[esp-r] Re: Bi-directional air flow component for VERTICAL airex change

[Jeremy Cockroft]

As already stated by other posters, the bi-directional flow component models the physics of vertical openings, and has no meaning when applied to a horizontal opening.  Maybe the complexity of air flows within atria and the like would justify the use of the CFD domain within ESP-r - perhaps that is where development activity to address this class of problem should be applied.
Jeremy Cockroft
University of Strathclyde

-----Original Message-----
From: esp-r-bounces at lists.strath.ac.uk [mailto:esp-r-bounces at lists.strath.ac.uk] On Behalf Of Pueltz, Gunter
Sent: 13 September 2006 10:02
To: esp-r at lists.strath.ac.uk
Subject: [esp-r] Re: Bi-directional air flow component for VERTICAL airex change

Very interesting discussion about the vertical air exchange of stacked zones !

1) First I want to affirm Jan´s statement, that a bi-directional air flow component should NOT be used for vertical air exchange ! The bi-directional door element has been developed for verical elements like doors or windows, thus the results for vertical air exchange (i.e. skylights) would be absolutely meaningless (or even wrong) !!!!

2) The interesting discussion shows however the strong requirement/needness of a bi-directional air-flow component for VERTICAL air flow exchange, which always takes place in an atrium or in a large open space over several floors ... 
The physical phenomena, which drives the vertical air flow exchange in such spaces are also well known:

a) thermal instable stratification (means cold air above warm air), which initiates the so called "Raleigh-Bernard-convection" (= small eddys at the interface between upper cold and lower warm air); the intensity of this vertical air exchange rate is depending on the difference of air temperature at the upper/lower air flow node ...

b) boundary layers at vertical facades, which initiate an upward(warm) or
downward(cold) air
flow within the boundary layer; the intensity of this vertical air exchange rate is depending on the difference between node air temperature and the internal surface temperature of the adjacent surfaces ...  


It would be a great enhancement of ESP -r, if an air flow component would be
developed for
the vertical air flow exchange, based on the two main driving physical
phenomena listed above.

Gunter 

--
Dr. Gunter Pültz

Müller-BBM GmbH
Robert-Koch-Straße 11
82152 Planegg
Telefon +49 (0)89 85602 - 336
Telefax +49 (0)89 85602 - 111
http://www.MuellerBBM.de 

> -----Original Message-----
> From: esp-r-bounces at lists.strath.ac.uk
> [mailto:esp-r-bounces at lists.strath.ac.uk]On Behalf Of Hensen, J.L.M.
> Sent: Wednesday, September 13, 2006 10:05 AM
> To: esp-r at lists.strath.ac.uk
> Subject: [esp-r] Re: 1) Bi-directional Doors in Horiontal
> surfaces2)Dummy-nodescheme
> 
> 
> 
> In my opinion, you shouldn't use a bi-directional flow large 
> opening in
> a horizontal position. It is totally out of the theoretical 
> scope of the
> model. The results are more than likely to be meaningless.
> You can use multiple one-way flow openings instead.
> 
> Jan
> 
> -----Original Message-----
> From: esp-r-bounces at lists.strath.ac.uk
> [mailto:esp-r-bounces at lists.strath.ac.uk] On Behalf Of Oliver Bucks
> Sent: Wednesday, September 13, 2006 9:56 AM
> To: esp-r at lists.strath.ac.uk
> Subject: [esp-r] Re: 1) Bi-directional Doors in Horiontal
> surfaces2)Dummy-nodescheme
> 
> Jake,
> 
> I'm not an expert, but I think I have overcome this problem when
> simulating big 
> trombe walls. The delta H should be precisely that between 
> the nodes....
> eg, a 
> horizontal skylight with an exterior node @ 0.5m above the 
> skylight, and
> the 
> zonal node @ 1.5m below the skylight, the delta H would be 2m and
> -2m.....
> 
> I might be wrong though
> 
> Olli Bucks
> 
> ----- Original Message ----- 
> From: "Jake Zwart" <jake.zwart at sympatico.ca>
> To: <esp-r at lists.strath.ac.uk>
> Sent: Tuesday, September 12, 2006 9:10 PM
> Subject: [esp-r] 1) Bi-directional Doors in Horiontal surfaces 
> 2)Dummy-nodescheme
> 
> 
> > Two questions:
> >
> > 1) I have heard of a trick using bi-directional door components in
> horiontal
> > surfaces.  In fact this is mentioned in the FAQ regarding atriums.
> However
> > the input data for using a bi-directional door assumes it is in a
> vertical
> > surface because it asks for the height difference between 
> the base of
> the
> > door and the center of both zones which it seperates.  I looked up
> Hensen's
> > thesis and the door component seems to have these assumptions built
> in.  So,
> > how can I implement a bi-directional door component between 
> vertically
> > stacked zones in my atrium?
> >
> > 2) I am using the dummy node scheme for my window controls 
> as follows:
> >
> > I am implementing a control strategy for opening and closing window
> with two
> > separate controls in series.  The controls are:
> >
> > 1. When the indoor temperature exceeds a set temperature, 
> say 20 C the
> > windows will open.
> > 2. When the ambient temperature exceeds the indoor temperature, the
> dummy
> > windows
> > will close to prevent convective heating.
> >
> > When I run the simulation, the dummy nodes stays at a constant 20?C
> (the
> > temperature which I set the node to for the start of the run).
> > Interestingly, although the dummy nodes stayed at a constant 20 C,
> interior
> > temperatures did drop below 20 C as a result of (what looks like)
> > ventilation.
> >
> > Now, it seems to me that the dummy node should be a calculated node
> and not
> > following some other node temperature.  Say for example 
> that the dummy
> > follows the ambient, then, when the dummy window is open but the
> window
> > between the dummy to outside is closed, the zone will still interact
> with
> > outside.  Now say that the dummy follows the interior node/zone
> temperature.
> > In this case when both windows are open, all incoming 
> ventilation air
> will
> > be no help since it will be at the interior node/one temperature
> already.
> >
> > How can I ensure that the dummy node is a calculated temperature and
> that
> > the dummy node scheme will work properly?
> >
> > Thanks,
> >
> > Andrew Zwart
> >
> >
> >
> > -----Original Message-----
> > From: esp-r-bounces at lists.strath.ac.uk
> > [mailto:esp-r-bounces at lists.strath.ac.uk]On Behalf Of Jon Hand
> > Sent: Saturday, 09 September, 2006 11:58
> > To: kostas ordoumpozanis
> > Cc: esp-r at lists.strath.ac.uk
> > Subject: [esp-r] Re: tutorial help
> >
> >
> >
> > The best current tutorial for ESP-r is the ESP-r cookbook
> > which is available on the ESRU web page publications or
> > as part of the ESP-r source distribution.
> >
> > The browsing function is somewhat old and is probably
> > trying to invoke netscape.  There are quite a few useful
> > resources on the ESRU web page which can be invoked
> > manually via your favorite browser.
> >
> > -ESRU
> >
> >
> > -----Original Message-----
> > From: esp-r-bounces at lists.strath.ac.uk on behalf of kostas
> ordoumpozanis
> > Sent: Sat 9/9/2006 12:10 PM
> > To: esp-r at strath.ac.uk
> > Subject: [esp-r]  tutorial help
> >
> > Hi. I am trying to launch the tutorial button on project manager and
> after
> > it shows the message "Starting  Browsing..." it does nothing.  Any
> answer to
> > that.
> >
> > Thanks
> > Ordoumpozanis Kostas
> > Greece
> >
> >
> >
> > _______________________________________________
> > esp-r mailing list
> > esp-r at lists.strath.ac.uk
> > http://lists.strath.ac.uk/mailman/listinfo/esp-r
> >
> 
> 
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> 
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> > esp-r mailing list
> > esp-r at lists.strath.ac.uk
> > http://lists.strath.ac.uk/mailman/listinfo/esp-r
> 
> 
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