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Re: [EnergyPlus_Support] Enquiry
1. It depends on whether the zones are all similar and also on what type of
system this is. For example, a dual duct system with fixed supply air
temperature setpoints will give nearly the same result for one large AHU
compared to multiple AHUs. But if it is a VAV system with supply air
temperature reset (warmest setpoint manager), it may be different depending on
the types of zones connected to it. If the zones are divided up so that one
AHU serve perimeter (exterior) zones and another AHU serves core (interior)
zones, then it would not be good to combine these AHUs in the simulation. But
if each AHU serves an entire floor, for example, including perimeter and core
zones, then combining the AHUs for multiple floors into one large AHU would be
reasonable.
2. If I remember correctly, the User Des Air Flow Rate includes the impacts of
the sizing factor, any user specified flow rates, and the outside air flow
requirement. To see which flow rate was actually used, see the flow rate
assigned to the air terminal unit for that zone.
3. That depends on your equipment design philosophy. Most engineers in North
America use an oversizing factor, or "safety factor", to allow for the
approximate nature of sizing calculations so that the actual equipment will be
adequate. 1.1 to 1.2 are not uncommon factors to use.
Mike
On 31 Oct 2005, at 14:07, eric_zhou1223 wrote:
> Hi£¬
>
> I am simulating an all-air system,in which actually there are multiple
> AHUs serving different zones, then here come my questions--- the first
> one: do I need to use several AHUs to meet loads as in real life, or,
> simply to use a single "conceptual" AHU to satisfy the whole building?
>
> The second one , what is the difference between "Des Air Flow Rate"
> and "User Des Air Flow Rate"? I used autosizing everwhere, without
> defining the flow rate at all.
>
> The last qustion is in which condition I would have to change the "zone
> sizing fator" from the default 1 to whatever. I read the document and
> was not sure of the implications.
>
> Thank you
> Eric YP Zhou
>
>
>
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> 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.idf and press the
> "search" button.
>
> Yahoo! Groups Links
>
>
>
>
>
>
>
>
========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support
EnergyPlus-Support@xxxxxxxx
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