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Re: [EnergyPlus_Support] Minimum Unloading Ratio

To: "EnergyPlus_Support@xxxxxxxxxxxxxxx" <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Subject: Re: [EnergyPlus_Support] Minimum Unloading Ratio
From: "Jim Dirkes jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Date: Wed, 5 Oct 2016 10:54:10 -0400
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Francesco,

That should be "close enough" for most energy models. Actual performance, however, is not linear with the number of compressors. In order to know more closely, the manufacturer literature should tell you the actual performance.

Also, a scroll compressor can sometimes unload by operating a fraction of the time. Once again, the manufacturer literature (or a sales representative or the design engineer) should be helpful.

Since you recognize the impact of oversizing and minimum unloading, it is probably worthwhile to investigate more closely.

On Wed, Oct 5, 2016 at 5:53 AM, fpasserini.tn@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

Â

Hello,Â if a chiller has 4 scroll compressors, then theÂ Minimum Unloading Ratio shall be 1/4 (i.e. 0.25), correct?
I want to be sure, because in a model that I'm considering the chiller is oversized and theÂ Minimum Unloading Ratio influences a lot the annual consupmtion.
Regards
Francesco
Â

James V Dirkes II, PE, BEMP, LEED AP
CEO/President
The Building Performance Team Inc.
1631 Acacia Dr, GR, Mi 49504

Direct: 616.450.8653
jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx

Website l Â LinkedInÂ | May 2016 ASHRAE Journal article on energy modeling

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Posted by: Jim Dirkes <jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx>

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- [EnergyPlus_Support] Minimum Unloading Ratio
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