[Equest-users] CHW Pump differential temperature

[Aulbach, John]

All:
 
I have run a Base Case and a Parametric run for a Central Plant serving an office complex. Everything in both runs is the same, EXCEPT that the Base run has a 10°F differential temperature and the Parametric run has a 15°F differential temperature. The CHW pump is variable speed.
 
As expected, electric energy is saved (about 40,000 kWh/year for a 600 ton plant).  However, about 15,000 kWh is saved at the Chilled Water pump, and 22,000 kWh is saved at the chiller.
 
I changed the Loop Design DT to 15°F and the CHW Coil Design Delta T to 15°F.
 
Why is my chiller energy reducing?
 
Thanks.
 
John R. Aulbach, PE, CEM
Project Manager
Nexant, Inc.
701 West Kimberly Ave., Suite 245
Placentia, CA 92870-6342 USA
Phone: 714-524-4402
Fax: 714-524-4407
email: jaulbach at nexant.com
 
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