Re: [EnergyPlus_Support] Independent Control of Humidity and Supply Air Temperature

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

There are several ways in which EnergyPlus can control humidity and temperature 
at the same time depending on the system type.  

For chilled water systems, cool-reheat control of chilled water coils is 
currently available to meet humidity control requirements (see 
5ZoneWaterCooled_HighRHControl.idf example file).  

For DX coils, cool-reheat (FurnaceWithDXSystemRHcontrol.idf, or using 
DXSystem:Airloop - no example but similar to SmOffPSZ-MultiModeDX.idf - new in 
v1.2.2) and a 2-position coil bypass or sub-cool reheat option is also 
available (SmOffPSZ-MultiModeDX.idf - new in v1.2.2).

Plus a desiccant dehumidifier can be used to control humidity 
(DesiccantCVRhZoneRHCtrl.idf).  

A variable bypass for chilled water coils is under development, planned for the 
Fall 2005 release.

Mike


On 26 Apr 2005, at 0:03, t_graham_carter wrote:

> 
> 
> Dear All,
> I've had a search through the message archive on a number of keywords 
> with no hits that directly answer my question.
> 
> My exposure to E+ has been limited to a recent two day workshop and 
> skimming of various technical reports / documents on the software's 
> development so I apologise for any dumb questions.
> 
> From the workshop it is my understanding that you have a supply side 
> and a demand side of loops be it an air or water loop.  In the case of 
> air loops you can control supply temperature to meet the zone of 
> greatest demand (based on a calculated load as opposed to a return or 
> room temperature).  I believe you can also control the supply side 
> humidity off of the connecting nodes (between supply and demand loops) 
> humidity or temperature (either supply or return node).  But you cannot 
> not currently achieve the two togeher within E+?
> 
> For passive / active chilled beams and chilled ceiling systems and in 
> particular for underfloor air conditioning systems, there are good 
> reasons to independently control supply humidity and temperature via 
> face and bypass dampers on a cooling coil(s).  I understand that this 
> type of control would require a Spark module to be developed (well 
> beyond my current knowledge)?  
> 
> The introduction of nodes and loops in E+ is a key area where E+ can 
> distinguish itself from DOE-2.2.  However, the limitations of TAS or 
> Apache (IES) aside, these two packages allow relative freedom in 
> achieving the bypass control noted above.  I suspect there are other 
> packages that also allow greater freedom in controls than currently 
> allowed for in E+.
> 
> Are there plans to address these issues within E+ or current work 
> arounds? Or would a Spark module be easier to develop / utilise than I 
> currently fear?
> 
> Regards,
> Graham
> 
> 
> 
> 
> 
> 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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