[EnergyPlus_Support] Re: RoomAirModel - RoomAirSettings:ThreeNodeDisplacementVentilation

["Jean marais" <jeannieboef@xxxxxxxxx>]

thanks James. I basically have to predict some sort of temp vs height. I would like to run a basic CFD analysis with DB as a sanity check. measuring the preretrofit conditions on site, will only give me spring conditions...by summer the equipment will be in.

we're hoping to gain some insite into controlling the system.

I'll make sure everyone knows what the model weaknesses are.



--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jim Dirkes" <jim@...> wrote:
>
> Dear Jean,
> 
> Keep in mind that if the modeling algorithm is not appropriate for your
> situation, the results are a) completely wrong, b) meaningless,  or c)
> suspect.  If you ask me to predict the winner of a Formula 1 race (about
> which I know almost nothing), don't rely on my prediction!
> 
> In your situation be careful about promising good results based on E+
> results.
> 
>  
> 
> The Building Performance Team
> James V. Dirkes II, P.E., BEMP , LEED AP
> 1631 Acacia Drive NW
> Grand Rapids, MI 49504
> 616 450 8653
> 
>  
> 
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Jean marais
> Sent: Wednesday, April 25, 2012 2:20 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Re: RoomAirModel -
> RoomAirSettings:ThreeNodeDisplacementVentilation
> 
>  
> 
>   
> 
> 
> Thanks. I thought as much. This is one huge factory wall with adiabatic
> boundries on 3 sides, so no hot or cold surfaces to drive convection flows.
> That being said, the hall is ventilated by supply air at the 1m height level
> and exhausted at ceiling height. It's showing good results. I was guessing
> that the passage relating to solar gains implied on the side wall and side
> wall windows (which I don't have), but the large equipment gains is still a
> question mark. I have assigned 1 pleum per operator and one per the machine
> they are working on (so x2 per person). I'll still go and measure on site
> when it gets warmer, but for a 29 deg C day, I'm getting about 1 to 1.4 K
> per meter vertical temperature stratification. seemed okay.
> 
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> , "Griffith, Brent"
> <brent.griffith@> wrote:
> >
> > That roomair model was developed for office-type spaces that are interior
> zones. For example, hot or cold exterior walls will drive air movement that
> leads to a different airflow pattern in the space than the one that model is
> intended for. Your zone has much higher ceilings and quite different
> internal gains than a typical side-wall displacement ventilated office.
> There is no simple roomair model available for your specific type of space,
> so you could try it. Check that the results for different subzone
> temperatures are reasonable though.
> > 
> > From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> ] On Behalf Of Jean marais
> > Sent: Tuesday, April 24, 2012 2:40 PM
> > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> 
> > Subject: [EnergyPlus_Support] Re: RoomAirModel -
> RoomAirSettings:ThreeNodeDisplacementVentilation
> > 
> > 
> > 
> > Anyone?
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com>
> <mailto:EnergyPlus_Support%40yahoogroups.com>, "Jean marais"
> <jeannieboef@<mailto:jeannieboef@>> wrote:
> > >
> > > io ref:
> > > "The model should be used with caution in zones which have large heat
> gains or losses through exterior walls or windows or which have considerable
> direct solar gain."
> > >
> > > Can someone elaborate why? I have a factory 12 x 90 x 150 m with 25%
> skylight/roof so large solar gains an high machine heat gains (CNC milling
> machines) and 15 W/m² lighting.
> > >
> > > Supply air is brought in at 0-1 m and exhaust is up at ceiling height.
> > >
> > > Any clarification is welcome.
> > >
> >
>




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