If you have a manufactured system that does this, you should have some performance data for it that would allow you to use a water coil vav to calculate loads
and then post process energy use outside E+, or you might be able to use EMS to manipulate/resize an available DX object to perform like your manufactured system. If you think you can just connect the VRV to a coil and go, you are likely mistaken. Typical
DX systems have coils matched to air and refrigerant flow, which is what E+ models. There is no VRV object in E+ to model what is a highly complex process and system control to try to do what you propose. My quick review of available VRV equipment all show
the VRV unit serving multiple fixed flow DX coils, but even if you could model your system as parallel units in E+ and step between them to increase airflow, you are not likely to match the energy use correctly assuming a one size fits all DX coil in the real
world.
Ned Lyon, P.E. (MA)
Staff Consultant
SIMPSON GUMPERTZ & HEGER
781.907.9000 main
781.907.9350 direct
781.907.9009 fax
www.sgh.com
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
On Behalf Of joao.rosa83
Sent: Thursday, May 03, 2012 1:27 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Re: AHU with a DX coil and variable air flow
Hello,
In the real system i have a VRV heat pump connected to a coil in the AHU. I don't know which is the best way to simulate this system in E+, especially with the variable air flow rate.
Thanks for your help.
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Edward G. Lyon" <eglyon@...> wrote:
>
> I don't know if the Energy+ software/equipment will do this, but practically DX equipment has a narrower constraint on airflow variations. If your flow goes outside the boundaries of what the equipment is designed for, you risk either coil freezing or compressor
overloads/damage. E+ will give you warnings about these deviations. Variable airflow systems typically use fluid coils as that configuration is more easily controlled without equipment risks.
>
> Ned Lyon, P.E. (MA)
> Staff Consultant
> SIMPSON GUMPERTZ & HEGER
> 781.907.9000 main
> 781.907.9350 direct
> 781.907.9009 fax
> www.sgh.com
>
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of joao.rosa83
> Sent: Thursday, May 03, 2012 11:49 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] AHU with a DXcoil and variable air flow
>
>
>
> Hello,
>
> I'm trying to setup an AHU 100% Outside air with a DX coil and a variable air flow rate?
>
> It is possible to use de unitary equipment "AirLoopHVAC:UnitaryHeatPumpAirToAir" with a Fan: VariableVolume ? I'm using the "AirLoopHVAC:UnitaryHeatPumpAirToAir" with a Fan:CostantVolume with Coils:DX:SingleSpeed and a AirTerminal:SingleDuct:VAV:HeatAndCool:NoReheat,
but the OA remains constant.
>
> The goal is to have a constant temperature at the exit of the AHU and change the mass flow according to the zones internal loads and the zone setpoint temperature.
>
> Thanks for your help
> João
>
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