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Re: [EnergyPlus_Support] Model Underfloor Air Distribution?


We looked at using 2 zones to simulate the stratification, this is roughly 
how we had proceeded.  I believe we even hooked up the second zone on the 
Return Air Path of the first zone; this can be verified using the node 
debug report and the *.bnd node name file.  This does give you another zone 
temperature lag, but the flow is the amount that the system is supplying 
even for variable flow configurations.  We assigned the height for each 
zone and scheduled loads as appropriate, and put all the windows in the 
lower zone.  You do have to completely specify the geometry for both zones 
which is more tedious.  We even put in a surface between the zones that was 
highly conductive.

Our biggest problem is that we could not setup a surface between the zones 
that would allow the participation of radiation transfer from the surfaces 
and loads between the 2 zones.  We did experiment with combinations of 
properties on the surface for both short and long wave radiation.  We were 
trying to setup conditions that would absorb radiation from one side and 
re-radiate some of that energy on the other side of the surface.  Our 
problem is that we could not verify the results even though we did get some 
results that looked interesting.  But, there are some additional 
possibilities that you could pursue.

Thanks Richard Liesen

At 08:44 AM 7/26/2002, TangoJim wrote:
>Could you use the MIXING command in E+ to achieve the
>transfer of air from a lower zone (with a height about
>5 feet) to the upper zone (with the remaining height
>of the room)? Most of the overhead light energy should
>be assign to the upper zone. I would think some of the
>equipment and people (radiation) energy should also be
>assign to the upper zone as well. The solar radiation
>from the windows in the upper zone could be simulated
>using an interior upper floor glazing. This will allow
>the solar radiation be absorbed by the lower zone.
>The lower zone would be a conditioned space
>controlling the supply air temperature and the upper
>zone would be an un-conditioned space with air
>transferred to it from the lower zone.
> >From my understanding of underfloor air distribution
>systems, people are comfortable with a supply air
>temperature of around 65 degree F. The ceiling return
>air temperature is much higher, about 85 degree F. I
>would think this system would extend the time period
>of an outside economizer and also reduce the amount of
>dehumidification from the cooling coils.
>I have been thinking of how to simulate this situation
>for sometime. I am planning to experiment with this
>model further.
>James Trowbridge
>Director of Research & Development
>Taylor Systems Engineering
>--- "Richard J. Liesen" <r-liesen@xxxxxxxx> wrote:
> > It is possible to model the underfloor air
> > distribution in EnergyPlus.  At
> > this time it is NOT possible to include the
> > stratified air, and the
> > transfer of the warm stratified to perimeter zones
> > above.
> >
> > Thanks Richard Liesen
> >
> >
> > At 02:43 PM 7/26/2002, mtagles wrote:
> > >Is it possible to model underfloor air destribution
> > with E+,
> > >including stratified air, and the transfer of the
> > warm stratified to
> > >perimeter zones above?
> > >
> > >If not E+, any suggestions?
> > >
> > >Thanks in advance.
> > >
> > >Michael Tagles.
> > >
> >
> >
> >

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