6-6
October 2012
Savings Potential
Single-pass cooling can be eliminated by retrofitting the existing equipment with a
recirculating system or replacing with air-cooled equipment.
Potential savings can be estimated by measuring the existing cooling water dis-
charge with a gallon bucket and stopwatch and determining how often the cooling
water flows (e.g., how many hours per day and days per year). Many applications of
single-pass cooling water flow continuously. To estimate facility-specific water sav-
ings and payback, use the following information.
Current Water Use
To estimate the current water use of existing equipment cooled with single-pass
water, identify the following information and use Equation 6-1:
••
Flow rate of the discharge water from the equipment cooled with single-pass
water.
••
Average daily use time. This will vary by facility and the type of equipment
cooled with single-pass water.
••
Days of facility operation per year.
Equation 6-1. Single-Pass Cooling Equipment Water Use (gallons per year)
= Single-Pass Cooling Equipment Flow Rate x Daily Use Time x Days of
Facility Operation
Where:
••
Single-Pass Cooling Equipment Flow Rate (gallons per minute)
••
Daily Use Time (minutes per day)
••
Days of Facility Operation (days per year)
Water Savings
Replacing existing equipment cooled with single-pass water with an air-cooled
system or retrofitting with a recirculating cooling water system will entirely eliminate
discharge water use, as shown in Equation 6-2.
6.2
Single-Pass Cooling
