Re: [EnergyPlus_Support] Re: Split type Inverted heat pump model with multiple indoor units [1 Attachment]

["m.waseemahmad@xxxxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx>]

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 touch/intersect 35C and 5C IWB. 

I am making a mistake somewhere but don't know where. Any ideas? 

Thanks

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Posted by: m.waseemahmad@xxxxxxxxxxx

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D:\Eudora\Attach\cooling_performance_curve.png