[Bldg-sim] water-econo condenser flow

[Dahlstrom, Aaron]

Anyone understand how condenser flow gets assigned for the FREE-COOLING chiller type?

Is the operating head of the FREECOOLING chiller over-ridden to force the flow rate and delta-T to match the chilled flow rate and delta T?

My building has 3200 gpm condenser water pumps with 10 deg F delta T, approx. 1200 tons rejection during normal operation. (2000 gpm chilled water pumps at 15 deg F delta T.)

One of these CW pump is used to provide water for free cooling via a shell-and-tube HX at a reduced delta T (6.25) at the same rough gpm (3200). The chiller is smaller than the main building chillers. (800 tons - chilled water side is designed for lower delta T 10 deg F at same flow rate 200 gpm in this case.)

However, no matter my inputs, the hourly flow on the condenser side is 2000 gpm, which exactly matches the flow rate and delta T of the chilled water side.

I would expect my specified constant-speed pump to operate at the operating point given by the component pressure drops to yield the design flow rate. However, the head on the condenser side appears over-ridden high to decrease flow to match the chiller side.

Any experience or ideas here?

Thanks,

Aaron Dahlstrom , PE, LEED(r) AP
In Posse - A subsidiary of AKF| 1500 Walnut Street, Suite 1414, Philadelphia, PA 19102
d: 215-282-6753| m: 267-507-5470| In Posse: 215-282-6800| AKF: 215-735-7290
e: ADahlstrom at in-posse.com | in posse web: www.in-posse.com<http://www.in-posse.com/> | akf web: www.akfgroup.com<http://www.akfgroup.com/>





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