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Re: [EnergyPlus_Support] Re: (Still) airflow balances!
So my suggestion is:
Zone 1 is served by the air loop and contains the exhaust fan. This fan
exhausts
the air to the outside. The air flow will now be correct for the heat
recovery device.
Zone 2 is unconditioned (is not served by the air loop).
To account for the exhaust fan really being in Zone 2 and inducing air
from Zone
1, there should be Mixing object with Zone 2 as the receiving zone and
Zone 1
as the source zone. The flow rate should match the exhaust flow rate.
There is
no need to balance the air from the Mixing object entering Zone 2 - the
zone will not
explode. EnergyPlus does not concern itself with air mass balance from
inputs
such as Mixing, Infiltration, Ventilation. These objects simply generate
heat gains or losses
for the zone energy balance. The real Zone 2 will exhaust the induced
air, but we don't
have to do that in EnergyPlus.
Fred Buhl
Fred Buhl wrote:
> Thanks Ana; that seems clear - now let me think about it.
>
> Fred Buhl
>
> anarui.oliveira wrote:
>
>> Zone 1 gets its supply air from a CAV central system with heat
>> recovery.
>> Part of the airflow supplied to Zone 1 is collected again and
>> becomes return airflow, passing through the central heat exchanger
>> before being discarded. The remaining airflow is supposed to pass to
>> the adjacent Zone 2 simply by pressure difference.
>> In Zone 2 there is just an exhaust fan (in the project), which keeps
>> this zone in depression and forces air renovation.
>>
>> Thank you for the patience,
>> Ana.
>>
>> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Fred Buhl <wfbuhl@...>
>> wrote:
>>
>>
>>> Ana,
>>>
>>> I guess we don't understand what you are trying to simulate. You
>>>
>>>
>> have 2
>>
>>
>>> zones,
>>> one of which gets supply air. Just tell us what happens to this
>>>
>>>
>> air after it
>>
>>
>>> is supplied to the 1st zone. Don't explain it in terms of
>>>
>>>
>> EnergyPlus,
>>
>>
>>> just tell us
>>> what you actually want to happen. Are there any real exhaust fans,
>>>
>>>
>> or
>>
>>
>>> did they get
>>> introduced as an attempt to model the actual situation? Just
>>>
>>>
>> explain
>>
>>
>>> what the system
>>> is that you are attempting to model (maybe you did this already,
>>>
>>>
>> but
>>
>>
>>> please do it again).
>>>
>>> Fred Buhl
>>>
>>> anarui.oliveira wrote:
>>>
>>>
>>>> Thank you all for your previous answers, and please tolerate my
>>>> insistence...
>>>> I see your point about balancing airflows in the source zone,
>>>>
>>>>
>> and I
>>
>>
>>>> think I've got that covered.
>>>>
>>>> ...But, returning to a simple example of 2 zones:
>>>> - one conditioned (Zone 1), with forced supply air (which can be
>>>> modelled by E+ system and zone level objects)
>>>> - and another unconditioned (Zone 2), which:
>>>> - receives some airflow by depression from the conditioned
>>>>
>>>>
>> zone
>>
>>
>>>> (here I would use a Mixing object(source Zone 1, target Zone 2),
>>>>
>>>>
>> and
>>
>>
>>>> an exhaust fan in Zone 1 (a plain E+ Exhaust fan, no tricks),
>>>>
>>>>
>> just
>>
>>
>>>> to make sure that the source zone also feels the effect of
>>>>
>>>>
>> losing
>>
>>
>>>> that amount of conditioned air)
>>>> - but then in the unconditioned zone, the HVAC project says
>>>>
>>>>
>> there
>>
>>
>>>> will also be a regular, forced exhaust airflow (although there
>>>>
>>>>
>> is no
>>
>>
>>>> mechanical air supply directly to this zone), and it is this
>>>>
>>>>
>> part,
>>
>>
>>>> this exhaust... this balance at the unconditioned zone (which is
>>>>
>>>>
>> the
>>
>>
>>>> target zone for the mixing object), that I don't quite see how
>>>>
>>>>
>> to
>>
>>
>>>> implement...
>>>> - and should I care?... It's not very clear to me, but I
>>>>
>>>>
>> seems
>>
>>
>>>> that if I do force the exhaust of that amount of air, the
>>>> unconditioned zone will continuosly lose some its partially
>>>> conditioned air (energy), at the same time as it receives new
>>>>
>>>>
>> air
>>
>>
>>>> from the adjacent zone, while if I don't balance it, it seems it
>>>> continuosly accumulates warm air and only loses heat through the
>>>> envelope?...
>>>>
>>>> Sorry, I have the feeling I'm not making myself very clear,
>>>>
>>>>
>> but...
>>
>>
>>>> ... again, any additional hint would be greatly appreciated!
>>>>
>>>> Ana.
>>>>
>>>>
>>>> ------------------------------------
>>>>
>>>> The primary EnergyPlus web site is found at:
>>>> http://www.energyplus.gov
>>>>
>>>> The group web site is:
>>>> http://groups.yahoo.com/group/EnergyPlus_Support/
>>>>
>>>> Attachments are not allowed -- please post any files to the
>>>>
>>>>
>> appropriate folder in the Files area of the Support Web Site.
>>
>>
>>>> EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf
>>>>
>>>>
>> under the Documentation link and press the "search" button.
>>
>>
>>>> Yahoo! Groups Links
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>
>> ------------------------------------
>>
>> The primary EnergyPlus web site is found at:
>> http://www.energyplus.gov
>>
>> The group web site is:
>> http://groups.yahoo.com/group/EnergyPlus_Support/
>>
>> Attachments are not allowed -- please post any files to the appropriate folder in the Files area of the Support Web Site.
>>
>> EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
>> Yahoo! Groups Links
>>
>>
>>
>>
>>
>
>
> [Non-text portions of this message have been removed]
>
>
> ------------------------------------
>
> The primary EnergyPlus web site is found at:
> http://www.energyplus.gov
>
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
>
> Attachments are not allowed -- please post any files to the appropriate folder in the Files area of the Support Web Site.
>
> EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
> Yahoo! Groups Links
>
>
>
>
[Non-text portions of this message have been removed]
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