The Naval Air Station (NAS) on Whidbey Island believes that national defense and environmental protection must be compatible goals. Their recent effort to develop and execute a targeted plan for upgrading the chilled water system serving their critical Naval Facilities Engineering Command (NAVFAC) facility is another great example of the commitment the NAS has for environmental stewardship and continual improvement.
The NAS, in combination with Bonneville Power Administration and Puget Sound Energy, teamed up with University Mechanical Contractors, Inc. (UMC) to complete an energy-based full variable flow retrofit of the chilled water system serving the Fleet Readiness Center (FRC). This building is a highly secure mission-critical facility for the Navy with an acute need for 24 hour cooling of high-tech equipment. Given the continuous load, it is imperative that the system operate efficiently and without interruption.
The first step in the turn-key energy upgrade of the chilled water system required a custom retrofit of two existing 140-ton chillers with highly efficient Danfoss Turbocor compressors. UMC performed the retrofit and mounted the new compressors in place of the existing screw compressors. During the work, UMC found the original chiller’s evaporator and condenser bundles to be in excellent shape. UMC proposed to simply clean up the evaporator and condenser bundles and retain them for re-use with the newly retrofitted chiller compressors. This ultimately reduced the implementation cost and provided a key sustainable element to the project.
Completing the conversion of the FRC chilled water system to full variable primary flow required upgrades to all chilled water and condenser water pumps as well as new cooling towers. All pump motors and fans now operate with variable frequency drives controlled by a newly installed chiller plant energy control system (CPECS). Kiltech provided the CPECS, which monitors the operating characteristics of the chiller plant and utilizes continual data feedback loops and advanced control algorithms to process chiller plant data in real time. CPECS is essentially the brains of the operating system; it analyzes the load profiles of the building, climate data, and equipment performance models to implement precise load based matching. This ensures the maximum level of system performance while respecting chiller, tower and building flow as well as temperature limits.
With the optimization project complete, the plant now operates at a highly efficient kW/Ton over the full range of operating loads. With an annualized plant operating efficiency of less than 0.7 kW/Ton (including chillers, pumps & cooling tower fans), this facility will function in the top 5% of current chiller plants. This results in an overall energy savings of 50% when compared to the baseline operation prior to the upgrades. When combined with the resulting reduction in ongoing maintenance requirements and the improved reliability, this project has been a great success for NAS Whidbey.
Chiller Plant Upgrade Summary
- Turn-key re-design & retrofit of existing chiller plant to operate as a full variable flow plant
- Custom retrofit of two existing chillers with new Danfoss Turbocor magnetic drive compressors
- Converted all chilled water and condenser water pumping systems to variable flow; including the installation of new VFDs
- Installed new cooling towers with variable frequency drives for all tower fans
- Installed a new Chiller Plant Energy Control System (CPECS) to incorporate all system equipment and efficiently manage ongoing plant operation and energy usage
- Chiller plant energy savings of over 50%
- Combined utility incentives of over $100,000
- Significant reduction in ongoing maintenance costs
- Improved system reliability and CHW productivity
- Reduction in plant noise issues
- Ongoing monitoring & tracking of system operating efficiency