[BLDG-SIM] Active Chilled Beam Model

[Graham & Megan]

This is a good discussion, I am glad others are trying to find work arounds as the humidity control and central heating aspects are not straight forward.
I am not fmailiar with the fan energy problems, but I am familiar with the following:

1) There is a lower limit on CHW DT across the chiller which I believe is 6DegF.

2) The OA-FROM-SYSTEM is the way to go in EQuest/2.2.  TAS, Apache and I suspect other programs allow the heating / humidity control to be handled more easily and accurtely but fall down on the waterside.

3) The OA-FROM-SYSTEM cannot 'see' the zones you are passing the air to so therefore off-coil temperatures cannot be directly controlled from the zone unless you replicate a dummy building that mimics your actual model's latent loads etc.

4) Further to #3 the OA-FROM-SYSTEM cannot see the zone heating demands thus space heating must be local by baseboards or by a 4-pipe IU/FCU.

5) Given above I have tended to se up my OA-FROM-SYSTEM as a SZRH system with the cooling coil off-coil controlling to an outdoor air reset schedule to dehumidify and the zone heating coils reheating to maintain a minimum zone supply temperature (nominally 15C).  In Australia we use this configuration as we have warm to hot and humid climates with a small heating load in comparison to most North American climates.  In winter the central heating coil (zone coil in this case on a SZRH) would heat to satisfy zone of greatest heating demand and other zones would recool.  Reheat and recool sounds inefficient but when the heating is done with CW heat recovery and periods of simultaneous heating and cooling are in cooler months when plant effcieincy is at a maximum, the whole system is actually quite efficient.

6) I then iterate on the outdoor air reset schedule and observe humidity levels in key zones to satisfy myself that I am getting space dewpoint control.

7) Ultimately with a chilled beam system that is most sensitive to space dewpoint control this is still only a good approximation that is time consuming to ensure it is right.

I mentioned last week that the EQuest/2.2 team could fix this up (IU system with no OA-FROM-SYSTEM, dewpoint contrl and central heaing / reheat) if the $ could be found - keep in mind we enjoy freeware.  Speaking with Jeff Hirsch over the years we aren't talking a lot of money but it is too much for me to justify paying 100%.  Anyone feeling generous or like me, frustrated at the time consuming work arounds, please contat Jeff and/or myself as this enhancement would extend the application of EQuest/2.2 dramatically (from my point of view).

Regards,
Graham Carter
----- Original Message ----- 
  From: Paul Erickson 
  To: BLDG-SIM at GARD.COM 
  Cc: Eric.Yang at smithgroup.com 
  Sent: Wednesday, September 13, 2006 12:23 AM
  Subject: [BLDG-SIM] Active Chilled Beam Model


  Eric,

  As Peter stated, an induction unit can have a dedicated system supply source (for Trace it is OA; for eQUEST/DOE-2 you specify source...OA or rom a chosen AHU).  The same is true with the fan coil unit.  

  For DOE-2.2/eQUEST specifically, there are a few of snags that one runs into.  One, the induction ratio doesn't really matter...play around and you'll see.  Two, DOE-2 doesn't seem to account for the fan energy used to pull off the CFM that goes to the beams...I'd love for someone to prove I'm wrong.  Three, I've had difficulties with loop temperatures and delta T for the loops...i.e. DOE-2 didn't seem to like the higher water temps going to the IU/FCU.  I'd like to hear feedback if someone else got around this.

  Trace had some similar drawbacks...I'll work on recalling them.

  Paul


  >>> "Peter Simmonds" <peter.simmonds at ibece.net> 9/12/2006 8:48 am >>>



  Peter Simmonds Ph.D.
  Associate
  IBE Consulting Engineers
  14130 Riverside Drive Suite 201
  Sherman Oaks, CA 91423
  p:   (818) 377-8220
  f:    (818) 377-8230
  m:  (818) 219-1284
  IDEAS FOR THE BUILT ENVIRONMENT

  This e-mail message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure, or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message.




----------------------------------------------------------------------------
    From: Peter Simmonds 
    Sent: Monday, September 11, 2006 3:47 PM
    To: 'Eric Yang'
    Subject: RE: [BLDG-SIM] Active Chilled Beam Model


    OK so you are talking about an active beam and not a static beam, right. Then you need an outside air supply to be incorprated into the conditioning system, so I guess the induction unit will suffice, just check the minmum turndown ratio and check the induction rate to match the profile of the active beam.

    Peter Simmonds Ph.D.
    Associate
    IBE Consulting Engineers
    14130 Riverside Drive Suite 201
    Sherman Oaks, CA 91423
    p:   (818) 377-8220
    f:    (818) 377-8230
    m:  (818) 219-1284
    IDEAS FOR THE BUILT ENVIRONMENT

    This e-mail message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure, or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message.




--------------------------------------------------------------------------
      From: Eric Yang [mailto:Eric.Yang at smithgroup.com] 
      Sent: Monday, September 11, 2006 3:40 PM
      To: Peter Simmonds
      Subject: RE: [BLDG-SIM] Active Chilled Beam Model


      Thanks for your inputs.  How about the air which is induced into the beams?   For example, I supply only 105 CFM per beam, but I will have around 300 CFM total supply air.  

       

      Eric

       


--------------------------------------------------------------------------

      From: Peter Simmonds [mailto:peter.simmonds at ibece.net] 
      Sent: Monday, September 11, 2006 6:36 PM
      To: Eric Yang; BLDG-SIM at GARD.COM
      Subject: RE: [BLDG-SIM] Active Chilled Beam Model

       

      Very simple. Model the chilled beam as a fan coil for cooling only and remove the associated fan power.

       

      Peter Simmonds Ph.D.

      Associate
      IBE Consulting Engineers

      14130 Riverside Drive Suite 201

      Sherman Oaks, CA 91423
      p:   (818) 377-8220
      f:    (818) 377-8230
      m:  (818) 219-1284
      IDEAS FOR THE BUILT ENVIRONMENT

      This e-mail message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure, or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message.

       

         


------------------------------------------------------------------------

        From: BLDG-SIM at GARD.COM [mailto:BLDG-SIM at GARD.COM] On Behalf Of Eric Yang
        Sent: Monday, September 11, 2006 2:34 PM
        To: BLDG-SIM at GARD.COM
        Subject: [BLDG-SIM] Active Chilled Beam Model

        Greetings

         

        I am seeking for any suggestions or input on the model of active chilled beam system.   In my previous Trace model, it can not handle it very well by induction system.  I am very curious to get inputs and helps from other folks.   Thanks in advance.

         

         

        Eric 

         

        Eric Yang

        Mechanical Engineer, LEED.A.P.

        SmithGroup

         

        1850 K Street, NW, Suite 250

        Washington, DC 20006

        t  202.974.4555 (direct)

        f. 202.974.4500

        eric.yang at smithgroup.com 

        www.smithgroup.com

         

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