R718 turbo chillers and vacuum ice generation - Two applications of a new generation of high speed, high capacity R718 centrifugal compressors.

Some of the physical properties of water (especially the low vapour density and operation under sub atmospheric pressure) cause major challenges for the design and application of water as refrigerant in vapour compression chillers. On the other hand water is the only natural, non-toxic and non-flammable refrigerant that reaches an efficiency level comparable to other refrigerants used in chillers today. Since 1993 ILK has been working in the field of vapour compression refrigeration with “water as refrigerant, R718” for high capacity water chillers. During the past two decades significant advancement in scientific research and product development has been made. Based on the self-developed compressor technology the world’s first vapour compression chillers using R718 were introduced in 1999 by a German start-up company. Several installations have been completed until 2003. Some of them are still in operation today proofing the applicability of water as refrigerant in vapour compression chillers. In an attempt to reduce the investment cost of R718 technology a new compressor design was developed. So far this semi-hermetic compressor was deployed in an 800 kW chiller and a 50 kW vacuum ice generation and storage system. The design of both the chiller and the vacuum ice plant, experiences made during installation and operation as well as experimental results are discussed within this contribution.