24 June 2014

HIGH TEMPERATURE MAGNETIC BEARING CENTRIFUGAL HEAT PUMP


There is great interest for high temperature industrial heat pumps. But the offer of such machines is still limited. Potential users also fear that thermodynamic machines may be
complicated and unreliable. To address this concern, Johnson Controls developed a new generation of centrifugal heat pumps using refrigerant R-245fa with magnetic bearing centrifugal compressors. This technology offers superior efficiency and outstanding reliability. YORK – Johnson Controls introduced it in 1998 for nuclear submarines, where reliability and availability are highly critical. Over 100 such chillers were sold to various navies. In 2011, Johnson Controls launched a range of standard chillers called “YMC²” (York Magnetic
Centrifugal Chillers) using this technology. Over 500 of these machines have been built. Heat
pumps per this article are derived from these chillers. These oil free units avoid the issues of miscibility of refrigerant in oil at high temperature. This makes magnetic bearings an ideal choice for high temperature heat pumps. Their heating capacity ranges from 600 to 2000 kW. The machine is currently available for 95°C leaving water temperature; tests are ongoing to
reach 120°C.