[Bldg-sim] Air mixer for fresh air loop in E+?

[Aaron Boranian]

Thanks for the tips, everyone! I'll try to get a hold of someone on the
EnergyPlus forums.  I'm trying to stick with E+, as the model as 100+ zones
and we have devoted lots of time already.  We are thinking of possibly
modelling the unit with and without the mixing damper in TRNSYS to apply a
correction factor to E+ results.

In the meantime, I've attached a schematic of the dehumidification unit I
discussed.
1 - Untreated outdoor air, inlet to primary side of HX
2 - Outlet of primary side of HX, inlet to CC
3 - Outlet of CC, inlet to secondary side of HX
4 - Outlet of secondary side of HX, mixed with air state 3 to achieve
desirable supply air temperature
5 - Supply air

[image: Inline image 2]

Thanks again,

Aaron


On Wed, May 28, 2014 at 2:14 AM, Timothy Moore <timothy.moore at iesve.com>wrote:

>  Aaron,
>
>
>
> A cooling coil with heat exchanger (heat wheel, enthalpy wheel,
> counter-flow heat exchanger, heat pipe, etc.) connected immediately
> upstream and/or downstream of the coil as you have described to assist in
> cooling and/or to provide “free” reheat immediately following sub-cooling
> for dehumidification can readily be modeled in the ApacheHVAC module of the
> IES Virtual Environment. In the example below, I’ve added the damper set
> highlight in red to show how your mixing damper downstream of the cooling
> coil can be explicitly modeled; however, this is necessary only if you want
> to query air network node results for the inputs for this damper. A
> functionally equivalent bypass damper is built into the heat exchanger
> component. In this particular system network, there is a heating coil to
> provide backup source of reheat if/when the heat exchanger is insufficient
> to reheat the supply air to the desired temperature after sub-cooling for
> dehumidification. There is also an explicitly modeled bypass damper for the
> supply side of the heat exchanger and duplicate supply fan component (think
> of this as a meter with a performance curve) on the path through the supply
> side of the heat exchanger to account for the added pressure, and thus
> added fan power required, to move air through the heat exchanger when this
> component is not bypassed. I’m not sure whether this can be done in E+, but
> this ApacheHVAC example may give you some ideas:
>
>
>
>
>
> Cheers,
>
> Timothy
>
>
>
> [image: IES] <http://www.iesve.com/>
>
> *Timothy Moore*
> *Senior Product Manager*
>
>     T: +1 (415) 983-0603
>
> Internal IP ext. 8549
>
> T: +44 (0) 141 945 8500
>
> timothy.moore at iesve.com
>
> www.iesve.com
>
>
>
> ** *Design + Simulate + Innovate with the IES* *<Virtual Environment> ***
>
> Integrated Environmental Solutions Limited. Scotland registration SC151456
> Helix Building, West Of Scotland Science Park, Glasgow G20 0SP
>
> Email Disclaimer <http://www.iesve.com/disclaimer.html>
>
>
>
>
>
> *From:* Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org] *On
> Behalf Of *Keith Swartz
> *Sent:* Tuesday, May 27, 2014 8:29 AM
> *To:* Aaron Boranian; bldg-sim at lists.onebuilding.org
> *Subject:* Re: [Bldg-sim] Air mixer for fresh air loop in E+?
>
>
>
> Aaron,
>
>
>
> I don’t know enough about EnergyPlus to know if it can model the system
> you described, but the main programs that I use, Trane TRACE and eQUEST,
> cannot. I have dealt with it in the past by using the manufacturer’s
> software to model the DOAS, removing the ventilation from the main model,
> then combining the results in a spreadsheet. The spreadsheet for the SEMCO
> Pinnacle (which sounds similar to what you have) is available at
> http://www.semcohvac.com/index.php?page_id=94&pl_category=9. The
> spreadsheet does not directly output the energy numbers that I needed, but
> I was able to get them indirectly by manipulating the utility costs. For
> example, to get kWh I entered $1/kWh for the kWh cost and $0 for the other
> utility costs so that the cost output equaled the kWh that I needed.
>
>
>
> For a project that had a more complex DOAS, I had to create a custom
> spreadsheet to model it using basic psychrometrics. You might be able to
> access the presentation I did at last year’s ASHRAE Energy Modeling
> Conference at
> https://www.ashrae.org/membership--conferences/conferences/ashrae-conferences/emc2012.
> I was told afterwards by someone from IES VE that their software could
> model the system I had, so that may be worth looking into if EnergyPlus
> won’t do it for you.
>
>
>
> Sincerely,
>
> Keith Swartz, PE, BEMP, LEED AP
>
> Senior Energy Engineer | *Energy Center of Wisconsin* |
> *Madison.Chicago.Minneapolis*
>
> 608.210.7123 | www.ecw.org
>
>
>
> *From:* Aaron Boranian [mailto:flyn.hawyn at gmail.com <flyn.hawyn at gmail.com>]
>
> *Sent:* Friday, May 23, 2014 12:45 AM
> *To:* bldg-sim at lists.onebuilding.org
> *Subject:* [Bldg-sim] Air mixer for fresh air loop in E+?
>
>
>
> Hey all,
>
>
>
> I am trying to model a heat exchanger assisted cooling coil for the fresh
> air system of a laboratory building in Singapore.  Essentially, outdoor air
> (32C DB/ 26C WB) passes through the supply side of the heat exchanger (24C
> DB/ 24C WB), then passes through the cooling coil (13C DB/ 13C WB).  Outlet
> air from the cooling coil then passes through the secondary side of the
> heat exchanger (28C DB/ 18C WB).  In order to attain constant supply air DB
> temperature of 22C, design has allowed for mixing of outlet air from the
> cooling coil with outlet air from the secondary side of the heat exchanger.
>  Is it possible to model this in E+?  Somehow "trick" it with the OA mixer
> component?
>
>
>
> Regards,
>
> --
> Aaron Boranian
> Research Associate, Energy Research Institute @ Nanyang Technological
> University (ERI at N)
> M.S. Civil Engineering, Building Systems Program, University of Colorado
> at Boulder
> B.S. Engineering - Civil Specialty, Colorado School of Mines
> Cell: (+65) 8588-5961
>



-- 
Aaron Boranian
Research Associate, Energy Research Institute @ Nanyang Technological
University (ERI at N)
M.S. Civil Engineering, Building Systems Program, University of Colorado at
Boulder
B.S. Engineering - Civil Specialty, Colorado School of Mines
Cell: (+65) 8588-5961
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