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Re: [EnergyPlus_Support] Re: Variable Speed Fan

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Re: Variable Speed Fan
From: Richard Raustad <RRaustad@xxxxxxxxxxxx>
Date: Fri, 01 Aug 2008 13:04:59 -0400
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This will be a bit tricky and I have never tried it. You can use the 
DXSystem:Airloop object and schedule the coil off all the time. The 
tricky part is getting the air primary loop to operate at the outside 
air flow rate you want. If you set the Controller:Outside air object to 
give a Fixed Minimum amount of outside air and add a minimum outside air 
fraction schedule you may be able to change the air flow rate as you 
wish, but you will have to set the schedule up to do this. You may also 
have to use zone exhaust fans to remove the air from the zones.

Elreq wrote:
>
> Many Thanks.
> But I see that the Coil:DX: MultiSpeed:Cooling (and also Heating) can
> only be referenced by a Unitary System MultiSpeed Heat Pump air to
> air. The problem is that I do not want to include any coils in my
> model, just mechanical ventilation. Is there a way to set the coils
> capacity to zero, in such a way that the air is only passing through
> it without warming up or cooling down?
> I would like to make it more simple. Until now I can make variations
> on the amount of outside air coming in, but the fan is running always
> at the same capacity, so I suppose it mixes the return air in the OA
> mixer in such a way that the incoming volume is always constant. So I
> am sure there must be a way to make the supply fan have 3 different
> speeds without having to introduce a coil and a heat pump. I will keep
> on searching and also waiting for suggestions or comments.
>
> Rgds,
> Santiago
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>, Richard Raustad
> <RRaustad@...> wrote:
> >
> > See documentation for Coil:DX:MultiSpeed:Cooling and
> > Coil:DX:MultiSpeed:Heating.
> >
> > Elreq wrote:
> > >
> > > I want to simulate a typical 3-speed variable fan, for example, 100%,
> > > 66% and 33% of its nominal capacity.
> > >
> > > That is: option B)
> > >
> > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>, "JV Dirkes II"
> <jvd2pe@>
> > > wrote:
> > > >
> > > > Dear Santiago,
> > > >
> > > > I am still not clear about what you are trying to accomplish. Do you
> > > > want to model:
> > > > a) a fan which operates at many speeds, proportional to the
> heating /
> > > > cooling load?
> > > > b) or a fan which operates at 2 or 3 discrete speeds, for example --
> > > > 100% and 50% of capacity?
> > > >
> > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>, "Elreq"
> <tolteca33@> wrote:
> > > > >
> > > > > Dear Forum
> > > > >
> > > > > I still cannot make the variable fan to run at different
> speeds. Does
> > > > > anybody has an example where this happens? Maybe if I take a
> look I
> > > > > can see what I am missing.
> > > > >
> > > > > Regards
> > > > >
> > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>, "jvd2pe" <jvd2pe@>
> wrote:
> > > > > >
> > > > > > Dear Elreq,
> > > > > >
> > > > > > Assuming that you are using one of the constant volume fan
> > > objects....
> > > > > >
> > > > > > Constant volume and constant pressure = constant power.
> > > > > >
> > > > > > Normally, the variation in outdoor air is accomplished by a
> > > mixing box
> > > > > > ("Mixer" object in E+), which just adjusts the ratio of
> outdoor and
> > > > > > return airflows.
> > > > > >
> > > > > > If you are using a variable volume fan, something is forcing th
> > > fan to
> > > > > > remain at constant volume.
> > > > > >
> > > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>, "Elreq" <tolteca33@>
> > > wrote:
> > > > > > >
> > > > > > > Thanks for the recommendation but I obviously read all this.
> > > > > > >
> > > > > > > Now I have a big question because I have created a schedule
> > > for the
> > > > > > > minimum outside air flow, depending on the occupancy, and
> in the
> > > > > > > results it clearly shows that the air changes per hour on each
> > > > zone is
> > > > > > > not constant anymore, being higher in the hours of occupancy,
> > > > but the
> > > > > > > supply fan, that is supposed to provide this outside air, is
> > > always
> > > > > > > running at the same power. So I dont know how is possible that
> > > > the air
> > > > > > > flow is changing but the fan is always running at the same
> speed.
> > > > > > >
> > > > > > > Any suggestions greatly appreciated.
> > > > > > >
> > > > > > > Santiago.
> > > > > > >
> > > > > > >
> > > > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>, "JV Dirkes II"
> > > <jvd2pe@>
> > > > > > > wrote:
> > > > > > > >
> > > > > > > > Dear Elreq,
> > > > > > > > I recommend that you review the Input Output Reference,
> > > > starting at
> > > > > > > > page 1162. Several fans are discussed. In short:
> > > > > > > > Fan:Simple:Const Volume is a constant volume, continuous
> > > > > operation fan
> > > > > > > > which can be turned on and off via a schedule.
> > > > > > > > Fan:Simple:OnOff is similar to the one above, but it cycles
> > > > > itself on
> > > > > > > > and off as required by its thermostat ... all during the
> > > scheduled
> > > > > > > > operation period. This is a typical mode of operation for a
> > > home
> > > > > > > furnace.
> > > > > > > > Fan:Simple:Variable Volume runs continuously during the
> Schedule
> > > > > > > > period, but varies its volume to meet the heating or cooling
> > > > demand.
> > > > > > > >
> > > > > > > > I hope that this is helpful!
> > > > > > > >
> > > > > > > > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx 
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> > > <mailto:EnergyPlus_Support%40yahoogroups.com>, "Elreq" <tolteca33@>
> > > > > wrote:
> > > > > > > > >
> > > > > > > > > Dear Forum,
> > > > > > > > >
> > > > > > > > > I am simulating a typical house with balanced
> ventilation and
> > > > > > > > > baseboard heating units. I want that the supply fan of
> the Air
> > > > > Loop
> > > > > > > > > has three different speeds, so I introduce the fan
> > > coefficients
> > > > > > > > > mentioned in the input output reference that
> correspond to the
> > > > > > > > > variable speed motor. The problem is that the fan is
> constant
> > > > > > all the
> > > > > > > > > time at a constant speed. Could somebody tell me how
> to make
> > > > > it work
> > > > > > > > > as a variable speed fan?
> > > > > > > > >
> > > > > > > > > Many thanks.
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> > >
> >
> > --
> > Richard A. Raustad
> > Senior Research Engineer
> > Florida Solar Energy Center
> > University of Central Florida
> > 1679 Clearlake Road
> > Cocoa, FL 32922-5703
> > Phone: (321) 638-1454
> > Fax: (321) 638-1439 or 1010
> > Visit our web site at: http://www.fsec.ucf.edu <http://www.fsec.ucf.edu>
> >
> > UCF - From Promise to Prominence: Celebrating 40 Years
> >
>
>  

-- 
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
1679 Clearlake Road
Cocoa, FL  32922-5703
Phone:   (321) 638-1454
Fax:     (321) 638-1439 or 1010
Visit our web site at: http://www.fsec.ucf.edu

UCF - From Promise to Prominence: Celebrating 40 Years


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References:
- [EnergyPlus_Support] Re: Variable Speed Fan
  - From: Elreq

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