Re: [EnergyPlus_Support] comparison of displacement ventilation with mixing ventilation

["Michael J. Witte" <mjwitte@xxxxxxxx>]

Just to let you know we are looking into this issue, but I do not have an 
answer yet.

Mike


On 2 Jul 2005, at 0:27, johnarent wrote:

> Hello,
>   I am a new EnergyPlus user looking to use the UCSD displacement
> ventilation model to compare the energy use to a space served by DV to
> the energy use of a comparable space served by an overhead mixing
> ventilation system.
> 
> One thing has me puzzled.  I am using Version 1.2.2 build 030.  If I
> take the DisplacementVent_1ZoneOffice.idf input file, and simply
> change the Room Air Modeling type to "Mixing", changing no other
> parameters, and re-run the simulation, the zone load changes from
> 80416W in the DV case to 70221 in the mixing case.
> 
> Now, of course the SAT and possibly other parameters would be
> different in the mixing case, but shouldn't the design load be the same?
> 
> DV Case: (From eio file) 
> 
> ! <Zone Sizing Information>, Zone Name, Load Type, DesLoad {W}, Calc
> Des Air Flow Rate {m3/s}, UserDes Air Flow Rate {m3/s}, Design Day
> Name, Time of Peak, Temperature at Peak {C}, Humidity Ratio at Peak
> {kgWater/kgAir}
>  Zone Sizing, ZONE1, Cooling,   80416.    ,   6.4152    ,   8.3398   
> , SAN_FRANCISCO_CA_USA COOLING .4% CONDITIONS DB=>MWB, 17:15:00,  
> 31.215    ,  0.93169E-02
> 
> 
> Mixing Case: 
> 
> ! <Zone Sizing Information>, Zone Name, Load Type, DesLoad {W}, Calc
> Des Air Flow Rate {m3/s}, UserDes Air Flow Rate {m3/s}, Design Day
> Name, Time of Peak, Temperature at Peak {C}, Humidity Ratio at Peak
> {kgWater/kgAir}
>  Zone Sizing, ZONE1, Cooling,   70221.    ,   8.9721    ,   11.664   
> , SAN_FRANCISCO_CA_USA COOLING .4% CONDITIONS DB=>MWB, 17:15:00,  
> 31.215    ,  0.93169E-02
> 
> 
> I don't see why the design cooling load should be significantly
> different, if the room thermostat setpoint, building envelope and
> internal loads don't change.  If the room is a normal ceiling height,
> the average room temperature in a space with DV won't be significantly
> different than the room temperature in the mixing case.  I am a new
> user so maybe I am missing something obvious.
> 
> Thanks, John
> 
> 
> 
> 
> The primary EnergyPlus web site is found at:
> http://www.energyplus.gov
> 
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
> 
> Attachments are not allowed -- please post any files to the appropriate folder
> in the Files area of the Support Web Site.
> 
> Yahoo! Groups Links
> 
> 
> 
> 
> 
> 
> 
> 



========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx




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