Re: [EnergyPlus_Support] Re: Underfloor Cooling Plenum

["Long T. Phan" <ltb.phan@xxxxxxxxx>]

First of all, I would like to thank you all for your great suggestions.

@Jean: 

1) The data center would be inside a building with no exterior surfaces. So I guess the boundary conditions would be adjacent zone.

2) This is really one of my concerns. I have big IT equipment boxes, and I ask myself whether I should draw the geometry of these boxes or just simply ignore it and do volume subtraction as you suggested.

3) I would go with the well-mixed assumption since I am interested in the surface temperature at all the walls inside the data center. I am not sure if this is a correct approach but I will do more research on these stuff.

4) I will consider it.

5) Another good point here.

6) I will research more on this.

@ Edwin: Thank you for your suggestion.

@ Karen: Thank you. Your suggestions are really helpful.

Regards,
Long

On Wed, Jul 25, 2012 at 9:29 AM, Edwin Lee <leeed2001@xxxxxxxxx> wrote:

 

E+ can do UFAD with the room air models as Jean mentioned in #3.  Check out 5ZoneSupRetPlenRAB.idf and 5ZoneSupRetPlenVSATU.idf for examples with supply and return plenums.

On Wed, Jul 25, 2012 at 2:43 AM, Jean marais <jeannieboef@xxxxxxxxx> wrote:

 

Wow! What a great problem. Very interesting. Without looking at other replies, I will comment:

1) The bounding conditions (outside of floor slab) should be considered. Is it ground or adjacent zone?

2) The volume of the main zone must be overwritten in the Zone object to subtract the space of the IT Boxes.

3) Is the zone air ventilation stradegy using displacement ventilaion (UFAD) or is the zone air (temperature) well mixed? If the first case is prevalent, then consider the other RoomAirModel objects available in e+.

4) I would consider to model the underfloor partition as a seperate zone, i.e. a plenum supply zone. This may then require the use of an AFN or a ZoneMixing object.

5) I would consider other simpler ways such as not modelling the underfloor partition and assigning a constant temp (that of the supply air) to the thin floor plate (which contruction mass and thermal properties should take into consideration the missing mass from the perforation and thermal breaks) using the OthersideCoefficient objects on the floor.

6) I would consider using very high convection coefficient on the floor surface (There is an eplus object that can assign this to a surface...I don't remember the name.

Sorry...only six points now...if I think of more I'll post.

Enjoy!

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Long Phan" <ltb.phan@...> wrote:
>
> Hi Group,
>
> I'm modeling a simple data center with only one single zone. This data center has a raised floor plenum in which the supply cooling air flows into the upper zone where IT equipment are situated. The air is flowing through perforated tiles installed on the raised floor. My question is how do you model such an inter-surface for a perforated tile? There are a bunch of tiny holes on the tile. Should I model them as air wall? Any suggestions would be appreciated.
>
> Thanks,
> Long
>

--

Edwin Lee

Doctoral Candidate, Oklahoma State University

ASHRAE Student Member, Former ASHRAE OSU Student Branch President

Office: ATRC 303: 405-744-3727

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