Continuous Monitoring and Partial Water Softening for Cooling Tower Water Treatment

Gregg Tomberlin, Jesse Dean, Michael Deru

Research output: NRELTechnical Report


Cooling towers are an integral component of many refrigeration systems, providing comfort or process cooling across a broad range of applications. They are the point in the system where heat is dissipated to the atmosphere through the evaporative cooling process. Cooling towers are commonly found in industrial applications and are also often applied to water-cooled chilled water plants in medium to large commercial buildings. Cooling towers used in medium to large commercial buildings are the focus of this paper. While there are many vendors of AWT systems, this project assesses the effectiveness of one technology provided by Aqualogix. This system is a chilled water plant monitoring and control system optimizing system performance by reducing the blowdown occurrences used to remove mineral build-up. The technology consists of two components – continuous programmable logic control (PLC) monitoring and side-stream filtration with partial water softening. PLC monitoring calculates cycles of concentration and determines the optimum amount of blowdown water required to satisfy all water chemistry limits. Side-stream filtration removes suspended matter and improves biocide efficacy while precisely dispensing softened water to achieve optimal makeup water hardness. Unlike other AWT systems evaluated by GSA to date, this system does not replace the legacy treatment system but is used in addition to chemical water treatment. The vendor claims their technology will reduce water consumption, water discharge, and maintenance costs. This project assesses the effectiveness of this technology at lowering GSA’s operating costs and reducing cooling tower blowdown while maintaining proper water treatment. The GPG program selected the Lloyd D. George Courthouse, located in Las Vegas, NV, as the test bed for evaluating the Continuous Monitoring and Side Stream Filtration for Cooling Towers technology provide by Aqualogix. The AWT system consists of a PLC controller and side stream filtration system that are mounted on a skid is approximately 91 inches tall, 40 inches long and 40 inches wide.
Original languageAmerican English
Number of pages43
StatePublished - 2020

NREL Publication Number

  • NREL/TP-7A40-76756


  • cooling tower
  • GSA
  • water treatment


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