. You may delete any objects
related to exhaust fans entirely as follows:
- Last two objects of AirflowNetwork:Distribution:Node
- Last two objects of AirflowNetwork:Distribution:Linkage
- Exhaust fan object of AIRFLOWNETWORK:DISTRIBUTION:COMPONENT CONSTANT
VOLUME FAN
- ZoneExhausts in Node List object
- No Zone Exhaust Fan objects
- Leave the blank in the "Node List or Node Name: Zone Air Exhaust Node"
field of Controlled Zone Equip Configuration object
Please let me know if you need more information. We definately consider your
application as our future feature.
Lixing
----- Original Message -----
From: "Kristin Field" <fieldkm@xxxxxxxxx>
To: <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Sent: Sunday, September 24, 2006 4:50 AM
Subject: [EnergyPlus_Support] Severe Geometry & Fatal Airflow Network
Iterations Errors
> If anyone could help me with the following errors I've been
> receiving, I would be *very* grateful.
>
> Background: My file, which I'll upload shortly (titled
> BAB_Baltimore_092306.idf), is supposed to represent a simple 30'x30'
> house that's 16' tall with a 4-sided, unconditioned attic on top (2
> triangles and 2 rectangles). The attic peak is at 23.5'. This house
> should have typical DX cooling and furnace heating, with natural
> ventilation when weather permits. I have attempted to implement a
> simple airflow network model with several cracks for infiltration and
> operable windows/doors for natural ventilation. To the greatest
> extent possible, I followed the simple house airflow network example
> file with EP-V1.3.0.
>
> First (Severe) Error: I get the following geometry error after having
> experimented with several different view factor combinations and
> after thoroughly reviewing what seem to be logical vertices to me.
>
> "View factors not complete. Probably bad surface descriptions in
> zone="MAIN ZONE". Enforced reciprocity has tolerance (ideal is 0.0)
> =3.0292E-002. Enforced value is not within normal convergence
> tolerance (<.0001)."
>
> Second (Fatal) Error: I get this message after EP aborts following
> the "Initializing HVAC" line in the command prompt window. I have
> also tried several combinations of new values for the parameters it
> suggests - including increasing and decreasing them by several orders
> of magnitude. No effect except increased processing time in some
> cases. The audit file doesn't tell me anything. I actually wonder
> if the first error is influencing EP's ability to converge here.
>
> "Too many iterations (SOLVZP) in AirflowNetwork simulation
> AirflowNetwork: SOLVER, Changing values for initialization flag,
> Relative airflow convergence, Absolute airflow convergence,
> Convergence acceleration limit or Maximum Iteration Number may solve
> the problem. Occurrence info: Occurrence info=STERLING VA USA TMY2-
> 93738 WMO#=724030, 01/01 01:00 - 02:00
> AirflowNetwork: SOLVER, The previous error causes termination."
>
> Any ideas/help appreciated - thanks!
>
> --Kristin Field
>
>
>
>
>
>
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