[EnergyPlus_Support] Re: AFN width & height factor / detailed opening

["tobiasschulzeoooitu" <tobias.schulze@xxxxxxxxxxxxxx>]

Dear Linxing,

the opening factor AFN:Surface is 1 as you told me to check. And the window geometry is also same - BUT the flow rates should be different because of the different opening geometry (as part of the window geo) due to the h&w factors. Lets say due to the h&w in factors in AFN:DetailedOpening I assumed that in 1) the opening is 0,1m wide and 1m high. And in 2) the opening is 1m wide and 0,1m high -> different opening geometry -> should result in different ACH.

3) and 4) are geometrically modelled and 3) is close 1)&2) and 4) is much less (less height = less ACH = correct)
BUT therefore I assume 2) to be wrongly calculated. Should be close to 4)

I compare the "AirflowNetwork Zone Infiltration Air Change Rate". No weather file necessary -> only DesignDay. In & Outdoor temp is fixed (20/24°C).
You can see that from the idf file containing all 4 scenarios. I will send you per mail (I hope it works).

What do you think?

Regards



--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Lixing Gu <gu@...> wrote:
>
> Tobias:
> 
> There are two issues. The first issue is window opening factor. If the
> opening factor for Cases 1 and 2 are 1.0, both windows should get the same
> flow rate due to the same geometry. Since the input files are not attached,
> you may check the opening factor by yourself first.
> 
> The second issue is flow rate comparison. Since a two way flow is expected,
> what flow rate do you compare, incoming flow, outgoing flow or a sum?
> 
> Please let me know what happens after check. You may also send your input
> files and provide weather date file name if the weather file is available in
> the web site. Then you need to specify which part of output file (rows and
> columns) make you think a program code fault. 
> 
> Thanks.
> 
> Lixing 
> 
>    
> 
> -----Original Message-----
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of tobiasschulzeoooitu
> Sent: Monday, June 06, 2011 12:09 PM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] AFN width & height factor / detailed opening
> 
> Hello,
> 
> after some parametric analysis I realized, that for a single sided
> ventilation strategy, the volume flow is same for these two options:
> 1) width factor = 0,1 & height factor = 1
> 2) height factor = 0,1 & width factor = 1
> 
> One can assume, that the volume flow in case 1) is higher because of the
> bidirectional opening model and higher density differences from top of the
> opening to the bottom of the opening as the opening height is bigger.
> 
> Therefore I repeated the same cases, but changing the window geometry
> according the previously mentioned factors (leaving the factors as 1). Here
> the resulting volume flow for 
> 3) opening width=0,1 & opening height=1
> is much higher than with a 
> 4) opening height=0,1 & opening width=1
> 
> This is as I assumed and flow for case 3)is very close to 1) & 2)
> 
> Concluding, there may be is a program code fault with the opening factors
> when changing the height factor.
> 
> Unfortunately the analytic solution for the cases as it is described in the
> engineering reference is very difficult to realize but I can send the 3 idf
> test files.
> 
> Best Regards,
> Tobias
> 
> 
> 
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