[BLDG-SIM] Major disagreement on Chiller Performance Curves in DOE-2.1E and DOE-2.2

["Mike Tillou" <miket@xxxxxxxxxx>]

Title: Message

John, I think the answer to your question has two parts:

 

1. DOE uses two curves for modifying the full load EIR (1/COP) of a constant speed chiller.  The first adjusts for part load and the second for temperature. 

 

I use a curve with fixed CHWT and CWT at various part load conditions (at design conditions not ARI rated conditions) for the EIR f(PLR) curve (the one you're asking about) and create a second curve based on various combinations of CHWT, CWT at full load for the EIR f(LCHWT, ECWT) curve.  The assumption, I think, is that the PLR curve reamins relatively uniform as the water temperatures change so once you have the shape of the PLR curve you can account for temperature differences with a second curve.

 

 

2. The above methodology works fine for constant speed chillers but needs to be modified for variable speed chillers.  Rather than using EIR F(PLR) you need to use EIR f(PLR,dT).  This curve now accounts for the change in the difference of the water temperature across the chiller.  See Volume 6 of the DOE 2.2 v41 reference manual available at www.DOE2.com, there is a section on chiller performance that explains this much better than I could do.  DOE 2.2 v41 incorporates this change and has default curves for both.

 

It sounds like you both may be correct depending on the type of chiller you want to model.

 

Mike Tillou, PE

etc Group, Inc

413-664-9070

 

 

-----Original Message-----
From: postman@xxxxxxxx [mailto:postman@xxxxxxxx] On Behalf Of Aulbach, John
Sent: Wednesday, October 15, 2003 2:23 PM
To: BLDG-SIM@xxxxxxxx
Subject: [BLDG-SIM] Major disagreement on Chiller Performance Curves in DOE-2.1E and DOE-2.2

I am having a "friendly" disagreement with a colleague on what chiller curves to ask for from a manufacturer to input into DOE-2 (could be either 2.1E or 2.2). We both agree that the infamous ARI point for a 100% load should be input. But the curves are where we disagree.

Is the Default DOE-2 curve for % Power versus % Tons the ARI curve with the allowable reduction in condenser water temperature, or is it based on the FIXED 85°F entering condenser water and FIXED 44°F leaving chilled water ALL the way down the curve?

Therefore, when I am given a chiller with a variable speed drive installed, what parameters should I ask for in such a Power/Tons to be FIXED ???

John R. Aulbach, PE, CEM
Project Engineer
Sempra Energy Solutions
555 West Fifth Street
Mail Location 27F3
Los Angeles, CA 90013
Tel: (213) 244-8551 Cell (213) 219-4875
 

"Sempra Energy Solutions is not the same company as SDG&E/ SoCalGas, the Utilities.  Sempra Energy Solutions is not regulated by the California Public Utilities Commission, and you do not have to buy Sempra Energy Solutions products or services to continue to receive quality regulated service from the Utilities." 

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