Let me explain a little more. For the boundary curve, you should predict ODB given IWB, as I show in the spreadsheet. To plot these points on the same graph as CapFT vs ODB, you need to convert the IWB used to regress the boundary curve to a CapFT value at the intersection of the low and high curves. This is simple since the low curves are flat vs IWB. So for each IWB, swap out the low CapFT value and then plot the boundary curve using the "IWB converted to CapFT" vs ODB (or CAPFTiwb vs ODB).
Don't forget you can use table objects to describe performance.
http://www.fsec.ucf.edu/en/publications/pdf/FSEC-CR-1910-12.pdf
If anyone is interested in doing this, Figure 6 shows how and you would only need the one table and NOT need the boundary curve or the high ODB curve (if I remember correctly).
On 7/7/2015 8:08 AM, Richard Raustad
RRaustad@xxxxxxxxxxxx [EnergyPlus_Support] wrote:
See if this helps. I rouged guessed at the ODB points for each WB and the curve is still very close.
On 7/6/2015 10:52 AM, m.waseemahmad@xxxxxxxxxxx [EnergyPlus_Support] wrote:
Hi,I have been trying to create performance curve for a VRF system. I have followed Richard's paper to create them. I am misunderstanding the way extrapolation is done. The way I extrapolated is;1) Use Cooling capacity ration function for Low and high temperatures to predict CPFT (predicted) for all temperature range (e.g. -5C to -43C) for both these curves.2) Finding the intersection of these curves (or very close points) and taking that ODB (outdoor dry-bulb) as a boundary curve point for a particular indoor wet-bulb temperature. However, by doing this I don't have any discontinuity (as points do tend to nearly overlap/intersect).3) In order to plot boundary curve, I used cooling capacity ratio boundary curve to predicted ODB for each extrapolated IWB e.g. 5C, 10C IWB etc. Then, I used that predicted temperature to calculate predicted CPFT.Please see attached performance curve for cooling. The cubic curve does not even
-- Richard Raustad Florida Solar Energy Center 1679 Clearlake Road Cocoa, FL 32922 Ph: (321)638-1454 http://www.fsec.ucf.edu/en/ Program Director Electric Vehicle Transportation Center http://evtc.fsec.ucf.edu/
-- Richard Raustad Florida Solar Energy Center 1679 Clearlake Road Cocoa, FL 32922 Ph: (321)638-1454 http://www.fsec.ucf.edu/en/ Program Director Electric Vehicle Transportation Center http://evtc.fsec.ucf.edu/
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