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[EnergyPlus_Support] Re: Mechanical ventilation for passive dwellings
mmm...I see your point.
For the non-AFN, your mixing object will rob a set amount of air from the supplied zone. The return air from that zone will automatically be the supply - xmixing and e+ will issue a warning (one of Jim's favourites) that the supply steam does not equal the exhaust.
If you are then exhausting from the adjacent zone to the same airloop, I.e. the zone receiving air from your crossmixer, then set the supply air termanal for this exhaust zone to zero or something very small.
...I've not tested this.
For the AFN version, I suspect you'll have to couple the exhaust node to a plenumn zone and which is your exhaust zone, while in the exhaust zone you set the supply terminal to (almost) zero.
...again I've not tested this.
Don't forget that using dummy zones to achieve this sort of design may be part of the workaround.
This topic comes up again and again. If there is an example in the examples folder, I would love to know it.
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "gosset_serge" <gosset_serge@...> wrote:
>
> Thanks for the hints...
>
> A mindset shift towards greener buildings indeed...
>
> Well, I do not plan to build a baloon, zeppelin or other strange things ;)
>
> I already tried to simulate airflow transfer between zones using the AFN and (cross)mixing with success.
>
> The core problem is that the AirLoop requires both an inlet and an outlet for each zone, and we apparently have no way to avoid this setup, or did I miss something?
>
> So, let me rephrase my "quest"...
>
> 1.- Is it possible to have zones with an Airloop inlet only and others with an airloop outlet only, knowing that the airflow between them will be handled by the AFN or mixing ? If yes, how ?
>
> 2.- If we cannot have a single airloop (AL) connection in each zone, is it possible hence having both the inlet and outlet, to force an airlfow to one or several zones? Let us say we want tohave an AL zone inlet only in z1 and an outlet only in z9. How to force all the air from z1 into an intermediate zone, say z5 and then into z9 to complete the loop? This forced flow must take priority over the AirLoop. I guess a part of the flow blowed into z1 can exit through AFN/mixing and be substracted from the flow returned to the AL which then becomes unbalanced. But it seems that the other way round is not working: when the incoming AL flow is set to zero, the system expect the return flow to be zero also, and I am stuck.
>
> Any suggestion is welcome, of course...
>
> Thanks in advance...
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jean marais" <jeannieboef@> wrote:
> >
> > This is a bit of a mindset shift. "Every zone must have an inlet and an outlet." If air flows into a zone, it must also flow out somewhere, else the zone will pressurize till it explodes. Both inlets and outlets can be cracks, uncontroled air terminals, VAV or controlled terminals, a combination, it does not bother the air much. In e+ only one classical exhaust node is allowed. One can introduce other "outlet ports" to this "zone tank" (Dr Li's analogy) by means of the zonemixing objects or AFN. I understand the comfort criteria in the areas of the house must be modelled, hence the need to keep them splitup and not lumped. If you have approximately 10 or less zones, the AFN is a good solution.
> >
> > Zonemixing objects are the easiest, but may be impossible to tie in to a complexly controlled and varying supply air flow (EMS may be required). Zonemixing objects are well suited to "join" the air volumes of to seperate zones by mixing back and forth at high mixing rates. If you have a very simple constant air supply, then it also works well. Maybe some new objects have been released in the newer versions of e+ for your kind of problem.
> >
> > The last kind of problem of this sort is that users want to connect 2 or more airloops to one zone. This is (was?) not possible, with virtual zone splitting a possible work around. This is (was?) also on the devloper's list.
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "gosset_serge" <gosset_serge@> wrote:
> > >
> > > In accordance to passive house and belgian standards, the mechanical ventilation is done as follows:
> > > - a MV group with heat exchanger
> > > - blows the (eventually preheated) air in "dry" rooms (sleeping and living rooms, offices, ...)
> > > - takes it back from the "wet" or more polluted rooms (kitchen, bathrooms, storage rooms, ...)
> > > - in between, the air moves by various openings, hallways, staircaises, ...
> > >
> > > We often need to split those areas in several zones, meaning that some have an air inlet only while other have an outlet only.
> > >
> > > Since both flows cross each other in the heat exchanger, they have to belong to the same HVAC Airloop. The problem here is that every zone must have one inlet and one outlet. I tought using a return plenum (a zone indeed) but only one can be used in the airloop and I have several "wet" zones.
> > > |...
> > > in---| > |--supply fan--splitter|--z1--|
> > > | | |--z2--|--z4----|
> > > |HEX| |--z3--| |
> > > | | |
> > > out--| < |--return fan--mixer|------------------|
> > > |...
> > >
> > > The air can be moved from one zone to another using either (cross)mixing either the airflow network, I guess.
> > >
> > > Did anyone model this ? Do you have some suggestions ? Any clue ? I did not reach any efficient or fully working model yet...
> > >
> > > Thanks in advance ...
> > >
> >
>
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