Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page
Ask Your Question
5

How to normalize experimental data to a performance curve?

asked 2019-07-12 18:06:54 -0500

mldichter gravatar image

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!

edit retag flag offensive close merge delete

1 Answer

Sort by ยป oldest newest most voted
4

answered 2019-07-15 07:22:25 -0500

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

edit flag offensive delete link more

Comments

@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 gravatar imagemldichter ( 2019-07-16 11:49:55 -0500 )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 gravatar imagerraustad ( 2019-07-16 11:53:44 -0500 )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 gravatar imagemldichter ( 2019-07-16 12:01:27 -0500 )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 gravatar imageMatt Koch ( 2019-09-02 18:21:19 -0500 )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 gravatar imagerraustad ( 2019-09-24 13:31:22 -0500 )edit

Your Answer

Please start posting anonymously - your entry will be published after you log in or create a new account.

Add Answer

 

Question Tools

3 followers

Stats

Asked: 2019-07-12 18:06:54 -0500

Seen: 349 times

Last updated: Jul 15 '19