High Efficiency Chiller Compressor for Ships Driven by a Permanent Magnet Motor on Magnetic Bearings via a Variable Speed Drive

Customer Specifications

Johnson Controls Navy Systems (JCNS), a supplier of heating, ventilation, air conditioning and refrigeration (HVAC/R) systems for use on all types of Navy vessels selected Calnetix Technologies to provide design and engineering assistance for the drive portion of its next generation, two-stage, variable speed, oil-free hermetically sealed centrifugal chillers. They needed a compact, highly efficient, low-maintenance and low-emission shipboard HVAC system to increase cooling capacity and performance while reducing acquisition and lifecycle costs. Improvements to mission critical cooling were required for newer/advanced weapons and command and control systems.


The HES-C Chiller was developed jointly by Calnetix and Johnson Controls Navy Systems. Calnetix supplied key components for the new-generation high-efficiency super capacity (HES-C) chiller system, consisting of the HES-C Chiller and the HES-C Vericycle™ variable speed drive. Calnetix provided Powerflux™ oil-free magnetic bearings, a Magnaforce™ sensorless high-speed permanent magnet motor, a magnetic bearing controller and a backup bearing system for the two-stage variable speed compressor at the heart of the system. Calnetix also provided the variable speed power module and controls for the HES-C variable frequency drive.


The HES-C chiller had to be subjected to a sequence of four different shock impacts generated by explosive charges from varying angles and standoff distances under the water. The centrifugal chiller successfully demonstrated operation during the three blasts and in standby mode for the fourth blast. The backup bearing system of the compressor absorbed the shock impacts, and the magnetic bearings recovered levitation as designed and the motor performed without any issue. The U.S. Navy’s production launch is an important validation of Calnetix’s patented magnetic bearing technology, permanent magnet motor expertise and power electronics technology.


The systems are projected to save 1,000 barrels of oils per year per ship, all with no change in the system’s weight or seawater chiller capacity. The compressor has also been designed as a retrofit option to improve the performance and energy usage of more than 200 chillers already in fleet use. The next generation HES-C Chillers are expected to:

  • Reduce fuel consumption by 25 percent and maintenance by at least 50 percent
  • Increase cooling density by 85 percent and reliability by at least 200 percent
  • Meet environmental objectives by cutting refrigerant leakage by 90 percent

The Secretary of the Navy (SECNAV) presented 2022 SECNAV Energy Award in the Technology Development & Acquisition category to Naval Surface Warfare Center, Philadelphia Division (NSWCPD) for the HES-C chiller. 

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U.S. Navy Ship
U.S. Navy Ship


U.S. Navy Floating Shock Platform (Photo courtesy of the U.S. Navy)
U.S. Navy Floating Shock Platform (Photo courtesy of the U.S. Navy)


High-efficiency compressor prototype
High-efficiency compressor prototype undergoes shock and vibration testing at NuLabs in Annandale, New Jersey. (Photos courtesy of the U.S. Navy, YORK® Navy Systems and NuLabs)


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