The choice of curve for VRF system

asked 2022-02-17 16:38:21 -0600

wei_zhang

137 ●2 ●5

updated 2022-02-17 18:39:55 -0600

Aaron Boranian

14155 ●83 ●24 http://bigladdersoftware.com/

Hi everyone I am trying to model a VRF system in OpenStudio with model AirConditioner:VariableRefrigerantFlow. I found many choices for the curve of cooling part, as well as for heating part: My question is if there is some visual or practical guide to choose the curve for a customized VRF system? by default, all the curves seem to be the "6". Or what's the difference amongst these curves in each choice?

Thanks in advance

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answered 2022-02-17 16:53:21 -0600

rraustad

13804 ●79 ●12 http://www.fsec.ucf.edu/

See https://www.fsec.ucf.edu/en/publicati...

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Great, Thanks a lot

wei_zhang ( 2022-02-17 17:02:28 -0600 )edit

@rraustad there are a lot of LG brand specific VRF objects on the Building Component Library. Do you know if LG generated these or someone else?

Ski90Moo ( 2023-12-19 01:26:51 -0600 )edit

Ok, I see it was part of the TPex project from 2015: https://www.energy.gov/sites/prod/fil...

Ski90Moo ( 2023-12-19 01:50:07 -0600 )edit

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answered 2022-02-18 22:30:58 -0600

wei_zhang

137 ●2 ●5

@rraustad

Hi Richard, Thanks for your excellent paper. I read it and learned a lot. As far as I understand, the curves need Manufacturer's data as described as Figure 1(Graphical data) or Figure 2(Tabular data). Unfortunately, I do not have such data for the VRF I am modeling. I searched in Internet but did not find such data. For example, we use the Multi-Split Heat pump "MXZ-3C24NAHZ2" from Mitsubishi Electric. Do you know where could I get the Manufacturer's specification/data ?

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I also looked and could not find the data. You have to call the manufacturer if you can't find the data. You really need those graphs or tables because you can't guess at the performance.

rraustad ( 2022-02-18 22:50:40 -0600 )edit

Thanks for your quick response; I contacted them today, they said they would send me the specification. But I wait until sunset without getting the documents. Is there some kind of general VRF performance data we can rely on?

wei_zhang ( 2022-02-18 22:56:06 -0600 )edit

The VRF systems I have looked at have very different performance, at least between manufacturers. If you could find a Mitsubishi model that seems close to what your looking for you could use it. But without seeing the actual data you don't know if you have the right curves (i.e., is it similar or not). So I would say if you don't hear back then call again.

rraustad ( 2022-02-18 23:02:59 -0600 )edit

Thank you for your insightful advices

wei_zhang ( 2022-02-18 23:13:38 -0600 )edit

DesignBuilder has a VRF curve tool (Excel spreadsheet) which allow input of manufacturer data and visualization.