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Re: [EnergyPlus_Support] Pumps: riding the curve



Thanks Jim,

It was a great help! I am looking for a similar kind of document for Chiller performance curve generation. Could you please help on this.

Thanks in Advance!

On Thu, Nov 17, 2011 at 12:47 AM, Jim Dirkes <jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
 

Dear Camilo,

You will need to model the pump as though it is a variable speed pump, and use a power vs flow curve similar to what I develop in the attached file.  Although it is actually a constant speed pump, it is not constant flow or constant power.  Therefore, E+ must treat it as variable speed.  The power curve results in calculation of the appropriate power for flow variations.

The curve object is as shown below.

 

 

Curve:Quadratic

Name

Curve_PumpPower1,

Coeff1 Constant

0,

Coeff2 x

1.339155,

Coeff3 x**2

-0.330745,

minimum value of x

0,

maximum value of x

1;

Minimum Curve Output

Maximum Curve Output

 

The Building Performance Team
James V. Dirkes II, P.E., BEMP , LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653

 

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of caveleza
Sent: Wednesday, November 16, 2011 1:02 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Pumps: riding the curve

 

 

Hello Everybody!

I'm modeling a building following ASHRAE 90.1 Appdx G, but i have a problem regarding primary/secondary pumps loop...

According to appendix G (G3.1.3.10):

"Chilled water
pumps in systems with less than 300 tons
cooling capacity shall be modeled as
primary/secondary systems with
secondary pump riding the pump curve."

I know that the secondary pump (in this case) must be a constant speed pump (just like the primary), but as they want that it "rides the curve" the loop should have an arrangement of two-way or a three-way valves, but i'm not sure of this or how to do it in energyplus. Anyone has the same problem?? Any help will be appreciated!!

Thanks!

Camilo.




--


Javed Iqbal, LEED AP, CEA
Energy Analyst   




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