RE: [EnergyPlus_Support] Accurately model a multi-compressor dx unit?

["James V Dirkes II, PE" <jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

Doug,

 

A couple other possibilities might work:

·         Two DX coils in series, controlled for 1^st and 2^nd stage operation

·         Custom part load performance curves for a 2 or 4 stage system that duplicate the system you’re trying to model

 

p.s., If the manufacturer you are evaluating does not publish extensive part load information, I suspect that you’re unlikely to get a better result than is available from a 2 stage system with custom curves.

 

The Building Performance Team
James V. Dirkes II, P.E., LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653

 

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Richard Raustad
Sent: Wednesday, October 13, 2010 7:48 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] Accurately model a multi-compressor dx unit?

 

 

You can model up to 4 stages with the AirLoopHVAC:UnitaryHeatPump:AirToAir:MultiSpeed object.

On 10/12/2010 5:52 PM, normandoug wrote:

 

I need to model a (6) compressor DX rooftop unit to compare the annual energy consumption with that of a comparable building that uses chilled water. Has anybody done something similar or have tips for how to model the multiple compressors?

The information available from EnergyPlus seems to say the program is limited to a high/low speed on a max 2 compressor unit. Am I misreading this?

Thanks ahead of time!

Doug in KC

-- 

Richard A. Raustad

Senior Research Engineer

Florida Solar Energy Center

University of Central Florida

1679 Clearlake Road

Cocoa, FL  32922-5703

Phone:   (321) 638-1454

Fax:     (321) 638-1439 or 1010

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