Re: [EnergyPlus_Support] electric power (watts) of PTAC

On Fri, Nov 20, 2009 at 12:50 PM, Richard Raustad <RRaustad@xxxxxxxxxxxx> wrote:

9 watts is too low.

Hu,Jia wrote:
>
>
>
> Thank you for your specific explanation.
>
> HVAC I used is the templated PTAC provided by EnergyPlus, that is, the
> heating is provided by electric power and cooling is supplied by
> cooling coil.
>
> I calculate the fan electric power using the first method you
> provided, and find the maximum of fan electric power (W) is about 9W
> at the design day.
>
>
> On Fri, Nov 20, 2009 at 10:49 AM, Richard Raustad

> <RRaustad@xxxxxxxxxxxx <mailto:RRaustad@xxxxxxxxxxxx>> wrote:
>
>
>
> You need to identify the maximum power draw of your fan and
> compare that
> to your design intent.
>
> Report these 2 report variables:
>
> Output:Variable,*,Fan Electric Power,timestep;
> Output:Variable,*,Packaged Terminal Air Conditioner Fan Part-Load
> Ratio,timestep;
>
> and, if you are using an On/Off Fan object:
> Output:Variable,*,On/Off Fan Runtime Fraction,timestep;
>
> Maximum fan power is then roughly equal to Fan Electric Power /
> Packaged
> Terminal Air Conditioner Fan Part-Load Ratio or is equal to Fan
> Electric
> Power / On/Off Fan Runtime Fraction.
>
> Another method is to either look for a time during the simulation
> when
> the PTAC is operating at full load or force the PTAC to operate at
> full
> load and then look at the reported fan power for that time period.
>
> You will then need to determine if this maximum fan power is
> representative of your system.
> Fan power of 900 W sounds high for a PTAC (unless it is very
> large), my
> AC system at 3 tons (10.5 kW) gives an estimated fan power of 0.018 W
> per W of rated capacity.
>
>
>
> Hu,Jia wrote:
> >
> > Thank you, Richard.
> >
> > It is realistic then to have the HVAC consumption of 200 W per hour
> > (let's say on average) or in the range of 200-900 W per hour
> > depending on a day, time, that is, external weather conditions.
> >
> --
> 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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