[EnergyPlus_Support] Re: Question about the initial load when turn on the chiller

[Rongxin Yin <rongxinyin@xxxxxxxxx>]

Hi JV,

Yes, it is really a difficult thing to calibrate the hourly energy consumption of the simulated model. and ususally we just did the comparison between the model and real data in Monthly. Now i have the breakdown energy consumption of some real buildings and do the calibration research. Some simulated results are really close to the actual energy usage (a plus/minus 5% agreement between real and predicted energy Monthly), but some are not good. 

As to what Richard says, I would check the model to find out what happen. Thanks a lot!

Rongxin


----- Original Message ----
From: JV Dirkes II <jvd2pe@xxxxxxx>
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Sent: Tuesday, April 15, 2008 12:44:41 PM
Subject: [EnergyPlus_Support] Re: Question about the initial load when turn on the chiller

Dear Rongxin Yin,

Everything Richard says below is correct. 

In addition, I suggest that it is not reasonable to attempt to match
actual energy usage with Energy Plus predicted usage on such a small
time increment.

There are too many variables which affect a real HVAC system that are
not possible to account for in a computer model. If I got a plus /
minus 10% agreement between real and predicted energy MONTHLY, I would
be VERY happy!

--- In EnergyPlus_Support@ yahoogroups. com, Richard Raustad
<RRaustad@.. .> wrote:
>
> For the first hour of operation:
> 
> 1) does the chiller part-load ratio match for the real vs tested data?
> 2) does the return water temperature match for the real vs tested data?
> 3) does the outdoor temperature match for the real vs tested data?
> 4) does changing the loop volume change these results?
> 
> Rongxin Yin wrote:
> >
> > Hi All,
> >
> > Resently i did some calibration to get the baseline model by means of 
> > comparing the real tested data to the simulated output results.
then i 
> > found the simulated electrical consumption of the chiller was much 
> > higher than the real tested data at the beginning of the operation 
> > hours. and about one hour later, the load profile would be normal as 
> > the real data. So i am not sure whether this result is ok or not.
Does 
> > anyone meet the same question?
> >
> > Thanks,
> > Rongxin
> >
> > ____________ _________ _________ _________ _________ _________ _
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> 
> -- 
> Richard A. Raustad
> Senior Research Engineer
> Florida Solar Energy Center
> University of Central Florida
> 1679 Clearlake Road
> Cocoa, FL 32922-5703
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>


 


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