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Re: [EnergyPlus_Support] Re: Problems in maintaining humidity control
elmofuddly wrote:
>
> Hello,
>
> I've manually increased the flowrate in the `sizing' objects (or
> specifically, in the zone sizing object). This has had the desired
> effect over the humidity (and by association the setpoint node's
> fluctuations have levelled out). Thanks very much.
>
> I would like to ask a follow up question if I may; is there
> something wrong in my input that didn't allow EnergyPlus to autosize
> a larger volumetric flowrate to offset this problem before my manual
> input?
The sizing routine calculates the sensible capacity required to meet the
zone set point temperature.
Future revisions to EnergyPlus will allow sizing based on sensible
and/or latent capacity (sized for the
dehumidification load) requirements. The dehumidification load was
probably the limiting factor here.
>
> Also, I am getting too much fresh air in the summer design day (I
> would like a minimum intake but I seem to be getting maximum
> intake). I have scheduled a minOA Sched in the OA controller,
> however it does not seem to take effect here. The winter OA intake
> works fine, does this flag anything in particular?
The minOA Sched only works when the outside air flow rate is set to the
minimum. You are not seeing
an impact due to the minOA Sched since the outside air flow rate is at
the maximum. Are you using the
ReturnAirTemp limit, Temperature limit or the Enthalpy limit to envoke
the minimum outside air flow rate?
See the IO Ref manual for further details on Controller:Outside Air.
>
> Kind regards
>
> -Elmer
>
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Michael J. Witte"
> <mjwitte@g...> wrote:
>
> > When using humidity control on the central chilled water coil, the
> controller
> > changes the chilled water setpoint to provide the required
> humidity ratio
> > needed to meet the humidistat setpoint. The varying setpoint
> values reflect
> > the adjusted setpoints for humidity control. Given the low
> numbers being seen,
> > it appears that the airflow rates are not adequate to meet the
> humidity loads?
> >
> > Mike
> >
> >
> > On 18 Feb 2005, at 8:25, Elmer Morrissey wrote:
> >
> > >
> > >
> > > Hello all,
> > >
> > >
> > >
> > > I am wondering if anyone has any experience in modelling VAV
> systems that
> > > maintain strict control over temperature AND humidity in a zone.
> > >
> > >
> > >
> > > I am modelling an AHU that provides air to two interior zones in
> an art gallery.
> > > I cannot seem to force the system to maintain control over the
> zones over a 24hr
> > > period as required by the Art Gallery.
> > >
> > >
> > >
> > > One of my major problems that I have found is a floating
> setpoint on my VAV
> > > system outlet node. During the winter, the setpoint output on
> the csv emulates
> > > the idf input, however during the summer design day, the csv
> output for the
> > > setpoint value floats from -57oC to 3oC. I cannot seem to locate
> the source of
> > > this error as I have no errors or warning. It is scheduled to a
> set value of
> > > 17.5oC during the summer and 16oC during the winter. I also have
> trouble
> > > stipulating the flow using the sizing objects, they seem to be
> ignored but I am
> > > guess this is due to an error elsewhere in the idf.
> > >
> > >
> > >
> > > I have uploaded the file to the yahoo page...
> AHU3_AirLoop_PurchasedPlant_V1.idf
> > >
> > >
> > >
> > > I would appreciate anyone's experience or advice with this
> matter.
> > >
> > >
> > >
> > > Kind regards
> > >
> > >
> > >
> > > -Elmer Morrissey
> > >
> > >
> > > PhD Researcher, IRUSE, NUIC, Ireland.
> > >
> > > __________________________________________________
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> > >
> > >
> > >
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> > > http://www.energyplus.gov
> > >
> > > The group web site is:
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> > >
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> > >
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> > >
>
>
>
>
>
> The primary EnergyPlus web site is found at:
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>
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--
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
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