Re: [EnergyPlus_Support] Chiller Coefficients.

["Michael J. Witte" <mjwitte@xxxxxxxx>]

To detemine the coefficients, you will need a table of data from the chiller 
manufacturer which gives chiller capacity and efficiency (or power input) for a 
range of leaving chilled water temperatures and entering condenser water 
temperatures.

The "rated" temperatures are the nominal conditions for the chiller.  These are 
fixed for any given chiller.  The "required" temperatures are the alternate 
temperatures provided in the catalog data.  The catalog data is used to 
calculate the coefficients.  Then during the course of the simulation, the 
"required" temperatures are determined by the simulation and controls and the 
model then calculates the resulting acutal capacity and power consumption.

Mike


On 13 Oct 2005, at 14:03, Shantanu P wrote:

> Hi,
> 
> I am trying to simulate a large office building with central chiller plant. This
> is the first time I am using EnergyPlus, and I am having doubts on how to obtain
> coefficients for chiller model. I read the Engineering documentation and I/O
> reference, but still not clear to me.
> 
> It is mentioned in the I/O ref that:
> 
> 1) Temp Rise coeff = (TCEnt,required -TCEnt,rated)/(TELv,req- TELv,rated)
> 
> One question I have is how is the require value and the rated value 
> differtent, since both are supposed to have rated capacity. A change in 
> TCEnt,Req will change the TElv,Req also to obtain the same capacity. However how
> do we know the relationship between TCEnt,Req and TElV,Req for the entire range
> of operation. Am I missing some thing here?
> 
> 2) Similarly for the coefficients in the capacity ratio curve, the 
> definition of delta T also raises a simlar doubt. How do we know the 
> TCond,in and TEvap,out for a simulation. Doesn't these values change over 
> the entire simulation?
> 
> It would be very helpful if any one could point if I am moving in a wrong 
> direction.
> 
> Shantanu
> 
> Thanks
> 
> 
> 
> 
> 
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> 
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> 
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> 
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> "search" button.
> 
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> 
> 
> 
> 
> 
> 
> 
> 
> 
> 



========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx




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