[Equest-users] Add-On Desiccant for simulating passivedehumidification wheel?

Kathryn Kerns kathryn.kerns at bceengineers.com
Fri Dec 13 09:25:16 PST 2013


Well, it is a little weird, but create 2 HVAC systems, like packaged
single zones, and attach them to two spaces that don't mind having some
possibly odd space temperatures, like mechanical rooms. The first HVAC
unit uses heat recovery and heats/cools OSA and develops a space
temperature and humidity profile. Feed that space air into the second
HVAC unit via the Outside Air from System and further heat/cool (heat
recovery won't work at this point, I think) to create tempered, dry air
to feed to all the building terminal units. Sometimes you have to get
creative with equipment that heats and cools, like using a magic no
energy consumption electric boiler to represent the hot gas bypass
portion of a DX cooling unit, but as long as the resulting space
temperature and humidity profiles make sense, and you keep track of the
power consumed, I figure the work around is close enough.

 

It seems to work.

________________________________

From: Bishop, Bill [mailto:bbishop at pathfinder-ea.com] 
Sent: Friday, December 13, 2013 9:03 AM
To: Kathryn Kerns
Subject: RE: [Equest-users] Add-On Desiccant for simulating
passivedehumidification wheel?

 

Thanks! I assume I'm not the only one who would be curious how you model
two DOAS in series?

 

From: Kathryn Kerns [mailto:kathryn.kerns at bceengineers.com] 
Sent: Friday, December 13, 2013 12:01 PM
To: Bishop, Bill; equest-users at lists.onebuilding.org
Subject: RE: [Equest-users] Add-On Desiccant for simulating
passivedehumidification wheel?

 

I remember talking to James Hirsch about the desiccant pre-conditioner
software and he warned me that the software was never officially
verified as functional for all design conditions. I steered clear of
those subprograms after that and started experimenting with adding two
DOAs in series to simulate dehumidification control. I don't know if
that solution is really any better, but it seemed to work, and at least
used subprograms I was sure functioned.

 

________________________________

From: equest-users-bounces at lists.onebuilding.org [
mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Bishop,
Bill
Sent: Friday, December 13, 2013 8:38 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Add-On Desiccant for simulating
passivedehumidification wheel?

 

Any thoughts on using a System -> Preconditioner -> Add-On Desiccant for
modeling a passive dehumidification wheel in the configuration shown
below?

It would be a workaround. One problem I see is the Add-On Desiccant
doesn't interact with the return air. You would have to derate the total
energy wheel somehow, such as by reducing the effectiveness or
decreasing the exhaust airflow.

 

 

Thanks,

Bill

 

William Bishop, PE, BEMP, BEAP, LEED AP | Pathfinder Engineers &
Architects LLP

Senior Energy Engineer

 

 

134 South Fitzhugh Street                 Rochester, NY 14608

T: (585) 325-6004 Ext. 114            F: (585) 325-6005

bbishop at pathfinder-ea.com <mailto:wbishop at pathfinder-ea.com>            
www.pathfinder-ea.com <http://www.pathfinder-ea.com/> 

P   Sustainability - the forest AND the trees. P       

 

 

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