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[EnergyPlus_Support] Re: Is there any way to simplify DX Unit Model?

Jim and Chandan,
Thanks for your replies.

I was aware of the existence of curve fit tool, but the problem is that I am now modeling an existing building,the DX unit is McQuay ALP 041C installed in 1999,the performance table I am able to find from the manufacture is the capacity correlating with ambient temperature and SAT. Suct. Temp, which I assumed is the saturated suction temperature, but the E+ DX model requires Capacity modification curves as a function of outside wet bulb temperature, entering air wet bulb temperature and airflow, which are not even included in the manufacture's table. So I can't use the curve fit tool provided by E+.

But I did see a table provided by the manufacture that has "percent of fully load capacity" and "percent of full load KW", so I am wondering if there is other ways in E+ to avoid those series curves and define a simpler curve myself to correlate the Unit KW with Coil Load.

Ke
 
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jim Dirkes" <jim@...> wrote:
>
> Dear Ke,
> 
> Consider using the curves from an example file that is similar to your
> project.  They are reasonable representation of many coils.
> 
> Also, on the Help Desk Web site in the Downloads section
> (http://energyplus.helpserve.com/index.php?_m=downloads
> <http://energyplus.helpserve.com/index.php?_m=downloads&_a=view> &_a=view),
> you will find a helpful Excel spreadsheet for creating bi-quadratic curves
> called "Creating a BQuadraticCurve using LINEST".
> 
>  
> 
> 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 Ke Xu
> Sent: Monday, April 02, 2012 11:16 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Is there any way to simplify DX Unit Model?
> 
>  
> 
>   
> 
> Dear all,
> Since a single-speed DX coil model stated in E+ engineering reference
> involves 5 curves (TotCapTempModFac,
> EIRTempModFac,EIRFlowModFac,PartLoadFrac,ect.), which requires over 20
> constant parameters as inputs, but in my case, it is almost impossible to
> obtain all curves from the manufacture,I am wondering if there is a way that
> I can avoid all those curves input? or put it in other words, is there a
> simpler DX model built in E+? for example, a curve directly correlate coil
> part load ratio to the energy use ratio? and if E+ does allow users to
> develop such a curve, where can I define it?
> 
> Thanks in advance.
> 
> Ke
>



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