Re: [EnergyPlus_Support] Re: Adding more chillers doesn't reduce the autosized value

Hisham,

Interesting (and thoughtful) analysis! I do not think, however, that the Sizing Factor for the chilled water loop affects the condenser water loop (or vice versa). That means you should apply 0.5 to both Chiller and Cooling tower.

I recommend that you continue using the output reports to confirm that E+ is doing as you expect.

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of hisham.rashrash
Sent: Thursday, October 17, 2013 9:40 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Re: Adding more chillers doesn't reduce the autosized value

Thanks for the reply, and I am sorry for I couldn't reply earlier.
What I understood from the experiment I did is that the sizing factor of chiller object affects the chiller's size, the primary chilled water pump size, the tower fan size and the condenser water pump size. On the other hand, the tower's sizing factor affects the tower's fan size and the condenser water pump size. So applying a sizing factor of 0.5 for both chillers along with applying a sizing factor of 0.5 for both towers will result in multiplying the two types of sizing factors 0.5x0.5=0.25 (25% in my before previous reply) for the towers' fans and the condenser water pumps.
So, I need a confirmation whether setting a sizing factor of 0.5 for both chillers and leaving the sizing factor to 1 for both towers is the correct way to model water cooled chillers as per "ASHRAE 90.1-2007 section G3.1.3.7 Type and Number of Chillers (Systems 7 and 8)" as I described in my earlier post and replies under this title.

Thank you very much.

Hisham

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Jim Dirkes <jim@...> wrote:
>
> Hisham,
> I would apply the same Sizing Factor to all Plant components Ã¢?" chiller, towers, pumps Ã¢?" as as long as they are all together serving the same load.
> Keep in mind that the sizing factor is concerned about CAPACITY, not power. Nonetheless I would expect power to normally be almost proportional to capacity. From your description I do not understand what you are seeing , but you may need to report part load factors, flow or other variables to understand why the power is not proportional.
>
>
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of hisham.rashrash
> Sent: Sunday, October 13, 2013 2:41 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Re: Adding more chillers doesn't reduce the autosized value
>
>
>
> Dear all,
> Kindly, advise regarding the chillers and towers sizing factors mentioned in my previous reply.
>
> Best regards,
> Hisham
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx>, "hisham.rashrash" <hisham.rashrash@<mailto:hisham.rashrash@>> wrote:
> >
> > Dear James,
> > What about the cooling towers sizing factor? should it be set to 0.5 too? or just for the chillers? because after setting chillers sizing to 0.5 and towers sizing to 0.5 too, I have the towers fans power (at high speed mode) and the condensers pumps powers reduced to only 25% of the previous power before putting 0.5 sizing factor to both chillers and both towers and having all set to 1 (chillers and towers).
> > Please advise. Thank you very much.
> >
> > Best regards,
> > Hisham
> >
> > --- In EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx>, Jim Dirkes <jim@> wrote:
> > >
> > > ..or 1.25 in Sizing:Parameters which applies to all zone sizing (plus 0.5 in the object Sizing Factor
> > >
> > > James V Dirkes II, PE, BEMP, LEED AP
> > > www.buildingperformanceteam.com<http://www.buildingperformanceteam.com/<http://www.buildingperformanceteam.com%3chttp:/www.buildingperformanceteam.com/>>
> > > Energy Analysis, Commissioning & Training Services
> > > 1631 Acacia Drive, Grand Rapids, MI 49504 USA
> > > 616 450 8653
> > >
> > > From: EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of fpasserini.tn@<mailto:fpasserini.tn@>
> > > Sent: Friday, October 11, 2013 6:32 AM
> > > To: EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx>
> > > Subject: [EnergyPlus_Support] RE: Adding more chillers doesn't reduce the autosized value
> > >
> > >
> > >
> > > If I model a baseline model according to ASHRAE 90.1-2007 and two boilers are connected in parallel (e.g. in System 5) shall I use 1.25 as "zone heating sizing factor" in the object Sizing:Zone and 0.5 in "Sizing Factor" in the object Boiler:HotWater?
> > >
> > > Best Regards
> > >
> > >
> > > ---In energyplus_support@xxxxxxxxxxxxxxx<mailto:energyplus_support@xxxxxxxxxxxxxxx<mailto:energyplus_support@xxxxxxxxxxxxxxx%3cmailto:energyplus_support@xxxxxxxxxxxxxxx>>, <jim@<mailto:jim@>> wrote:
> > >
> > > Dear Hisham,
> > >
> > > An autosizing value always represent the entire load serve by the autosized component. When there is more than one component (e.g., chillers) on a single loop, EACH component is assigned 100% of the autosize value. Not very intuitive, but thatÃ?Â¢Ã¢?Â¬Ã¢?Â¢s how it works in En E+.
> > >
> > > If you want each chiller to have 50% of the autosized value, assign 0.50 to the Ã?Â¢Ã¢?ÂÂ¬Ã?"Sizing FactorÃ?Â¢Ã¢?Â¬Ã?Â?.
&ggt; > >
> > >
> > >
> > > James V Dirkes II, PE, BEMP, LEED AP
> > > www.buildingperformanceteam.com<http://www.buildingperformanceteam.com/<http://www.buildingperformanceteam.com%3chttp:/www.buildingperformanceteam.com/>>
> > > Energy Analysis, Commissioning & Training Services
> > > 1631 Acacia Drive, Grand Rapids, MI 49504 USA
> > > 616 450 8653
> > >
> > >
> > >
> > > From: EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx%3cmailto:EnergyPlus_Support@xxxxxxxxxxxxxxx>> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of hisham.rashrash
> > > Sent: Thursday, October 10, 2013 6:50 AM
> > > To: EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx%3cmailto:EnergyPlus_Support@xxxxxxxxxxxxxxx>>
> > > Subject: [EnergyPlus_Support] Adding more chillers doesn't reduce the autosized value
> > >
> > >
> > >
> > >
> > >
> > > Dear all,
> > > I am modeling baseline for some project, and I am trying to follow ASHRAE's 90.1-2007 section G3.1.3.7 "Type and Number of Chillers (Systems 7 & 8)" by adding more chillers until no chiller's size is above 2813[kW] (refer to table G3.1.37). The problem is no matter how many chillers I add, this doesn't reduce the autosized value! it is always the same=4258257.73[W] for all chillers, while I expected to have this value divided on chiller's number I add, for example, for one chiller it was autosized to 4258257.73[W], for two chillers I expected it to be 4258257.73[W]/2=2129128.865[W], while it was autosized to 4258257.73[W] for each chiller!
> > > Please advise.
> > >
> > > Thank you very much,
> > > Hisham.
> > >
> >
>

Reply via web post