[BLDG-SIM] Chilled Beams and eQUEST

Timothy Moore tcm at berkeley.edu
Wed Apr 25 18:03:58 PDT 2007


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)
> 921-1981
> 
> F  (415) 625-0735                   F  (916)
> 921-1921
> 
> E  RHammond at gb-eng.com
> 
> W www.gb-eng.com
> 
>  
> 
> 
> 
>
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