Re: [EnergyPlus_Support] model VRF system

["Crawley, Drury" <Drury.Crawley@xxxxxxxxxx>]

This is an email list for questions on EnergyPlus, not equest.

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From: EnergyPlus_Support@xxxxxxxxxxxxxxx <EnergyPlus_Support@xxxxxxxxxxxxxxx>
To: EnergyPlus_Support@xxxxxxxxxxxxxxx <EnergyPlus_Support@xxxxxxxxxxxxxxx>
Sent: Thu Jun 18 04:30:20 2009
Subject: Re: [EnergyPlus_Support] model VRF system

thanx alot Dear

But actually iam looking for using VRF system by eQuest simulation program

iam totally understand your replay, but eQuest have alot of systems and a lot of parameters that must be specified.

Do you have any idea how to use it in equest? i have to be sure.

Regards

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From: Richard Raustad <RRaustad@FSEC.UCF.EDU>
To: EnergyPlus_Support@yahoogroups.com
Sent: Wednesday, June 17, 2009 3:52:41 PM
Subject: Re: [EnergyPlus_Support] model VRF system

I think the closest you could get on the cooling side would be to use an
AirloopHVAC: UnitaryCoolOnly with AirTerminal: SingleDuct: VAV:NoReheat air
distribution units. The power side of the VRF would have to be modeled
using a squared curve on PLR where Power is proportional to the square
of speed (or PLR). However, with this configuration the fan power will
be low since VRF systems typically use constant volume fans. You can
modify the fan power in a spreadsheet after the simulation is complete.
Sorry if the jpg doesn't come through but it just shows the squared
power law of power vs speed..

For heating it is much harder. Using the
AirloopHVAC: UnitaryHeatPump: AirToAir with
AirTerminal: SingleDuct: Uncontrolled will model both cooling and heating,
however, the compressor control is limited to a single zone. If the zone
loads are balanced (flow through air distribution units are balanced
based on load) this will be a fair approximation, at least with what is
available in EnergyPlus. You could still use the squared curve for power
in this object.

So there is no simple answer, you would have to pick a system and review
the results to see how close you are to manufacturers performance data.
Then modify the input to more closely model the system using different
configurations. There are many EnergyPlus users that would be interested
in your findings.

VRFPower.jpg

mohammd al masri wrote:
>
>
> Dear all,
> I have a VRF (variable refrigerant flow) system , how I can model it ?
> can I use something closeor similar to that system , some mechanical
> engineers tolds me to select cooling tower system .
>
> Any help,
> Thanx
>
>

--
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
Visit our web site at: http://www.fsec. ucf.edu

UCF - From Promise to Prominence: Celebrating 40 Years

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