doi: 10.3850/978-981-08-7614-2_IMPRES083

ABSTRACT

The main freedom in designing absorption chillers lies in the choice of the working pair and in the principle of multistaging. 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, has lead us to consider a vastly expanded class of interesting liquids, known as Ionic Liquids (ILs). The authors succeeded in overcoming the mentioned drawbacks by customizing a new multifunctional working pair based on new, multifunctional Evonik Degussa ILs. Having screened the state of the art concerning the potential use of IL-absorbents in absorption cooling devices it becomes obvious that most of the requirements for using ILs are either not evaluated at all or not evaluated sufficiently. Therefore, this paper aims to highlight the most important IL-requirements and to present newest results on how the performance of absorption chillers can be substantially improved by using a new IL-based working pair.

Keywords: Ionic liquid, Absorption chiller, Heat pump, Lithium bromide, Working pair.

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