Development of Oil-Free Turbo-Chillers Equipped With Magnetically-Levitated Compressors

The chiller market has increasingly adopted oil-free technology due to the ease of maintenance and the use of variable-speed direct drive. Oil-free bearings also eliminate the possibility of contaminating refrigerant with lubricating oil, resulting in the prolonged use of refrigerant and avoiding performance degradation. In this paper, the development of oilfree chillers which have been recently introduced in the market is described. The centrifugal compressor of the chiller is equipped with active magnetic bearings: two radial bearings and one thrust bearing. We present some results of performance validation tests.