[EnergyPlus_Support] Re: HP Coefficient Calculator High Error

["luke_dorna" <luke.dorna@xxxxxxxxx>]

This is helping immensely. I appreciate the input. I'm getting much better numbers now. 

However, I have a small problem. The cut sheet I'm working from has this at the bottom of the performance table. 

"Cooling performance data is tabulated at 80.6°F DB/66.2°F WB entering air at ARI/ISO 13256-1 rated cfm"

So I have 3/4 factors varying. The entering water temp and flow vary in the sheets. And, I used the fan correction factors to varying the flow on the air side. However, how do I vary the entering air temperature?

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Karen Walkerman <kwalkerman@...> wrote:
>
> I also had issues with the spreadsheet calculator... until I used the
> manufacturer's modification tables to create many many lines of data with
> varying temperatures.  THEN I got decent curves.
> 
> ... and listen to Richard, he knows his stuff.
> 
> --
> Karen
> 
> On Thu, Jan 26, 2012 at 4:31 PM, Richard Raustad <RRaustad@...>wrote:
> 
> > **
> >
> >
> > If any of the independent variables are constant, load or source side,
> > then the coefficients for that variable will be 0 and you will have to
> > operate the system at that condition. In your case, you will have to
> > operate the HP with a 70F load side air inlet temp. If you deviate from
> > 70F, the answer will be inaccurate. Since always having a 70F inlet air
> > temp during your simulation is unlikely, you need more data which shows you
> > how performance changes with changes in inlet air temperature. Constant
> > flow is OK since you can force the HP to operate at that flow rate, you
> > just can't use these coefficients for a simulation with a different flow
> > rate (unless you assume that the performance does not change at a different
> > "rated" flow rate).
> >
> >
> > On 1/26/2012 4:23 PM, Chandan Sharma wrote:
> >
> >
> >
> > Both load and source side have to vary.
> >
> > On 1/26/2012 4:20 PM, luke_dorna wrote:
> >
> >
> >
> > The cut sheet I have has constant load side air temp and flow with varying
> > source side water flow and temp. When you say these cannot be constant, do
> > both load and source side have to vary, or just the source?
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Chandan Sharma <csharma@><csharma@>wrote:
> > >
> > > Hi Luke,
> > >
> > > In the "Catalog Data" tab, the data points must have varying inlet
> > > conditions which covers entire range of heat pump operation. There
> > > should be at least 6 data points and flow rates/temperatures columns
> > > must _not_ be constant.
> > > If the manufacturer has provided you correction factors to extend the
> > > performance data, it would help to generate more accurate coefficients.
> > > In general equation fit model is preferred over parameter estimation
> > > model and one of the reason is that curve fit coefficients are easier to
> > > calculate. Also, the curve fit model allows you to calculate
> > > coefficients for 410A.
> > >
> > > "Rated..." values in the CoeffCalculator tab also affect the curve fit
> > > coefficients.
> > >
> > > Hope this helps.
> > > Chandan
> > >
> > >
> > >
> > > On 1/26/2012 3:16 PM, luke_dorna wrote:
> > > >
> > > > I am currently trying to generate the equation fit coefficients for a
> > > > water to air heat pump cooling coil. Unfortunately, the
> > > > waterair_pe_cooling.xls file seems to be giving me an incorrect result
> > > > with average % of over 100.
> > > >
> > > > Has anyone run into a situation like this? It looks like can get a
> > > > better result from the parameter estimation method, however it does
> > > > not support 410a, which is the refrigerant from the design.
> > > >
> > > > Thanks,
> > > >
> > > > Luke
> > > >
> > > >
> > >
> >
> >
> > --
> > Richard A. Raustad
> > Senior Research Engineer
> > Florida Solar Energy Center
> > University of Central Florida
> > 1679 Clearlake Road
> > Cocoa, FL  32922-5703
> > Phone:   (321) 638-1454
> > Fax:     (321) 638-1439 or 1010
> > Visit our web site at: http://www.fsec.ucf.edu
> >
> > UCF - From Promise to Prominence: Celebrating 40 Years
> >
> >  
> >
>




------------------------------------

Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx

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 currently allowed but be mindful that not everyone has a high speed connection.  Limit attachments to small files.

EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
Yahoo! Groups Links

<*> To visit your group on the web, go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/

<*> Your email settings:
    Individual Email | Traditional

<*> To change settings online go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/join
    (Yahoo! ID required)

<*> To change settings via email:
    EnergyPlus_Support-digest@xxxxxxxxxxxxxxx 
    EnergyPlus_Support-fullfeatured@xxxxxxxxxxxxxxx

<*> To unsubscribe from this group, send an email to:
    EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx

<*> Your use of Yahoo! Groups is subject to:
    http://docs.yahoo.com/info/terms/