Re: [EnergyPlus_Support] Re: How can I simulate a stuck open economizer?

Thanks for your attention.

No, I do not want to simulate the damper stuck only for a period of time. I do want to see the behavior and more important, the energy consumption for the full year's operation of the stuck damper.

Regarding your message. when you say "schedule the OA to the 'stuck' value...", do you mean to set the Controller:OutdoorAir>Min Outdoor Air Flow Rate to the design value (as I am doing)? Or, do you have a suggestion on how to better simulate the stuck damper?

The method I'm using is not very realistic, since I am not actually setting the damper position, instead setting the flow. Do you have a suggestion on how to make a more realistic simulation?

Richard,

I'm painfully debugging using your suggestions. Thanks.

Regards,

Homero.

Homero Noboa, Ph.D.

On Mon, Mar 26, 2012 at 3:58 PM, YuanLu Li <yli006@xxxxxxxxxxx> wrote:

I thought, if you only wanted to see the result, simply schedule the OA to the "stuck" value for the period you wanted to see.

Run a simulation, find the period when the economiser is on. Change the OA schedule for a short while during that period. Run again, the OA damper is stuck during that period.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: RRaustad@xxxxxxxxxxxx
Date: Mon, 26 Mar 2012 16:50:01 -0400
Subject: Re: [EnergyPlus_Support] Re: How can I simulate a stuck open economizer?

This one would be hard for a typical user to find since you can't see
what's happening during each of the 25 iterations, only what the result
is for the last (25th) iteration. The best you could do is to report
node temperatures and/or flow rates around the air and plant loop and
see if anything looks strange at 7/7 17:40. For example a set point not
met, a spike in temp or flow, etc.

You could turn on debugging data, but I don't recommend that detailed a
view of the simulation results.

Output:DebuggingData,1,0;

On 3/26/2012 4:36 PM, hnoboam wrote:
> Hello List.
>
> Thanks for your advise, yes, I have read the I/ORef carefully. I think I understand how the controller:OutdoorAir works.
> Following Jim's advise, to simulate an stuck open Outdoor Air damper, I am setting up the Controller:Outdoor Min and Max OA Flow Rates (in m3/s) slightly less than the Autosize values that I found (thanks Linda) in the eio file.
>
> When I run the simulation, though, now I'm getting four warnings telling me that E+ cannot reach a solution to the system of equations. This is part of one of the warnings;
> ** Warning ** SimHVAC: Maximum iterations (25) exceeded for all HVAC loops, at BEIJING - CHN IWEC Data WMO#=545110, 07/07 17:30 - 17:40
> ** ~~~ ** SimFlags=[TFFFF] AirLoops[T],ZoneEq[F],NonZoneEq[F],PlantLoops[F],ElecCircuits[F]..F=ok,T=fail
> ** ~~~ ** Plant Tolerance Flags=[10000000] Enthalpy[1],MassFlow[0],HumRat[0],Pressure[0],FlowQual[0],Energy[0],Temp[0],PlantFlowMassFlow[0]..0=ok,1=fail
> ** ~~~ ** Plant EnthalpyTol=718.958, MassFlowTol=0.000, HumRatTol=0.0000, PressureTol=0
> ** ~~~ ** FlowQualTol=0.00, EnergyTol=0.000, TempTol=1.35E-003
>
> Note that the warnings are at the peak of the summer. For this reason, I thought that the tower could not handle the extra load of the hot and humid OAir. So, I increased the tower water flow capacity, but it did not help.
>
> Any idea how to trace this problem?
>
> Thanks.
>
> Homero.

>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jean marais"<jeannieboef@...> wrote:
>> Watch out! Read very carefully the object section on the Controler for ODA in the ioRef. Some fields override or take the maximum of others. Be careful of default setting also in fields you are not planning to use. This can be a tricky object and it includes the control of the economizer action.
>>
>> I stand corrected, but as I understand it "econimizer" means a control methodology of the Mixing Damper in the "Umluftkammer" of an AHU (in e+ this is the mixing box). If the damper is jammed open, you have only circulating air. If the damper is jammed closed you have a dedicated outdoor air system without mixing.
>>
>> I've not seen an AHU with a 3rd duct to outside serving as an extra intake.
>>
>
>
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--
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
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Homero Noboa, Ph. D.