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Re: [EnergyPlus_Support] Re: heat exchanger:Air to air: general



The set points for economizer control in CONTROLLER:OUTSIDE AIR are set 
at a maximum outdoor dry bulb temperature of 20C and a minimum outdoor 
dry bulb temperature of 14C.  This means that the HEAT EXCHANGER:AIR TO 
AIR:GENERIC is only in economizer control when the outdoor air is 
between these values.  Notice the outdoor air dry bulb temperature is 
above 20C during the morning hours of the summer design day.  Since the 
indoor temperature is 25C the heat exchanger heats the incoming outdoor 
air.  If you raise the maximum outdoor dry bulb temperature to 25.6C the 
heat exchanger is in economizer during this time and the "Heat Exchanger 
Sensible Heating Rate" goes to 0.0.  The user is responsible for 
determining the proper economizer set points for the particular climate 
they wish to simulate.  See Controller:Outside Air economizer 
description and the description for Heat Exchanger: Air to Air:Generic 
economizer mode for further details.

fortierengineer wrote:

> I have uploaded the file.  It is called SHback to basics9-21.idf
>
> I am using the Pittsburgh TMY2 weather data.
>
> If it is of any help, currently the active control elements relating
> to the controller:outside air and the heat exchanger:air to air, are
> the set point manager:mixed air and the exchanger supply air outlet
> control (controlled by the "Seasonal Reset Exchanger Air Temp
> Sch"). 
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "donbshireyiii"
> <shirey@f...> wrote:
> > Please upload your idf file to the EnergyPlus yahoogroups web site
> > (http://groups.yahoo.com/group/EnergyPlus_Support/) 
> <http://groups.yahoo.com/group/EnergyPlus_Support/%29> or send it
> > EnergyPlus-Support@g... and we'll take a quick look at it.
> >
> > If the temperature of the relief air is greater than the
> temperature
> > of the incoming outdoor ventilation air, then you will see a
> positive
> > value.
> >
> > What weather file are you using?
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Joseph Lewis
> > <fortierengineer@y...> wrote:
> > > Hello,
> > > 
> > > I have a heat exchanger:air to air:general in a model that only
> > transfers sensible heat between the relief airflow and the outdoor
> air
> > flow.  Running it in the summer design day, I have discovered that
> no
> > matter what control strategy for the out door air system, there are
> > hours where the "Heat Exchanger Sensible Heating Rate" is
> positive.  I
> > have looked at the  HVACStandAloneERV_Economizer.idf example for
> help,
> >  and it has the same issue.   I have also looked at
> DesiccantCVRh.idf
> > and in this file the sensible heating rate is zero for the summer,
> > but if I remove the desiccant unit from the loop you have the same
> > issue. 
> > > 
> > > Is there a control strategy that can be used along with an
> outdoor
> > air controller (with economizer) to eliminate this?
> > > 
> > > Thank you,
> > > 
> > > Joe Lewis
>
>
>
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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 40 Years



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