A significant effort is being made to improve the fuel economy and environmental friendliness of maritime fleets. Most of the efforts have been placed on the diesel engines and lubricants used for propulsion and shipboard electrical generation needs. However, there are other key shipboard system that can make a significant contribution today, such as the integration of high-efficiency compressors.
These systems can reduce onboard chillers’ fuel consumption by better than 25 percent, increase cooling capacity by at least 50 percent, improve reliability by more than 50 percent, meet environmental objectives of reducing refrigerant leakage by 90 percent and eliminate hazardous oily waste.
As part of an American Recovery and Reinvestment Act program, the U.S. Navy spearheaded an initiative to integrate high-efficiency small and large capacity compressors to mate with existing shipboard R-134a refrigerant chiller heat exchangers shells to dramatically improve chiller capacity and performance. YORK® Navy Systems, a Johnson Controls Company, led the chiller prototype development program.
The chiller compressors were comprised of a variable speed, two-stage compressor with Calnetix Technologies’ Powerflux™ oil-free magnetic bearings and a Calnetix Magnaforce™ high-speed permanent magnet motor. The marine chiller systems are saving 1,000 barrels of oils per year per ship, all with no change in the system’s weight or seawater chiller capacity.
In addition, the Navy chilled water plants are providing mission-critical cooling to weapons as well as command and control systems in addition to crew comfort. As these chiller systems advance to include high-energy radars and directed energy weapons, the cooling demand along with acquisition, fuel and life cycle cost will increase dramatically.
The Navy chillers are very robust and have been designed to operate for 35-50 years in extreme environments, such as weapons-effect shock, ship heavy-weather vibration and Arctic as well as tropic conditions. The high-efficiency centrifugal compressors being built under the Navy’s initiative are able to work under these circumstances while also providing space, weight, power, cost and environmental benefits.
The marine chiller systems with variable speed motor capabilities and magnetic bearings are proving to be 200 percent more effective than the existing systems for the following reasons:
The ship compressor system successfully passed Navy MIL-STD-167 vibration and MIL-S-901D shock testing requirements in 2013. Production units underwent further testing in 2015. The first shipboard installation was completed in 2016 and multiple units continue to be installed annually.