[EnergyPlus_Support] Re: Many coils in one AHU

["FrancescoP" <fpasserini.tn@xxxxxxxxx>]

Perfect! Thank you very much.


--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad <RRaustad@...> wrote:
>
> The Eng Ref says not to use a recovery efficiency higher than 30%. Why, 
> because if you do, the model will not include the added evaporator 
> capacity (it will be lost).
> 
> This is not an internal HX. In your figure, the desuperheater would be 
> between the compressor and condenser. The desuperheater would recovery 
> 30% of the condenser heat, and the condenser would remove the rest of 
> the heat (i.e., 70% instead of 100%).
> 
> Your equation is correct. In the figure you provided, the condenser 
> removes the evaporator heat plus the work of the compressor. If a 
> desuperheater is used, the desuperheater removes a portion of this heat 
> and the condenser removes the remainder.
> 
> On 5/28/2013 10:33 AM, FrancescoP wrote:
> > Thank you, Richard, it is the object I was looking for! I didn't get the issue of the Heat Reclaim Recovery Efficiency, probably because of my lack of knowledge about refrigerant circuits.
> >
> > I quote the Engineering Reference guide:
> > "The heat reclaim recovery efficiency (specified by the user) defines the amount of heat available for use by this coil. Approximately 25-30% of the energy rejected by typical refrigeration system condensers is to reduce the superheated refrigerant vapor temperature to the condensing temperature. Recovery efficiencies higher than 30% may cause the refrigerant gas to condense which in turn impacts the performance of the refrigeration compressor rack. For this reason, the maximum heat reclaim recovery efficiency for this coil for all sources except the Refrigeration:Condenser:(Air, Water, or Evap) Cooled is 30%."
> >
> > Does it refer to a system with an internal heat exchanger, like in this picture http://en.wikipedia.org/wiki/File:Diagram1234321.png ?
> > In my case there is no internal heat exchanger.
> >
> > If the following equation were valid,
> >
> > heat provided by the DX heating coil = heat subtracted by the cooling coil + work of the compressor
> >
> > the Heat Reclaim Recovery Efficiency should be equal to 1, shouldn't it?
> > With Regards
> >
> >
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad <RRaustad@> wrote:
> >> See the Coil:Heating:Desuperheater object for details.
> >>
> >> This object reclaims waste heat from a DX system operating in cooling
> >> mode and provides that heat to an air stream. This object does not
> >> account for sub-cooling refrigerant (i.e., does not impact the
> >> performance of the system where heat is reclaimed from) so care should
> >> be used when selecting the value for Heat Reclaim Recovery Effectiveness.
> >>
> >> On 5/27/2013 1:04 PM, Jim Dirkes wrote:
> >>>
> >>> Francesco,
> >>>
> >>> I am not aware that E+ can model hot gas reheat directly.
> >>>
> >>> ·
> >>>
> >> -- 
> >> 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 50 Years
> >>
> >
> >
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> 
> -- 
> 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 50 Years
>




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