[BLDG-SIM] Chilled Beams and eQUEST

[Shivani Shah]

Tim,
Thanks for your email. If we model active chilled beams as a PIU units,
how does one take account of the chilled water coil in a chilled beam
unit? From my understanding, PIU in eQUEST only has a re-heat coil and
no chilled water coils, which means that all the cooling is being done
at the AHU which is not actually the case. Can you throw us a light on
that?

Thanks.


--
Shivani Shah
Atelier Ten
-----Original Message-----
From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Timothy
Moore
Sent: Wednesday, April 25, 2007 9:04 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Chilled Beams and eQUEST

In the case of the PIUs (fan-powered boxes), it is true that both series
and parallel PIUs modeled in eQuest/DOE-2.2 presently assume a
constant-volume fan in the box. For series units the fan is always on
per schedule and draws from both the primary and secondary air streams.
For the parallel unit the fan draws only from the secondary air and runs
as needed (on/off only) to meet zone demands. If you have a chilled beam
that is essentially an actively cooled diffuser with no fan in it, you
can simply set the fan kW/cfm to zero (or near zero if eQuest gives you
an error massage for an entry of zero). 

If an active chilled beam includes a fan with variable speed drive, the
method is presently the same as for any PIU with a variable speed drive:
Run the model; Then, based upon SIM file bin results for part-load
operational hours, determine the average part-load fraction; Finally,
based on performance curves for the terminal unit, or approximated using
peak power and fan laws, etc., determine an appropriate average kW/cfm
for the PIU in your application.

While I'm using a beta version of eQuest with a bunch of new stuff (and
with quite a bit of functionality disabled until everything is worked
out) I'm pretty sure the above PIU features hold true for the standard
version as well.

FYI: Pending developments for the UFAD-enabled version of eQuest (which
thus far includes zone plume factors, diffuser efficiency factors,
modeling of the UFAD supply plenum as a thermal zone, and some
improvements to airflow sizing --- presently in rough beta form) support
that it will, if all goes as we hope, have variable-speed fans for PIUs
and a few other helpful changes by the time it's ready for public
release. However, be patient as the number of changes to be made may
take a little while for our good friend Steve Gates to turn into code.
(Many thanks to Steve for his efforts thus
far!) 

Cheers again,
Timothy

*************************************
Timothy Moore
Building Science Research
 
Center for the Built Environment (CBE)
University of California at Berkeley
390 Wurster Hall #1839
Berkeley, CA 94720-1839
 
Ph: (510) 525-4809 at office in North Berkeley
Ph: (510) 642-2720 at CBE Building Science Lab
Mobile: (303) 324-1044
eFax: (413) 480-7252
tcm at berkeley.edu 



-----Original Message-----
From: BLDG-SIM at gard.com [mailto:BLDG-SIM at gard.com] On Behalf Of Fred
Porter
Sent: Wednesday, April 25, 2007 4:28 PM
To: BLDG-SIM at gard.com
Subject: [BLDG-SIM] Chilled Beams and eQUEST

Correct me if I'm wrong, but the one drawback to the IU SYSTEM in
DOE-2.x is
that the supply air volume is constant, or off. A system that varies
primary
airflow in response to ventilation needs can't be modeled directly.

--
Fred W. Porter, B.S., LEED A.P.
Architectural Energy Corp.

-----Original Message-----
From: Gerald Pde [mailto:geraldpde at yahoo.com]
Sent: Wednesday, April 25, 2007 2:53 PM
To: BLDG-SIM at gard.com
Cc: Nathan Fleischer
Subject: [BLDG-SIM] Chilled Beams and eQUEST

You can use induction units to simulate a chilled beam system but you
might
also need to configure a seperate (or secondary) warmer chilled-water
loop
and cooler hot-water loop for the zonal coils. You might also need to
check
the induced ratio to scale the capacity of the primary air delivery and
the
secondary induced air component.

Hope this helps.

Gerald
 
--- Ryan Hammond <RHammond at gb-eng.com> wrote:

> All,
> 
>  
> 
> Has anyone out there had experience modeling chilled beams with 
> eQUEST?
> 
> 
>  
> 
> How's it done?
> 
>  
> 
> Thanks,
> 
> R. Ryan Hammond, LEED(r) AP
> 
> Designer
> 
>  
> 
> G U T T M A N N & B L A E V O E T
> 
> C o n s u l t i n g E n g i n e e r s
> 
>  
> 
> 2351 Powell Street                  1111 Howe Ave.,
> Suite 155
> 
> San Francisco, CA 94133       Sacramento, CA 95825
> 
> P  (415) 625-0730                   P  (916)
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> 
> F  (415) 625-0735                   F  (916)
> 921-1921
> 
> E  RHammond at gb-eng.com
> 
> W www.gb-eng.com
> 
>  
> 
> 
> 
>
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