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RE: [EnergyPlus_Support] EPlus vs Design Builder - Modelling Air Handling Units with Heat Recovery



It is likely possible, but this is a challenge, even for an advanced user.  I don't believe any interfaces are setup to provide this sort HVAC.  I'll try to provide a brief overview of how I would approach modeling this system.

 

If the VRV is air-to-air, then like Rich said, models for those are under development and not yet available.  You would have to go with another DX coil model. 

 

But it sounds like your VRV is air-to-water, if that's right you could treat it like a small, air-cooled chiller plant with a Chiller:Electric:EIR as the primary component.  Because the chiller models are empirical curve fits, the inner workings of the cooling equipment's handling of refrigerant may not be important.  What does matter (a lot) is what you use for performance curves and this will require access to good performance data and refitting that data to the input formulations in E+.

 

Your first ventilating FCU sounds like what we call a dedicated outdoor air system (DOAS) that dumps neutral temperature air into the zone.  These are usually built up as an Air Primary Loop with a fan, water coils, an outside air system (with a Heat Exchanger:Air-to-Air), and Direct Air terminal unit.  A schedule for the "neutral" air temperature (at the FCU outlet) is then used to place a setpoint on the supply side outlet node.  Your "secondary" FCU would actually be a Fan Coil Unit:4 Pipe zone unit and be listed second in the zone equipment list (behind the Direct Air).  There would also be plant loops for the chilled and hot water.  Note, autosizing is not going to work for something this complicated.   

 

 

 

 

________________________________

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Maria Agustin
Sent: Tuesday, January 22, 2008 10:05 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: RE: [EnergyPlus_Support] EPlus vs Design Builder - Modelling Air Handling Units with Heat Recovery

 

Thanks for the input Mahabir.
I need to model a reidential single detach where it uses a Variable Refrigerant Systems (VRV).
The Outside air requirement is treated via a fancoil unit fitted with a heat exchanger and the internal loads are served by a secondary FCU connected to the same condensiong units.
Is it possible to model this systems in E+ or DB?

appreciate your help.

regards

MT D Agustin

Mahabir Bhandari <bhandari@xxxxxxxxxxxxxxxxxxxxxxxxx <mailto:bhandari%40designbuildersoftware.com> > wrote:
Allen,

Here is the definition of purchased air from E+ Input Output Reference
Manual.. 

Purchased Air

The simplest piece of zone equipment is the Purchased Air component. The
name -

Purchased Air - is an analogy with Purchased:Chilled Water and Purchased:Hot
Water. Of

course one can't normally buy conditioned air. Purchased air is used in
situations where the

user wishes to study the performance of a building with an ideal system. In
such a case,

purchased air is usually the sole conditioning component: the user does not
need to specify

air loops, water loops, etc. All that is needed for the ideal system are
zone controls, zone

equipment configurations, and the purchased air components.

It is not correct that DesignBuilder only uses purchased air . Purchased air
(Simple HVAC) is one of the options. Another option is Compact HVAC. For
more information on Compact HVAC systems, please visit: 

http://www.designbuilder.co.uk/programhelp/hvac_system_type.htm <http://www..designbuilder.co.uk/programhelp/hvac_system_type.htm> 

Currently in DesignBuilder, you can't simulate heat recovery with fan coil
units. Heat recovery is used only centralized systems such as VAV with
terminal reheat. This option will be available in version 2.0 (expected to
be released this summer) which will have detailed HVAC option as well. 

Regards,

Mahabir Bhandari

_____ 

From: EnergyPlus_Support@xxxxxxxxxxxxxxx <mailto:EnergyPlus_Support%40yahoogroups.com> 
[mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx <mailto:EnergyPlus_Support%40yahoogroups.com> ] On Behalf Of Maria Agustin
Sent: Tuesday, January 22, 2008 11:20 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx <mailto:EnergyPlus_Support%40yahoogroups.com> 
Subject: Re: [EnergyPlus_Support] EPlus vs Design Builder - Modelling Air
Handling Units with Heat Recovery

Can you please provide definition of purchased air.

Bing Dong <bingcat2007@ <mailto:bingcat2007%40gmail.com> gmail.com> wrote:
No airloop, plant and water loop.
Only purchased air if I was not wrong

Allen

On Jan 22, 2008 9:41 AM, André Lopes <andr_lopes2000@
<mailto:andr_lopes2000%40yahoo.com> yahoo.com> wrote:

> Hello
>
> What do you mean by: "There is real HVAC system in there."
>
> Regards
>
> A L
>
>
> ----- Original Message ----
> From: Bing Dong <bingcat2007@ <mailto:bingcat2007%40gmail.com> gmail.com
<bingcat2007%40gmail.com>>
> To: EnergyPlus_Support@ <mailto:EnergyPlus_Support%40yahoogroups.com>
yahoogroups.com<EnergyPlus_Support%40yahoogroups.com>
> Sent: Tuesday, January 22, 2008 2:31:29 PM
> Subject: Re: [EnergyPlus_Support] EPlus vs Design Builder - Modelling Air
> Handling Units with Heat Recovery
>
> DesignBuilder will simulate the purchased air. There is real HVAC system
> in
> there.
>
> Allen
>
> On Jan 22, 2008 9:28 AM, André Lopes <andr_lopes2000@ yahoo.com> wrote:
>
> > Hello
> >
> > I am modelling a System that has:
> >
> > Heating: Boiler, Water Radiators
> >
> > Cooling: Chiller, Fan-Coil
> >
> > Fresh-Air:Air- Handling Units with Heat Recovery
> >
> > Using Design Builder and / or EnergyPlus, how should I Simulate the
> > Air-Handling Units with Heat Recovery?
> >
> > Best Regards
> >
> > A L
> >
> > ____________ _________ _________ _________ _________ _________ _
> > Never miss a thing. Make Yahoo your home page.
> > http://www.yahoo. com/r/hs
> >
> >
>
> [Non-text portions of this message have been removed]
>
> __________________________________________________________
> Never miss a thing. Make Yahoo your home page.
> http://www.yahoo. <http://www.yahoo.com/r/hs <http://www.yahoo.com/r/hs> > com/r/hs
>
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>
> 
>

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