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Ionic liquids: new high-performance working fluids for absorption chillers and heat pumps.



The main freedom in designing absorption chillers lies in the principle of multistaging and, connected to this, in the choice of the working pair. Although many innovative working pairs have been suggested over the last decades, only two meet the prevailing industrial requirements: H2O/LiBr for water chillers and NH3/H2O for refrigeration. However, these state of the art working pairs show a number of drawbacks, including corrosiveness, a restricted temperature lift due to crystallization (H2O/LiBr), toxicity, high working pressure and the need for rectification (NH3/H2O). A thorough search for improved chiller absorbents, e.g. for the replacement of LiBr, suggests to consider a vastly expanded class of interesting liquids, known as ionic liquids (ILs). The mentioned drawbacks can be overcome by customizing a working pair based on ionic liquids which have been produced by Evonik Degussa. Having screened the state-of-the-art concerning the potential use of IL-absorbents in absorption cooling devices, it became obvious that most of the requirements for using ILs are either not evaluated at all or not evaluated sufficiently. Furthermore, heat and mass transfer for the different apparatus and the whole process dynamic is not known yet. Therefore, this paper aims to highlight the most important IL-requirements. At TU Berlin a small scale absorption chiller with glass shell has been built to investigate heat and mass transfer characteristics and operational behaviour of promising Evonik Degussa ILs as absorbents. Test results are shown and discussed.

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Pages: 95-106


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  • Original title: Ionic liquids: new high-performance working fluids for absorption chillers and heat pumps.
  • Record ID : 30001182
  • Languages: English
  • Source: Sources/sinks Alternative to the Outside Air for Heat Pump and Air-conditioning Techniques (Alternative Sources - AS), Padua, Italy, April 5-7, 2011. / International Sorption Heat Pump Conference (ISHPC11), Padua, Italy, April 6-8, 2011.
  • Publication date: 2011/04/06


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