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[EnergyPlus_Support] Re: Many coils in one AHU
Jim,
the AHU is shown schematically here:
http://img191.imageshack.us/img191/9510/ahuqq.jpg
If you consider the picture, #22 and #23 are coils that are connected with a cooled water loop. #1 is the compressor, #3 is the DX cooling coil, and #4 is the DX heating coil.
Thermal loads are met by the heated/cooled floor while the goal of the AHUs it to decrease the humidity in order to avoid condensation on the floor when the floor is cooled. The AHUs are controlled by the air relative humidity (it must be less than 50%).
Regards
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Jim Dirkes <jim@...> wrote:
>
> Francesco,
> Normally, a DX heating coil is part of a heat pump system and it is never the case that both the DX heating coil and DX cooling coil operate at the same time. It is always true, as you say, "heat provided by the DX heating coil = heat subtracted by the cooling coil + work of the compressor"
> It is not clear to me what you are trying to accomplish, but it is clear that #1 and #2 (below) are not a normal system if you want to operate both DX heating and cooling at the same time.
> p.s., E+ describes / defines the DX cooling coil and DX heating oil in a heat pump as though they are separate components. In the actual heat pump equipment, they are a single component.
>
>
> James V Dirkes II, PE, BEMP, LEED AP
> www.buildingperformanceteam.com<http://www.buildingperformanceteam.com/>
> Energy Analysis, Commissioning & Training Services
> 1631 Acacia Drive, Grand Rapids, MI 49504 USA
> 616 450 8653
>
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of FrancescoP
> Sent: Monday, May 27, 2013 4:19 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Re: Many coils in one AHU
>
>
>
> A problematic issue is that the DX cooling coil and the DX heating coil are part of the same refrigerant circuit. The goal of the system is the dehumidification. I would like to impose the condition:
>
> heat provided by the DX heating coil = heat subtracted by the cooling coil + work of the compressor
>
> Is it possible? Or does a better way to model such a system exist? E.g., does a method exist to model explicitly a refrigerant circuit within an AHU?
>
> If it is impossible, I would like to impose at least the following conditions:
>
> 1. IF the DX cooling coil works THEN the DX heating coil works
>
> 2. IF the DX heating coil works THEN the DX cooling coil works
>
> And then I would adjust the COP values.
>
> Any suggestion, please?
>
> Regards
> Francesco
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support%40yahoogroups.com>, "FrancescoP" <direzionecontraria@<mailto:direzionecontraria@>> wrote:
> >
> > Hello,
> > I have to model a dehumidification system (an AHU without outdoor air, only recirculation) in which there are a water cooling coil, a DX cooling coil, a DX heating coil, and another water cooling coil.
> > I begin to model in DesignBuilder, then I export the .idf file in EnergyPlus. As you can read at the following link, modeling such a system directly in DesignBuilder isn't possible:
> > http://www.designbuilder.co.uk/index.php?option=com_forum&Itemid=1&page=viewtopic&p=12704#12704
> > What is the best way, in your opinion?
> > In DesignBuilder shall I begin with an Unitary heat pump or with a Generic Air loop?
> > Best Regards
> >
>
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