I am working on a project where my building has a VRF/VRV system. The ambient conditions at which the system designed is 46 deg C. Now as it's a LEED project & will be compared with ASHRAE 90.1.2010, which takes the COP for baseline system at standard conditions.
What should I do now? Should I take my actual case system COP in the model at standard condition instead of it's cop at 46 degC.
Because if I don't my system efficiency will be less as compared to ASHRAE?
Please suggest?
Jean Marais
b.i.g. Bechtold DesignBuilder Expert832 thumbs up
November 29, 2019 - 6:08 am
Rated COP Rating Values are at rating conditions. The equipment datascheets should specify them. Really your question is software specific. Presumably you should enter the rating values for your model. Your model then creates the correct performance curves or matrixes to correctly model the performance at all points during the simulation. Or you have to input the curves or matrix into your model yourself, and you will need to get the performance information from the manufacturer.
Judhajit Chakraborty
AssociateStantec
2 thumbs up
December 3, 2019 - 7:23 pm
Second that. The simulation program should allow you to enter the VRF COP at various temperatures and conditions (which you should be able to get it from the cut sheet). Enter that and the software will create the normalized COP and the performance curves. The baseline COP doesn't change in any case.
Neeraj Sharma
Sustainability ManagerConserve Solutions- Riyadh, Kingdom of Saudi Arabia
1 thumbs up
December 26, 2019 - 8:04 am
Thank you Jean & Judhajit for your response. However the point again remain the same of considering the COP at 100% load. The COP at 100% load for baseline case will be at AHRI conditions whereas for my case is at 46 deg C. Also eQUEST model doesn't have capability to have COP at different temperature.
Please advice, Is it okay if the COP I am inserting in baseline is at 41 deg C, Could I insert the COP in my actual case as well at 41 deg C?
Please advice, a prompt response is really appreciated.
Thanks
Jean Marais
b.i.g. Bechtold DesignBuilder Expert832 thumbs up
December 30, 2019 - 3:32 am
Hi Neeraj,
Equest will expect the entered value of 100% Load COP to be the value that the equipment would have at AHRI Rating Value conditions. If you have the performance matrix of your equipment, you can deturmine the COP at the AHRI rating point. The rating point conditions depend on which equipment you have, so you'll have to look up what that point is.
I suggest a tool like Chiller_PerformanceCurve_Coefficients.xls
After you've entered your available data, you can use the generated curves to interpolate your COP at the required AHRI Rating Point Condition.
To model the equipment performance in eQuest you must create the correct performance curves and input them. The default curves are not going to describe your equipment performance correctly. And the input of rated COP only works in conjuction with the input of the correct curves (because the curves are normilized against it).
I know it all looks a little scary, but you'll get the hang of it. It looks worse than it is.