Modeling Chiller Efficiency

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To eQuest users,

Only EIR is required for the chiller efficiency input.
This can be converted easily to COP from which most of the manufacturers specify this on their cut sheets/catalogues to get the EIR.
Questions are:

1. What is this COP/EIR input in eQuest?
??? Is this for Full Load or Partial Load?

2. Does anybody know how to convert the ASHRAE Chiller's ARI Condition listed in ASHRAE 90.1 to our weather condition here in Dubai?
Or is there a formula in converting the ARI Condition to the local weather where the project will be built?

Any related help from their own experience will be helpful.
Thanks in advance


reniel barroso's picture
Joined: 2011-09-30
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The EIR input?is at full load.

To answer your other question, here is the text from the Online DOE-2 Help menu in eQuest, which speaks so much better than I:

Rated vs. Design Conditions
The program allows chillers to be specified at either the:
???? Rated conditions ? as specified by ARI or other rating organizations. For all chiller types, ARI rates the evaporator conditions as 54?F entering and 44?F leaving chilled water (which corresponds to 2.4 gpm/ton).? For water-cooled chillers, the condenser conditions are 85?F entering condenser water at a flow of 3 gpm/ton.? Air-cooled chillers are rated at 95?F entering outdoor drybulb temperature.? Chillers with remote condensers, are rated at 125?F saturated-condensing temperature.
???? Design conditions ? the actual conditions at which the chiller is sized and designed to operate.
When specifying a chiller, it is important to distinguish whether the stated chiller performance (capacity and energy consumption) are defined at the rated or actual conditions. Most chiller types can be specified at either the ARI rated conditions, or the actual design conditions.? However, for centrifugal chillers, it may not make sense to specify performance at the ARI rated conditions, as the chiller may not be able to actually operate at those conditions.
For example, consider a water-cooled centrifugal chiller serving a building in a relatively cool, dry climate. The engineer specifies the chiller capacity and efficiency at 46?F leaving chilled water and 76?F entering condenser water.? To achieve the specified efficiency at minimum cost, assume the chiller manufacturer configures the the impeller and heat-exchangers to exactly meet the design conditions.? If this chiller is then operated at the more extreme ARI conditions of 44?F/85?F, the compressor may not be able to overcome the pressure differential between the evaporator and condenser, and the chiller will surge if it tries to deliver water at 44?F. To operate successfully at 85?F entering condenser water, it will have to deliver water warmer than 44?F.
For this reason, the program defaults assume that centrifugal chillers are specified at the design conditions. All other chiller types are assumed to be specified at the rated conditions, unless you specify otherwise.
So I THINK if you specify ARI conditions and ran the chiller in your climatic condition, it would be a correct simulation.
Others input please...
John R. Aulbach, PE, CEM

John Aulbach's picture
Joined: 2011-09-30
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