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

[Jim Dirkes]

Dear Aaron,
I think you are describing something like a wrap-around heat pipe which provides its own reheat.  A schematic would be helpful to understand your actual intent!

The scenario below is something E+ does easily, and I think it would not be too hard to move the source for the HX secondary inlet (now #1002) to #1006.

[cid:image002.jpg at 01CF79AF.BA17E6C0]

James V Dirkes II, PE, BEMP, LEED AP
www.buildingperformanceteam.com<http://www.buildingperformanceteam.com/>
Energy Analysis, Commissioning & Training Services
1631 Acacia Drive, Grand Rapids, MI 49504 USA
616 450 8653

From: Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Keith Swartz
Sent: Tuesday, May 27, 2014 11:29 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<http://www.ecw.org/>

From: Aaron Boranian [mailto:flyn.hawyn at gmail.com]
Sent: Friday, May 23, 2014 12:45 AM
To: bldg-sim at lists.onebuilding.org<mailto: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
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