[Bldg-sim] modeling chilled beams in eQuest

[Ellen Franconi]

Vishnu,
I am not sure I completely follow what you did but perhaps you are not aware
that the induction unit system includes a central fan for pretreating
outside air delivered to the induction units. So if you used the "outside
air from sys" approach,the central fan of the induction unit would still be
modeled with its default parameters. Also, if you don't set the induction
ratio high enough (e.g. default is 3, max value is 10), you will get return
air mixing with your supply (e.g it will no longer be 100% OA), which will
make your supply air flow higher. This will increase your fan energy use as
well.

I don't think the eQUEST documentation includes a description of the
induction unit system (TPIU or FPIU) but its relevant keywords can found in
the DOE2.1E BDL Summary. You could also insert the following commands in
your input file.

DIAGNOSTICS  DEFAULTS ..   $ before the SYSTEM command and
DIAGNOSTICS  CAUTIONS ..    $ after the SYSTEM command

Adding the above will show in the BDL file the value for all keywords not
explicitly listed but with default values being used.
Ellen

On Wed, May 5, 2010 at 11:14 PM, Vishnuraj Nair <vishnu at kalpakrit.com>wrote:

>  Dear friends,
>
>
>
> I am modeling the active chilled beams system using an induction unit. I
> have created a separate treated outside air system (TOAS) from where the
> fresh air would be supplied to
>
> the induction unit. I have hard coded the fresh air requirement for each
> zone at the outdoor air CFM field under outside air tab as well as under
> design flow cfm field under air flow tab
>
> so that the only the fresh air requirement is supplied to the zone. The
> cooling will be done by chilled beams modeled as induction unit.
>
>
>
> when I see the simulation report the amount of fan energy consumed is huge
> which is nearly about 20% percent of the overall energy consumption.
>
> So then I zeroed out the fan energy i.e kW/CFM for fans =0 and only the
> TOAS has the fan energy but the fan energy consumption decreased very
> little.
>
> I have no other source in the model for which the fan energy could be
> accountable for.
>
>
>
> Can anyone please tell what can be the reason for this or if I am missing
> out on something?
>
> Am I modeling the system right? How is the fan energy for this system to be
> modeled?
>
> Vishnuraj Nair
>
> Kalpakrit Sustainable Environments Pvt. Ltd.
>
> New Delhi
>
> Tel: +91.124.4309490-92 Ext: 312 , Fax: +91.124.4309493
>
> E-mail : vishnu at kalpakrit.com
>
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-- 
Ellen Franconi, PhD, LEED AP
Senior Consultant, Built Environment Team

Rocky Mountain Institute
1820 Folsom Street
Boulder, CO 80302
303.567.8609 (Desk)
303.245.7213 (Fax)

Rocky Mountain Institute drives the efficient and restorative use of
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