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How to normalize experimental data to a performance curve?

asked 2019-07-12 18:06:54 -0600

mldichter's avatar

Are there any examples of taking curve fitted experiment data for a DX coil and creating the normalized cooling capacity curve in energyplus? We are trying to do that as part of a research project, but we've clearly done something wrong since the simulation results are way off the experimental data.

Is the curve normalization procedure in any of the energyplus documentation? I was having trouble finding out how to do it.

Also, an example of normalizing a cooling capacity curve from real data would be awesome!

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answered 2019-07-15 07:22:25 -0600

This document describes the procedure to VRF DX equipment but the method is similar for any coil type that uses performance curves.

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@rraustad Are the rated conditions values in the energyplus documentation? At the very least, the code must contain the reference conditions because the curves are being evaluated at the rated conditions and output is checked to be 1.0 plus minus 10%.

mldichter's avatar mldichter  ( 2019-07-16 11:49:55 -0600 )edit

19.44 C (67 F) indoor wet-bulb and 35 C (95 F) outdoor dry-bulb temperatures are typically used and called out in AHRI standards. I'm sure these are in the docs.

rraustad's avatar rraustad  ( 2019-07-16 11:53:44 -0600 )edit

@rraustad You are correct! The cooling coils tend to have the test conditions values in the explanation of the curve field, but another good place to look is the related fields like COP which can have the test conditions values instead like in some of the heating coils documentation in the Input Output Reference.

mldichter's avatar mldichter  ( 2019-07-16 12:01:27 -0600 )edit

I just used the AEDG VRF with DOAS measure. It generated one outdoor unit and 21 indoor units. So far, so good. Furthermore, the cooling CapFT curve looks more or less plausible, but the heating CapFT and the cooling and heating EIRFT curves not so much. I believe I have a good idea what these are to look like as I spent weeks scrubbing Daikin data. I noticed in particular that none of the AEDG VRF with DOAS EIRFT curves pass through 1, as they should at the rating conditions. I believe this causes unrealistically low energy consumption numbers. Any thoughts, anybody?

Matt Koch's avatar Matt Koch  ( 2019-09-02 18:21:19 -0600 )edit

The VRF data I had when the VRF example file (VariableRefrigerantFlow_5Zone) curves were created did not use the rating point (if the AEDG/DOAS curves are the same as those I created). So a warning is issued with the VRF example file. But the curves themselves along with the rated capacity and COP should provide the correct result. If those fields are autosized, then I believe there is an issue, although moderate (because the selected rating was close to the AHRI condition). I have been meaning to correct this but because I believe the results are fairly accurate I have been procrastinating.

rraustad's avatar rraustad  ( 2019-09-24 13:31:22 -0600 )edit

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Asked: 2019-07-12 18:06:54 -0600

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Last updated: Jul 15 '19